A highly durable AgOx cluster/mesoporous TiO2 photocatalyst with synergistic effects induced superior H2 evolution and CO2 reduction

Abstract

Unique morphological structure and tunable physicochemical properties have made cluster-catalysts promising candidates to effectively drive artificial solar fuel generation. However, such catalysts still suffer from instability during reaction, while durability – another evaluation aspect for commercialization has yet to be considered. Making use of the abundant surface hydroxyl groups on hydrogen titanate as in situ anchoring sites, a facile synthesis of well-defined and highly active AgO_x clusters on mesoporous TiO₂ (ACTs) is demonstrated that improves the stability and efficiency for the photocatalytic hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CO₂RR). Comparable to the HER performance of the Pt on TiO₂ with the same metal loading (24.6 mmol g⁻¹ h⁻¹), a HER efficiency of 22.8 mmol g⁻¹ h⁻¹ is reached by the ACTs with exceptional reproducibility over ∼120 h cyclic measurement consisting of 23 cycles and five overnight intervals (14 h each), with the last interval being under ambient conditions without vacuum protection. Additionally, no activity decay is observed for the sample kept under ambient conditions over 12 months. The composites also exhibit excellent CO₂RR activities of 72.1/32.6 μmol g⁻¹ h⁻¹ for the CO/CH₄ production, and visible light (>420 nm) HER activity (377.1 μmol g⁻¹ h⁻¹). Comprehensive experimental and computational studies suggest that such outstanding activity and stability can be derived from the tuneable barrier height at the AgO_x/TiO₂ interface, the increase in electron–hole pairs generated by plasmonic Ag, the rapid charge separation and transfer, and the advanced HER and CO₂RR kinetics.