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

Semimetal Bi-0 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 Bi-0 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 Bi-0 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 Bi-0 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.