bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Analysis of Titanium Based Metal Organic Frameworks for Photocatalysis
Authors: Kurowski John , Pearce Emily , Kissel Daniel
Published: February 2024

Metal-Organic Frameworks (MOFs) are porous inorganic networks that have recently shown potential in energy applications as photocatalysts. The porosity of MOFs make them excellent for guest-host interactions, however, most MOFs are slightly insulating due to metal oxide nodes, resulting in larger band gaps and poor conductivity. In order to combat these issues, post-synthetic modifications (PSM) can be used to slightly alter MOF properties. In this study, PSM’s were introduced to Titanium-based MOFs with MIL topology, such as MIL-125 and MIL-125-NH2, to improve their ability to photocatalytically degrade organic dyes through the addition of polyaniline nanofibers and additional metal interactions. The performance of these modified MOFs were tested and compared to the unmodified MOFs. In addition, titanium-based MOFs, were investigated because their nodes that are more semiconducting than other MOF types. Each MOF was characterized using BET surface area analysis, infrared spectroscopy, and powder X-ray diffraction. The conductivity of different MOFs were compared using cyclic voltammetry. The relative photocatalytic properties of each MOF was determined by monitoring their efficiency for photocatalytic degradation of rhodamine B and phenol red dyes in solution under controlled environments.
Photo-Generated Charge Carrier Dynamics in Metal Oxide Photocatalysts
Authors: Tachibana Yasuhiro
Published: February 2024

Solar water splitting is one of the most attractive energy carrier generation processes to utilize solar energy. Light generated hydrogen is a clean energy carrier, since their consumption for energy generation produces only water. Moreover, generated hydrogen can be stored and used whenever required. Hydrogen is mostly used as a feedstock in the chemical and petrochemical industries, e.g. production of ammonia, methanol and fertilisers.[1]

The photocatalytic solar water splitting process has been studied extensively over the last half century. However, despite the efforts, no ideal photocatalyst has yet been identified to meet three main requirements for commercialisation: (1) low cost, (2) high solar to hydrogen (STH) efficiency and (3) durability. Over the last two decades, considerable efforts have focused on developing visible light active photocatalysts, and some promising photocatalysts with relatively high water splitting efficiency were discovered.[2] In contrast to search of appropriate photocatalyst (nano)materials, mechanisms of photocatalytic water splitting reactions, in particular charge carrier dynamics of photocatalysts, were little studied. Understanding charge carrier dynamics in photocatalysts will certainly provide an opportunity to design high efficiency photocatalysts.

In this presentation, we will show dynamics of photo-generated charge carries in metal oxide photocatalyst by employing a series of transient absorption spectroscopies covering from 150 fs to 100 s over UV-VIS-NIR wavelength ranges.[2] Correlation of the charge carrier dynamics with photocatalysis reactions will be discussed.

This work was partly supported by ARC DP fund (DP180103815) and ARC LIEF funds (LE170100235 and LE200100051), Australia, and the Collaborative Research Program of Institute for Chemical Research, Kyoto University (grant number 2023-45 and 2022-99), Japan. We also acknowledge supports from School of Engineering, RMIT University, and Forefront Research Center, Faculty of Science, Osaka University.

References

[1] N. Armaroli and V. Balzani, ChemSusChem
4 (2011) 21-36.

[2] H. Mai, D. Chen, Y. Tachibana, H. Suzuki, R. Abe, Rachel A. Caruso, Chem. Soc. Rev., 50(24) 13692-13729 (2021).

[3] H. Liu, M. Liu, R. Nakamura, Y. Tachibana, Appl. Catal. B-Environ., 296 (2021) 120226.
(Invited) Mulitjunction III-V Semiconductors for Photo-Electrochemical Hydrogen Production: Recent Progress in Efficiency, Durability, and Cost
Authors: Deutsch Todd G , Wyatt Keenan , Steiner Myles A. , Young James L.
Published: February 2024

Photo-electrochemical (PEC) hydrogen production is a route to carbon-free fuel that combines light absorption and water electrolysis into one device. Challenging targets for solar-to-hydrogen (STH) efficiency, durability, and semiconductor absorber costs must be realized for this approach to be economically competitive with other hydrogen production pathways. Research on PEC hydrogen production at the National Renewable Energy Laboratory (NREL) has focused on III-V semiconductor absorber materials because their tunable bandgaps, high photon conversion efficiencies, and ability to make multi-junction structures have resulted in the highest STH efficiencies yet demonstrated.

This talk will focus on recent NREL results showing progress toward PEC hydrogen production efficiency, durability, and cost targets. Specifically, we have been able to improve theoretically achievable STH efficiency through bandgap engineering in multijunction devices. Photon management strategies to close the gap between theoretical and measured STH efficiency will also be discussed. Durability remains a significant challenge for III-V materials in a PEC environment. We will describe modifications to the semiconductor surface and the electrolyte constitution that can make the photoabsorber less susceptible to photocorrosion during operation. Finally, we will present preliminary results on III-V PEC materials synthesized via hydride vapor phase epitaxy, an alternative route to high-efficiency photoelectrodes that could potentially have much lower costs than the metalorganic vapor phase epitaxy method traditionally used. These improvements have yielded III-V PEC devices that are close to the STH efficiency target (17% vs. 25%) while the demonstrated durability and cost are still considerably far from their target values.
Solar Hydrogen Production and Biomass Reforming Using Earth-Abundant Non-Toxic Si-Based Photocatalysts
Authors: Ryu Jungki
Published: February 2024

