Linking Defect Chemistry to Photo- and Electrocatalytic Performance

Doping or alloying strategies are heavily employed in the design of new catalysts for photoelectrochemical, photochemical and electrochemical conversion reactions with enhanced solar energy harvesting efficiencies and/or desired surface chemistry. In the electrochemical reduction of CO₂ for example, efforts are focused on the development of electrocatalysts with high activity and selectivity towards C₂₊ products ideally breaking the scaling relations currently observed for metal surfaces.¹ In photoelectrochemical and photocatalytic devices research has focused on developing catalysts with light harvesting in the visible, strong surface electric fields and long charge carrier lifetimes.^2,3 In both, electro- and photocatalytic systems, perovskite oxides have been employed heavily, offering a more versatile defect chemistry platform. <br/>Here, I will showcase some of our studies on oxide perovskite materials employed in photo- and electrocatalysis discussing links between defect chemistry and catalytic performance. One example will be the visible light absorber (La,Sr)(Rh,Ti)O₃ employed in the Z-scheme photocatalyst sheet device from Profs. Wang and Domen which led to a record 1% solar-to-hydrogen efficiency.^4,5 Taking inspiration from this material, we have been investigating the performance of other dopants and compositions in photo- and electrocatalytic conversion of CO₂ leading us to look very closely into the material surface compositions and the ways of reporting of catalytic activity.<br/> <br/> <br/>1 Stephens, I. E. L.<i> et al.</i> 2022 roadmap on low temperature electrochemical CO₂ reduction. <i>Journal of Physics: Energy</i> <b>4</b>, doi:10.1088/2515-7655/ac7823 (2022).<br/>2 Corby, S., Rao, R. R., Steier, L. & Durrant, J. R. The kinetics of metal oxide photoanodes from charge generation to catalysis. <i>Nature Reviews Materials</i> <b>6</b>, 1136-1155, doi:10.1038/s41578-021-00343-7 (2021).<br/>3 Luo, H.<i> et al.</i> Progress and Perspectives in Photo- and Electrochemical-Oxidation of Biomass for Sustainable Chemicals and Hydrogen Production. <i>Advanced Energy Materials</i> <b>11</b>, 2101180, doi:https://doi.org/10.1002/aenm.202101180 (2021).<br/>4 Wang, Q.<i> et al.</i> Scalable water splitting on particulate photocatalyst sheets with a solar-to-hydrogen energy conversion efficiency exceeding 1%. <i>Nature Materials</i> <b>15</b>, 611-+, doi:10.1038/nmat4589 (2016).<br/>5 Moss, B.<i> et al.</i> Linking in situ charge accumulation to electronic structure in doped SrTiO3 reveals design principles for hydrogen-evolving photocatalysts. <i>Nature Materials</i> <b>20</b>, 511-517, doi:10.1038/s41563-020-00868-2 (2021).