bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monolithic Lead Halide Perovskite Based Photoanode with 9.16% Applied Bias Photon-to-Current Efficiency
Authors: Kim Tae Gyun , Park Jong Hyeok 
Published: December 2024

The quest for sustainable hydrogen production through solar energy conversion has directed attention towards photoelectrochemical (PEC) cell water splitting, a promising avenue for hydrogen (H₂) generation. Traditional metal-oxide-based photoelectrodes such as TiO2 and WO3, despite their extensive study, fail to absorb visible light effectively and exhibit poor charge transport properties. In contrast, lead halide perovskites (LHPs) emerge as a superior alternative, endowed with exceptional optoelectronic properties that enhance the solar spectrum photoresponse, critical for the efficient utilization of solar energy in hydrogen production.
This study focused on optimizing the photoanode materials by improving the intrinsic properties of LHPs through bandgap tuning and enhanced charge transfer to the oxygen evolution reaction (OER) catalyst. However, the operational stability of LHPs in PEC applications poses a formidable challenge, primarily due to vulnerability to moisture-induced degradation.
Addressing the stability concerns, some researches about application of ultrathin Ni surface layers and the use of low-melting-point field metals for protective encapsulation are reported. However, these methods have shown limited success in preventing moisture-induced degradation. In response, this work proposes the innovative use of conductive carbon poweder (CCP) as a superior alternative for enhancing electrical connectivity and stability between LHP solar cells and the OER catalyst.
Our findings reveal that CCP's superior conductivity facilitates efficient charge transfer from LHP-based solar cells to OER catalysts, maintaining negligible current and voltage loss. To optimize the LHP photoanode's performance, we focused on enhancing the individual efficiencies and stabilities of the PSC and OER catalyst components. For the PSC, we improved stability by integrating a smaller cation (methylammonium, MA) into the FAPbI3 (formamidinium, FA) lattice, thereby stabilizing the α-phase and enhancing hydrogen bonding. This modification was substantiated through various spectroscopic and X-ray diffraction. Meanwhile, the OER catalyst's efficiency was amplified by employing a 3D-structured NiFe on an Ni foil substrate, improving catalytic activity and stability through enhanced hole mobility and increased electrochemically active surface area.
The integrated LHP photoanode demonstrated a notable onset potential of 0.56 V and a peak photocurrent density of 24.26 mA/cm² at 1.23 V vs RHE, achieving a 9.16% applied bias photon-to-current efficiency and sustained performance over 48 hours in a pH 14 aqueous solution under simulated solar illumination. This performance is attributed to the synergistic effect of the optimized PSC and OER catalyst, facilitated by CCP's efficient electrical connectivity.
(Invited) Enhancing Efficiency, Stability and Versatility in Dye-Sensitized Photoelectrochemical Cells Via Spatially Controlled Cascade Charge Transfer
Authors: Kwon Tae_Hyuk 
Published: December 2024

In this talk, I will present my group's recent research on dye-sensitized photoelectrochemical cells (DSPECs) aimed at green energy generation. Initially, I will introduce a molecular-design strategy that integrates both strong and relatively weak electronic couplings within a single sensitizer. This approach aims to facilitate vectorial electron transfer, mirroring the efficiency seen in natural photosystems, thereby improving light harvesting efficiency.
Next, to overcome the challenges of low photocurrent and limited stability in DSPECs, we develop a buried junction-type DSPEC. This utilizes a platinum-sputtered nickel foil to encapsulate both the dye-sensitized TiO2 layer and the redox mediator electrolyte. This design facilitates spatially controled cascade charge transfer, effective photoconversion, and water oxidation without the issues of current leakage. It also ensures high stability and versatility. By altering the photoredox electrolytes, we are able to reduce the onset potential required for water oxidation. Additionally, optimizing the kinetics of water oxidation is achieved by replacing the Ni catalyst with NiFe-LDH catalysts, which result in the photocurrent densities of 14.5 mA/cm² at 1.23 V versus the reversible hydrogen electrode.
Moreover, by substituting the Pt catalyst with oxygen-doped carbon nanotubes, we broaden the application of our buried-junction DSPECs to include the bias-free production of hydrogen peroxide with a solar-to-fuel efficiency (STF) of approximately 3.76%, and a high photostability.
Coupling Time-Resolved Mass Spectrometry Techniques to Unravel Cobalt Degradation Mechanisms in Acidic Media for Oxygen and Hydrogen Electrocatalysis
Authors: Aleman Ashton M. , Crago Colin Flynn , Kamat Gaurav A. , Mule Aniket Sandip S. , Nielander Adam C , Burke Stevens Michaela , Jaramillo Thomas F. 
Published: December 2024

