Active Cu species in Cu/TiO2 for photocatalytic hydrogen evolution

In this work highly active Cu/TiO2 was prepared by an impregnation method for enhancing photocatalytic hydrogen production. The samples were characterised by hydrogen temperature-programmed reduction (H2-TPR), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller specific surface area (BET). At the optimum Cu loading (0.5 wt%), H2-TPR analysis indicated the presence of readily reducible Cu species. Literature suggests these are isolated Cu atoms coordinated to oxygen atoms of the TiO2 surface, and small Cu2O clusters on the defect sites of the TiO2 surface. At higher Cu loadings (1 and 2 wt%), a second H2- TPR peak appeared which, according to literature, suggests the additional presence of bulk Cu2O particles on the TiO2 surface. Calcination conditions were found to influence performance with the best activity achieved at a temperature of 300 degreesC. Optimised conditions gave a Cu/TiO2 hydrogen production yield 3.5 times greater than bare TiO2. This significant enhancement was mainly attributed to the presence of fine Cu2O clusters and highly dispersed Cu on the TiO2 surface.