Integrated p-n/Schottky-junctions for a high near-infrared photocatalytic H2 production upon CdZnS/CoP/CoO ternary hybrids with steering charge transfer

The development of novel photocatalysts with broad optical absorption windows and high charge separation efficiency is vitally important for the solar-hydrogen economy, but remains a challenge at present. In this study, a near-infrared (NIR) light active heterostructure photocatalyst was constructed by simultaneously integrating CoP nanorods and CoO nanoplates with a nanosized CdZnS solid solution. The prepared CdZnS/CoP/CoO ternary composite exhibited a bubbling H2 generation activity (65.44 mmol g−1 for 7 h) from water under the irradiation of real sun-light, and a high NIR-activity of H2 evolution (93.35 µmol h−1 g−1) with an apparent quantum efficiency of 0.01 % under a single wavelength light of 1020 nm, which has been rarely reported. Various characterizations were adopted to reveal the mechanism of such impressive photocatalytic performance, and the results indicated that under visible light, steered photoelectrons transfer from the CoO to CdZnS and thereafter to CoP with significantly accelerated carrier separation, which can be realized owing to the existence of a double heterojunction (a p-n junction between the CdZnS and CoO and a Schottky-junction between the CdZnS and CoP) in this ternary composite. Under NIR light, hot electrons generated by the CoP nanorods functioned as a photothermal antenna that could migrated to the CdZnS to participate in the proton reduction reaction. This study provides an idea for constructing efficient photocatalysts with NIR-active performance by employing a photothermal antenna and designing the appropriate transfer routes for photo-electrons and hot-electrons.