The efficient production of electrochemical hydrogen and biomass refinement is crucial for the decarbonization of various industries. However, their low efficiency and high energy requirements make them impractical. In this talk, we propose using earth-abundant and non-toxic photocatalysts that can produce hydrogen and reform biomass efficiently by utilizing solar energy. Our approach involves using low bandgap Si flakes (SiF) for efficient light absorption. SiF was further modified with Ni-coordinated N-doped graphene quantum dots (Ni-NGQDs) to enable stable light-driven biomass reforming and hydrogen production. SiF/Ni-NQGDs enabled a record hydrogen productivity and concurrent vanillin production when using kraft lignin as model biomass under simulated sunlight without any buffering agent or sacrificial electron donors. SiF/Ni-NQGDs can also be easily recycled without noticeable performance degradation due to the prevention of Si deactivation through oxidation. Our findings provide valuable insights into the practical application of biomass refinement and electrochemical hydrogen production and efficient use use of solar energy.

Reference)

1. Y. Choi, S. Choi, I. Lee, T. V. T. Nguyen, S. Bae, J. Ryu, Y. H. Kim, S. Park, J. Ryu, Solar Biomass Reforming and Hydrogen Production with Earth-Abundant Si-Based Photocatalysts. Advanced Materials
2023, Accepted.

Figure 1
(Invited) Stabilization and Activation of Copper(I)-Oxide-Semiconducting Interfaces for Photoelectrochemical Reduction of Carbon Dioxide
Authors: Kulesza Pawel J. , Rutkowska Iwona A.
Published: February 2024

Electroreduction of carbon dioxide to simple organic fuels and chemicals is a topic of growing scientific and technological interest. The reaction provides means for both reducing emissions of CO2 into atmosphere and storing renewable energy. The presentation will address low-temperature CO2-conversion processes based on electrocatalytic and photoelectrochemical approaches. Among important issues are choice of the catalytic or semiconducting materials, their morphology and operating conditions including temperature, solvent, electrolyte, pH etc. There is a need to improve the reaction dynamics and selectivity toward specific products. In practical electrolysis cells, the CO2-reduction (at cathode) is accompanied by water oxidation (at anode or photoanode).

Recently, we have concentrated on the development of hybrid materials by utilizing combination of metal oxide semiconductors thus capable of effective photoelectrochemical reduction of carbon dioxide. For example, the combination of conducting polymers, or titanium (IV) oxide, and copper (I) oxide has been considered before and after sunlight illumination. Application of the hybrid system composed of both above-mentioned oxides resulted in high current densities originating from photoelectrochemical reduction of carbon dioxide mostly to methanol (CH3OH) as demonstrated upon identification of final products. Among important issue is intentional stabilization, activation, and functionalization of the mixed-metal-oxide-based photoelectrochemcal interface toward better long-term performance and selectivity production of small organic molecules (C1-C4) and other chemicals. In this respect, ultra-thin films of conducting polymers (simple or polyoxometallate-derivatized) and supramolecular complexes (with nitrogen containing ligands and certain transition metal sites), sub-monolayers of metals (Cu, Au), networks of noble metal (Au, Ag) nanoparticles or layers of robust bacterial biofilms have been considered. The photobiocathode utilizing robust biofilms have also been demonstrated to stabilize copper(I) oxide surfaces and to induce the system’s activity toward reduction of carbon dioxide under illuminations with visible light.

In the presentation, special attention will be paid to the mechanistic aspects of electroreduction of carbon dioxide, fabrication and characterization of highly selective and durable semiconductor photoelectrode materials and to the importance of the reaction conditions.
(Invited) Exploring Solar-Driven CO2 Reduction to C2+ Products
Authors: King Alex J , Bui Justin C. , Kim Chanyeon , Wei William , Kim Keon-Han , Safipour John , Kusoglu Ahmet , Toma Francesca Maria , Bell Alexis T. , Weber Adam Z.
Published: February 2024

Use of solar irradiance to drive CO2 reduction (CO2R) holds great promise for the sustainable generation of energy-dense fuels and chemicals, especially as it relates well to carbon capture technology. Multicarbon (C2+) products (e.g., ethylene, ethanol, propanol) are particularly attractive because they have a large market size and can be further converted to higher molecular weight hydrocarbons fuels that have high volumetric and mass energy densities. Metallic copper (Cu) has the unique ability to catalyze CO2 to C2+ products with high faradaic efficiency; however, the product distribution of CO2R on Cu is potential and microenvironment dependent. In this talk, we will explore CO2R via different routes using both experiments and simulation. We will focus on obtaining C2+ products via tailoring the microenvironments including the use of ionomer films that are quite effective at the lower current densities that match against the solar irradiance. We will demonstrate how control of the local environment and dynamic operation provide metastable states of high pH and high CO2 concentration, thereby enabling high CO2R to C2+ production.

In addition, for direct photoelectrochemical CO2R, there is an optimum cell design and operating photovoltage that is not at the maximum power point (unlike water splitting) due to the selectivity dependence on potential. Using a continuum model of PEC CO2R, we will explore the co-design of the photoelectrode bandgaps and device architecture for the generation of C2+ products. The simulation results demonstrate the critical importance of simultaneously engineering the photoelectrode and device design and operation in order to ensure the photovoltage and photocurrent from the photoelectrode enables operation at the optimum potential. Finally, for PEC CO2R, we will explore the use of metal-insulator-semiconductor (MIS) structures to obtain high rates of CO2R. This includes both theoretical and experimental investigations that elucidate the controlling phenomena and when coupled with the ionomer films provide high rates of direct PEC CO2R. Overall, the insights between the photoelectrode and device design is critical for the design of monolithic, unassisted PEC CO2R systems that yield high STC2+ efficiency.

