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

Abstract

Herein, H+ in oxalic acid is used instead of Na+ to obtain titanate nanosheets through P200 hydrolysis, which further curls to form a multilayer TiO2 nanotubes (NTs) structure. Then, Cu2O quantum dots (QDs) are successfully loaded on TiO2 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 H2 production and CO2 reduction efficiency of Cu2O QDs/TiO2 NTs are lower than those of TiO2 NTs. However, the molar ratio of CH4 to CO produced by CO2 reduction of Cu2O QDs/TiO2 NTs composite catalyst is greater than that of pure TiO2 NTs. The CH4 production accounts for 97%, indicating that the composite catalyst has a high CH4 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.