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Shaping the energy landscape through development of more efficient electrochemical energy conversion and storage devices requires significant advancements in the catalysis of key electrochemical processes involving oxygen. This is especially the case for the oxygen evolution reaction (OER), which is largely challenged by the cost-ineffectiveness of the best performing electrocatalysts (i.e., Ru, Ir), along with their limited stability under acidic conditions. This presents a roadblock in the development of robust acid-based polymer exchange membrane electrochemical systems, currently the most advanced technologies for electrochemical energy conversion. Approaches such as dilution of Ru/Ir into flexible mixed metal oxide frameworks have been used as alternative strategies in designing robust OER electrocatalysts. Herein, we discuss the state of research in this area and detail the effect of the composition and structure of mixed metal oxides on their acidic OER activity and stability. Future directions for developing mixed metal oxide electrocatalysts suitable for acidic electrochemical environments are devised.

Metal–metal oxide interfaces can manipulate catalytic selectivity in multistep reactions, including hydrodeoxygenation (HDO) of biomass derivatives like furfuryl alcohol. These interfaces combine active sites of different functionalities towards hydrogen activation, HDO and subsequent hydrogenation. However, examining the interplay between these different sites is essential to achieve control over the interfacial properties, and thus over the reaction selectivity towards 2-methylfuran. Herein, through DFT calculations, we investigate the role of TiO2 encapsulated Pd interfacial sites towards dictating HDO product selectivity. A rutile TiO2 (1 1 0) nanowire over a Pd (1 1 1) surface is used as the interfacial model. TiO2/Pd sites are found to provide a bifunctional role at the interface. The results show that TiO2 generates reduced oxide sites such that C O bond of furfuryl alcohol is activated relative to Pd (1 1 1), with the alcohol group re-oxidizing the reduced site. The Pd surface activates H2 and enables hydrogenation to the final product. Consequently, deoxygenation is accelerated over a TiO2−x/Pd oxygen deficient interface, with an approximate kinetic analysis suggesting that reduced interfacial sites accelerate direct deoxygenation by ∼108 at 443 K, altering the Pd selectivity from the undesired furan product to the desired 2-methylfuran.

Carbon-induced catalyst deactivation is one of the main problems associated with the electrocatalytic and catalytic reforming of hydrocarbons over supported Ni catalysts. We have used DFT calculations to study various aspects of carbon chemistry on Ni surfaces. We demonstrate that the carbon tolerance of Ni can be improved by synthesizing Ni-containing surface alloys that, compared to monometallic Ni, preferentially oxidize C atoms rather than form C–C bonds and have a lower thermodynamic driving force, associated with the nucleation of carbon atoms on low-coordinated Ni sites. Using the molecular insights obtained in the DFT calculations, we have identified Sn/Ni surface alloy as a potential carbon-tolerant reforming catalyst. The predictions of the DFT calculations were supported by our reactor and catalyst characterization studies, which showed that Sn/Ni is much more resistant to carbon poisoning than monometallic Ni in the steam reforming of methane, propane, and isooctane at moderate steam-to-carbon ratios.