Review
Chemistry, Physical
Shouwei Zuo, Zhi-Peng Wu, Huabin Zhang, Xiong Wen (David) Lou
Summary: This review elaborates on recent advances in the study of OER electrocatalysts using several in situ/operando techniques, with an emphasis on tracking the structural evolution processes, recording reaction intermediates, and establishing the structure-activity/stability relationship.
ADVANCED ENERGY MATERIALS
(2022)
Review
Chemistry, Physical
Verena Streibel, Juan J. Velasco-Velez, Detre Teschner, Emilia A. Carbonio, Axel Knop-Gericke, Robert Schloegl, Travis E. Jones
Summary: The combination of operando and computational X-ray spectroscopies has the potential to build accurate models of active catalyst surfaces. This review discusses recent efforts and future opportunities to study the oxygen evolution reaction (OER) using these techniques.
CURRENT OPINION IN ELECTROCHEMISTRY
(2022)
Article
Chemistry, Physical
Nipon Deka, Travis E. Jones, Lorenz J. Falling, Luis-Ernesto Sandoval-Diaz, Thomas Lunkenbein, Juan-Jesus Velasco-Velez, Ting-Shan Chan, Cheng-Hao Chuang, Axel Knop-Gericke, Rik V. Mom
Summary: In the search for rational design strategies for OER catalysts, understanding the link between catalyst structure and activity and stability is crucial. Highly active catalysts like IrO x and RuO x undergo structural changes under OER conditions, requiring consideration of the operando structure of the catalyst. X-ray absorption spectroscopy (XAS) and electrochemical scanning electron microscopy (EC-SEM) were used to study the activation of amorphous and crystalline ruthenium oxide under OER conditions. The data showed that the activation of the oxygen lattice, especially in amorphous RuO x , is key for its high activity and low stability.
Article
Chemistry, Multidisciplinary
Andrew R. Akbashev, Vladimir Roddatis, Christoph Baeumer, Tianchi Liu, J. Tyler Mefford, William C. Chueh
Summary: Mechanistic studies have primarily focused on activity origins of oxide electrocatalysts for water oxidation, with limited attention to fundamental properties related to stability. This work presents a dynamic view of perovskite stability through operando electrochemical atomic force microscopy, tracking Sr leaching and perovskite dissolution during the oxygen evolution reaction. The study reveals that Sr leaching occurs before perovskite dissolution, leading to a wide voltage window of stability for water oxidation. The stability of the perovskite surface is strongly influenced by the electrolytic environment and the corrosion rates vary with dissolved Sr concentration. Ultimately, the overall stability of perovskite oxides during electrocatalysis can be greatly improved by suppressing A-site leaching.
ENERGY & ENVIRONMENTAL SCIENCE
(2023)
Review
Chemistry, Multidisciplinary
Janis Timoshenko, Beatriz Roldan Cuenya
Summary: X-ray absorption spectroscopy (XAS) is a crucial method for investigating the structure and composition of heterogeneous catalysts, revealing the nature of active sites and establishing links between structural motifs, local electronic structure, and catalytic properties. Recent advancements in instrumentation and data analysis approaches for deciphering X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra have been discussed, with emphasis on applications in the field of heterogeneous catalysis, particularly in electrocatalysis.
Article
Chemistry, Multidisciplinary
Xueqin Mu, Xiangyao Gu, Shipeng Dai, Jiabing Chen, Yujia Cui, Qu Chen, Min Yu, Changyun Chen, Suli Liu, Shichun Mu
Summary: The Ru single-atom system constructed on an iron-cobalt layered double hydroxide exhibits low overpotentials and high stability, surpassing commercial RuO2. Its mass activity is significantly higher than Ru and FeCo-LDH. The formation of an in situ Ru-O-TM nanocompound promotes O-O coupling and suppresses heteroatomic interface instability.
