bluuebunny/crossref_metadata_2025_split huggingface dataset:
CO2 Reduction to Formate on Amine Modified Pb Electrodes
Authors: Zouaoui Nidhal , Ossonon Benjamin , Fan Mengyang , Mayilukila Dilungane , Garbarino Sebastien , Botton Gianluigi A. , Guay Daniel , Tavares Ana C 
Published: May 2020

The electrochemical conversion of CO2 into high value-added chemicals and fuels using renewable energy sources is of considerable interest. Lead is among the best electrode materials for the reduction of CO2 to formic acid (or formate). However, the Faradic efficiency and energy efficiency of this process are hindered by the competing hydrogen evolution reaction (HER) at high reduction potentials. Strategies to improve the performance of Pb electrodes include the formation of metastable Pb oxide layers [1], the formation of 3D porous structures [2], and the growth of active Pb (100) surfaces on a dendrite-like secondary structure [3].
In this work, the growth of islands-like aryl-aliphatic, aminophenyl and nitrophenyl amines on Pb surfaces is proposed as an effective way to improve toward the Faradic efficiency of the reduction of CO2 to formate [4]. The aryl-aliphatic amines and aminophenyl porous layers were grafted on the surface of Pb surfaces using diazonium chemistry. The grafting of the amines results in a lower Pb electroactive sites which in turn hinders the HER but without blocking the active sites for the CO2 reduction, Figure 1.a. In fact, the porous organic film lowers the overpotential for the CO2 reduction reaction. Because of these combined effects, the Faradic efficiency for formate increases from 8% for the bare Pb to 94% for modified Pb electrodes, Figure 1.b. The present study offers a new route to decouple CO2 reduction from the HER, thus allowing the development of highly efficient and selective electrodes for the electroreduction of CO2 into value added products.

Figure 1. (a) Current densities recorded at -1.09 V vs RHE in Ar- and CO2- saturated electrolyte and their difference (Δ(CO2-Ar)) and normalized to Pb electrochemical surface area as a function of the extent of grafting (t) of Pb – modified electrodes with 4-ABA (4-aminomethylbenzene); (b) Faradic efficiency for formate as a function of the (N/Pb) atomic ratio determined by XPS for various Pb – modified electrodes: 4-ABA (4-aminomethylbenzene), 3-ABA (3-aminomethylbenzene), AEA (4-(2-aminoethyl)benzene), 4-NB (nitrobenzene).

Acknowledgments

This work was financially supported by NSERC (Canada). N. Z. acknowledges the Tunisian government for the INRS-Tunisia agreement scholarship. M.F. acknowledges the FRQNT (Quebec, Canada) for the PBEEE scholarship.

References

[1] C.H. Lee, M.W. Kanan, ACS Catalysis

2015,
5, 465-469.
[2] Z. He, J. Shen, Z. Ni, J. Tang, S. Song, J. Chen, L. Zhao, Catalysis Communications

2015
, 72, 38-42.
[3] M. Fan, S. Garbarino, G.A. Botton, A.C. Tavares, D. Guay, Journal of Materials Chemistry A

2017,
5, 20747-20756.
[4] N. Zouaoui, B. Ossonon, M. Fan, S. Garbarino, G. de Silveira, G. A. Botton, D. Guay, A. C. Tavares, Journal of Materials Chemistry A
2019
, 7, 11272-11281.

Figure 1
Surface Modified Layered Iron Vanadate As Bifunctional Electrocatalyst for Overall Water Splitting
Authors: Sari Fitri Nur Indah , Ting Jyh-Ming 
Published: May 2020

Electrocatalysis water splitting is an attractive method to generate hydrogen from water. To date, the state-of-the-art catalysts to split water are based on noble metal, such as platinum for hydrogen evolution reaction (HER) and IrO2 and RuO2 for oxygen evolution reaction (OER). However, their scarcity and high cost limit the application. Therefore, great efforts have been devoted to explore highly active and cost effective catalyst materials. Recently, noble-metal free Fe-based catalysts have been demonstrated to be highly efficient for OER. It would then be a great advance if such Fe-based catalysts can become bifunctional for overall water splitting. In this work, surface modification of layered iron vanadate was performed to serve this purpose. The surface modification provides and protects additional electrochemical active sites during the reaction. Remarkably, the surface modified iron vanadate exhibits excellent activity for HER and OER, and hence great overall water splitting performance is demonstrated. This discovery not only provides a novel, low-cost, and efficient electocatalyst, but also expands the scope of non-precious metal elements for overall water splitting.
Keywords: layered iron vanadate, surface modification, HER, OER, water splitting.
Ionomer Content Optimization in Ni-Based Anodes for Alkaline Exchange Membrane Water Electrolysis
Authors: Baranova Elena A. , Cossar Emily , Barnett Alejandro Oyarce , Seland Frode 
Published: May 2020

