Engineering ZnIn2S4 Nanoflowers on NiCo2S4 Cathode for Enhanced H2O2 Production Boosting Tetracycline Degradation and Synchronous Power Output

In this study, ZnIn2S4 nanoflowers were deposited on the surface of NiCo2S4 hexahedrons using nickel foam (NF) as the substrate, employing a facile two-step solvothermal approach. The fabricated ZnIn2S4/NiCo2S4/NF cathode, in conjunction with a TiO2–Si solar panel integrated photoanode, was employed to assemble a photocatalytic fuel cell (PFC) aimed at treating tetracycline (TC) in wastewater and simultaneously generating electricity. The results reveal that the PFC featuring the ZnIn2S4/NiCo2S4 cathode significantly enhanced the yield of H2O2 (260 μmol/L), which was 3.3 times higher than that of the PFC with the NiCo2S4 cathode (78 μmol/L). The constructed PFC exhibits the capability to function across a broad pH range of 3–11, achieving its peak degradation efficiency at pH 7. Under optimized conditions, the system exhibited a high TC removal efficiency of 96.7% within 60 min, alongside remarkable electricity generation, achieving a short-circuit current density of 0.69 mA cm–2 and a maximum power density of 0.53 mW cm–2. Quenching experiments and electron paramagnetic resonance analyses indicate that 1O2, •O2–, •OH, and h+ species are generated in the system, with •O2 and 1O2 primarily contributing to the TC degradation process. This research offers new perspectives on the strategic design of cathodes in PFC systems for the effective degradation of organic pollutants and concurrent electricity generation.