ENERGY & ENVIRONMENTAL SCIENCE
(2022)
Article
Chemistry, Physical
Minkai Qin, Jiadong Chen, Xiaozhong Zheng, Menghui Qi, Rui Yang, Shanjun Mao, Yong Wang
Summary: In this study, the effect of iron incorporation on the phase structure transform and regulation of intermediate species in Fe incorporated Ni-based catalysts was investigated. The results provide new insights into the activity origins of NiFe-based catalysts.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2022)
Article
Multidisciplinary Sciences
Chun-Kuo Peng, Yu-Chang Lin, Chao-Lung Chiang, Zhengxin Qian, Yu-Cheng Huang, Chung-Li Dong, Jian-Feng Li, Chien-Te Chen, Zhiwei Hu, San-Yuan Chen, Yan-Gu Lin
Summary: In this study, two steps of surface reconstruction were observed from initial catalytic inactive Cu1+ state to Cu2+ state and further to catalytic active Zhang-Rice singlet state during the oxygen evolution reaction for water splitting. The hydrogen treated Cu2O catalyst showed superior catalytic activity and stability for water splitting and competed effectively with other 3d-transition-metal catalysts. Multiple operando spectroscopies confirmed that Zhang-Rice singlet is the real active species, as it only appeared under oxygen evolution reaction condition. This work provides insight into developing electrochemical catalysts from catalytically inactive materials and improves understanding of the mechanism of a Cu-based catalyst for water oxidation.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Daniel Eggart, Xin Huang, Anna Zimina, Jiuzhong Yang, Yang Pan, Xiulian Pan, Jan-Dierk Grunwaldt
Summary: The Pt/CeO2 catalysts have been studied for the direct catalytic conversion of methane to olefins, aromatics, and hydrogen. The Pt-Ce interface formed in the catalysts enhances the activation of methane and suppresses coke formation, significantly improving the catalytic performance of the ceria-based catalysts.
Article
Chemistry, Multidisciplinary
Meng-Di Zhang, Jia -Run Huang, Wen Shi, Pei-Qin Liao, Xiao-Ming Chen
Summary: In this study, a stable metal-organic framework (PcNi-Co-O) was reported as a bifunctional electrocatalyst for efficient CO2 overall splitting. PcNi-Co-O achieved a commercial-scale current density of 123 mA cm-2 and a Faradic efficiency (CO) of 98% at a low cell voltage of 4.4 V when used as both cathode and anode catalysts. Mechanism studies revealed the synergistic effects between two active sites and the energy-level matching of cathode and anode catalysts.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Haoyue Zhang, Lingling Wu, Ruohan Feng, Sihong Wang, Chia-Shuo Hsu, Yuanman Ni, Ashfaq Ahmad, Chaoran Zhang, Haofei Wu, Hao-Ming Chen, Wang Zhang, Yao Li, Pan Liu, Fang Song
Summary: Oxygen vacancies (Ov) engineering has been shown to greatly enhance electrocatalytic kinetics for oxygen evolution reaction (OER) by improving electronic transport. However, the mechanism behind this enhancement is not well understood. In this study, we investigate the role of superficial Ov in enhancing the catalytic potential of NiFe layered double hydroxides for OER. We find that superficial Ov engineering significantly reduces the charge transport resistances and modulates the utilization rate of active sites for OER catalysis.
Article
Chemistry, Physical
Steffen Czioska, Alexey Boubnov, Daniel Escalera-Lopez, Janis Geppert, Alexandra Zagalskaya, Philipp Roese, Erisa Saraci, Vitaly Alexandrov, Ulrike Krewer, Serhiy Cherevko, Jan-Dierk Grunwaldt
Summary: The structure of IrO2 during the oxygen evolution reaction was studied using operando X-ray absorption spectroscopy, revealing strong structural changes under different applied potentials, potentially due to the formation of oxygen vacancies and lower oxidation state of iridium. Additionally, it was observed that at higher OER potentials, the well-known OER mechanisms need to be modified, and stronger Ir-Ir interactions were observed in the calcined IrO2 samples.
Article
Chemistry, Multidisciplinary
Yanqiang Li, Zehao Yin, Xuan Liu, Ming Cui, Siru Chen, Tingli Ma
Summary: Molybdenum carbide-based catalysts show great potential in electrochemical reactions such as the hydrogen evolution reaction and oxygen evolution reaction due to their unique electronic structure and physicochemical properties. Research has systematically summarized the synthesis strategies, structure, and catalytic performance of these catalysts, highlighting the relationships between process-structure-property and analyzing catalytic mechanisms. Existing challenges and future perspectives for further development of molybdenum carbide-based catalysts have also been discussed.