Acknowledgements

This material is based partially on work performed by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DE-SC0021266 and a University of California grant.
(Invited) High-Rate CO2 Reduction Reactions: From Electrocatalysts to Gas-Diffusion Electrodes
Authors: Kamiya Kazuhide
Published: February 2024

Excessive emissions of carbon dioxide (CO2) from the use of fossil fuels are becoming a serious obstacle to the sustainable development of society. Electrochemical CO2 reduction (CO2RR) into value-added products using solar electricity is a promising technology to close the carbon cycle and sequester anthropogenic CO2 into chemical feedstocks.[1] The practical implementation of CO2RR requires a high current density, as the current density for CO2RR is directly correlated to the capital cost of the electrodes and electrochemical cells. The use of gas diffusion electrodes (GDEs) effectively accelerates CO2RR by overcoming the mass transport limitation due to the inherently low diffusion and solubility of CO2 in water. This presentation summarises our recent studies on high-rate CO2RR from the point of view of both novel electrocatalyst designs and appropriate electrode assembly.

Single-atom electrocatalysts (SAECs), consisting of single isolated metal sites dispersed on heterogeneous supports, are one of the promising electrocatalysts for high-rate gaseous CO2RR. We have employed various single metal-doped covalent triazine frameworks (M-CTFs) as a platform for CO2RR electrocatalysts on GDEs and systematically investigated them to derive sophisticated design principles using a combined computational and experimental approach.[2-4] The Ni-CTF exhibited both high selectivity and high reaction rate for CO production. In contrast, the Sn-CTF exhibited selective formic acid production, and the faradaic efficiencies (FEs) and partial current density reached 85% and 150 mA/cm2, respectively.[2] These results were in close agreement with the intermediate CO2RR adsorption strength obtained by DFT calculations.

In addition to the synthesis of efficient electrocatalysts, the triple phase boundary (TPB) at the GDE, where the catalyst material, electrolyte, and gas pores intersect, needs to be enlarged for high-rate gaseous CO2RR.[5,6] We successfully increased the partial current density for multicarbon products (C2+) over cupric oxide (CuO) nanoparticles on gas diffusion electrodes in neutral electrolytes to a record value of 1.7 A/cm2 by maximizing the area of the CO2RR active interface.[5] In particular, we demonstrated that the thickness of catalyst layers was one highly sensitive factor in determining the maximum current density for C2+. Although the GDE and electrocatalyst used in this case are not unique, the optimized assembly elicits their undermined potential.

[1] K. Kamiya, Nakanishi* et al. Chem. Lett. 2021, 50, 166-179.

[2] S. Kato, K. Kamiya* et al. Chem. Sci., 2023, 14, 613–620.

[3] P. Su, K. Kamiya*et al. , Chem. Sci., 2018, 9, 3941-3947.

[4] K. Kamiya* Chem. Sci. 2020, 11, 8339–8349.

[5] A. Inoue, K. Kamiya* et al. EES Catal. 2023, 1, 9-16.

[6] T. Liu*, K. Kamiya* et al. Small 2022, 18, 2205323.
(Invited) Towards Broadband Photocatalysis
Authors: Ma Dongling
Published: February 2024

Forming nanomaterials junctions and using plasmons represent two important, promising strategies for realizing broadband photocalysis in strategically important applications such as solar fuels and photocatalytic degradation of pollutants. In this talk, I will present some of our recent work on the rational design of nanohybrids and their applications in solar fuels and photocatalysis. One example is about the in situ synthesis of plasmonic Ag nanoparticles (AgNPs) and Ag-MOF. The intimate and stable interface between the AgNPs and Ag-MOF and hot electron transfer from the plasmonic AgNPs to MOF led to highly efficient visible-light photocatalytic H2 generation in aqueous solution, which surpasses most of reported MOF-based photocatalytic systems. This work sheds light on effective electronic and energy bridging between plasmonic NPs and MOF.

References: [1] Nature communications, 12: 1231 (2021); [2] Nature communications, 2023, in press; [3] Chemistry of Materials, 2021, 33, 695-705; [4] Adv. Funct. Mater. 2019, 1902486.
Unintended Cation Crossover in CO2 Conversion MEA Cells: Causes and Effects
Authors: El-Nagar Gumaa , Haun Flora , Gupta Siddharth , Stojkovikj Sasho , Mayer Matthew T.
Published: February 2024

Membrane electrode assemblies in gas diffusion cells enable CO2 reduction at industrially relevant rates, yet their long-term operational stability is often limited by the formation of solid precipitates (e.g. K2CO3) in the cathode pores. This is a consequence of a combination of 1) local alkalization due to the electrochemical reaction, 2) generation of (bi)carbonate by chemical reaction of CO2 with the alkaline electrolyte, and 3) the presence of alkali metal cations. In catholyte-free, zero-gap cells using anion exchange membranes, the presence of electrolyte cations at the cathode is the result of unintended crossover from the anolyte, and a detailed understanding of the factors enabling this crossover is lacking. Here we show that the anolyte concentration governs the flux of cation migration through the membrane, and this substantially influences the behaviors of copper catalysts in catholyte-free CO2 electrolysers. Systematic variation of the anolyte ionic strength (using aqueous KOH or KHCO3) correlated with drastic changes in the observed product selectivity – most notably, at low ionic strength, Cu catalysts produced predominantly CO, in contrast to the mixture of C2+ products typically observed on Cu. In this talk, we examine the factors influencing ion crossover and the resulting effects on catalyst structure and activity, under conditions of both CO2 and CO reduction. Operando X-ray absorption spectroscopy and quasi in situ X-ray photoelectron spectroscopy were used to study how the catalyst is affected by operation conditions. Our results show that even in catholyte-free cells, cation effects (including unintended ones) can significantly influence reaction pathways, and this must be considered in future development of catalysts and devices.

