In situ construction of semimetal Bi modified BiOI-Bi2O3 film with highly enhanced photoelectrocatalytic performance

Abstract

Semimetal Bi0 modified BiOI-Bi2O3 (Bi/BiOI-Bi2O3) composite film was fabricated via in situ UV reduction method. Dot-like bismuth particles were originated from partial reduction of lattice Bi3+ by accumulated conduction band electrons in BiOI-Bi2O3. Photoelectrochemical techniques (LSV, EIS, IPCE and I-V characteristics) were applied to investigate possible changes in generation, recombination, separation and transfer of photogenerated charges. It was found that the introducing of Bi0 led to many beneficial photoelectrochemical properties, such as enhanced charge density and IPCE, decreased charge transfer resistance and recombination rate. For example, the photocurrent density on optimized Bi/BiOI-Bi2O3 was 2.0 times that on BiOI-Bi2O3 at 0.1 V vs. Ag/AgCl. Due to synergistic effect between Bi0 and BiOI-Bi2O3 heterojunction, satisfactory results were observed in the simultaneous photoelectrocatalytic (PEC) removal of phenol and Cr(VI). Herein, the as-prepared films were applied as photoanode with Ti sheet as cathode. Without Bi0 modification, after 2.5 h PEC reaction under visible light, the removal efficiencies for phenol and Cr(VI) were 78.0% and 54.6% on BiOI-Bi2O3 photoanode, respectively. Whereas, the corresponding values increased to 92.4% and 99.5% on Bi/BiOI-Bi2O3 photoanode, respectively. Furthermore, good stability was also observed after 4 cyclic runs.