SnO2/SnS2 heterojunctions anchored on biochar through the −CSn− bonds: ∙CO2– cooperation with e− to effectively convert Cr(VI)

Controlling the migration behavior of photogenerated carriers by designing the microstructure of materials remains a significant challenge. In this work, the solvothermal method was used to fabricate a SnO 2 /SnS 2 heterojunction anchored on biochar through −C Sn− bonds between biochar and SnS 2 , as demonstrated by X-ray photoelectron spectroscopy characterization. DFT calculations further confirmed −C Sn− bonds can shorten theoretical band gap of SnS 2 @biochar from 1.01 eV to 0.66 eV and provide a pathway for swift electron migration, which can effectively modulate the separation of photo-induced carriers and promote the generation of e − and h + . Additionally, the oxalate activated by −C Sn− bonds can effectively capture h + and produce abundant ∙CO 2 – free radicals. When the obtained composites were used as photocatalysts , Cr(VI) was thoroughly reduced by the SnO 2 /SnS 2 @biochar composite with a molar ratio of SnO 2 and SnS 2 of 2 within 20 min under visible light irradiation when oxalate was 1.0 mM (CSO-2/H 2 C 2 O 4 -1). Furthermore, CSO-2/H 2 C 2 O 4 -1 exhibited excellent reusability, and the degradation efficiency of Cr(VI) remained above 91.71% after five cycles. The remarkable photocatalytic properties can be ascribed to the synergistic effects of e − and ∙CO 2 – . This work proposes a new strategy for the preparation of an applied photocatalyst with a high separation rate of photoinduced carriers.