Cu₇S₄/MxSy (M=Cd, Ni, and Mn) Janus Atomic Junctions for Plasmonic Energy Upconversion Boosted Multi-Functional Photocatalysis

Abstract

Rational design/synthesis of atomic-level-engineered Janus junctions for sunlight-impelled high-performance photocatalytic generation of clean fuels (e.g., H2O2 and H2) and valuable chemicals are of great significance. Especially, it is appealing but challenging to acquire accurately-engineered Janus atomic junctions (JAJs) for simultaneously realizing the plasmonic energy upconversion with near-infrared (NIR) light and direct Z-scheme charge transfer with visible light. Here, a range of new Cu7S4/MxSy (M=Cd, Ni, and Mn) JAJs are designed/synthesized via a cation-exchange route using Cu7S4 hexagonal nanodisks as templates. All Cu7S4/MxSy JAJs show apparently-enhanced photocatalytic H2O2 evolution compared to Cu7S4 in pure water. Notably, optimized Cu7S4/CdS (CCS) JAJ exhibits the outstanding H2O2 evolution rate (2.93 mmol g−1 h−1) in benzyl alcohol aqueous solution, due to the following factors: i) NIR light-impelled plasmonic energy upconversion induced H2O2 evolution, revealed by ultrafast transient absorption spectroscopy; ii) visible-light-driven direct Z-scheme charge migration, confirmed by in situ X-ray photoelectron spectroscopy. Besides, three different reaction pathways for H2O2 evolution are disclosed by in situ electron spin resonance spectroscopy and quenching experiments. Finally, CCS JAJ also exhibits super-high rates on H2 and benzaldehyde co-generation using visible-NIR light or NIR light. This work highlights the significance of atomic-scale interface engineering for solar-to-chemical conversion.