bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solar-Driven Polyvinyl Alcohol Remediation: Black Phosphorus Quantum Dot Sensitized g-C3N4 Photocatalyst Vs. H2 Evolution in Photocatalytic Fuel Cells
Authors: Sun Qiong , Sun Likun , Zhang Baoning , Dong Lifeng 
Published: December 2024

In response to polyvinyl alcohol (PVA) waste pollution, we developed a composite photocatalyst by sensitizing g-C3N4 with black phosphorus quantum dots (BPQDs) using a simple mechanical stirring technique. Both g-C3N4 and BPQDs are inorganic semiconductors, enabling efficient photoinduced charge transfer. Leveraging the adjacency of C, N, and P elements in the periodic table facilitated the formation of P-N or P-C bonds, resulting in uniform BPQD decoration on two-dimensional layered g-C3N4, with an average size of 2.2 nm. Under solar light simulator irradiation for 20 minutes, the composite photocatalyst exhibited significantly enhanced photocatalytic activity, increasing PVA degradation efficiency from 27.1% (pure g-C3N4) to 85.9%. Experimental observations and theoretical calculations suggest the establishment of a Z-scheme route at the g-C3N4/BPQDs interface, facilitating photoinduced electron transfer from g-C3N4 to BPQDs, leading to augmented carrier generation and separation, reduced charge-transfer resistance, and accelerated PVA degradation. The proposed composite photocatalyst holds promise in addressing PVA pollution and promoting environmental sustainability.
Additionally, in a dual-chamber photocatalytic fuel cell setup, simultaneous degradation of PVA and hydrogen evolution were achieved, employing commercial P25 as the photoanode and Ag@Fe2O3 nanoparticles as the cathode. Moreover, the feasibility of a Fenton-like reaction at the cathode, utilizing Fe2+ ions and pumped O2, was demonstrated. The effects of different cathode materials, PVA types, and pH values on device performance were assessed, with quenching tests highlighting the pivotal roles of h+ and OH· radicals in PVA degradation. The device's long-term stability was established through cycling experiments.
Colloidal Synthesis and Photoluminescence Properties of Near-IR-Responsive Ag8GeS6 Quantum Dots
Authors: Rismaningsih Nurmanita , Kubo Junya , Akiyoshi Kazutaka , Kameyama Tatsuya , Yukawa Hiroshi , Baba Yoshinobu , Torimoto Tsukasa 
Published: December 2024

Near-infrared (NIR)-responsive quantum dots (QDs) hold immense promise for a range of applications, such as photovoltaics, photocatalysts, and biomedical imaging. Their unique optoelectronic properties, including tunable photoluminescence (PL) peaks and high PL quantum yields (QY), originate from the quantum confinement effect. In biomedical imaging, QDs offer superior photostability and enhanced biocompatibility compared to traditional organic fluorophores. Although binary QDs, such as CdTe, CdSe, PbS, and HgTe, have been extensively explored, their practical use is limited by the content of heavy metals with high toxicity. Here, we report the first synthesis of Ag8GeS6 QDs emitting a NIR PL peak at 920 nm and their potential as luminescent probes for in vivo bioimaging.
Ge(gly)2(H2O)2 was prepared by the modified method described in previous study, as a germanium precursor resistant to air and moisture.[1] Precursor powders of Ge(gly)2(H2O)2, silver(I) diethyldithiocarbamate, and thiourea were dispersed in a mixture solvent containing 1-dodecanethiol and oleylamine, followed by the heat treatment at 423 K for 20 min. The obtained Ag8GeS6 QDs were surface-coated with a ZnS shell layer with different shell thicknesses.
Spherical Ag8GeS6 QDs were formed with the average size of 4.2–4.6 nm. XRD diffraction patterns showed that the obtained QDs had an orthorhombic Ag8GeS6 crystal structure. The absorption spectra were broad and structureless, with an onset wavelength at around 850 nm. The energy gap was almost constant at 1.48-1.48 eV, regardless of the Ge/(Ag+Ge) ratio in the precursors. The Ag8GeS6 QDs prepared with Ge/(Ag+Ge) = 0.82 exhibited a broad PL peak at 920 nm with a PLQY of 11%. The surface coating with a ZnS shell enhanced the PLQY to 40–42%. The ligand exchange of the QDs with 3-mercaptopropionic acid (MPA) enabled uniform dispersion in an aqueous solution for the application to in vivo bioimaging. The resulting MPA-modified Ag8GeS6@ZnS QDs maintained similar size distribution but the PL QY was slightly decreased to ca. 23%. These QDs were successfully applied for in vivo bioimaging by injecting them into the back of mouse, in which a clear PL image was obtained and the detected PL intensity was proportional to the concentration of injected QDs.In conclusion, the present Ag8GeS6@ZnS QDs seem promising as a probe for bio-imaging, marking a significant advancement in the field and opening avenues for safer and more effective NIR-responsive QDs.
[1] A.S.R. Chesman, et al., Chem. Mater, 26, 5726 (2014).
Synthesis of (9-Triptycyl)Tin Halides for Application in Perovskite Solar Cells
Authors: Hasegawa Akio , Chen Chien-Yu , Nakamura Tomoya , Truong Minh Anh , Murdey Richard , Wakamiya Atsushi 
Published: December 2024

