In situ formation of oxygen-deficient WO3-x nanosheets for enhanced photocatalytic activity in water splitting and plastic reforming

Abstract

Photocatalytic pathways are essential for the sustainable production of chemicals and fuels, pivotal for achieving a pollution-free planet. Electron-hole recombination is a critical problem that has, so far, limited the efficiency of the photocatalytic materials. Here, oxygen-deficient WO_3-x nanosheets were in situ grown in a polymeric carbon nitride (PCN) support during the thermal polycondensation of melamine. The introduction of defect in WO_3-x, accompanied by spin polarization and the formed WO_3-x/PCN heterostructure, greatly accelerated the charge separation and transfer. The synthesized WO_3-x/PCN composite exhibited a tenfold increase in hydrogen generation activity than pure PCN under visible-light (420 ≤ λ ≤ 780 nm). The WO_3-x/PCN also demonstrated consecutive 24 h and stable photocatalytic H₂ production in the aqueous plastic-containing [poly(vinyl alcohol) (PVA), poly(ethylene terephthalate) (PET) and the PET bottle] solutions under visible light. The hydrogen production rates were determined to be 111.2, 50.5, and 7.8 μmol·h⁻¹·g⁻¹ in PVA, PET and PET bottle, respectively. In addition, the oxygen vacancies WO₃ with their localized surface plasmon resonance effect, facilitated efficient utilization of NIR photon and the hydrogen evolution rate over WO_3-x/PCN reached to 120 μmol h⁻¹·g⁻¹ under NIR light (700 ≤ λ ≤ 780 nm). This research not only advances the potential applications of WO_3-x/PCN in sustainable energy production but also provides insights into environmental remediation through the conversion of plastic wastes.