Efficiently photocatalytic degradation of monochlorophenol on in-situ fabricated BiPO4/β-Bi2O3 heterojunction microspheres and O2-free hole-induced selective dechloridation conversion with H2 evolution

Abstract Herein, hierarchical BiPO4/β-Bi2O3 microspheres have been successfully synthesized via one-step annealing pyrophosphate anchored (BiO)2CO3 microspheres, and utilized as efficient and recyclable photocatalysts for CPs degradation. Notably, the amount-optimized heterojunctional microspheres display high photocatalytic activity for 2-CP degradation, even with 5-time enhancement compared to the classical TiO2 (P25). By means of the surface photovoltage spectra, photocurrent action spectra and CPs adsorption curves, the exceptional photoactivities are mainly attributed to the strong adsorption of 2-CP due to the complexation of Bi on Bi2O3 with empty orbitals and Cl of 2-CP with lone-pair electrons for efficiently modulating holes, and to the prolonged charge lifetime by transferring the photogenerated proper-energy-level electrons of β-Bi2O3 to the in-situ formed nano-BiPO4. It is confirmed that the photogenerated holes are dominant to induce the degradation of 2-CP on BiPO4/β-Bi2O3, and to initiate the selective conversion to the value-added intermediates like 4-acetoxyphenol on O2-free condition, along with H2 evolution.