Solar cells using ABX3-type perovskite semiconductors are attracting attention due to their high photoelectric conversion efficiency. However, since most of them use lead (Pb), there is a need to develop Pb-free perovskite solar cells from the viewpoint of environmental impact. Perovskites using tin (Sn) have shown promise as an alternative material for Pb-based perovskites, but many challenges remain in achieving high performance because Sn2+ is more susceptible to oxidation than Pb2+. We have previously improved the quality of Sn-based perovskite films by scavenging the Sn4+ ions1 and applying different surface passivation methods.2,3 Most of the materials used for surface passivation have ammonium groups that can bind to the A-site of the perovskite lattice, or thiocyanate or carboxyl groups that can bind to the X-site. In this work, we present a novel modification method using halometallylene, a highly reactive chemical species that is expected to replace the metal at the B-site of the perovskite structure. For this purpose, we designed a series of halostannylenes, (Trp)XSn: (Trp = 9-triptycyl group, X = F, Cl, Br, and I). These compounds can be added to the precursor solution or applied to the surface of the perovskite layer.
The reaction of 9-triptycyl lithium, which was generated by a lithiation of 9-bromotriptycene with n-BuLi, with SnX2 (X = Cl, Br) gave thermally stable yellow crystals of the product (Figure 1a). The crystals were determined to have a novel five-membered ring structure, {(Trp)XSn}5 (Figure 1b). In a coordinating solvent (dimethyl sulfoxide (DMSO) or pyridine), the compounds transformed into monomeric halostannylene complexes. From cyclic voltammetry (CV) measurements of (Trp)XSn: in DMSO solutions, the shift of the oxidation potential below any tin halide (SnX2, X = F, Cl, Br, and I) confirms that reaction active Sn2+ species, which can reduce Sn4+, were obtained. When (Trp)ClSn: was added to the solution of SnI4 in DMSO-d
6, in the 119Sn NMR spectra, a peak at –2030 ppm corresponding to SnI4 disappeared, and a new peak at –685 ppm was observed corresponding to SnI2. From these results, it’s expected that the compound will function as a reductant for Sn4+ generated in the perovskite precursor solution. In the presentation, we will further discuss the characteristics of (Trp)XSn: and its application to tin perovskite solar cells.
1) T. Nakamura, A. Wakamiya et al, Nat. Commun.
2020, 11, 3008. 2) T. Nakamura, A. Wakamiya et al., ACS Appl. Mater. Interfaces
2022, 14, 56290. 3) S. Hu, A. Wakamiya et al., Adv. Mater.
2023, 35, 2208320.

Figure 1
Alternating Substrate-Ligand Coordination Provides a Lower Energy C-O Bond Cleavage Pathway for Electrochemically Driven Catalytic CO2 Reduction
Authors: Agarwala Hemlata 
Published: December 2024

