Designed Synthesis of Cu2O Quantum Dots/TiO2 Nanotubes Heterostructure as a Photocatalyst for Converting CO2 to CH4

Herein, H + in oxalic acid is used instead of Na + to obtain titanate nanosheets through P200 hydrolysis, which further curls to form a multilayer TiO 2 nanotubes (NTs) structure. Then, Cu 2 O quantum dots (QDs) are successfully loaded on TiO 2 NTs via a hydrothermal method using fructose as a reducing agent. The optical, impedance, and photocurrent tests indicate that the composite structure improves its optoelectronic performance. The photocatalytic H 2 production and CO 2 reduction efficiency of Cu 2 O QDs/TiO 2 NTs are lower than those of TiO 2 NTs. However, the molar ratio of CH 4 to CO produced by CO 2 reduction of Cu 2 O QDs/TiO 2 NTs composite catalyst is greater than that of pure TiO 2 NTs. The CH 4 production accounts for 97%, indicating that the composite catalyst has a high CH 4 selectivity. The experimental and density functional theory calculation results prove that the Z-scheme heterojunction accelerates the separation and transfer of photogenerated carriers, and broadens the absorption range of visible light.