Transfer learning aided high-throughput computational design of oxygen evolution reaction catalysts in acid conditions

Sluggish oxygen evolution reaction(OER)in acid conditions is one of the bottlenecks that prevent the wide adoption of proton exchange membrane water electrolyzer for green hydrogen production.Despite recent advancements in developing high-performance catalysts for acid OER,the current electrocatalysts still rely on iridium-and ruthenium-based materials,urging continuous efforts to discover better performance catalysts as well as reduce the usage of noble metals.Pyrochlore structured oxide is a family of potential high-performance acid OER catalysts with a flexible compositional space to tune the electrochemical capabilities.However,exploring the large composition space of pyrochlore compounds demands an imperative approach to enable efficient screening.Here we present a highthroughput screening pipeline that integrates density functional theory calculations and a transfer learning approach to predict the critical properties of pyrochlore compounds.The high-throughput screening recommends three sets of candidates for potential acid OER applications,totaling 61 candidates from 6912 pyrochlore compounds.In addition to 3d-transition metals,p-block metals are identified as promising dopants to improve the catalytic activity of pyrochlore oxides.This work demonstrates not only an efficient approach for finding suitable pyrochlores towards acid OER but also suggests the great compositional flexibility of pyrochlore compounds to be considered as a new materials platform for a variety of applications.

Nature of surface oxygen intermediates on TiO2 during photocatalytic splitting of water

Titanium dioxide（TiO2） is the most widely studied solid photocatalyst, but when applied to photocatalytic splitting of water to H2 and O2, the evolution rate of H2 is low and decreases with reaction time. The origin of the decreasing evolution rate for the photocatalytic splitting of water was investigated for the first time by directly monitoring the surface species on TiO2 during water photocatalysis with in situ attenuated total reflectance（ATR）-Fourier transform infrared（FTIR）spectroscopy. The in situ ATR-FTIR spectroscopic analysis during UV illumination of TiO2 immersed in water reveals that surface dioxygen and hydroxyl species are formed on TiO2： charged Ti—OOH-, peroxo Ti（O2）2-, and bridging Ti—（OH＋）—Ti groups. The accumulation of these surface oxygenated species on the TiO2 photocatalyst blocks the activation of H2O on the surface titania sites and is responsible for the decreasing H2 evolution rate and absence of O2 evolution.