Oxygen Vacancy-Rich Sr2MgSi2O7:Eu2+,Dy3+ Long Afterglow Phosphor as a Round-the-Clock Catalyst for Selective Reduction of CO2 to CO

Solar-driven CO2 conversion to fuels is a central technique for closing the anthropogenic carbon cycle, but to date is limited by the intermittent solar flux. To face this challenge, a catalyst is needed that can work well in both light and dark. Here, surface oxygen vacancies are created in a Sr2MgSi2O7:Eu2+,Dy3+ long-afterglow phosphor with long-time and high charge storage capacity (denoted as Vo-SMSED) as both electron transfer station and active sites for molecule activation. The strong ability for oxygen vacancies to store and extract electrons from charge storage centers enables the Vo-SMSED to work efficiently in both light and dark. As a result, Vo-SMSED manifests nearly 100% selectivity for catalyzing CO2 reduction by H2O to CO with high light stability and over 3 h dark activity. These results demonstrate that creating the bifunctional sites as electron-storing/extracting and molecule-activating center is an efficient route to change the long-lived charge into the highly active species for catalysis, thus making the long-afterglow phosphors with high charge storage capacity a highly efficient round-the-clock photocatalyst.