Large-scale employment of electrocatalysts requires diving deep into their structure and operative mechanism. My talk will focus on the ruthenium-polypyridyl class of electrocatalysts for CO2 reduction to CO, improved over time to reduce the overpotential of electrochemical CO2-reduction. Focus will be on the bottleneck C-O bond-breaking step. Often Brønsted or Lewis acidic metal ions are employed to facilitate C-O bond cleavage. The former usually lead to loss in product selectivity, H2 being a co-product, while the latter usually form insoluble carbonates in anhydrous conditions. We present herein a mechanism with the aforementioned catalyst framework, selective for CO production at a low overpotential, without necessarily requiring an additional acid or base.
1,2
This pathway embodies a metallacyclic intermediate promoting C-O bond cleavage with lower activation barrier compared to C-O cleavage in the acyclic intermediate (Figure 1). Detailed computational studies (DFT), corroborated with FT-IR spectroscopy, substantiate the involvement of the metallacyclic intermediate in the catalytic cycle. Two principal factors dictate the formation of the metallacycle: (1) the flexible
denticity of the polypyridyl ligands, (2) the choice of metal center: one that can exhibit optimal electronic coupling with the ligands and bound CO2, hence functioning as a Lewis base (donates electrons to the incoming CO2) as well as a Lewis acid (accepts electrons from the bound CO2, hence forming the metallacycle), in a single catalytic cycle. Solvation of the intermediates also play a critical role.
References:

1
Agarwala, H.;* Chen, X.; Lyonnet, J. R.; Johnson, B. A.; Ahlquist, M.; Ott, S. Angew. Chem. Int. Ed.
2023, 62, e202218728.

2
Agarwala, H.;* Lyonnet, J. R.; Ott, S. Influence of π-π stacking on electroreduction of CO2. (Manuscript in preparation)

Figure 1. Energetics of two different catalytic pathways for C-O bond cleavage

Figure 1
Solid Oxide Cell Tests inside a Transmission Electron Microscope
Authors: Simonsen Soren Bredmose , Ma Zhongtao , Mølhave Kristian Speranza , Chatzichristodoulou Christodoulos 
Published: December 2024

Simultaneous electrochemical and nano-scale structural/compositional analyses allow for a direct link between a material’s properties and its electrochemical performance. We present a method that merges high-temperature solid-state electrochemical analysis with transmission electron microscopy (TEM)1-3. This method can be important for the further development of solid oxide electrolysis and fuel cells (SOEC/SOFC), and may be applicable to other solid-state electrochemical technologies, such as solid-state batteries and thermoelectric devices.
The presentation shows how to conduct high-temperature electrochemical operando TEM experiments, including electrochemical impedance spectroscopy (EIS) analysis by using an environmental TEM (ETEM) and a MEMS chip-based heating-biasing TEM holder connected to a potentiostat (Fig. 1). The capability of executing electrochemical cell tests in the TEM is validated for both single materials1-2 and full solid oxide cells3 at temperatures up to 800 ˚C in gases such as O2 and H2/H2O, with applied electrical polarization. EIS analysis in the TEM will be showcased. Furthermore, we present results from experiments of polarization-induced degradation at an SOEC electrode-electrolyte interface.

Acknowledgements

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 850850)”

References

Ma, W.L. Dacayan, C. Chatzichristodoulou, K.S. Mølhave, F.M. Chiabrera, W. Zhang, S.B. Simonsen, “Electrochemical Impedance Spectroscopy integrated with Environmental Transmission Electron Microscopy” Small Methods 7 (2023) 2201713. doi.org/10.1002/smtd.202201713

Ma, C. Chatzichristodoulou, W.L. Dacayan, K.S. Mølhave, F.M. Chiabrera, T.E.L. Smitshuysen, C.D. Damsgaard, S.B. Simonsen, “Experimental requirements for high temperature solid state electrochemical TEM experiments”, Small Methods (2024) 2301356, DOI:10.1002/smtd.202301356

Ma, C. Chatzichristodoulou, F.M. Chiabrera, K.S. Mølhave, S.B. Simonsen, “Operando electron microscopy and impedance analysis of solid oxide electrolysis/fuel cells”, ACS Energy Letters, 9 (2024) 2007-2012, DOI: 10.1021/acsenergylett.4c00671

Fig. 1: Heating-biasing MEMS chip for temperature control and electrical polarization; TEM image over symmetric model solid oxide cell mounted on the chip; Nyquist plot of EIS data recorded at OCV at 800 ˚ C from the symmetric model cell in the TEM in a gas mixture of H2 and H2O.