Cobalt plays a significant role within sustainable energy technologies, including but not limited to hydrogen fuel cells for transportation, lithium-ion batteries for electric vehicles and portable devices, and electrolyzers for renewable hydrogen production. For devices that contain a proton exchange membrane (PEM), such as proton exchange membrane fuel cells (PEMFCs) and proton exchange membrane water electrolyzers (PEMWEs), cobalt-based materials are commonly used to perform the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), respectively. However, the PEM in these devices induces an acidic environment (pH = 1) that cobalt is thermodynamically unstable in under ORR and HER relevant potentials. This instability results in cobalt dissolution and as a consequence, substantial decreases in device performance and lifetime. To mitigate such dissolution of cobalt-based materials in acidic environments, a holistic understanding of cobalt’s degradation mechanism is required. To gain such an understanding, we have developed an experimental platform with comparable in-situ and operando techniques, including on-line inductively coupled plasma mass spectrometry (ICP-MS) and electrochemical mass spectrometry (EC-MS), to concurrently monitor relationships between electrochemical output (current/voltage), time, cobalt dissolution, and product formation (i.e, H2 and H2O).
Under HER relevant potentials in acidic media (0.1 M HClO4), it was observed that cobalt is active for HER and undergoes little to no dissolution (< 10 ppb Co2+) while evolving H2, per comparable EC-MS and ICP-MS experiments. These observations suggest that cobalt stability in acidic media strongly coincides with hydrogen evolution. Additionally, these data showcase a surprising window of stability for cobalt that is different than would have been predicted with classical chemical thermodynamics (i.e., Pourbaix diagrams). Along with cobalt being HER active, we have also uncovered its activity for ORR in acidic media (O2 saturated 0.1 M HClO4). Furthermore, the rate of cobalt dissolution was different in O2 versus N2 saturated electrolyte, where it was observed that cobalt dissolution initially occurs faster (~3x more dissolution) in the presence of O2. Altogether, this work showcases how time-resolved techniques such as ICP-MS and EC-MS can be combined to unravel material degradation mechanisms, with cobalt as a case study. This experimental platform has high potential to accelerate current understandings of material degradation, paving the way for new avenues to design and develop more robust and affordable materials and devices.
(Invited) First Principles Treatments of Oxygenate Electrooxidation – Structure Sensitivity and Influence of Solvent on Chemically Diverse Elementary Reaction Steps
Authors: Greeley Jeffrey , Deshpande Siddharth , Dupleiss Brady , Zeng Zhenhua 
Published: December 2024

Advances in the theoretical understanding of electrochemical systems have, over the past decade, led to growing use of periodic Density Functional Theory (DFT) studies to treat a surprisingly large ensemble of electrocatalytic reactions, ranging from carbon dioxide electroreduction to oxygen evolution. Many such studies have employed simplified models of the electrochemical environment to determine reactivity trends across a broad space of catalytic materials, while other efforts have focused on developing detailed descriptions of electrochemical phenomena, such as the structure of electrochemical double layers, on model catalyst structures. An emerging challenge is to combine these approaches to ultimately enable theoretical design of electrocatalysts for reactions of significantly expanded chemical and materials complexity.
In this talk, we begin by discussing how we develop and apply DFT-based methods to study the electrooxidation of ethanol and related oxygenated species on Pt surfaces. We show how explicit double layer models and ab initio molecular dynamics provide exciting insights beyond the traditional computational hydrogen electrode treatments, leading to improved descriptions of elementary reaction steps involving adsorption/desorption of reaction intermediates and proton-coupled electron transfer processes. By combining the aggregate results with detailed microkinetic models and explicit descriptions of adsorbate-adsorbate interactions, we further demonstrate how these effects can influence both the predicted overpotentials and the selectivities to acetic acid, acetaldehyde, and carbon dioxide. We conclude with some perspectives on how these insights may be used to enhance the search for improved oxygenate electrooxidation catalysts.
Theoretical Studies of Hydrogen Evolution Involving Imidazolium Proton Donors
Authors: Bagbudar Zeynep , Warburton Robert 
Published: December 2024