Anion exchange membrane water electrolysis (AEMWE) is an efficient and cost-effective solution to renewable energy storage due to its compact cell design and potential to operate using non-noble metal catalysts. [1] A known challenge to water electrolysis is the kinetically unfavourable oxygen evolution half-cell reaction (OER). Studies have shown that combining nickel (Ni) with small quantities of iron (Fe) can significantly enhances activity towards OER [2], and it has been shown that adding cerium oxide (CeO2), an oxygen conducting support, to catalyst materials can enhance catalytic processes. [3] AEMWE electrodes typically consist of a catalyst material, an ionomer and a solvent. For an efficient cell design, it is crucial to have an active catalyst, as well as the right amount of ionomer to properly stabilize and bind the catalytic layer, while still allowing for high hydroxide ion transport [4]. As such, this study covers the ionomer content optimization of NiFe-based nanoparticles (NPs) supported on CeO2 for anodes in AEMWE using a catalyst coated surface (CCS) electrode configuration. Preliminary AEMWE testing of the NiFe materials without ink optimization is covered in our previous work [5]. The materials tested were synthesized by chemical reduction in ethanol with sodium borohydride, and in-situ testing was done with a Fumatech membrane and ionomer. The ionomer content was tested on pure Ni NPs and the amounts tested were 7, 15, 25, 35 and 45 wt%. Scanning Electron Microscopy (SEM) of the resulting electrodes, Particle-size Distribution (PSD) of the catalyst inks, and in-situ testing showed that the best and most active catalytic layer was formed with 15 wt% ionomer. With the optimal ionomer content found, a more rigorous evaluation of AEMWE performance was carried out on NixFe(100-x) (x=90, 80 at%) both of which were also tested with 10 wt% CeO2. Polarization curves and electrochemical impedance spectroscopy results in 1 M and 0.1 M KOH are summarized and discussed. Additionally, catalyst stability of each of the materials was characterized by holding 0.5 A cm-2 for 12 hours, while measuring impedance every hour. Future work of this study will include long-term stability testing as well as testing the performance of different commercial and lab produced ionomer-membrane combinations with the Ni-based materials.
[1] M. Tahir, L. Pan, F. Idrees, X. Zhang, L. Wang, J. Zou and Z. L. Wang, Nano Energy
2017, 37, 136.
[2] M. Gong and H Dai, Nano Research
2015, 8, 23.
[3] H. A. E. Dole and E. A. Baranova, ChemCatChem
2016, 8, 1977.
[4] G. Li, D. Yang and P. A. Chuang, ACS Catal. 2018, 8, 11688.
[5] E. Cossar, A. O. Barnett, F. Seland, E. A. Baranova, Catalysts
2019, 9, 814.
Modeling Gas Diffusion Layers in Polymer Electrolyte Fuel Cells Using a Continuum-based Pore-network Formulation
Authors: García-Salaberri Pablo A. , Zenyuk Iryna V. , Gostick Jeff T. , Weber Adam Z. 
Published: May 2020

A pore-network formulation is presented to model gas diffusion layers (GDLs) in polymer electrolyte fuel cells (PEFCs) using a continuum-based approach. The formulation can easily be integrated into macroscopic models in CFD codes, thus improving the modeling predictions while keeping a moderate computational cost.
The continuum-based pore-network formulation is based on a cubic lattice [1], which is divided into control volumes (cubes) of prescribed size. Pores and throats are placed inside the control volumes, and “connectors” of negligible volume interconnect the control volumes. The “connectors” are used to regulate the invasion-percolation pattern according to the size of the throat that links the pores within neighboring control volumes. Hence, the formulation can account for both invasion-percolation between pores as well as evaporation/condensation in the pore volume inside each control volume. This is a major advantage compared to traditional pore-network models based on a fully discrete formulation where phase-change phenomena are difficult to implement. Local anisotropic effective transport properties (permeability and diffusivity) are determined using a 1D resistor network analogy inside each control volume according to the size of the pore and throats in it.
The model is validated against capillary pressure curves and effective transport properties (effective diffusivity and permeability) measured ex situ. In addition, water saturation profiles are compared with distributions obtained using X-ray computed tomography [2].
[1] Jeff T. Gostick, Marios A. Ioannidis, Michael W. Fowler, Mark D. Pritzker, Pore network modeling of fibrous gas diffusion layers for polymer electrolyte membrane fuel cells, J. Power Sources 173 (2007) 277-290.
[2] P.A. García-Salaberri, G. Hwang, M. Vera, A.Z. Weber, J.T. Gostick, Effective diffusivity in partially-saturated carbon-fiber gas diffusion layers: Effect of through-plane saturation distribution, International Journal of Heat and Mass Transfer 86 (2015) 319–333.
(Invited) Water-Splitting Electrocatalysts Made By Pulsed-Laser in Liquids Synthesis
Authors: Müller Astrid M 
Published: May 2020

