Unraveling the effect of low Cu2O loading on P25 TiO2 and its self-reduction during methanol photoreforming

Abstract

Using noble metal-free catalysts is highly promising for sunlight-driven photocatalytic H2 production. Copper compounds have gained considerable interest in this regard. Cu2O/semiconductor composites exhibit superior photocatalytic activity compared to individual compounds. This study focuses on different CuXO/TiO2 composites synthesized via chemical reduction, using Cu2O weight ratios ranging from 1 to 0.05 concerning the TiO2 source. Characterization techniques were employed, including XRD, SEM, XPS, UV–Vis DRS, PL, and TRMC. Surface modification of TiO2 with Cu species (CuO, Cu2O, and Cu0) was observed during the photocatalytic reforming of methanol under simulated solar light. By loading small amounts of CuXO (0.05–0.1%) on TiO2, the highest H2 production and methanol mineralization were achieved, along with the formation of metallic copper. The coexistence of the Cu species and TiO2 facilitated the effective separation of photogenerated electrons and holes, promoting the photoreduction of protons and photooxidation of methanol, respectively.