Cu Nanocluster-Loaded TiO2 Nanosheets for Highly Efficient Generation of CO-Free Hydrogen by Selective Photocatalytic Dehydrogenation of Methanol to Formaldehyde.

Safe storage and transportation of H2 is a fundamental requirement for its wide applications in the future. Controllable release of high-purity H2 from a stable storage medium such as CH3OH before use offers an efficient way of achieving this purpose. In our case, Cu nanoclusters uniformly dispersed onto (001) surfaces of TiO2 nanosheets (TiO2/Cu) are selectively prepared by thermal treatment of HKUST-1 loaded TiO2 nanosheets. One of the TiO2/Cu composites, TiO2/Cu_50, exhibits remarkably high activity toward the selective dehydrogenation of CH3OH to HCHO with a H2 evolution rate of 17.8 mmol h-1 per gram of catalyst within a 16-h photocatalytic reaction (quantum efficiency at 365 nm: 16.4%). Theoretical calculations reveal that interactions of Cu nanoclusters with TiO2 could affect their electronic structures, leading to higher adsorption energy of CH3OH at Ti sites and a lower barrier for the dehydrogenation of CH3OH by the synergistic effect of Cu nanoclusters and TiO2, and lower Gibbs free energy for desorption HCHO and H2 as well.