C-doped BiOCl/Bi2S3 heterojunction for highly efficient photoelectrochemical detection and photocatalytic reduction of Cr(VI)

Novel C-BiOCl/Bi2S3 composites are prepared by hydrothermal C doping in BiOCl and in-situ growth of Bi2S3 on C-BiOCl. Compared with BiOCl, C-BiOCl has a larger exposed surface area and can effectively absorb visible light. The construction of a heterojunction in C-BiOCl/Bi2S3 further promotes the separation and transfer of photogenerated carriers. With improved photoelectric properties, the optimized 5C-BiOCl/5Bi2S3 is applied as a dual-functional composite for photoelectrochemical (PEC) detection and photocatalytic (PC) reduction of Cr(VI). The 5C-BiOCl/5Bi2S3 shows a linear range of 0.02–80 μM for PEC cathodic detection of Cr(VI) with a detection limit of 0.01628 μM. Additionally, 99.5% of Cr(VI) can be removed via absorption and PC reduction by 5C-BiOCl/5Bi2S3, with the reduction rate constant (k) 336 times higher than that of BiOCl.