Bridge-type interface optimization on a dual-semiconductor heterostructure toward high performance overall water splitting

Abstract

Interfacial carrier transportation is a key step in photocatalytic water splitting reaction. Herein, we fabricated a series of Cu₂O@ZnCr-layered double hydroxide (LDH) photocatalysts with tunable interfacial properties, by precise regulation over a covalent-bonding-bridge structure at the heterointerface. The Cu₂O@ZnCr-LDH photocatalyst with an optimized interface exhibits a stoichiometric production of H₂ and O₂ with a generation rate of 3.42 and 1.63 μmol h⁻¹, respectively, without any sacrificial agents or co-catalysts. This activity is among the highest reported for photocatalysts under the same conditions. By using extended X-ray absorption fine structure (EXAFS) and coincidence Doppler broadening positron annihilation spectroscopy (CDB-PAS), for the first time, we substantiated that a bridge-type bonding at the heterointerface strongly facilitates the interfacial transportation of photo-induced carriers via a Z-scheme route. This provides direct experimental evidence for carrier interfacial transportation, beyond previously reported theoretical predictions and simulations. It is expected that this modulation and optimization over the heterostructure interface can be extended to other dual-semiconductor photocatalysts with high performance.