Conversion of solar energy into storable fuels is urgently needed to combat climate change. Efficient, robust materials that are exclusively made of non-precious elements are imperative for tomorrow's global sustainable energy economy and necessitate the development of new nanostructured multi-metallic electrocatalysts that turn our most abundant feedstocks, water or carbon dioxide, into carbon-neutral fuels. The sheer number of possible elemental compositions in multi-metallic nanostructures requires a deep understanding of electrocatalytic mechanisms, including identification of reactive intermediates, to rationally design new materials and guide their optimization.
We used pulsed-laser in liquids synthesis to realize series of earth-abundant multi-metallic first-row transition metal oxide and hydroxide nanostructures. The pulsed-laser in liquids technique is a flexible synthetic strategy for surfactant-free nanomaterials with independently controlled compositional, morphological, and structural properties, and defect densities. It permits rapid preparation or modification of tailored, complex nanostructures in sufficiently large quantities to study them in bulk. Importantly, metastable materials become accessible as nanoparticles form from a laser-induced plasma that is confined by the liquid and characterized by very high temperatures and pressures, thus enabling access to extreme regions of the material's phase diagram.
Our approach enabled unprecedented atomistic-level structural and mechanistic insights into highly active and robust nickel–iron layered double hydroxide nanocatalysts for water oxidation in base; this understanding allowed rapid optimization. Operando spectroscopy data allowed us to identify a cis-dioxo iron(VI) reactive intermediate as the lowest-energy species before O–O bond formation during water oxidation electrocatalysis. Further, we capitalized on the unique advantages of the laser process for integration of our water-splitting electrocatalysts with photoanodes.
(Keynote) Electrochemical Conversion of Sustainable Energy
Authors: Chorkendorff Ib 
Published: May 2020

In this presentation, I will give an overview of some our recent progress in making nanoparticles in relation to electrochemical conversion of sustainable energy [1]. In the first case it will be used to elucidate size dependence and efficiency for catalysts related to the Water splitting i.e. Hydrogen- and in particular Oxygen-evolution reaction (OER) which is the limiting reaction and evaluate the scalability of scarce and expensive elements like the Pt-group metal under acidic conditions [2-4]. We shall discuss caveats of testing catalysts for water splitting [4] and investigate size dependence and isotope labelled experiments will be presented for NiFe nanoparticles for oxygen evolution under alkaline conditions [5]. Here we shall demonstrate a new principle for dynamic detection of gas evolution [6] allowing for a clear distinction between redox states and actual OER by simply measuring the amount of oxygen generated. This will be further pursued for OER catalysis on both Ir and Ru [7] and in the latter case down to 90 mV overpotential [8]. The change of Tafel slopes over many orders of magnitude in current density and mechanisms shall be discussed. If time allow we shall also discuss some of these catalysts used in connection with PEC [9].

References

[1] Z. W Seh, ..., I. Chorkendorff, J. K. Nørskov, T. F. Jaramillo, Science (2017) 355.
[2] E. Kemppainen, .. I. Chorkendorff, Energy & Environmental Science, 8 (2015) 2991.
[3] E. A. Paoli, F. ... I. E.L Stephens, I. Chorkendorff, Chem. Science, 6 (2015) 190.
[4] J Kibsgaard & I, Chorkendorff, Nature Energy, 4 (2019) 430.
[5] C. Roy, ... I. Chorkendorff; Nature Catalysis 1 (2018) 820.
[6] D. T. Bøndergaard, I Chorkendorff ...Electrochem. Acta 268 (2018) 520.
[7] R. R Rao, ...., I. Chorkendorff, I. E.L Stephens and Y. Shao-Horn,
Energy & Environmental Science 10 (2017) 2626.
[8] S. Scott, .... I. Chorkendorff. Submitted (2019).
[9] C. Moon,.... I. Chorkendorff. In preparation (2019).
Gas Diffusion Electrode Design for CO2 Electroreduction Beyond 1 a cm-2
Authors: Dinh Cao Thang 
Published: May 2020

