Integrated p-n/Schottky junctions for efficient photocatalytic hydrogen evolution upon Cu@TiO2-Cu2O ternary hybrids with steering charge transfer

Solar-driven photocatalytic H2 evolution could tackle the issue of fossil fuels-triggered greenhouse gas emission with sustainable clean energy. However, splitting water into hydrogen with high performance by a single semiconductor is challenging because of the poor charge separation efficiency. Herein, a novel ternary Cu@TiO2-Cu2O hybrid photocatalyst with multiple charge transfer channels has been designed for efficient solar-to-hydrogen evolution. Indeed, the ternary Cu@TiO2-Cu2O hybrid by coupling Cu@TiO2 with Cu2O nanoparticles shows highly-efficient photocatalytic hydrogen generation with rate of 12000.6 μmol·g-1·h-1, which is 4.4, 2.1, and 1.9 times higher than the pure TiO2 (2728.8 μmol·g-1·h-1), binary Cu@TiO2 (5595.5 μmol·g-1·h-1), and TiO2-Cu2O (6076.8 μmol·g-1·h-1) composite, respectively. In such a Cu@TiO2-Cu2O hybrid, the formed internal electric field in the TiO2-Cu2O p-n junction allows the electrons in Cu2O to migrate to TiO2, while the electrons in the CB of TiO2 could flow into Cu via the Schottky junction at the Cu@TiO2 interface. In this regard, a multiple charge transfer is achieved between the Cu@TiO2 and Cu2O, which facilitates promoted charge separation and results in the construction of electron-accumulated center (Cu) and hole-enriched surface (Cu2O). This p-n/Schottky junctions with steered charge transfer assists the hydrogen production upon the Cu@TiO2-Cu2O ternary photocatalyst.