Directional Charge Pumping from Photoactive P-doped CdS to Catalytic Active Ni 2 P via Funneled Bandgap and Bridged Interface for Greatly Enhanced Photocatalytic H 2 Evolution.

Loading cocatalysts onto semiconductors is one of the most popular strategies to inhibit charge recombination, but the efficiency is generally hindered by the localized built-in electric field and the weakly connected interface. Here, this work designs and synthesizes a 1D P-doped CdS nanowire/Ni 2 P heterojunction with gradient doped P to address the challenges. In the composite, the gradient P doping not only creates a funneled bandgap structure with a built-in electric field oriented from the bulk of P-CdS to the surface, but also facilitates the formation of a tightly connected interface using the co-shared P element. Consequently, the photogenerated charge carriers are enabled to be pumped from inside to surface of the P-CdS and then smoothly across the interface to the Ni 2 P. The as-obtained P-CdS/Ni 2 P displays high visible-light-driven H 2 evolution rate of ≈8265 µmol g -1 h -1 , which is 336 times and 120 times as that of CdS and P-CdS, respectively. This work is anticipated to inspire more research attention for designing new gradient-doped semiconductor/cocatalyst heterojunction photocatalysts with bridged interface for efficient solar energy conversion.