Efficient photothermal-assisted photocatalytic hydrogen production over a plasmonic CuNi bimetal cocatalyst

It is challenging to maximize the utilization of solar energy using photocatalysis or photothermal catalysis alone. Herein, we report a full spectrum solar energy driven photothermal-assisted photocatalytic hydrogen production over CuNi bimetallic nanoparticles co-loaded with graphitized carbon nitride nanosheet layers (Cu_xNi_y/CN) which are prepared by a facile in-situ reduction method. Cu₅Ni₅/CN shows a high hydrogen production rate of 267.8 μmol g^-1 h^-1 at room temperature, which is 70.5 and 1.34 times of that for pure CN (3.8 μmol g^-1 h^-1) and 0.5 wt% Pt/CN (216 μmol g^-1 h^-1), respectively. The photothermal catalytic hydrogen activity can be further increased by 3.7 times when reaction solution is external heated to 100 °C. For the photothermal catalytic system, the local surface plasmon resonance (LSPR) effect over active Cu nanoparticles can absorb near-infrared light to generate hot electrons, which are partially quenched to generate heat for heating of the reaction system and partially transported to the active sites, where the Ni nanoparticles as another functional component couple the electrons and heat to finally promote the photothermal catalytic activity. Our result suggests that a rational design of the catalyst with bifunctional atomic components can photothermocatalysis-assisted photocatalysis to maximize utilization solar energy for efficient full spectrum conversion.