The hydrogen evolution reaction (HER) is an important electrocatalytic reaction used for the electrochemical production of hydrogen gas. Its reverse reaction, the hydrogen oxidation reaction, is used to produce protons used in electrocatalytic reduction reactions for various electrochemical energy conversion and storage applications. While many fundamental studies have analyzed interfacial reactivity in aqueous HER, analogous mechanistic understanding of HER reactivity in nonaqueous media remains limited.
In this presentation, periodic density functional theory (DFT) calculations are applied to mechanistic studies of HER on Pt(111) using various imidazolium proton donors. These studies incorporate analyses of imidazole adsorption and potential-dependent activation energies. The conjugate bases of imidazole adsorb strongly to the electrode surface. Yet, the adsorption geometries and energetics are sensitive to substituent effects and isomeric configurations at the interface. The potential-dependent binding geometries and adsorption energies of different imidazoles adsorbed to Pt(111) are analyzed in a dielectric continuum implicit solvent. These calculations demonstrate how imidazole derivatization and electrode surface charge impact the adsorption of imidazole conjugate bases during HER. To gain insights into the kinetics of the elementary Volmer and Heyrovsky steps of HER, potential-dependent reaction energies and activation barriers were calculated using the charge extrapolation method. Energetics were calculated for different electrode potentials by modifying the coverage of protons. This approach was used to develop relationships between reaction thermodynamics and kinetics via Brønsted–Evans–Polanyi relationships for various imidazoles, where this relationship gives charge transfer coefficients in the Butler–Volmer equation. The goal of assessing these reaction parameters is to enhance understanding of charge transfer processes and molecular interactions at the electrode-electrolyte interface, which is essential for the design of high-efficiency energy conversion and storage devices. The potential-dependent adsorption behavior and kinetics of elementary proton-coupled electron transfer steps are used to understand the reaction kinetics of hydrogen evolution in a nonaqueous imidazole-based electrolyte through comparisons to voltammetry measurements. Through these analyses, we identify kinetic trends across functionalized imidazoles, providing valuable perspectives for the development of catalytic systems and energy storage technologies.
(Invited) Operando Spectroscopy-Inspired Design of Electrolyte-Electrode Interface
Authors: Katayama Yu 
Published: December 2024

There has been a growing recognition that not only electrocatalysts but electrolytes influence the activity of surface electrocatalytic reactions. Therefore, understanding the electrolyte-electrode interface under realistic operating conditions is critical to designing active and stable electrochemical devices. The past few decades of research have focused on developing a range of spectroscopic and imagining tools to enable the study of the chemical and structural changes at the electrolyte-electrode interface. Here, we introduce operando surface-enhanced infrared absorption spectroscopy (SEIRAS), a promising lab-based tool for gaining a molecular-level understanding of interfacial electrochemical processes.
This talk will bring the most recent understanding of the electrochemical interface during the operation of electrolysis applications, including electrochemical CO2 reduction reaction and water splitting, using operando SEIRAS. Furthermore, we demonstrate that the holistic information about the complex interaction in the electrochemical interface can alter the reaction energetics/kinetics in a way incapable of electrode-centered design strategy. We will highlight the significance of advanced operando techniques to accelerate the design of electrochemical interfaces by providing additional knobs to tune the reaction energetics/kinetics, leading further improvements in electrocatalytic activity for energy conversion and storage reactions.
PtPdSn Electrocatalysts for Nitrous Oxide Reduction
Authors: Kato Masaru , Sarker Abinash Chandro , Zheng Jinhang , Saito Fumie , Kawamura Mitsuki , Unuma Yuki , Yagi Ichizo 
Published: December 2024

