In situ sulfidation induced a Bi2S3 heterogeneous phase on CuBi2O4 for boosting photoelectrochemical ammonia production

Abstract

The photoelectrochemical nitrate reduction reaction (PEC-NIRR) provides a sustainable solution for addressing nitrogen-containing wastewater pollution and green ammonia synthesis. However, the reported catalysts are still limited by issues such as low carrier separation efficiency and competition from the hydrogen evolution reaction (HER). A surface sulfidation strategy was employed to epitaxially grow Bi₂S₃ in situ on the surface of CuBi₂O₄, successfully constructing a CuBi₂O₄/Bi₂S₃ catalyst. Based on the narrow bandgap (1.67 eV) and sulfur atom active sites of Bi₂S₃, a type II band arrangement and atomic level contact were configured. The oxygen vacancy (O_v) concentration could be regulated to 48.98%, significantly promoting charge separation and the generation of hydrogen radicals (H*). Under illumination, CuBi₂O₄/Bi₂S₃ achieves a high NH₃ production rate of 33.69 μg h⁻¹ cm⁻², which is 3.84 times that of CuBi₂O₄. The by-product NO₂⁻ production rate was significantly suppressed, contributing to an excellent selectivity (59.71%). FTIR and ¹H NMR spectroscopic analyses further confirmed that NH₃ generation was entirely derived from NO₃⁻. Therefore, this work offers a novel strategy of in situ sulfidation for boosting the intrinsic activity of polymetallic oxide catalysts.