Bifunctional S-scheme Fe7S8/CuIn5S8 heterostructures with S-vacancies for boosted photocatalytic antibiotic degradation and hydrogen evolution

The reasonable designing, interfacial tuning and construction of S-scheme heterostructures offering high performance water pollutants treatment and energy production still remains challenging. Following the structure, band structure and interface function perspective, we prepared Fe7S8/CuIn5S8 heterostructures photocatalysts with sulfur vacancies for superior norfloxacin (NOR) degradation and hydrogen production under visible light. In particular, for optimal 30FS/CIS (30%Fe7S8/CuIn5S8), the H-2 evolution was up to 35.6 mmol g(-1) h(-1) which was 11.5 times than pristine Fe7S8 with TEOA as sacrificial agent. The heterojunction could also show 98.7% degradation of NOR in 90 min under visible light. Interestingly, using NOR pollutant as sacrificial agent under synergistic conditions, 22.7 mmol g(-1) h(-1) H-2 evolution and 98.9% degradation of NOR (in 45 min) was achieved. The significantly boosted photocatalytic pollutant degradation and hydrogen generation performance over Fe7S8/CuIn5S8 hybrids is ascribed to the efficient S-scheme charge transfer and active sites provided by sulfur vacancies (V-s). The deep electron transfer mechanism and the charge transfer efficiency were supported by insitu XPS, UPS, electrochemical experiments and photoluminescence. Experimental results including scavenging tests and ESR findings provided the direct evidence of photogenerated holes and (OH)-O-center dot radicals for pollutant degradation and electrons in hydrogen generation. This work contributes to effective designing and developing high-activity visible light/solar light assisted heterojunction photocatalysts for realizing superior clean energy generation and pollutant degradation.