Electronegativity Assisted Synthesis of Magnetically Recyclable Ni/NiO/g-CN for Significant Boosting H Evolution.

A magnetically recyclable Ni/NiO/g-CN photocatalyst with significantly enhanced H2 evolution efficiency was successfully synthesized by a simple ethanol-solvothermal treatment. The presence of electronegative g-CN is found to be the key factor for Ni formation in ternary Ni/NiO/g-CN, which provides anchoring sites for Ni absorption and assembling sites for Ni nanoparticle formation. The metallic Ni, on one side, could act as an electron acceptor enhancing carrier separation and transfer efficiency, and on the other side, it could act as active sites for H evolution. The NiO forms a p-n heterojunction with g-CN, which also promotes carrier separation and transfer efficiency. The strong magnetic property of Ni/NiO/g-CN allows a good recyclability of catalyst from aqueous solution. The optimal Ni/NiO/g-CN showed a full-spectrum efficiency of 2310 μmol·h·g for hydrogen evolution, which is 210 times higher than that of pure g-CN. This ethanol solvothermal strategy provides a facile and low-cost synthesis of metal/metal oxide/g-CN for large-scale application.