Electrochemical CO2 conversion to fuels and chemicals addresses the CO2 emission and renewable energy storage problems simultaneously. Existing infrastructure can be leveraged to take advantage of these fuels, and recycling CO2 results in a low- or zero-carbon fuel cycle. Converting CO2 into chemical feedstock enables the sequestration of CO2 into valuable products such as polymers.
Electrochemical CO2 conversion can be performed in aqueous- or gas-phase systems. Aqueous electrolysis, wherein the gaseous reactants are dissolved in the electrolyte, can achieve high selectivity. However, due to the low solubility of the gas reactants in the aqueous electrolyte and the long diffusion distance, current densities remain below few tens of mA/cm2—far from the >500 mA/cm2 regime needed to make ECC economically viable.
Gas-phase electrolysis of CO2 could overcome the diffusion limitation of the aqueous system, thereby enabling a much higher current density. In a gas-phase ECC system, a catalyst to reduce CO2 is deposited onto a porous hydrophobic substrate (gas diffusion layer) to form a gas diffusion electrode. The CO2 reaches the catalyst through the gas diffusion layer, reducing the required diffusion length and improving the mass transport. Current densities in the hundreds of mA/cm2 have been achieved using a gas-phase electrolysis system. However, other liquid-phase electrochemical technologies such as water electrolysis achieve multi Amperes/cm2. Also, critical challenges related to stability at high current densities remain.
Here, we present the gas diffusion electrode design that drives CO2 electroreduction to ethylene and ethanol at a current density > 100 mA/cm2 for > 100 hours. We then design the catalyst layer to achieve CO2 gas-phase electrolysis at current densities in the > 1 A/cm2 regime, and with the generation of multicarbon products. We report C2+ partial currents exceeding 1.3 A/cm2 at cathodic energy efficiencies above 40% – a sixfold increase relative to the best previously-reported comparable catalysts. These result in a full-cell energy efficiency towards C2 products of 20% above 1 A/cm2 operating currents.
Effective Conversion of CO2 to Ethanol over Sulphide Derived CuCd: The Importance of Cu2S/CdS Interfaces
Authors: Mosali Venkata Sai Sriram , Bond Alan M , Zhang Jie 
Published: May 2020

Electrochemical CO2 reduction (eCO2RR) is the most sustainable method to covert atmospheric CO2 to industrial fuels. Various transition metals have been widely studied for eCO2RR. The selectivity of the products formed during eCO2RR mainly depends on the binding strengths of the metals those used as catalysts. While the metals that possess lower binding strengths for CO2 intermediates favour either CO or formate, those with very high binding strengths facilitate only HER.1 Among different eCO2RR active catalysts, Cu possess unique property of moderate binding strengths for eCO2RR intermediates due to which it can produce different reduced carbon products with poor product selectivity. Therefore, improving the selectivity of products over Cu surface is much desirable.2 More specifically attaining C2 hydrocarbons and alcohols, due to their higher energy density and that involve a complex 12 electron transfer process from CO2 to achieve them, is of scientific interest. For this, an approach by combining Cu with other eCO2RR catalysts is promising where the C1 product formed over the surface of transition metal is spilled over the adjacent copper surface and coupled with the eCO2RR intermediate attached to the copper.3 CdS is a semiconductor known to produce CO as major product during eCO2RR which makes it desirable to combine with copper. On the other hand, the weak conductivity of CdS can lower the reaction kinetics stabilising Cu+, which is known to favour the stabilisation of the intermediates of C2 products. In this study, we have developed sulphide derived CuCd catalysts with varying CuS/Cu2S – CdS grain boundary distribution patterns. On varying the ratio between Cu and Cd, we found the variation in grain boundary distribution. The presence of higher concentration of Cd (hCd – CuCdS) is observed to form high intact structure of CuS/Cu2S and CdS with significant Cu – Cd boundaries. This structure has facilitated an enhanced ethanol formation at a very lower potential of -0.8 V vs RHE with an exceptional faradaic efficiency of ~32% in CO2 saturated 0.1M KHCO3 solution. Based on XRD and TEM characterisation after bulk electrolysis, the role of cadmium sulphide as well as the grain boundary distribution in tuning the selectivity is elucidated.

References:

1. Ross, M. B.; De Luna, P.; Li, Y.; Dinh, C.-T.; Kim, D.; Yang, P.; Sargent, E. H., Nat. Catal,

2
, 648 (2019).
2. Nitopi, S.; Bertheussen, E.; Scott, S. B.; Liu, X.; Engstfeld, A. K.; Horch, S.; Seger, B.; Stephens, I. E. L.; Chan, K.; Hahn, C.; Nørskov, J. K.; Jaramillo, T. F.; Chorkendorff, I., Chem. Rev,

119
, 7610, (2019).
3. Ren, D.; Ang, B. S. H.; Yeo, B. S., ACS Catal.

