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 H2 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 H2 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 (Vs). The deep electron transfer mechanism and the charge transfer efficiency were supported by in-situ XPS, UPS, electrochemical experiments and photoluminescence. Experimental results including scavenging tests and ESR findings provided the direct evidence of photogenerated holes and ●OH 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.