Infrared light driven overall water vapor splitting on a plasmonic semiconductor p-n heterojunction photocatalyst

Photocatalytic overall water splitting (OWS) has yet to be realized on plasmonic semiconductor photocatalysts. In this work, we reported a plasmonic heterojunction of p-Cu1.81S/n-CdS with homogeneously distributed p-type and n-type domains in a single nanoparticle. The plasmonic p-Cu1.81S/n-CdS heterojunction displays a strong localized surface plasmon resonance (LSPR) absorption peak at 1480 nm and can drive the OWS into hydrogen and oxygen under infrared light irradiation. The IR light-induced hot electrons and holes in Cu1.81S nanodisks alone can split water vapor into hydrogen and oxygen, but with poor efficiency. Surprisingly, the plasmonic p-Cu1.81S/n-CdS heterojunction shows significantly improved IR light-driven OWS performance. Under the irradiation of IR light (λ ˃ 800 nm), the hydrogen and oxygen production rates were 0.73 mmol gcat-1 h-1 and 0.33 mmol gcat-1 h-1, respectively. The heterojunction photocatalyst delivered a solar-to-hydrogen conversion efficiency (STH) of 0.02% under AM 1.5G irradiation. The present study has demonstrated that plasmonic semiconductors are promising photocatalysts to harvest IR light for green hydrogen generation.