6
, 8239 (2016).
Electrochemical Oxidation of Ammonia on Non-Noble Metals
Authors: Johnston Sam , Kemp Liam , Turay Bila , Simonov Alexandr N. , MacFarlane Douglas R. , Suryanto Bryan H R 
Published: May 2020

The electrochemical oxidation of ammonia has been studied in detail due to its inherent utility as a fuel cell reactant 1 for the remediation of wastewater systems 2 for sensors 3 and as a hydrogen carrier.4 However, the bulk of the research conducted has been focused on the use of noble metal-based catalysts such as Pt, Pd, Rh and Ir due to their inherent activity towards the ammonia oxidation reaction (AOR).5,6 Electrochemically, the ammonia oxidation reaction on platinum is a complex multistep reaction which tends to be sluggish and suffers from poor faradaic efficiency, with a variety of products being formed. Another notable feature of noble based systems is the tendency to become poisoned, by strongly adsorbed ‘N’ species.5 These have been shown to build up over time resulting in electrode de-activation.
In nature, transition metals are found at the core of AOR enzymes such as ammonia monooxygenase which suggests that it is possible to perform this reaction with non-noble catalysts.7 With the issues surrounding noble-metal catalysts and following nature as an example, we have begun investigating the oxidation of ammonia with transition-metal based catalysts. To this end our investigations have revealed that it is possible to conduct electrochemical ammonia oxidation to NOx species with faradaic efficiencies of up to 100%, at appreciable rates with no evidence of catalytic poisoning (see fig. 1). This work represents a step forward in our understanding of the electrochemical AOR reaction and may serve as a foundation for future work in this field.

1. M. H. M. T. Assumpção et al., Int. J. Hydrogen Energy, 39, 5148–5152 (2014).
2. L. Marinčić and F. B. Leitz, J. Appl. Electrochem., 8, 333–345 (1978).
3. A. Galdikas et al., Sensors Actuators B Chem., 67, 76–83 (2000).
4. F. Vitse, M. Cooper, and G. G. Botte, J. Power Sources, 142, 18–26 (2005).
5. Z.-F. F. Li, Y. Wang, and G. G. Botte, Electrochim. Acta, 228, 351–360 (2017).
6. S. Johnston, B. H. R. Suryanto, and D. R. MacFarlane, Electrochim. Acta, 297, 778–783 (2019).
7. J. A. Zahn, D. M. Arciero, A. B. Hooper, and A. A. DiSpirito, FEBS Lett., 397, 35–38 (1996).
Fig. 1. (A) Chronoamperometry conducted in 1 M KOH + 0.1 M NH3 over a time of 48 hours and (B) associated yields of NOx.

Figure 1
Synthesis and Diversification of Azanucleosides By Anodic Oxidation
Authors: Chiba Kazuhiro , Okamoto Kazuhiro , Tsutsui Mizuki , Okada Yohei 
Published: May 2020

Azanucleosides in which the 4'-oxygen atom is replaced with a nitrogen atom are attracting considerable attention due to their anticancer and antiviral activities and resistance to nucleases. However, traditional synthesis strategies require multiple steps and harsh conditions, limiting the structural and functional diversity of the product. Reactive intermediates can be generated by directly activating target C-H bonds on the substrate by electro-organic reactions. We have also developed various electrochemical synthesis methods. Here, we report a novel synthesis method of pharmacologically relevant azanucleosides, riboazanucleosides via site-specific anodic C-H activation.
The anodic oxidation reaction with a lithium perchlorate(LPC)–nitroethane medium activated N-acryloyl(Acr)-prolinol derivatives efficiently by decreasing the oxidation potential, possibly as a result of reduction of the Lewis acidity of Li+ by the nitroethane. When the activated prolinol substrate was coupled at the 5-position with nucleophiles, including nucleobases, the N-Acr group remained intact. The functionality of the prepared N-Acr-azanucleosides was readily increased by chemical modifications.
In addition, C-glycoside is also valuable analogue for naturally occurred O-, N-glycosides because of its stability in biological condition. Especially, C-azanucleoside was developed as transition-state analog of purine nucleoside phosphorylase (PNP), which showing therapeutic effect for leukemia. This gave incentive to establish efficient synthetic method for C-azanucleoside by anodic oxidation. As a result of examining many reaction conditions, a coupling reaction between electroauxiliary (4-methoxyphenylthio group)-tethered prolinol and non-protected 9-deazahypoxanthine was accomplished in the LPC–nitromthane medium (1.0 M). This method opens the way for the electrosynthesis of various C-azanucleoside.

Figure 1