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Journal articleMoss B, Liang C, Carpenter A, et al., 2025,
Operando ultraviolet–visible optical spectroelectrochemistry of surfaces
, Nature Reviews Methods Primers, Vol: 5Ultraviolet–visible spectroelectrochemistry (SEC) is a powerful and accessible operando technique for investigating redox-active interfaces such as electrodes. Its potential has not been fully realized owing to limitations in sensitivity, acquisition speed and analysis workflows. In this Primer, we describe how recent developments in optics, detection hardware and synchronization methods now allow for high-resolution, data-rich SEC measurements. We focus on practical strategies for building performant SEC set-ups, introduce a formalism based on differential coulometric attenuation for interpreting spectral changes and outline workflows for extracting redox stoichiometries, kinetics and coverage from complex data. Emphasizing process-sensitive over population-sensitive analysis, we show how this approach enables a clearer understanding of dynamic, disordered interfacial systems. Examples are provided from electrocatalysis, particularly the oxygen evolution reaction, but the principles described are broadly applicable. Throughout, we highlight pitfalls, assumptions and design choices to guide researchers looking to implement quantitative SEC in their own work.
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Journal articleSibug-Torres SM, Niihori M, Wyatt E, et al., 2025,
Transient Au-Cl adlayers modulate the surface chemistry of gold nanoparticles during redox reactions
, NATURE CHEMISTRY, ISSN: 1755-4330- Cite
- Citations: 1
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Journal articleQuintin-Baxendale R, Sokolikova M, Tao Y, et al., 2025,
Crystal-phase engineering of nanowires and platelets of KxIrO2 for efficient water oxidation
, ACS Materials Au, ISSN: 2694-2461IrO2 is one of the most widely investigated electrocatalysts for oxygen evolution reaction in an acidic environment. Increasing the mass activity is an effective way of decreasing the loading of Ir, to ultimately reduce costs. Here, we demonstrate the crystal-phase engineering of two different potassium iridate polymorphs obtained by designing a selective solid-state synthesis of either one-dimensional K0.25IrO2 nanowires with a hollandite crystal structure or two-dimensional KIrO2 hexagonal platelets. Both structures present increased specific and mass electrocatalytic activities for the water oxidation reaction in acidic media compared to commercial rutile IrO2 of up to 40%, with the 1D nanowires outperforming the 2D platelets. XANES, extended X-ray absorption fine structure, and X-ray diffraction investigations prove the structural stability of these two different allotropes of KxIrO2 compounds upon electrocatalytic testing. These low-dimensional nanostructured 1D and 2D KxIrO2 compounds with superior mass activity to commercial IrO2 can pave the way toward the design of new electrocatalyst architectures with reduced Ir loading content for proton exchange membrane water electrolyzer (PEMWE) anodes.
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Journal articleDuarte RPM, Rao R, Ryan MP, et al., 2025,
Beyond activity: a perspective on diagnosing instability of reversible O₂ catalysts for metal-air batteries
, EES Catalysis, ISSN: 2753-801XZinc–air redox flow batteries have high potential to penetrate the stationary energy storage market, due to the abundancy, and low cost of active species – oxygen and zinc. However, their technological fruition is limited by the development of reversible O2 electrodes operating at potentials between 0.6 VRHE to 1.7 VRHE, under which no catalyst material has been shown to be stable over long durations. Despite heavy research on the topic of reversible O2 catalysis, little is known about the parameters controlling the stability of the bifunctional catalyst. Several research accounts assess the activity of reversible O2 catalysts, but only a small portion cover degradation mechanism over such a large potential window. In this perspective, we summarize our current understanding of material challenges for Zn–air batteries, reversible O2 catalyst integration strategies, and electrochemical behaviour, with a particular focus on catalyst stability. Nickel cobalt oxide (NiCo2O4), a promising yet understudied system, is used as an example material for investigations at potentials of both the O2 reduction (ORR) and evolution (OER) reactions. We also report original data employing ex situ X-ray diffraction, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy, as well as electrochemical measurements to study the activity of NiCo2O4. Furthermore, electrochemical accelerated stress tests are coupled with post-mortem transmission electron microscopy, inductively coupled plasma, and X-ray photoelectron spectroscopy to study the dissolution, compositional changes and amorphization of the top surface 5 nm of the catalyst surface. In situ X-ray absorption spectroscopy revealed irreversible oxidation of Co centres in NiCo2O4 during OER, which explains the reduction in activity of the ORR after the catalyst was exposed to anodic OER potentials. This methodology provides a broader method to screen reversible O2 catalyst stability and enables us to sum
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Journal articleYe H, Favero S, Tyrrell H, et al., 2025,
Progress and Challenges in Electrochemical Glycerol Oxidation: The Importance of Benchmark Methods and Protocols
, CHEMCATCHEM, Vol: 17, ISSN: 1867-3880 -
Journal articleWang T, Iriawan H, Peng J, et al., 2025,
Confined Water for Catalysis: Thermodynamic Properties and Reaction Kinetics
, CHEMICAL REVIEWS, Vol: 125, Pages: 1420-1467, ISSN: 0009-2665- Cite
- Citations: 9
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Journal articleRao RR, Bucci A, Corby S, et al., 2024,
Unraveling the Role of Particle Size and Nanostructuring on the Oxygen Evolution Activity of Fe-Doped NiO
, ACS CATALYSIS, Vol: 14, Pages: 11389-11399, ISSN: 2155-5435 -
Journal articleLiang C, Rao RR, Svane KL, et al., 2024,
Unravelling the effects of active site density and energetics on the water oxidation activity of iridium oxides
, Nature Catalysis, Vol: 7, Pages: 763-775, ISSN: 2520-1158Understanding what controls the reaction rate on iridium-based catalysts is central to designing better electrocatalysts for the water oxidation reaction in proton exchange membrane electrolysers. Here we quantify the densities of redox-active centres and probe their binding strengths on amorphous IrOx and rutile IrO2 using operando time-resolved optical spectroscopy. We establish a quantitative experimental correlation between the intrinsic reaction rate and the active-state energetics. We find that adsorbed oxygen species, *O, formed at water oxidation potentials, exhibit repulsive adsorbate–adsorbate interactions. Increasing their coverage weakens their binding, thereby promoting O–O bond formation, which is the rate-determining step. These analyses suggest that although amorphous IrOx exhibits a higher geometric current density, the intrinsic reaction rates per active state on IrOx and IrO2 are comparable at given potentials. Finally, we present a modified volcano plot that elucidates how the intrinsic water oxidation kinetics can be increased by optimizing both the binding energy and the interaction strength between the catalytically active states.
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Journal articleLee H, Kim K-H, Rao RR, et al., 2024,
A hydrogen radical pathway for efficacious electrochemical nitrate reduction to ammonia over an Fe-polyoxometalate/Cu electrocatalyst
, MATERIALS HORIZONS, ISSN: 2051-6347 -
Journal articleAkkiraju K, Rao R, Hwang J, et al., 2024,
Regulating Oxygen Activity of Perovskites to Promote Activity and Selectivity for Methanol Oxidation to Formaldehyde
, ACS CATALYSIS, Vol: 14, Pages: 7649-7663, ISSN: 2155-5435
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