Mono- and bimetallic oxides as photo-electrocatalysts for the oxygen evolution reaction – A review

Photo-electrocatalytic (PEC) water splitting has been considered as a promising route to produce clean hydrogen by utilizing solar light under the influence of a photo-active semiconductor. However, the sluggish kinetics of the oxygen evolution reaction (OER) needs to be accelerated. This review focuses on the recent trends and accomplishments in applying monometallic and bimetallic oxide-based photo-electrocatalysts for the OER. Particular attention is given to the synthetic methods of these metallic oxide-based photo-electrocatalysts, their modification strategies towards performance improvement, their structure catalytic activity relationship, and a comparison of related activities. The peculiarities of the modification strategies, such as doping, morphological nanostructuring, oxygen vacancies creation, homojunctions/heterojunction formation, phase structure engineering, surface modification with oxygen evolution cocatalysts amongst others, to each photo-anode presented in the review are addressed. We furthermore highlight the electronic and optical properties from density functional theory (DFT) calculations for most reported photo-electrocatalysts, and provide future perspectives for further improvement.