Nitrous oxide (N2O) is a greenhouse gas almost 300 times more potent than CO2 and an ozone-depleting gas. N2O is increasing in the atmosphere by about one ppb per year. Electrocatalysis allows us to reduce N2O to N2 under ambient conditions at room temperature and atmospheric pressure, making electrocatalysis a promising approach for the removal of N2O. The electrochemical nitrous oxide reduction reaction (N2ORR) can be catalyzed on metals such as Pd [1,2]. Although bimetallic Au@Pd core@shell nanoparticles [3] have been reported as electrocatalysts for the N2ORR, synthetic strategies and design principles of multimetallic electrocatalysts for the N2ORR are still lacking.
Herein, we report our research progress on trimetallic PtPdSn electrocatalysts for the N2ORR in acidic media, inspired by electrocatalysts for the nitrate reduction reaction (NO3RR). The electrocatalytic NO3RR to N2 proceeds via N2ORR. It has been reported that Sn/Pd-Pt(100) electrodes produce NO, N2O and N2 in the NO3RR but Sn/Pt(100) does not [4], suggesting that the Sn/Pd-Pt interface plays an important role in the electrocatalysis for the N2ORR. This study encourages us to prepare co-deposited Pt and Pd nanoparticles on fluorine-doped tin oxide using the arc plasma deposition method [5]. Pt and Pd nanoparticles deposited on fluorine-doped tin oxide show higher electrocatalytic activity for both NO3RR and N2ORR than those deposited on glassy carbon [5]. This result also supports that the Sn/Pd-Pt interface is crucial for the efficient catalysis of the N2ORR. We are now working on PtPdSn nanoparticles supported on carbon black (PtPdSn/C) for the N2ORR in acidic media [6]. PtPdSn/C shows higher N2ORR activity than bimetallic PtPd/C or PtSn/C and exhibits almost 100% Faradaic efficiency for the the N2ORR to N2 at ≥ +0.06 V vs. RHE with no competition with the hydrogen evolution reaction. The trimetallic PtPdSn electrocatalysts will be a promising candidate for the efficient removal of N2O towards a sustainable society.
References.
[1] A. Kudo, A. Mine, J. Electroanal. Chem., 408, 267–269 (1996).
[2] B.H. Ko, B. Hasa, H. Shin, Y. Zhao, F. Jiao, J. Am. Chem. Soc., 144, 1258–1266 (2022).
[3] K. Kim, J. Byun, H. Kim, K.S. Lee, H. S. Lee, J. Kim, T. Hyeon, J.J. Kim, J.W. Han, ACS Catal., 11, 15089–15097 (2021).
[4] M. Kato, Y. Unuma, M. Okui, Y. Qu, J. Zheng, S. Taguchi, F. Kiguchi, M. Torihata, Y. Gao, N. Hoshi, I. Yagi, Electrochim. Acta, 398, 139281 (2021).
[5] A.C. Sarker, M. Kato, I. Yagi, Electrochim. Acta, 425, 140628 (2022).
[6] A.C. Sarker, M. Kato, M. Kawamura, T. Watanabe, I. Yagi, submitted.
Investigating the Effect of Copper Ion Impurities on the Structural Evolution and Electrocatalytic Activity of Catalysts for HER
Authors: Saini Sonakshi , Lee Seunghoon , Wright Salem Clay , Parvin Sahanaz , Weber Juliane , Baltrusaitis Jonas , McDowell Matthew Todd 
Published: December 2024

Seawater splitting has garnered significant research interest recently as a method to produce green hydrogen at reduced costs1. One major limitation is the effect of naturally present impurities on all parts of an electrolyzer2– from the membranes to the catalysts. Transition metal cations with reduction potentials in the range of the hydrogen evolution reaction (HER) could interfere with the electrocatalytic reaction. Although this effect has been investigated in the context of underpotential deposition3, there is limited understanding of how competitive redox processes involving impurity ions can influence HER on electrocatalytic electrodes. Here, we study the effect of copper as an impurity ion in the presence of electrocatalytic (platinum) and non-electrocatalytic (gold) electrodes to understand the dynamic competition between electrodeposition and HER. We find that copper deposition competes with HER on both platinum and gold surfaces, leading to a significant decrease in current density with increasing copper concentration. The electrode surfaces are characterized with scanning electron microscopy and atomic force microscopy to understand morphological evolution of the growing copper metal, and X-ray photoelectron spectroscopy is used to quantify the nanoscale thickness of deposited copper. At relatively high dissolved Cu2+ concentrations, copper metal is observed to electrodeposit uniformly on gold electrodes, whereas platinum features nonuniform copper growth with pits and channels likely due to the influence of hydrogen evolution. In situ atomic force microscopy is also used to gain insight into the nucleation and growth behavior of copper on these different electrodes. Together, the results clearly show that redox competition of copper impurities can occur even at the relatively low concentrations of Cu2+ found in seawater (~1 μM)4, highlighting the importance of studying the effect of different impurities on the catalyst under consideration. This work is intended to eventually lead to robust electrolyzers that can be used to efficiently produce hydrogen under impure input stream conditions, potentially lowering costs.
REFERENCES:

