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

Abstract

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 (Bi2S3) 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 Bi2S3 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 μmol·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.