One-step phosphorization preparation of gradient-P-doped CdS/CoP hybrid nanorods having multiple channel charge separation for photocatalytic reduction of water

The separation and transfer of photogenerated charge carriers are the crucial process in photocatalysis, and the realization of multiple charge separation and transfer routes in a single catalyst structure is very promising to achieve high-efficiency catalytic performance. We herein report a simple strategy to synthesize CdS/CoP hybrid nanorods (HNRs) via a one-step phosphorization treatment of the CdS/Co(OH)2 precursors, in which the gradient-P-doped-CdS NRs and CoP cocatalyst can be synchronously obtained (denoted as gP-CdS/CoP HNRs). The gradient P doping gradually reduced the band gap of CdS as well as elevated Fermi level with doping concentration up, resulting in the formation of a built-in electric field in the CdS NRs. The built-in electric field points from the surface towards the interior of the CdS NRs, which facilities the separation of photogenerated charge carriers in CdS and the transfer of electrons to the CdS/CoP interface. The transferred electrons are then captured by the CoP cocatalysts, leading to further separation of the charge carriers. Owing to the coupling of gradient-P-doped CdS nanorods with the CoP cocatalysts, the optimized gP-CdS/CoP HNRs exhibit remarkably enhanced photocatalytic water reduction performance, with a H2 production rate of 22.95 mmol g−1 h−1 which is 28.7 and 3.2 times higher than that of pristine CdS and gP-CdS, respectively. This work demonstrates the synergetic effects of charge carrier separation in the coupled nanostructure of the gradient-P-doped CdS NRs with the CoP cocatalyst, which provides a new platform for developing heterostructures with multiple charge separation and transfer routes for photocatalysis.