MATERIALS TODAY CHEMISTRY
(2021)
Article
Chemistry, Physical
Maria Gonzalez-Ingelmo, Miriam Lopez Garcia, Freddy E. Oropeza, Patricia Alvarez, Clara Blanco, Ricardo Santamaria, Victoria G. Rocha
Summary: Reduced graphene oxide 3D aerogels doped with low concentrations of nickel were prepared for efficient and sustainable hydrogen production via water electrolysis. The study shows that the incorporation of transition metals into carbon supports can greatly improve the catalytic properties for water splitting in alkaline media. The hybrid material exhibited an impressive ten-fold performance increase, highlighting the remarkable influence of Fe in promoting the in situ formation of highly active Ni-Fe oxyhydroxide.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
Xiaomin Cao, Ronglei Fan, Ju Zhou, Cong Chen, Shunshun Xu, Shuai Zou, Wen Dong, Xiaodong Su, Sheng Ju, Mingrong Shen
Summary: The bifunctional NiMoFe/Cu NW core-shell catalyst assembled into a practical solar-driven overall water splitting system achieved an unprecedented solar-to-hydrogen efficiency of 10.99% in neutral electrolytes, thanks to the unique 3D self-supported core-shell architecture and rapid electron/mass transfer properties.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Ilia I. Sadykov, Vitaly L. Sushkevich, Frank Krumeich, Rob Jeremiah G. Nuguid, Jeroen A. van Bokhoven, Maarten Nachtegaal, Olga V. Safonova
Summary: Operando X-ray absorption spectroscopy identifies a quantitative correlation between the concentration of Fe2+ species in Pt-FeOx catalysts and their carbon monoxide oxidation steady-state reaction rate. Deactivation of the catalysts occurs due to irreversible oxidation of active Fe2+ sites. Active Fe2+ species, presumed to be Fe+2O-2 clusters in contact with platinum nanoparticles, coexist with spectator trivalent oxidic iron (Fe3+) and partially alloyed metallic iron (Fe-0). The concentration of active sites and catalyst activity strongly depend on the pretreatment conditions. Fe2+ is the resting state of the active sites in the carbon monoxide oxidation cycle.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Nanoscience & Nanotechnology
Wenmei Liu, Jongmin Lee, Victoria Manzi-Orezzoli, Michail Ntalis, Thomas J. Schmidt, Pierre Boillat
Summary: The unassisted cold-start capability of polymer electrolyte fuel cells (PEFCs) is difficult to achieve for large-scale automotive applications due to blockage of oxidant gas caused by freezing of water at the cathode catalyst layer (CL) and gas diffusion layer (GDL) interface. The impact of GDL properties on freezing behavior of supercooled water is not thoroughly investigated.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Justus S. Diercks, Juan Herranz, Kathrin Ebner, Natasa Diklic, Maximilian Georgi, Piyush Chauhan, Adam H. Clark, Maarten Nachtegaal, Alexander Eychmueller, Thomas J. Schmidt
Summary: In recent years, operando/in situ X-ray absorption spectroscopy (XAS) has become an important tool in the electrocatalysis community. This study investigates the impact of catalyst layer (CL) thickness on Pd-hydride formation trends in carbon-supported Pd nanoparticles and an unsupported Pd aerogel. The results suggest the need for minimizing CL thickness in spectro-electrochemical experiments and using complementary thin-film control measurements.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Anna Zabilska, Maxim Zabilskiy, Rob Jeremiah G. Nuguid, Adam H. H. Clark, Ilia I. I. Sadykov, Maarten Nachtegaal, Oliver Kroecher, Olga V. V. Safonova
Summary: In this study, the origin of the volcano-shaped activity trend for VOx/CeOx catalysts in ethanol oxidative dehydrogenation (ODH) was clarified using operando quick V K- and Ce L-3- edge XAS experiments. It was found that both vanadium and cerium synergistically contribute to the alcohol ODH activity, with the concentration of reversible Ce4+/Ce3+ species being the main descriptor. The activity drop observed at a surface loading above ca. 3 V nm(-2) (ca. 30% VOx monolayer coverage) was attributed to the formation of spectator V4+ and Ce3+ species, which were identified for the first time.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Xi Zhang, Stephan Pollitt, Gihun Jung, Wenzhe Niu, Pardis Adams, Jan Buhler, Nora S. Grundmann, Rolf Erni, Maarten Nachtegaal, Neul Ha, Jisu Jung, Byungha Shin, Wooseok Yang, S. David Tilley
Summary: This work addresses the issue of short minority carrier diffusion length in Cu2S by synthesizing nanostructured Cu2S thin films, which enables increased charge carrier collection. The photocathode based on the nanoplate Cu2S reveals enhanced charge carrier collection and improved photoelectrochemical water-splitting performance. This work provides a simple, cost-effective, and high-throughput method to prepare phase-pure nanostructured Cu2S thin films for scalable solar hydrogen production.
CHEMISTRY OF MATERIALS
(2023)
Review
Chemistry, Physical
Natasha Hales, Thomas Justus Schmidt, Emiliana Fabbri
Summary: Nickel-based catalysts show excellent catalytic performance and stability in the alkaline oxygen evolution reaction (OER). However, a lack of understanding of the dynamic electronic and structural changes under OER conditions hinders the rational design of new materials. Recent advancements in operando spectroscopy and computational modeling have helped to elucidate the electrochemically-driven transformations of Ni-based materials, including redox transformations, adsorption and desorption of reaction intermediates, oxygen vacancy dynamics, phase transformations, and dissolution and redeposition mechanisms. Significant progress has also been made in understanding irreversible transformations, such as phase transformations related to ageing and operando surface reconstruction leading to the growth of new OER active phases.
