Ag/Ultrathin-Layered Double Hydroxide Nanosheets Induced by a Self-Redox Strategy for Highly Selective CO<sub>2</sub> Reduction
Tingting Zhang, Huishan Shang, Bing Zhang, Dongpeng Yan, Xu Xiang
Abstract
The carbon-neutral photocatalytic CO2 reduction reaction (CO2RR) enables the conversion of CO2 into hydrocarbon fuels or value-added chemicals under mild conditions. Achieving high selectivity for the desired products of the CO2RR remains challenging. Herein, a self-redox strategy is developed to construct strong interfacial bonds between Ag nanoparticles and an ultrathin CoAl-layered double hydroxide (U-LDH) nanosheet support, where the surface hydroxyl groups associated with oxygen vacancies of U-LDH play a critical role in the formation of the interface structure. The supported Ag@U-LDH acts as a highly efficient catalyst for CO2 reduction, resulting in a high CO evolution rate of 757 μmol gcat–1 h–1 and a CO selectivity of 94.5% under light irradiation. Such a high catalytic selectivity may represent a new record among current photocatalytic CO2RR to CO systems. The Ag–O–Co interface bonding is confirmed by Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and FTIR CO2 adsorption studies. The in situ FTIR measurements indicate that the formation of the *COOH intermediate is accelerated and the mass transfer is improved during the CO2RR. Density functional theory calculations show that the Ag–O–Co interface reduces the formation energy of the *COOH intermediate and accumulates localized charge. Experimental and theoretical analysis collectively demonstrates that the strong interface bonding between Ag and U-LDH activates the interface structure as catalytically CO2RR active sites, effectively optimizing the binding energies with reacted intermediates and facilitating the CO2RR performance.