Tong, W., et al., Nature Energy (2020) 5 (5), 367

Becker, H., et al., Sustainable Energy & Fuels (2023) 7 (7), 1565

Cadle, S. H., and Bruckenstein, S., Analytical Chemistry (1971) 43 (13), 1858

Leal, P. P., et al., Sci Rep (2018) 8 (1), 14763
Investigating the Impact of Electrochemical Active Surface Area of Cu with Surfactant-Modified Carbon on Electrochemical CO2 Reduction in Acidic Electrolyte
Authors: Noh Hwiyoon , Tackett Brian Michael 
Published: December 2024

Electrochemical CO2 reduction reaction (CO2RR) offers a promising avenue for transforming CO2 into valuable products, which can enable sustainable carbon utilization when powered by renewable energy sources. Traditionally, neutral or alkaline electrolytes are used in CO2RR to prevent hydrogen evolution reaction (HER). Employing such electrolytes, however, poses challenges due to homogeneous equilibrium reactions, leading to limiting CO2 availability and high energy consumption for electrolyte regeneration. Lowering electrolyte pH can address this issue and mitigate the required energy, resulting in industrially relevant efficiencies. Recent studies demonstrated encouraging results for CO2RR in acidic environments using flow cells. However, it remains unclear how conventional electrocatalysts perform under acidic conditions compared to neutral or alkaline ones. In addition, it is uncertain whether previous knowledge can be applied to acidic electrolytes in the same manner from neutral and alkaline conditions. Thus, in this study, we aim to evaluate the influence of surfactant-modified synthesis methods on the electrochemical active surface area (ECSA) of Cu and CO2RR performance in an acidic electrolyte.
Different types of surfactants were employed to synthesize size-modulated Cu nanoparticles (NPs) on carbon black. Specifically, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 represented cationic, anionic, and nonionic surfactants, respectively. Synthesis without surfactant treatment was further performed to elucidate surfactant-driven effects. Interestingly, variations in the size and distribution profiles of Cu NPs on carbon black were observed due to two roles of surfactant used in the synthesis: surface charge modifier and capping agent. In addition, the ECSA of Cu depended on the size and distribution of Cu NPs, highlighting the importance of both small size and uniform distribution to maximize ECSA. Finally, CO2RR activity was measured in a lab-made flow cell using 0.1 M H2SO4 with 0.4 M K2SO4. It was observed that large ECSA was beneficial to promoting CO2RR over HER with selective production of C2H4 over CH4 while the intrinsic activity of Cu itself was maintained. It was additionally reported that the selectivity of C2H4 over CH4 in the acidic electrolyte was more than 5 times higher than that in a neutral electrolyte, emphasizing the importance of the use of acid for CO2RR. Overall, this work provides critical electrocatalyst design criteria for efficient C2H4 production under acidic environments.
Enabling Photoelectrochemical CO2 Reduction Catalyzed by a Molecular Iridium Catalyst Anchored Onto Oxide-Coated Silicon
Authors: Shin Samuel Jaeho , He Shi , Keller Landon , Tereniak Stephen , Nevia Sampaio Renato , Dones Lassalle Christian Y , Powers Rebecca , Yang Hyuenwoo , Jordan Aldo , Parsons Gregory N. , Cahoon James , Leibfarth Frank A , Miller Alexander J. M. , Dempsey Jillian Lee 
Published: December 2024

(Photo)electrochemical CO2 reduction (CO2R) has been of great interest not only for its promising route to economic, transportable, storable, and sustainable fuels,but also for the fundamental study of factors that impact the identity of the reaction product(s). Among such well-behaved catalytic systems, the pentamethylcyclopentadienyl-ligated Ir(III) half-sandwich complex with 2,2’-bipyridine derivatives is a representative class with both electrochemical and photochemical CO2R catalysis reported. However, its photoelectrochemistry for CO2R has scarcely been studied.
In this work, we investigated the potential utility of half-metallocene Ir(III) complex anchored onto SiO2-coated silicon (prepared via rapid thermal annealing) and TiO2-coated silicon (prepared via atomic layer deposition) as a hybrid system and investigated their photoelectrochemical properties under illumination. Both formate and CO were produced from CO2
with high turnover numbers. Current investigations are focused on understanding how surface anchoring impacts selectivity.