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1. Enhancing the acidic oxygen evolution reaction efficiency of sol–gel synthesized SrCo0.5Ir0.5O3 catalysts through optimized ball milling and acid leaching

   https://doi.org/10.1063/5.0242496  

   Yang, Dongqi; Andreas, Nicolai; Yadav, Ankit K; Stylianou, Kyriakos C; Feng, Zhenxing (March 2025, APL Energy)

   High-efficiency and low-cost catalysts for the oxygen evolution reaction (OER) in acidic electrolytes are critical for electrochemical water splitting in proton exchange membrane (PEM) electrolyzers to produce green hydrogen, a clean fuel for sustainable energy conversion and storage. Among OER catalysts, solid-state synthesized SrCo1−xIrxO3 has demonstrated superior activity compared to commercial standards, such as IrO2 and RuO2. However, the solid-state synthesis process is economically inefficient for industrial use due to the potential for impurities and low yield of the final product. In addition, the requirement for electrochemical cycling to activate the catalyst introduces contaminations and uncertainties for industrial applications. In this study, a modified solution-based sol–gel method was employed to produce SrCo0.5Ir0.5O3 (SCIO) with high purity and yield. Subsequent ball milling and acid leaching treatments were applied, resulting in a catalyst with higher efficiency than those activated solely by electrochemical cycling. The electrochemical analysis and physical characterizations of our SCIO catalyst after ex-situ post-synthesis treatments show a similar active phase in composition and structure to those obtained through in situ electrochemical cycling and activation. Our approach simplifies the preparation process, making the catalyst ready for direct use in PEM electrolyzers without further treatment, offering a promising solution for producing high-performance, industrial-scale OER catalysts. 

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2. Directly Predicting Limiting Potentials from Easily Obtainable Physical Properties of Graphene-Supported Single-Atom Electrocatalysts by Machine Learning

   https://doi.org/10.1039/C9TA13404B  

   Lin, Shiru; Xu, Haoxiang; Wang, Yekun; Zeng, Xiao Cheng; Chen, Zhongfang (January 2020, Journal of Materials Chemistry A)

   Oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are three critical reactions for energy-related applications, such as water electrolyzers and metal-air batteries. Graphene-supported single-atom catalysts (SACs) have been widely explored; however, either experiments or density functional theory (DFT) computations cannot screen catalysts at high speed. Herein, based on DFT computations of 104 graphene-supported SACs (M@C3, M@C4, M@pyridine-N4, and M@pyrrole-N4), we built up machine learning (ML) models to describe the underlying pattern of easily obtainable physical properties and limiting potentials (errors = 0.013/0.005/0.020 V for ORR/OER/HER, respectively), and employed these models to predict the catalysis performance of 260 other graphene-supported SACs containing metal-NxCy active sites (M@NxCy). We recomputed the top catalysts recommended by ML towards ORR/OER/HER by DFT, which confirmed the reliability of our ML model, and identified two OER catalysts (Ir@pyridine-N3C1 and Ir@pyridine-N2C2) outperforming noble metal oxides, RuO2 and IrO2. The ML models quantitatively unveiled the significance of various descriptors and fast narrowed down the potential list of graphene-supported single-atom catalysts. This approach can be easily used to screen and design other SACs, and significantly accelerate the catalyst design for many other important reactions. 

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3. Electric Field Poling Effect on the Electrocatalytic Properties of Nitrogen-Functionalized Graphene Nanosheets

   https://doi.org/10.1002/ente.201800327  

   Jahan, Maryam; Li, Kuo; Zhao, Guang-Lin (June 2018, Energy Technology)

   Fuel cells are attractive new technologies for producing sustainable and green energy. However, the high cost of its components such as Pt electrocatalyst is a major challenge. Heteroatom doped carbon nano‐materials show potential applications for oxygen reduction reaction (ORR) which can be used for fuel cells and may be promising replacement of Pt catalyst. Recently, we implemented a facile method for preparing partially nitrogen functionalized graphene oxide (PNG) nano‐sheets. To achieve better nitrogen functionalization, graphene oxide was annealed in ammonia solution for 12 h at 220oC. The electrochemical measurement data show that the PNG synthesized in NH3 environment possesses good electrocatalytic activities for ORR. In addition, we identified a physical method for the first time to drive the randomly oriented graphene nano‐sheets to be aligned parallel to the surface of electrode for electrocatalytic application by using an AC electric field. An additional effect of the applied electric field is the induction of a polarization on PNG nano‐sheets that create a dielectrophoresis phenomenon. The poling effect of the electric field on the sample shows much improved electrocatalytic performance. The enhanced catalysis can be used for ORR as an important reaction in fuel cells. The reported new method can achieve a low cost capability for preparing new electrocatalyst electrodes for large‐scale applications. 

