Effects of Conduction Band Edge Regulation on the Photoreforming Efficiency of Plastic Waste: Taking BPNS/TiO₂ as a Photocatalyst

Photoreforming of plastic waste offers a solution for reducing environmental pollution while producing value-added products. This study investigates the impact of conduction band edge modulation on the photoreforming efficiency of waste polyethylene terephthalate (PET) using a TiO2/black phosphorus nanosheet (BPNS) heterojunction catalyst, leveraging the tunable bandgap and high carrier mobility of BPNSs. The BPNS/TiO2 heterojunction demonstrated remarkable PET degradation under simulated solar illumination, achieving an 80% weight loss after 35 h. Simultaneously, the system exhibited efficient hydrogen evolution, producing 345.2 μmol g–1 h–1 of H2. Bandgap modulation analysis revealed that as the conduction band edge (ECB) of the photocatalyst became more negative, the increase in CO evolution rates surpassed those of H2 and CO2, likely due to enhanced charge transfer, stronger oxygen adsorption, and a more negative reduction potential. The influence of bandgap tailoring on charge separation, transfer dynamics, and oxygen radical generation, directly linked to photoreforming efficacy, was analyzed through EIS, ESR, and DFT calculations. This study underscores the potential of BPNS/TiO2 heterojunctions for efficient and selective photoreforming of different plastic waste, offering valuable insights into catalyst design for environmental remediation and energy recovery.