Tuning metal-support interaction of NiCu/graphene cocatalysts for enhanced dye-sensitized photocatalytic H2 evolution

The modulation of metal-support interaction (MSI) is of particular interest in improving the catalytic performance of metal nanocatalysts. Herein, we adopt an alloying strategy to tune the MSI in graphene-supported Ni catalyst by introducing Cu. The NiCu/graphene cocatalysts (denoted as N(x)C(y)G) are facilely synthesized by directly calcinating the mixture of metal chlorides and graphene oxide for dye-sensitized photocatalytic hydrogen evolution reaction (HER). The results reveal the introduction of Cu significantly affects the MSI in N(x)C(y)G cocatalysts, and a reasonable Ni/Cu ratio (4:1) significantly enhances the MSI in N(4)C(1)G cocatalyst. Such an enhanced MSI facilitates the electron injection from excited dye to RGO and further transfer to the NiCu alloy, and leads to smaller size of NiCu alloy nanoparticles (NPs) with sufficient active sites. Moreover, the synergetic effect between Ni and Cu is conducive to optimize the hydrogen adsorption on NiCu surface. As a result, the N(4)C(1)G cocatalyst shows much improved electrocatalytic and photocatalytic HER performance compared with monometallic Ni/graphene and Cu/graphene. The apparent quantum yield (AQY) at 420 nm reaches up to 67.7 % in the dye-sensitization system. We believe that this work develops a facile and effective strategy to tune the MSI of metal/graphene catalysts for enhanced HER performance.