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4. Mechanistic insights into oxygen reduction reaction on metal/perovskite catalysts: Interfacial interactions and reaction pathways

   https://doi.org/10.1016/j.ssi.2025.116808  

   Li, Wenhao; Drozd, Vadym; Sozal, Md_Shariful_Islam; Li, Meng; Cheng, Zhe (March 2025, Solid State Ionics)

   The oxygen reduction reaction (ORR) is a critical process in energy conversion systems, influencing the efficiency and performance of various devices such as fuel cells, batteries, and electrolyzers. Perovskite-supported metal materials (metal/perovskite) offer several advantages as ORR electrocatalysts, including strong metal-support interactions, oxygen vacancy formation in the perovskite lattice, and synergistic triple-phase boundary (TPB) activity at the interface. Despite their significance, the mechanistic understanding of ORR on metal/perovskite catalysts remains incomplete, particularly at metal/perovskite interfaces. This study investigates ORR on BaZrO3 (BZO) perovskite-supported metal clusters (Pt or Ag) using density functional theory (DFT) to unravel critical insights into charge redistribution at the metal/BZO interface. Energy profiles for elemental steps along two different ORR pathways—oxygen adsorption on the metal cluster surface and direct oxygen adsorption at the TPB—were calculated to explore the effects of different active sites. The results provide a deeper understanding of ORR on metal/perovskite catalysts, emphasizing the role of interfacial interactions and pathway-dependent reaction mechanisms. This work paves the way for guiding the design of high-performance electrocatalysts for ORR in terms of composition, interface design, and local environment modification for a broad range of energy applications. 

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5. Managing the Nitrogen Cycle via Plasmonic (Photo)Electrocatalysis: Toward Circular Economy

   https://doi.org/10.1021/acs.accounts.1c00446  

   Nazemi, Mohammadreza and (November 2021, Accounts of chemical research)

   Burrows, Cynthia J. (Ed.)

   As renewable energy sources are either intermittent in nature or remote in location, developingng cost-effective, sustainable, modular systems and technologies to store and transport renewables at an industrial scale is imperative. Storing cheap renewable electricity into chemical bonds (i.e., chemical energy storage) could be a transformative opportunity for reliable and resilient grid energy storage. This approach enables renewables to be stored and shipped similarly to fossil fuels. Currently, the chemical industry primarily consumes fossil feedstock as an energy source, which has been the standard for over a century. A paradigm shift is required to move toward a more sustainable route for chemical synthesis by electrifying and decarbonizing the modern chemical industry. As renewable electricity costs decrease, (photo)electrosynthesis is gaining interest for synthesizing high-value and high-energy fuels and molecules in a clean, sustainable, and decentralized manner. The nitrogen cycle is one of the Earth’s most critical biogeochemical cycles since nitrogen is a vital element for all living organisms. Artificial nitrogen fixation via a (photo)electrochemical system powered by renewables provides an alternative route to resource- and carbon-intensive thermochemical processes.(Photo)electrochemical nitrogen fixation at a large scale necessitates the discovery of active, selective, and stable heterogeneous (photo)electrocatalysts. In addition, the use of advanced in situ and operando spectroscopic techniques is needed to pinpoint the underlying reaction mechanisms. The selectivity of nitrogen (N2) molecules on the catalyst surface and suppressing thermodynamically favorable side reactions (e.g., hydrogen evolution reaction) are the main bottlenecks in improving the rate of (photo)electrochemical nitrogen fixation in aqueous solutions. The rational design of electrode, electrolyte, and reactors is required to weaken the strong nitrogen−nitrogen triple bond (NN) at or near ambient conditions. This Account covers our group’s recent advances in synthesizing shape-controlled hybrid plasmonic nanoparticles, including plasmonic−semiconductor and plasmonic−transition metal nanostructures with increased surface areas. The nanocatalysts’ selectivity and activity toward nitrogen conversion are benchmarked in liquid- and gas-phase electrochemical systems. We leverage operando vibrational-type spectroscopy (i.e., surfaceenhanced Raman spectroscopy (SERS)) to identify intermediate species relevant to nitrogen fixation at the electrode−electrolyte interface to gain mechanistic insights into reaction mechanisms, leading to the discovery of more efficient catalysts. Operando SERS revealed that the nitrogen reduction reaction (NRR) to ammonia on hybrid plasmonic−transition metal nanoparticle surfaces (e.g.,Pd−Ag) occurs through an associative mechanism. In the NRR process, hydrazine (N2H4) is consumed as an intermediate species. A femtosecond pulsed laser is used to synthesize hybrid plasmonic photocatalysts with homogeneously distributed Pd atoms on a Au nanorod surface, resulting in enhanced optoelectronic and catalytic properties. The overarching goal is to develop modular photoelectrochemical systems for long-duration renewable energy storage. In the context of nitrogen fixation, we aim to propose strategies to manage the nitrogen cycle through the interconversion of N2 and active nitrogen-containing compounds (e.g., NH3,NOx), enabling a circular nitrogen economy with sustainable and positive social and economic outcomes. The versatile approaches presented in this Account can inform future opportunities in (photo)electrochemical energy conversion systems and solar fuel-based applications. 

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