El-Nagar, G. A., Haun, F., Gupta, S., Stojkovikj, S. & Mayer, M. T. Unintended cation crossover influences CO2 reduction activity in Cu-based zero-gap electrolysers. Nature Communications14, 2062 (2023) doi: doi.org/10.1038/s41467-023-37520-x

Figure 1
The Importance of Substrate Pore Size and Hydrophobicity in Gas Diffusion Electrodes for CO2 Reduction
Authors: Bernasconi Francesco , Senocrate Alessandro , Battaglia Corsin
Published: February 2024

Electrochemical CO2 reduction (CO2RR) is a promising way to convert detrimental CO2 emissions into sustainable fuels and chemicals, and move closer to a circular carbon economy.
1 To compete with traditional fuel/chemical production routes, electrocatalysts need to be highly active, selective towards a desired product, and stable. High activities can be achieved with gas diffusion electrodes (GDEs) that provide gaseous CO2 to the catalyst, however, product selectivity and stability still need to be improved before industrial implementation. In this work, we show that the selectivity and stability of Ag and Cu GDEs can be tuned by acting on the pore size and hydrophobicity of their polymeric substrates.2,3 We rationalize these findings with the extent to which electrolyte penetrates the polymer-based GDEs, which depends on both substrate pore size and hydrophobicity and is quantified by the water entry pressure. GDEs with larger pore size promote electrolyte penetration (low water entry pressure) and, in the Ag case, yield GDEs with poor CO selectivity and stability (Fig. 1). In contrast, GDEs with small pore size show a much higher resistance to electrolyte penetration (high water entry pressure), thus yielding a greatly improved Faradaic efficiency for CO (up to 95% at 100 mA/cm2 in neutral electrolyte) and remarkable long-term stability (97% of initial CO selectivity retained after > 40 h). In the Cu case, we observe a strong enhancement in C2H4 selectivity when employing GDE substrates with small pores and strong hydrophobicity (up to 55% Faradaic efficiency in neutral electrolyte at 200 mA/cm2 for > 3 h). Both CO2 and CO reduction reactions indicate that mass transport limitations are present for all GDEs, but can be mitigated by GDE's with small pore size. Our results emphasize the importance of substrate microstructure on GDE product selectivity and stability during CO2RR, and represent a new scalable strategy to improve GDE performance.

References

1A. Senocrate, C. Battaglia, J. Energy Storage
2021, 36, 102373

2A. Senocrate, F. Bernasconi, D. Rentsch, K. Kraft, M. Trottmann, A. Wichser, D. Bleiner, C. Battaglia, ACS Appl. Energy Mater.
2022, 5, 14504

3F. Bernasconi, A. Senocrate, C. Battaglia et al., in preparation

Figure 1
Modeling and Performance Projections of a Dual-Purpose CO2 Capture and Energy Storage Device from Oceanwater
Authors: Silcox Rachel , Bala Chandran Rohini
Published: February 2024

Carbon dioxide (CO2) capture and removal technologies are critical to limit global warming to 2 °C in the next few decades. In addition to the atmosphere, the oceans are large carbon sinks and have to-date captured about 25% of all anthropogenically released carbon. Therefore, ocean water CO2 capture can complement Direct Air Capture (DAC) technologies. To harness this source of CO2, this talk proposes, models, and analyzes the performance implications of a reversible, aqueous electrochemical flow device, which uses hydrogen and redox salt looping to achieve pH shifting. The reversible nature of this device enables its use in both power production and consumption modes, enabling CO2 capture to be powered exclusively by variable sources of renewable electricity. To model the performance of the proposed energy storage and CO2 capture device, we developed an equivalent circuit model to predict the current-voltage performance of this device mediated by ferricyanide/ferrocyanide and H2. Performance predictions are modeled as a function of key transport and thermodynamic conditions, specifically, for different mass transport rates of gases and aqueous electrolytes and different extents of pH shift between acidification and basification steps. Estimations of device performance are developed at both laboratory-scale and industrially relevant current densities. Modeled electrochemical energy intensity values of the overall device operation are compared to current state-of-the-art electrochemical ocean CO2 capture technologies to show the approach’s potential. Overall energy intensities are compared to current state-of-the-art DAC technologies. Our results show the energy intensity for CO2 capture during the reversible process has the potential to be reduced compared to present day DAC systems, but is highly sensitive to parasitics, ohmic losses, and the extent of competing reactions. Additionally, projections of the device energy-time profile are demonstrated to show the diurnal energy storage potential, specifically with applications to solar energy. Energy storage capabilities in the proposed device provide additional benefits of powering this CO2 capture device with renewable electricity while providing flexibility to manage grid-scale electricity demand. Overall, a reversible, pH-shifting based oceanic CO2 capture device offers holistic benefits from designing CO2 capture to operate exclusively from renewable electricity.
Manganese-Based Tunnel and Layered Oxide Cathodes for Secondary Alkali-Ion Batteries
Authors: Yadav Jaya , Vanam Sai Pranav , Senthilkumar Baskar , Amonpattaratkit Penphitcha , Barpanda Prabeer
Published: February 2024

Designing new cathode materials remains crucial in developing (post) Li-ion batteries. Mn-based oxide cathodes have received wide attention due to their sustainable nature, low cost, elemental abundance, structural diversity/polymorphism, and rich oxidation states (2+ to 7+), offering tunable redox potential [1]. Here, we have investigated different oxide-based cathode insertion compounds for secondary metal-ion batteries.