Figure 1
Decoding Electrochemical Interfaces with Computational Approaches: The Case of NiOOH Catalyst
Authors: Kowalski Piotr M. , Ting Yin-Ying , Price Conor , Tipp Fabian , Eikerling Michael 
Published: December 2024

Fundamental understanding of electrochemical interfaces is a prerequisite for designing well performing and economically viable electrocatalyst materials. The rapid increase in supercomputing power accompanied by methodical improvements in atomistic simulations enables an accelerated computer-aided materials design process. Our research in this context integrates theory and advanced simulation methods to decipher the relations between structure, properties and performance of electrochemical interfaces [1-4]. The presentation emphasizes the necessity of combining novel computational schemes [1,2,5,6] with knowledge from solid state chemistry and computational mineralogy in order to be able to rationalize the tremendous enhancement in the activity for the oxygen evolution reaction (OER) under alkaline conditions that is achieved upon Fe-doping of NiOOH [4,7]. Significant research has been dedicated to understanding the enhanced electrocatalytic activity of this material with different, often contradicting mechanisms proposed [7-11]. On the computational side, we identified the severe overestimation of the occupancy of d-orbitals by the widely used DFT+U computational approach as the origin of the problem and corrected it by employing localized Wannier functions as projectors for calculating the occupations of d-orbitals [4,2]. This approach allowed us to correctly compute the band gap of NiOOH and to reveal a realistic electronic structure of Fe-doped NiOOH. It occurred that Fe exists in the low-spin state for Fe contents below the solubility limit in Fe:NiOOH solid solution. The low-spin state of Fe dopant is responsible for lowering the OER overpotential relative to the value for pure NiOOH by ~300 mV, which agrees with the measured decrease [7] . The discovered state allows for the consistent explanation of measured data on ionic and electronic structure as well as magnetic and electrochemical properties. We will show that the miscibility of Fe in NiOOH is related to the sizes of Ni3+ and Fe3+ cations and that it is the closely matching cation radii of Ni and Fe in the low spin state that enable the formation of a mixed phase. Our results reconcile catalyst composition and structure with the mixing behavior in solid solution and the electrocatalytic activity.
[1] Tesch, Kowalski & Eikerling, J. Phys.: Condens. Matter 33, 444004 (2021)
[2] Ting & Kowalski, Electrochim. Acta 443, 141912 (2023)
[3] He et al., Angewandte Chemie 136, e202315371 (2023)
[4] He et al., Nat, Commun. 14, 3498 (2023)
[5] Nishihara & Otani Phys. Rev. B 96 115429 (2017)
[6] Kowalski et al. Front. Energy Res. 10, 1096190 (2023)
[7] Friebel et al., J. Am. Chem. Soc. 137, 1305 (2015)
[8] Conesa, J. Phys. Chem. C 120, 18999 (2016)
[9] Martirez & Carter, Chem. Mater. 30, 5205 (2018)
[10] Tkalych et al., Phys. Chem. Chem. Phys., 20, 19525 (2018)
[11] Rajan et al., J. Am. Chem. Soc. 142, 3600 (2020)
Multiscale Modeling Reveals Mass Transport-Controlled Product Selectivity in Electrochemical CO2 Reduction on Cu
Authors: Ramakrishnan Velmurugan Adith , Ringe Stefan 
Published: December 2024

Electrochemical CO2 reduction is one of the most promising processes for a sustainable closure of the artificial carbon cycle. A severe limitation for wide-scale industrial applicability has been the absence of an efficient and selective electrocatalyst for the reduction of CO2 to higher-reduced valuable chemicals and fuels. Cu is the only catalyst found to produce considerable amount of multicarbon products, albeit at high overpotentials. The mechanism of the conversion process is unclear, with different active sites and rate-determining steps being proposed. In addition, the mass transport of CO2 has been suggested to have a significant impact on the product selectivity1,2. Gas-diffusion-layer(GDL)-based electrolyzers have become a state-of-the-art solution to provide a high concentration of CO2 to the active sites to circumvent these mass transport limitations. In this work, we present a new multi-scale model based on first-principles kinetics3, and a modification of a recently reported gas diffusion electrode model4. We use this to generate a digital twin of experimental electrode systems and show that even in GDL systems, mass transport is the limiting factor governing all experimentally observed trends in product selectivity, irrespective of reaction mechanism or product pathway. We further find indications of C2 products being predominantly formed in wider, accessible pores, while C1 products are generated in deeper and thinner pores with less access to CO2. This work provides strong evidence for the importance of mass transport in designing CO2 electrolyzers.
References:

Watkins, N. B. et al. Hydrodynamics Change Tafel Slopes in Electrochemical CO2 Reduction on Copper. ACS Energy Lett.
8, 2185–2192 (2023).

Ringe, S. et al. Double layer charging driven carbon dioxide adsorption limits the rate of electrochemical carbon dioxide reduction on Gold. Nat. Commun.
11, 33 (2020).

