Robust Junction Formation of Copper(I) Oxide on Graphitic Carbon Nitride Enhances Aqueous Carbon Dioxide Photoreduction without Sacrificial Reagents

Abstract

<jats:p>Semiconductor hybrid structures containing multiple components have been considered an ideal photocatalyst design to generate long‐lived charge‐separated states. Particularly for the reactions requiring high activation energies, such as a CO2 reduction reaction (CO2RR), the reaction activity is highly susceptible to the catalyst component and morphology. In this study, we selected g‐C3N4 and Cu2O as photocatalytic components having bandgaps suitable for CO2RR. Our approach involved establishing robust electric junctions between these domains by direct growth of Cu on g‐C3N4 via a polyol process. The resulting g‐C3N4/Cu2O hybrid was employed as photocatalysts in an aqueous medium without hole acceptors. The catalyst exhibited notable activities for CO (94 µmol gcat‐1h‐1) and CH4 production (218 µmol gcat‐1h‐1), maintaining stability for over 6 h. The inherent synergy between g‐C3N4 and Cu2O, facilitated by strong coordination and the formation of conductive junctions, enabled efficient electron transfer to promote the Z‐scheme process for CO2RR. These findings ensured the importance of junctions and interfaces in the hybrid catalyst structures for unlocking superior photocatalytic CO2RR performance.</jats:p>