i) We have demonstrated tunnel-type sodium insertion material Na44MnO2(NMO) as an intercalation host for Li-ion and K-ion batteries. The solution combustion synthesized Na0.44MnO2 assuming an orthorhombic structure (space group Pbam), exhibited rod-like morphology. After electrochemical ion exchange from NMO, we obtained Na0.11K0.27MnO2 (NKMO) and Na0.18Li0.51MnO2 (NLMO) cathodes for K-ion batteries and Li-ion batteries, respectively [2]. These new compositions, NKMO and NLMO, showed excellent cycling stability with capacities of ∼74 and 141 mAh g–1 (first cycle, C/20 current rate). The underlying mechanistic features concerning charge storage and structural modifications in these cathode compositions were probed by combining ex-situ structural, spectroscopy, and electrochemical tools [3].

ii) Using composite formation, we have tried to improve the P2-type layered material. Here, the stable Na7(Li1/18Mn1/18Ni3/18Fe2/18χ1/18)O2–xNa2MoO4 biphasic composite was synthesized using Mo doping. Overall, the redox chemistry was investigated using various spectroscopy techniques to prove the net capacity resulted from both cationic and anionic redox reactions [4].

Keywords: energy storage; batteries; cathode; manganese oxides; intercalation; doping

References:

[1] N. O. Vitoriano et al., T. Rojo, Energy Environ. Sci. 2017, 10 (5), 1051−1074.

[2] K. Sada, B. Senthilkumar, P. Barpanda, Chem. Commun. 2017, 53 (61), 8588−8591.

[3] S.P. Vanam et al., P. Barpanda, Inorg. Chem. 2022, 61 (9), 3959−3969.

[4] S.P. Vanam, P. Barpanda, Electrochim. Acta. 2022, 431, 141122.
SO2-Tolerant Electrocatalytic Reduction of CO2 from Simulated Industrial Flue Gas
Authors: Papangelakis Panagiotis , Miao Rui Kai , Lu Ruihu , Ozden Adnan , Liu Shijie , Sun Ning , O'Brien Colin P. , Hu Yongfeng , Shakouri Mohsen , Xiao Qunfeng , Li Mengsha , Khatir Behrooz , Huang Jianan Erick , Wang Yakun , Xiao Yurou Celine , Li Feng , Shayesteh Ali , Zhang Qiang , Liu Pengyu , Liu Hanqi , Golovin Kevin , Howe Jane , Wang Ziyun , Li Jun , Sargent Edward H. , Sinton David
Published: February 2024

The electrochemical reduction of CO2 using copper-based electrocatalysts offers a route to produce high-value multicarbon (C2+) products from renewable electricity (Nat. Catal. 4, 952-958 (2021); Nature 614, 262-269 (2023)). To date, the efficient electrocatalytic conversion of CO2 to multicarbon products has only been possible when using impurity-free CO2 sources, such as from direct air capture. The generation of such high-grade CO2 streams is expensive, accounting for almost half of the total energy required for both capture and electroreduction processes (Nat. Catal. 4, 952-958 (2021)). Conversely, capturing CO2 from point sources, such as industrial flue gas, is more efficient due to the higher concentration of CO2 in the feed. However, trace amounts of sulfur dioxide (10 ~ 400 ppm SO2) inherently present in these streams will significantly degrade the CO2 conversion process. All previous attempts to convert CO2 with SO2 present in the feed have resulted in immediate catalyst poisoning and an irreversible loss of CO2 conversion activity.

In this study, we designed a modified catalyst layer to react a stream of dilute CO2 containing 400 ppm SO2 to multicarbon products with high stability and performance metrics that match or exceed those achieved with pure CO2 streams. Driven by density function theory and COMSOL simulations, we designed an ionomer:copper:polytetrafluoroethylene (PTFE) (ICP) electrode that features both hydrophobic and highly-charged hydrophilic domains to limit water adsorption and promote CO2 over SO2 transport near the electrochemically active sites. This deactivates the SO2 poisoning mechanism, thus enabling stable and efficient CO2 conversion (see figure). Our approach achieved a sustained C2+ Faradaic efficiency (FE) of 50% for the initial 160 hours at 100 mA cm-2.

In order to improve the overall C2+ current efficiency (jC2+) towards industrial scales, we applied our strategy in high-surface-area copper electrodes. We achieved CO2 conversion in the presence of 400 ppm SO2 with a C2+ FE of 76% at a current density of 700 mA cm-2, surpassing what can be achieved in existing integrated CO2 capture-electrolysis systems that use pure CO2. Overall, our approach provides a fully 140-fold increase in performance (FEC2+ × jC2+) compared to the best prior CO2 conversion systems with added SO2 (Nat. Nanotechnol. doi: 10.1038/s41565-022-01286-y (2023); J. Am. Chem. Soc. 141, 9902-9909 (2019)). These findings represent an important advancement in the field of CO2 conversion and highlight the potential of our strategy for industrial-scale applications.

