In-situ construction of metallic Ni3C@Ni core-shell cocatalysts over g-C3N4 nanosheets for shell-thickness-dependent photocatalytic H2 production

Herein, we designed the shell-thickness-controlled Ni3C@Ni/g-C3N4 photocatalysts with intimate Schottkyjunctions by an in situ high-temperature transformation strategy. Meanwhile, we found that the cocatalysts with optimized Ni shell-layer thickness of 15 nm could achieve the best visible-light photocatalytic H2-production performance of 11.28 mu molh-1, with an apparent quantum yield (AQY) of 1.49 % at 420 nm, which was 16 times higher than that of Ni3C/g-C3N4. Moreover, an excellent stability is achieved. The well-defined density functional theory (DFT) calculations indicate that the TOP_C1 sites of Ni3C@Ni can exhibit the H adsorption and Gibbs free energies of -0.07eV and 0.18 eV, respectively, which should be hydrogen-evolution active sites instead of two HOLLOW sites. Interestingly, the intimate Schottky-junctions, could hinder rapid charge recombination, increase reactive sites, boost catalytic kinetics and passivate unstable surface of Ni3C, thus achieving shellthickness-dependent hydrogen evolution. Therefore, the Ni3C@Ni core-shell cocatalysts will open a new avenue for robust solar fuel production.

Automated summary

The shell-thickness-controlled Ni3C@Ni/g-C3N4 photocatalysts were designed with intimate Schottky junctions using an in situ high-temperature transformation strategy. Optimized Ni shell-layer thickness of 15 nm achieved the best visible-light photocatalytic H2-production performance. The intimate Schottky-junctions hinder rapid charge recombination, increase reactive sites, and boost catalytic kinetics, leading to shellthickness-dependent hydrogen evolution.