CURRENT OPINION IN ELECTROCHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Tym de Wild, Jan Wurm, Pascal Becker, Detlef Guenther, Thomas Nauser, Thomas J. Schmidt, Lorenz Gubler, Tamas Nemeth
Summary: The use of hydrocarbon-based proton conducting membranes in fuel cells is limited by their insufficient durability. Membrane aging occurs due to reactive intermediates attacking the polymer, leading to chain breakdown and membrane failure. In this study, we demonstrate the feasibility of improving the stability of hydrocarbon-based membranes against oxidative attack by implementing a Nature-inspired antioxidant strategy, showing that metalated-porphyrins are suitable for damage transfer with minimal impact on fuel cell performance.
Article
Chemistry, Physical
Piyush Chauhan, Juan Herranz, Maximilian Winzely, Maximilian Georgi, Pavel Khavlyuk, Alexander Eychmueller, Thomas J. Schmidt
Summary: Despite increased relevance in energy transition, understanding of CO2 reduction reaction (CO2RR) is still limited, especially regarding the impact of surface-specific parameters such as interfacial pH on its kinetics and product outcome. In this study, CO2RR on polycrystalline Au and Au aerogel was investigated using a rotating ring-disk electrode (RRDE) setup, with the quantification of interfacial pH through measuring the pH value of the gold ring electrode. The results showed that the polycrystalline Au surface had approximately twice the current efficiency compared to the aerogel surface, suggesting a roughness factor effect on this key performance metric.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Multidisciplinary Sciences
Vera Giulimondi, Andrea Ruiz-Ferrando, Georgios Giannakakis, Ivan Surin, Mikhail Agrachev, Gunnar Jeschke, Frank Krumeich, Nuria Lopez, Adam H. Clark, Javier Perez-Ramirez
Summary: This study demonstrates the bifunctionality of carbon supports and metal sites in the acetylene hydrochlorination catalytic cycle, and proposes potential binding sites for acetylene and a viable reaction profile. The results highlight the importance of optimizing both metal and support components for catalyst design.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Natasa Diklic, Adam H. H. Clark, Juan Herranz, Dino Aegerter, Justus S. S. Diercks, Alexandra Beard, Viktoriia A. A. Saveleva, Piyush Chauhan, Maarten Nachtegaal, Thomas Huthwelker, Dmitry Lebedev, Paula Kayser, Jose Antonio Alonso, Christophe Coperet, Thomas J. J. Schmidt
Summary: The large-scale deployment of polymer electrolyte water electrolysis (PEWE) is limited by the use of scarce and expensive iridium-based O-2 evolution reaction (OER) catalysts in PEWE anodes. To gain a better understanding of the relationship between the catalysts' activity and their physicochemical properties, the oxidation state of surface iridium in different iridium oxides with varying compositions, crystal structures, and OER activities was determined. The results showed that regardless of the catalysts' properties, the surface iridium underwent a linear, potential-driven oxidation that stabilized at a +5 state, which correlated with the onset of O-2 evolution, indicating the involvement of iridium in oxidation states ≥+5 in the OER.
Article
Chemistry, Multidisciplinary
Lukas Rochlitz, Jorg W. A. Fischer, Quentin Pessemesse, Adam H. Clark, Anton Ashuiev, Daniel Klose, Pierre-Adrien Payard, Gunnar Jeschke, Christophe Coperet
Summary: This study investigates the effect of Ti doping on the catalytic performance of Pt and PtZn materials in propane dehydrogenation. The results show that Ti-doping significantly changes the electronic structure of nanoparticles and improves the stability of the materials.
Article
Electrochemistry
Meriem Fikry, Juan Herranz, Simon Leisibach, Pavel Khavlyuk, Alexander Eychmueller, Thomas J. Schmidt
Summary: The Pt-Ni aerogel material shows excellent durability under startup/shutdown conditions, but suffers from low water storage capacity at high current densities and low temperatures.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Yen-Chun Chen, Tim Dorenkamp, Christoph Csoklich, Anne Berger, Federica Marone, Jens Eller, Thomas J. Schmidt, Felix N. Buchi
Summary: In this study, product water transport in the microporous layer (MPL) and gas diffusion layer (GDL) substrate during the operation of a polymer electrolyte fuel cell (PEFC) was observed using X-ray tomographic microscopy (XTM). It was found that the high porosity of the MPL plays a significant role in promoting vapor transport and reducing water saturation near the catalyst layer (CL).