Figure 1
Solar-Rechargeable Redox Flow Battery: Drawbacks and Opportunities Under Thermal Loads
Authors: Bae Dowon
Published: February 2024

The PV-assisted and photoelectrochemical (PEC) solar-rechargeable redox flow battery (SRFB) is getting the spotlight as a means of simultaneously storing solar energy into chemicals [1,2]. However, most studies on the SRFB system overlook practical challenges arising from thermal voltage loss under light and heat [3]. For instance, an overheated c-Si solar PV system shows a severe power loss exceeding 20% due to thermal recombination-driven voltage loss [3]. According to our recent modelling, a PV-integrated or PEC-based SRFB can remedy the excess heat by the heat transfer to the electrolyte, maximising the solar-to-chemical conversion efficiency [3,4]. Regardless of the optimistic expectation, our recent computational fluid dynamics (CFD) works revealed that even state-of-the-art SRFB could not regulate the thermal efficiency loss, implying how important the understanding of physical and dimensional impact (e.g., flow channel (i.e., flow rate), electrolyte volume, etc.) is [4]. Ironically, the overheated electrolyte can offer enhanced reaction kinetics that can compensate for the thermal voltage loss of the PV device at elevated temperatures. In this work, the above-described thermal degradation is quantified by introducing a thermo-electrochemical device model, which covers heat transfer and electrochemical studies. Also, we present our recent CFD modelling results with supporting experimental results obtained under simulated sunlight at various electrolyte temperatures.

Bae, D. et al. Sustain. Energy Fuels (2019) 3, 2399–2408.

Bae, D. et al. Commun. Mater. (2020) 1, 17.

Bae, D. et al. Sustain. Energy Fuels (2020) 4, 2650–2655.

S. Whitley, D. Bae, J. Electrochem. Soc. (2021) 168, 120517.

Figure 1
Structural Tuning Strategy to Improve Ionic Conductivity of Eco, Cost-Effective Zr-Based Halide Solid Electrolyte
Authors: Noh Joohyeon , Kang Kisuk
Published: February 2024

Lithium-ion conductors based on halide anion frameworks have garnered significant attention as optimal ceramic conductors for composite cathodes due to their high oxidation stability and deformability. Recently, a cost-effective halide electrolyte, Li2ZrCl6, has been reported as a promising alternative to rare-metal-based halide solid electrolytes which are not suitable for manufacturing. Despite the economic advantage of using Zr, its ionic conductivity remains relatively low (0.36 mS cm-1), which could limit its applicability in high C-rate applications.

To enhance the ionic conductivity of Zr-based solid electrolytes, various structural tuning strategies have been employed. However, challenges persist, such as unstable cycling due to the redox reactions of metal ion and the uneconomical aspects of incorporating rare metals like Yttrium, Indium, and Lanthanides. In this study, we propose economical and rational strategies for tuning Li2ZrCl6 to achieve higher ionic conductivity without compromising stability and affordability.

By introducing zero-valent dopants, vacancies, we were able to increase the ionic conductivity of the Zr-based solid electrolyte to nearly twice its original value (0.8 mS cm-1). Our detailed analysis reveals that the enhanced conductivity and reduced activation energy are primarily due to the activation of local diffusion paths, resulting from the alleviated repulsion between transition metal ions and Lithium ions. Furthermore, we establish the relationship between the Lithium-ion content and Li diffusivity in the Zr-based solid electrolyte, uncovering a new aspect for structural tuning in Zr-based solid electrolytes.

Consequently, we optimized the content of Lithium ions and dopants in the solid electrolyte, synthesizing a super-ionic conductive Zr-based solid electrolyte with an impressive ionic conductivity of approximately 1.6 mS cm-1 and highest Zr percentage reported to date. Our findings offer a rational and economical design strategy for developing stable hcp-LZC structures with faster ionic conduction. This breakthrough has the potential to facilitate the widespread adoption of Zr-based solid electrolytes in lithium-ion batteries.
Nafion-Based Quasi-Solid-State Polymer Electrolyte for Lithium-Sulfur Batteries
Authors: Gerle Martina , Sievert Brigitta , Lufrano Ernestino , Nicotera Isabella , Friedrich K. Andreas , Nojabaee Maryam
Published: February 2024

Lithium-sulfur batteries are considered a strong contender for next-generation high-energy battery systems given their high gravimetric energy density. However, this battery chemistry is still facing challenges such as the polysulfide shuttle effect caused by the high solubility of long-chain lithium polysulfides (Li2Sn) resulting in active material loss and compromised cycle life. Solid-state polymer electrolytes (SPEs) represent a promising pathway to address this issue by preventing the formation and transport of these undesirable polysulfide intermediates.1,2 Moreover, the application of flexible polymer electrolytes promotes safe high energy batteries for smart textiles.

In this study, single lithium-ion conducting solid polymer electrolytes (SLIC-SPEs) based on lithiated Nafion membrane have been investigated, utilizing the chemical and thermal stability of this kind of ionomers. Among others, a mixture of ethylene carbonate (EC) and propylene carbonate (PC) was tested as organic aprotic swelling solvent offering advantageous characteristics such as great chemical stability and high ion mobility while avoiding phase separation issues and undesired leaching.

Sulfur-infiltrated ultramicroporous carbon composite cathodes were utilized in combination with the investigated SLIC-SPEs, facilitating a quasi-solid-state lithium-sulfur full cell with carbonate-solvent compatibility and high active material utilization.3

Electrochemical performance of the full cell was investigated elaborately and compared with a reference system using solely the liquid EC:PC solvent. While rapid capacity fading can be observed for the liquid electrolyte cell, an enduring high capacity is found in the lithiated-Nafion system. For better understanding of these effects, cycling analysis was accompanied by implementing impedance spectroscopy upon galvanostatic cycling. The electrochemical characterization indicates the formation of a stable film and high degree of reversibility during cycling of the lithiated-Nafion cell whereas an increased film resistance due to sulfur cross-over and electrolyte decomposition was observed within the liquid electrolyte system.

(1) Z. Li, W. Lu, N. Zhang, Q. Pan, Y. Chen, G. Xu, D. Zeng, Y. Zhang, W. Cai, M. Yang, J. Mater. Chem. A
2018,
6 (29), 14330-14338.

