Porphyrin Conjugated Polymer Grafted onto BiVO<sub>4</sub> Nanosheets for Efficient Z‐Scheme Overall Water Splitting via Cascade Charge Transfer and Single‐Atom Catalytic Sites
Jinming Wang, Lei Xu, Tingxia Wang, Renjie Li, Yuexing Zhang, Jing Zhang, Tianyou Peng
Abstract
Abstract This work shows a novel artificial Z‐scheme photosystem based on a heterometallic Zn‐/Pt‐porphyrin conjugated polymer (ZnPtP‐CP) grafted onto ultrathin BiVO 4 nanosheets via Zn–O–V bridging bonds for high‐efficiency overall water photosplitting. An impressive apparent quantum yield of 9.85% at λ = 400 nm is achieved over the resulting ZnPtP–CP/BiVO 4 composite, in which BiVO 4 nanosheets are in close contact with ZnPtP‐CP nanosheets via Zn–O–V bridging bonds to promote a Z‐scheme charge transfer mechanism with ZnPtP‐CP serving as electron‐rich unit and BiVO 4 as hole‐rich one. The photoexcited electrons of BiVO 4 transfer to the interface and recombine with the photogenerated holes of ZnPtP‐CP through the Zn–O–V bonds, and thus the strong reducibility of the photoinduced electrons in ZnPtP‐CP and the strong oxidation ability of the photogenerated holes in BiVO 4 are maintained. Moreover, the highly dispersed Pt centers (PtN 4 ) in Pt‐porphyrin bridging units act as single‐atom catalytic sites to facilitate a cascade charge transfer by fast migration of the photogenerated electrons from Zn‐porphyrin to Pt‐porphyrin units for the water reduction reaction. This Z‐scheme mechanism with two‐step excitation and cascade charge transfer pathway makes the composite acting as Z‐scheme dual‐function photocatalyst responsible for the efficient solar‐driven overall water photosplitting without the aid of a sacrificial reagent or external bias.