Liu, X. et al. pH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper. Nat. Commun.
10, 1–10 (2019).

Weng, L.-C., Bell, A. T. & Weber, A. Z. Modeling gas-diffusion electrodes for CO2 reduction. Phys. Chem. Chem. Phys.
20, 16973–16984 (2018).
Exploring the Role of Interfacial Water and Adsorbed Hydroxide in Oxygen Reduction Reaction (ORR) Transients
Authors: Spaulding Carolyn , Snyder Joshua David 
Published: December 2024

Recently, Caffeine has been shown to improve the kinetics of the oxygen reduction reaction (ORR)[1], [2]. This activity improvement has been attributed to the adsorption geometry of caffeine at the electrode interface. To better understand this phenomena, fundamental studies of the impact of interfacial water and adsorbed hydroxide species must be conducted. We will examine the transient behavior of ORR on a well-defined Pt(111) electrode to achieve this.
While transient current decay has been discussed regarding membrane electrode assemblies (MEAs), transients are rarely considered for rotating disk electrode (RDE) experiments [3]. We have found that Pt(111) transients in the ORR potential window last in the order of hundreds of seconds, notably longer than what is typically observed for polycrystalline electrodes. During these transients, initially slow current decay occurs until a critical point, where an inflection point indicates the transition to more rapid decay. We hypothesize that these dynamic transients are caused by 2D nucleation and growth of adsorbed spectator hydroxide islands. We will present our understanding of the surface processes occurring during ORR transients, gained from experiments in conjunction with microkinetic and kinetic Monte Carlo modeling. Understanding the kinetics of these surface processes will inform the development of small molecule interface modifiers, such as caffeine, that must balance ORR activity with transient behavior.

References

[1] R. Gawas, “Modifying Interface Solvation to Improve the Oxygen Reduction Reaction Electrocatalysis,” Doctor of Philosophy, Drexel University, Philadelphia, Pennsylvania, United States, 2023. doi: 10.17918/00001760.
[2] N. Hoshi, M. Nakamura, R. Kubo, and R. Suzuki, “Enhanced oxygen reduction reaction on caffeine-modified platinum single-crystal electrodes,” Commun Chem, vol. 7, no. 1, p. 23, Feb. 2024, doi: 10.1038/s42004-024-01113-6.
[3] J. Dang, F. Yang, Y. Li, X. Deng, and M. Ouyang, “Transient behaviors and mathematical model of proton exchange membrane electrolyzer,” Journal of Power Sources, vol. 542, p. 231757, Sep. 2022, doi: 10.1016/j.jpowsour.2022.231757.
Co-Ion Identity Affects Double Layer Structure and Reactivity Trends in the Hydrogen Evolution Reaction
Authors: Anderson Seth R. , Johnstone Samuel G. , Dent Aaron M. , Liu Beichen , Guo Wenxiao , Gebbie Matthew A. 
Published: December 2024

The formation of an electric double layer is ubiquitous in electrolytes undergoing electrochemical reactions. Currently, models for the double layer rely on the assumptions of dilute electrolyte theory where ions in solution do not interact. Dilute electrolyte theory predicts that solely hydrated counterions, or ions opposing the surface charge, occupy the near surface region and impact reactivity. Since this theory does not account for conditions like high applied potentials and high ion concentrations, understanding the relationship between double layer structure and electrochemical reactivity is critical for opening new domains for electrochemical modulation.
Notably, our recent work shows that co-ions, or ions with the same charge as the surface, can also have a definitive influence on reaction rates, particularly under conditions of high applied potential and large bulk ion concentrations. In this talk, I will discuss how to use the hydrogen evolution reaction as a model system to explore co-ion effects in electrocatalytic reactions. In our work, we systematically vary co-ion identity and track hydrogen evolution reactivity as a function of concentration to highlight how the co-ion becomes increasingly relevant in the concentrated regime. In particular, we highlight the unique ability of the tetrafluoroborate co-ion to undergo dynamic ligand exchange between hydroxide and fluoride. This allows tetrafluoroborate to act as a hydroxide sink to stabilize the hydrogen evolution byproduct. Furthermore, I will discuss our use of Raman spectroscopy to describe how co-ions impact interfacial hydrogen bonding networks, which can have a significant impact on aqueous electrochemistry. Our results highlight how co-ions influence double layer structures and have significant implications for tuning other aqueous reactions such as carbon dioxide and nitrate electroreduction.