(2) X. Hao, H. Wenren, X. Wang, X. Xia, J. Tu, J. Colloid Interface sci.
2020,
558, 145-154,

(3) M. Nojabaee, B. Sievert, M. Schwan, J. Schettler, F. Warth, N. Wagner, B. Milow, K. A. Friedrich, J. Mater. Chem. A
2021,
9 (10), 6508-6519,
A Tetramethylurea-Electrolyte-Based Lithium-Oxygen Battery with High Performance and Alternative Mechanism
Authors: Lin Xiaodong , Sun Zongqiang , Dong Quan-Feng
Published: February 2024

The electrolyte is a critical component in electrochemical energy storage devices as it creates the reaction environment for the electrode process. In lithium–oxygen (Li–O2) batteries, the oxygen electrode reaction involves a complex multiphase transition (e.g., gas, liquid, solid) and a variety of intermediates (e.g., O2
–, O2
2–, 1O2), making the role of the electrolyte system more prominent. As an ideal electrolyte for Li–O2 batteries, it should not only resist the attack of superoxide intermediate, but also provide a kinetically favorable O2 redox reaction mechanism. However, currently, no electrolyte solvent is perfectly suitable for Li–O2 batteries, which greatly limited their practical applications. Here, we present a new electrolyte solvent, 1,1,3,3-tetramethylurea, for Li–O2 batteries that exhibits high performance and an alternative mechanism. Specifically, it enables a kinetically favorable one-electron Li2O2 oxidation pathway upon charging. Furthermore, due to the absence of alpha-hydrogen atoms in its molecular structure, it also exhibits good stability in the presence of superoxide intermediates, significantly suppressing the related hydrogen extraction side reactions. Consequently, Li–O2 batteries utilizing this electrolyte show a much lower charge overpotential and a four-fold longer cycle life compared to those with the benchmark electrolyte.

Acknowledgments

X.L. acknowledges financial support from the Marie Skłodowska-Curie Actions (grant agreement No. 101064286) for his postdoctoral fellowship.
An Improved Lithium-Sulfur Battery By Using Porous Carbon As the Sulfur Template
Authors: HAN Jinseok , Kim Jae-Kwang
Published: February 2024

As global demand for electric vehicles (EVs) continues to rise, the rechargeable battery of high-energy density is actively researched. Lithium-ion batteries (LIBs) have been widely used in the electric vehicles (EVs) and have been leading the EVs market. However, LIBs have reached their limits due to their practical low-capacity and high-cost. Therefore, novel strategy is required to solve the problem of the LIBs.

Lithium-sulfur (Li-S) batteries attract attention because of high theoretical capacity (1675 mAh/g) and high energy density (2600 Wh/kg). Moreover, sulfur as electrode material is abundant and inexpensive. However, the sulfur-based batteries have serious disadvantages, which is the shuttle of intermediate polysulfides (Li2Sn, 2<n≤8), and low conductivity, result in poor cycle stability and low discharge capacity [1,2].

Therefore, in this study, the sulfur electrode is fabricated by impregnating sulfur into three-dimensional porous carbon. The porous structure suppressed the dissolution/shuttle of sulfur species and improved the cycling stability and discharge capacity. Moreover, three types of porous carbon templated of activated carbon cloth, activated carbon felt, and porous carbon foam were compared on electrochemical performances.

Reference

Jimin Yun, 2023, High Loading Sulfur Cathode with Three-dimensional Porous Current Collector for Lithium-Sulfur Battery, Department of Materials Engineering and Convergence Technology, Gyeongsang National University, P.11, p.14

Kimin Park, 2022, Design od metal phosphate based electrodes for high-performance Li-Ion & Li-S battery, Department of materials science and engineering seoul national university, P.1
Resolving the Incomplete Charging Behavior of Redox-Mediated Li-O2 Batteries Via Sustainable Protection of Li Metal Anode
Authors: Kim Hun , Kim Min-Jae , Sun Yang-Kook
Published: February 2024

Lithium-oxygen batteries (LOBs) have attracted worldwide attention due to their high specific energy. However, the poor rechargeability and cycling stability of LOBs hinders their practical use in applications. Here, we explore the incomplete charging behavior of redox-mediated LOBs operated at a feasible capacity for practical level (3.25 mAh cm–2) and resolve it using a sustainable lithium protection strategy. The incomplete charging behavior, promoted by self-discharge of redox mediators (RMs), hampers the reversible cycling of LOBs, which was investigated through multi-angle in-situ and ex-situ analyses. Meanwhile, the proposed lithium protection strategy; introducing an inorganic/organic hybrid artificial composite layer with a pre-formed stable interface between the lithium metal and the composite layer, enhances the stability of the lithium metal anode during the prolonged cycling by preventing the chemical/electrochemical interactions of RMs on the lithium metal surface, and thus, improving the overall rechargeability of LOBs. This work provides guidelines for the effective use of RMs with an adequate lithium protection strategy to achieve sustainable cycling of LOBs, creating a feasible approach for the practical use of LOBs with high areal capacity.
Ptve-Impregnated 3-Dimensional Porous Carbon for High-Properties Organic Battery
Authors: Kim Chae Kyoung , KIM Hye Jung , Kim Jae-Kwang
Published: February 2024

Lithium-ion batteries are the most common type because their operating potential and energy density are both higher than those of other rechargeable batteries. However, the associated electrochemical reaction involves the intercalation and deintercalation of the lithium transition-metal-containing electrodes. The constituent transition-metals of lithium-ion batteries, such as cobalt, nickel, manganese, and lithium are limited resources, the cost of which is increasing as the market expands. Therefore, organic electrode materials are gaining an increased level of attention as possible replacements for lithium transition-metal-based electrode materials. The use of organic materials would enable the design of metal-free batteries. In addition to the potential low-cost and ease of scalability, the structural diversity of organic molecules would allow the tailoring of both the physical and electrochemical properties of the electrode materials, thus offering excellent opportunities for constructing sustainable and environmentally friendly power sources and energy-storage systems. However, they present some serious issues, a high self-discharge as a result of the dissolution of organic active materials into the organic liquid electrolyte and the content of large amounts of carbon conductor material into the electrode due to the intrinsic low electrical conductivity of the organic active materials.

