Enhancing light harvesting and charge separation of Cu2O photocathodes with spatially separated noble-metal cocatalysts towards highly efficient water splitting

Abstract

Enhancing light harvesting and photoinduced charge separation is key to obtain highly efficient photoelectrochemical water splitting systems, and the integration of noble metals with semiconductors demonstrates a feasible strategy to address this challenge. In this work, spatially separated Au and Pt nanolayers are firstly deposited on the bottom and surface of Cu₂O nanogranules, respectively. The resulting novel Au/Cu₂O/Pt photoelectrodes comprise a plasmonic photosensitizer (Au) for intensively increasing light harvesting and generating hot electrons from the surface plasmon resonance (SPR) effect and an electron collector layer (Pt) for promoting photoinduced electron transfer. This synergy effect has been well supported by many photoelectrochemical measurements, especially surface photovoltage (SPV) measurements. As expected, the photocurrent density–voltage curves demonstrate that the Au/Cu₂O/Pt composites reach a photocurrent density of −3.55 mA cm⁻², which is almost 4.63 times higher than that of pure Cu₂O at 0 V vs. RHE. Moreover, this work provides a promising method for the development of high performance photoelectrodes by the integration of cocatalysts and semiconductors.