I self-grafting enables broad spectrum response and surface localized electric field promoting visible-light photocatalysis of CdBiO2I

Photocatalysis technology has promising application prospects in the treatment of water pollution. However, at present, the performance of photocatalytic pollutant degradation of photocatalysts is limited by the high recombination rate of photogenerated carriers and the low utilization rate of visible light. In this work, we develop a surface-I ion self-grafted CdBiO 2 I (CBOI-I) as an efficient visible-light photocatalyst via a facile precipitation route under ambient atmosphere. Compared with CdBiO 2 I, the self-grafted I ions allows CdBiO 2 I a grafting-concentration dependent light response range. With the increase in the grafting concentration of I ion, the absorption edge of CBOI-I red-shifts from 580 nm to 650 nm, with a band gap decrease of around 0.2 eV. In-situ Kelvin-probe force microscopy, photoluminescence spectra, photoelectrochemical tests and DFT calculation demonstrate, that the surface self-grafting of I ion on CdBiO 2 I enables the formation of surface localized electric field on the surface of the photocatalyst, which efficiently promotes the separation and transfer of photogenerated holes and electrons, producing more superoxide radicals and holes as reactive species. Thus, the optimal CBOI-I (CBOI-I4) exhibits an excellent photocatalytic performance for degradation of bisphenol A upon visible light illumination, in which the degradation rate reaches 94% within 60 min, beyond 4.9 times that of CdBiO 2 I. Besides, other contaminants, including tetracycline hydrochloride, aureomycin hydrochloride, rhodamine B, and methyl orange are also effectively degraded, demonstrating the photodegradation universality of CBOI-I. This work offers an alternative route for developing high-efficiency and broad-spectrum responsive via surface modification.