Hydrogen-interstitial CuWO4 nanomesh: A single-component full spectrum-active photocatalyst for hydrogen evolution

Abstract It is of practical and theoretical significance to realize full spectrum-active photocatalytic hydrogen (H2) evolution using a single-component photocatalyst. The bottleneck is the utilization of near infrared (NIR) light with 52% of the energy in solar spectrum due to the mismatch between its low single photon energy and the large bandgaps of many photocatalysts. In fact, except for the intrinsic inter-band transition, charge-transfer transition is another strategy to produce hot electrons as a result of light excitation. Herein, charge-transfer transition is achieved in hydrogen-interstitial CuWO4 nanomesh (H-CuWO4) by introducing low-valence Cu+ and W5+. The resulting polaron absorption produces abundant free electrons upon NIR irradiation. Meanwhile, the intrinsic inter-band transition supplies more electrons upon ultraviolet and visible (UV and Vis) irradiations. The mesh structure induced by the self-assembled orientated attachment facilitates the electron transport in the photocatalytic process. Further, the lattice stress resulting from the H intercalation raises the conduction band (CB) above the H+/H2 potential level. CuWO4, incapable of realizing photocatalytic H2 evolution, is therefore activated to be a single-component full spectrum-active photocatalyst based on the dual-channel mechanism without any assistance of cocatalysts. It exhibits an excellent H2 evolution rate and high stability. This advance may have great potential in the future environmental and energy engineering applications.