Z-scheme CoAl-layereddoublehydroxide/indium vanadate heterojunction for enhanced and highly selective photocatalytic reduction of carbon dioxide to carbon monoxide.

Development of efficient photocatalysts is essential for carbon dioxide (CO) photocatalytic reduction. In this study, Z-scheme CoAl-layered double hydroxide (LDH)/indium vanadate (InVO) heterojunction photocatalysts were synthesized using hydrothermal method, and their performance toward CO reduction and mechanism were determined. Results of characterizations showed that the CoAl-LDH/InVO-30 exhibited desired morphology, the most efficient photogenerated carriers separation and charge transfer, and the highest photocurrent response. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) manifested that charge transfer of the CoAl-LDH/InVO conformed to Z-scheme mechanism. The CoAl-LDH/InVO-30 exhibited the highest carbon monoxide (CO) yield of 174.4 μmol g within 2 h of reaction, which was 2.46 and 9.79 times of pure CoAl-LDH and InVO, respectively. The CO selectivity was up to nearly 100%. Moreover, in-situ fourier transform infrared spectroscopy (ISFT-IR) demonstrated that bicarbonate (HCO*) and carboxylate (COOH*) were the main intermediates during the CO reduction process, and possible CO reduction pathways were proposed. This work provides a reference for construction of Z-scheme LDH-based heterojunctions for efficient CO photoreduction.