Self-assembly synthesis of phosphorus-doped tubular g-C3N4/Ti3C2 MXene Schottky junction for boosting photocatalytic hydrogen evolution

Establishing highly effective charge transfer channels in carbon nitride(g-C3N4) to enhance its photocatalytic activity is still a challenging issue. Herein, the delaminated 2D Ti3C2MXene nanosheets were employed to decorate the P-doped tubular g-C3N4(PTCN)for engineering 1D/2D Schottky heterojunction(PTCN/TC) through electrostatic self-assembly. The optimized PTCN/TC exhibited the highest hydrogen evolution rate(565 μmol h-1g-1), which was 4.3 and 2.0-fold higher than pristine bulk g-C3N4and PTCN, respectively.Such enhancement may be primarily attributed to the phosphorus heteroatom doped and unique structure of 1D/2D g-C3N4/Ti3C2Schottky heterojunction, enhancing the light-harvesting and charges’ separation. One-dimensional pathway of g-C3N4tube and built-in electric field of interfacial Schottky effect can significantly facilitate the spatial separation of photogenerated charge carriers, and simultaneously inhibit their recombination via Schottky barrier. In this composite, metallic Ti3C2was served as electrons sink and photons collector.Moreover, ultrathin Ti3C2flake with exposed terminal metal sites as a co-catalyst exhibited higher photocatalytic reactivity in H2evolution compared to carbon materials(such as reduced graphene oxide). This work not only proposed the mechanism of tubular g-C3N4/Ti3C2Schottky junction in photocatalysis, but also provided a feasible way to load ultrathin Ti3C2as a co-catalyst for designing highly efficient photocatalysts.