Improving hydrogen peroxide photosynthesis over inorganic/organic S-scheme photocatalyst with LiFePO4

Abstract

With the rapid development of new energy industries, the utilization of waste batteries has attracted the attention of researchers. Developing a hydrogen peroxide photosynthesis system with battery recycling materials as photocatalysts presents a significant challenge. In this study, an ultrasonic self-assembly technique is employed to integrate LiFePO₄ (LFPO) nanoparticles, derived from spent batteries, with g-C₃N₄ (CN) nanosheets, thereby creating an inorganic/organic S-scheme photocatalyst for the production of H₂O₂. In situ analyses using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM) demonstrate that the interaction between LFPO and CN facilitates the development of an internal electric field (IEF), which in turn gives rise to a distinctive S-scheme charge transfer mechanism. Combining electron spin resonance spectroscopy, radical-trapping experiments, and in situ DRIFTS spectra, three pathways for H₂O₂ formation are identified. Benefited from enhanced carrier separation, strong redox power, and multichannel H₂O₂ formation, the optimal composite shows an impressive H₂O₂-production rate of 3.22 mol g⁻¹ h⁻¹ under simulated solar irradiation. This research provides a potential method to investigate a sustainable H₂O₂ photosynthesis pathway by designing S-scheme heterojunctions from spent battery materials.