In this study, to overcome these disadvantages, 3-Dimensional porous carbon have been applied to composite with poly(2,2,6,6-tetramethylpiperidine-N-oxyl-4-vinyl ether) (PTVE) organic electrode material. The use of the PTVE-impregnated porous carbon electrode structure enhanced the contents of active material and electrochemical performance.
A Dual-Approach for Extending the Lifespan of Cobalt-Free Na[Ni0.55Mn0.35Fe0.1]O2 cathode Via Bi5+-Doping and Bi2O3 Coating in Sodium-Ion Batteries
Authors: Mishra Raghvendra , Singh Rajendra Kumar
Published: February 2024

A cobalt-free layered Na[Ni0.55Mn0.35Fe0.1]O2(NFM) cathode material has been synthesized and dual surface and structural modifications have been performed. Bi5+ is doped into pure NFM in order to tune the structure, whereas, a thin layer of Bi2O3 is coated on surface of the Bi5+-coated NFM to modify the surface. The structure, morphology, and electrochemical performance of prepared samples are analyzed and compared by various characterization techniques. The pristine NFM cathode exhibits the specific discharge capacity of 170 mAh g-1, while Bi-doped cathode exhibits 181 mAh g-1, and Bi2O3 coated cathode renders 180 mAh g-1. It is observed that, pristine NFM cathode suffers rapid capacity degradation and nearly ~80% capacity loss within first 250 cycles. After 1000 cycles, BNFM shows 47% capacity retention, while, BNMF@Bi2O3 shows 73% capacity retention of initial capacity. This improvement in the rate capability is obtained due to the effect of Bi-doping and Bi2O3 coating, where, former enlarges interlayer spacing and latter provides the ionic conducting channel as well as protects the particle from the contact of the electrolyte. The combined effect of Bi-doping and Bi2O3 coating facilitates fast diffusion of Na-ions within the transition metal layers resulting in superior rate capability.

Fig:
Cyclability of pristine, Bi-doped and Bi2O3 coated NFM cathode materials

Figure 1
Advances in 2D Ultrathin Nanosheets of a2FeSiO4 (A= Li, Na, K) for Next-Generation Alkali-Ion Batteries
Authors: Singh Lalit Kumar , Kim Jaehoon
Published: February 2024

Although lithium-ion batteries (LIBs) have become ubiquitous in various applications, the limited resource of Li and increasing cost hinder their scalability for grid-scale energy storage applications. Thus, alternative rechargeable batteries that use more earth-abundant elements such as sodium and potassium have received significant attention. However, the distinct different properties of Li+, Na+, and K+ ions hinder the extensive development of universal host materials for alkali metal ions. Polyanion-type electrode materials, which contain polyanionic groups (XO4)n
−, (XO4F)n
−, and (XmO2m+1)n
− (X = P, Si, S, etc.), have garnered significant interest owing to their remarkable structural stability and adjustable electrode potential; this properties make them excellent candidates as cathode materials in sodium-ion batteries (SIBs) and potassium-ion batteries (KIBs). Among these, A2FeSiO4 (AFS) (A= Li, Na, K) is highlighted as a promising cathode material due to its abundant Fe resources, low cost, and non-toxicity. The crystal structure, transport pathways, and synthesis techniques of Li2FeSiO4 (LFS) have been extensively explored whereas research on Na2FeSiO4 (NFS) as a cathode material is still in the process of maturing and research on K2FeSiO4 (KFS) is very rare. The large ionic radius of sodium and potassium presents a significant challenge to effective ion-intercalation reactions for energy storage in electrodes, destabilizing the crystal structures of host materials. In addition, orthosilicates exhibit poor electronic conductivity, greatly limiting its practical application. To address this issue, various techniques have been explored, which include nanostructuring, coating with conductive polymers, and metal doping. In this study, a facile solvothermal technique for the fabrication of ultrathin 2D AFS nanosheets by hydrothermal transformation and propose the reaction mechanism for this chemical transformation. The as-obtained AFS nanosheets are highly exfoliated using oxalic acid as the exfoliating agent to improve their electrochemical performance. These nanosheets are designed to mitigate the diffusion limitations encountered by alkali ions when traversing the densely packed structure of AFS. The highly exfoliated AFS 2D nanosheets greatly improve the electrochemical performance and cyclability of the cathode. The nanosheets exhibit a specific discharge capacity of 149 mAh g-1 for Li+, 99 mAh g-1 for Na+, and 88 mAh g-1 for K+ when operated at a current density of 100 mA g-1. Moreover, the nanosheets display exceptional capacity retention, with a retention rate of 75% for Li+, 99% for Na+, and 65% for K+ after 100 charge/discharge cycles for each of the cathodes. This study demonstrates the potential of 2D nanosheets for stabilizing the silicate-based cathode materials against structural and volume changes, and for improving their electrochemical performance in SIBs and KIBs.

Figure 1