Surface reconstruction of BiSI nanorods for superb photocatalytic Cr(VI) reduction under near-infrared light irradiation

Semiconductor photocatalysis excited by low-photonic-energy photons hinders the improvement of photocatalytic efficiency and remains a huge challenge. Herein, we designed a high-efficient and near-infrared (NIR) light-responsive O-doped BiSI (O-BiSI) nanorods with rich sulfur vacancies (SVs) by a surface reconstruction strategy. X-ray photoelectron spectroscopy and X-ray absorption fine structure revealed the existence of O-doping and SVs. Density functional theory calculations showed that the synergetic effect of O-doping and SVs facilitated the Cr(VI) adsorption and it accelerated the electron transfer from O-BiSI to adsorbed Cr(VI) through inducing distinct charge distributions of Bi neighboring O and SVs. Moreover, the surface reconstruction promoted the transfer and separation of photogenerated carriers and reduced the energy barrier of the rate-determining hydrogenation step from –1.60 to –1.96 eV. Consequently, under visible, NIR, and AM 1.5G light irradiation, the Cr(VI) reduction rates of the optimized O-BiSI were approximately 13.4, 7.8, and 5.2 times higher than that of pure BiSI, respectively. This work provides insights into the surface reconstruction strategy and paves the way toward designing highly efficient photocatalysts for environmental applications.