Dynamic Evolution of Atomically Dispersed Cu Species for CO₂ Photoreduction to Solar Fuels

Probing the dynamic evolution of catalyst structure and chemical state under operating conditions is highly important for investigating the reaction mechanism of catalysis more in depth, which in turn advances the rational design of redox catalysis in using renewable energy to produce fuels. Herein, the evolution of atomically dispersed Cu species supported by mesoporous TiO₂ (mTiO₂) during the in situ photocatalytic reduction of CO₂ with H₂O to valuable solar fuels has been reported. The results unveil that the initial atomically dispersed Cu­(II) undergoes reduction to Cu­(I) and ultimately to Cu(0); the Cu­(I)/Cu(0) mixture is proposed to be more effective for CH₄ formation. In addition, the enhanced CO₂ adsorption ability benefited from the structural advantage of mTiO₂ and the elevated charge carrier transfer synergistically contributes to the CO₂ photoreduction. It is anticipated that this work would guide the rational design of Cu-based light-harvesting catalysts for artificial CO₂ reduction to value-added feedstocks and inspire further interest in using in situ techniques to study the structure–activity interplay of photocatalysts under operating reaction conditions.