Efficient photocatalytic overall water splitting on metal-free 1D SWCNT/2D ultrathin C3N4 heterojunctions via novel non-resonant plasmonic effect

[Display omitted] •1D SWCNT/2D ultrathin C3N4 was fabricated via a two-step air etching method.•The prepared catalyst can serve as a non-resonant plasmonic photocatalyst.•The green nanohybrid showed efficient photocatalytic overall water splitting activity.•Finite element method simulation demonstrated the non-resonant plasmonic effect. Localized surface plasmon resonance (LSPR) photocatalysts for water splitting have attracted extensive interests. Noble metal LSPR materials suffer from high costs and negative impacts to environment, while metal-free materials usually have low efficiencies. In this work, we demonstrate that one-dimensional carbon nanotubes/two-dimensional ultrathin carbon nitride (1D SWCNT/2D C3N4) can serve as non-resonant plasmonic photocatalysts. The catalyst shows a stoichiometric production of H2 (49.8 μmol g−1 h−1) and O2 (22.8 μmol g−1 h−1) in overall water splitting, with a prominent H2 production rate of 1346 μmol g−1 h−1. The significantly enhanced photocatalysis is attributed to the non-resonant plasmonic effect, as confirmed by the increased spectral response within both ultraviolet and visible light regions, and the results of finite element method simulation. Moreover, the contributions from ultrathin morphology, long average carrier lifetime (2.54 ns), and the electronic coupling effect of the nanohybrids collectively intensify the photocatalytic water splitting.