High-efficient Photoelectrochemical Reduction of Cr(VI) to Produce Chromium Formate over Pure Bi2S3 Thin Films

As a typical heavy metal ion pollutant in water and soil, Cr(VI) exhibits significant toxicity and carcinogenicity, which urges the development of an effective and environment-friendly technique for Cr(VI) treatment. Herein, bismuth sulfide (Bi 2 S 3 ) photoanode is fabricated through a chemical bath deposition followed by sulfurization treatments. The structure and physicochemical characteristics of the thin films were analyzed and optimized. The obtained Bi 2 S 3 thin films exhibit the photocurrent of 5.37 mA·cm −2 at 1.22 V vs RHE. It can achieve 100% reduction efficiency of 70 ppm Cr(VI) solution in 1 h, and the reduction rate is 159.47 × 10 −3 μ mol·min −1 ·cm −2 . Further, the mechanism of the photoelectrochemical reaction was explored, and the reduced Cr(Ⅲ) was converted into industrial raw material chromium formate, which realized the harmless recycling of Cr(VI)-contaminated wastewater.