Sub‐Band Assisted Z‐Scheme for Effective Non‐Sacrificial H2O2 Photosynthesis

Abstract

AbstractPhotosynthesis of H2O2 from earth‐abundant O2 and H2O molecules offers an eco‐friendly route for solar‐to‐chemical conversion. The persistent challenge is to tune the photo‐/thermo‐ dynamics of a photocatalyst toward efficient electron–hole separation while maintaining an effective driving force for charge transfer. Such a case is achieved here by way of a synergetic strategy of sub‐band‐assisted Z‐Scheme for effective H2O2 photosynthesis via direct O2 reduction and H2O oxidation without a sacrificial agent. The optimized SnS2/g‐C3N4 heterojunction shows a high reactivity of 623.0 µmol g−1 h−1 for H2O2 production under visible‐light irradiation (λ > 400 nm) in pure water, ≈6 times higher than pristine g‐C3N4 (100.5 µmol g−1 h−1). Photodynamic characterizations and theoretical calculations reveal that the enhanced photoactivity is due to a markedly promoted lifetime of trapped active electrons (204.9 ps in the sub‐band and >2.0 ns in a shallow band) and highly improved O2 activation, as a result of the formation of a suitable sub‐band and catalytic sites along with a low Gibbs‐free energy for charge transfer. Moreover, the Z‐Scheme heterojunction creates and sustains a large driving force for O2 and H2O conversion to high value‐added H2O2.