Fabrication of porous Pt-doping heterojunctions by using bimetallic MOF template for photocatalytic hydrogen generation

Abstract

Porous Pt-doping heterojunctions, Pt-ZnO-Co3O4, Pt-ZnS-CoS, and Pt-Zn3P2-CoP were fabricated by firstly the oxidation, sulfurization, and phosphorization of ZnCo-zeolitic-imidazolate-framework (ZnCo-ZIF) and then the doping of Pt nanoparticles. They exhibit excellent photocatalytic activity towards hydrogen generation from water splitting. These bimetallic metal-organic-framework (MOF) derivatives maintain the porous framework skeleton of ZnCo-ZIF precursor, there by significantly enhancing the light utilization and simultaneously affording abundant exposed catalytic active sites. Most importantly, suitable band matching and strong electron coupling in these heterojunctions are achieved by using the bimetallic MOF template, which facilitate the efficient electron-hole separation and transportation. In addition, Pt nanoparticles distributed on the porous heterojunctions as electron traps can offer rich redox active sites for the hydrogen generation. Correspondingly, the hydrogen generation rate of Pt-ZnO-Co3O4, Pt-ZnS-CoS, and Pt-Zn3P2-CoP was up to ~7.80, ~8.21, and ~9.15mmolh−1g−1, respectively, higher than those of respective ZIF-8 or ZIF-67-based derivatives. This work thus provides a new approach that using bimetallic MOF as template directs the fabrication of noble-metal doping heterojunctions to simultaneously enhance light absorption utilization, electro-hole separation, and transport, therefore promoting surface water oxidation reaction for efficient water splitting.