Waste wood-derived dual Z-scheme WO3/ZnIn2S4/biochar heterojunctions design: Renewable biomass transition for efficient photocatalytic hydrogen evolution

Waste-wood derived biochar was one of potential cocatalysts for catalyst construction, while relevant reports were scarce due to its irregularity, impeded connection properties, etc. necessitating further exploration. In this work, a waste wood-derived tungsten trioxide (WO 3 )/zinc indium sulfide (ZnIn 2 S 4 , ZIS)/biochar (BC) ternary heterojunction was fabricated for interfacial photocatalytic hydrogen (H 2 ) evolution via a two-step hydrothermal method. Under visible light irradiation, the WO 3 /ZIS/BC achieved a H 2 evolution rate of 4.82 mmol/g/h, which was 9.4 and 2.2 times higher than that of pure ZnIn 2 S 4 and ZIS/WO 3 material. Based on DFT calculations and ESR analyses, the electrons in composite were transferred from WO 3 to ZIS and from BC to ZIS, confirming the function of a dual Z -scheme system. Herein, the biochar was acted as both a structural supporter and an electron reservoir, enhancing light absorption, expanding charge-transfer regions, and improving stability of the ternary composite. This work provides a robust theoretical foundation and technique support for enhancing wood waste recyclability and advancing renewable energy transition from biomass to green hydrogen.