Selective Photoreduction of CO<sub>2</sub> to CH<sub>4</sub> Triggered by Metal-Vacancy Pair Sites
Jiacong Wu, Juncheng Zhu, Wenya Fan, Dongpo He, Qinyuan Hu, Shan Zhu, Wensheng Yan, Jun Hu, Junfa Zhu, Qingxia Chen, Xingchen Jiao, Yi Xie
Abstract
Selectively achieving the photoreduction of carbon dioxide (CO 2 ) to methane (CH 4 ) remains a significant challenge, which primarily arises from the complexity of the protonation process. In this work, we designed metal-vacancy pair sites in defective metal oxide semiconductors, which anchor the reactive intermediates with a bridged linkage for the selective protonation to produce CH 4 . As an example, oxygen-deficient Nb 2 O 5 nanosheets are synthesized, in which the niobium–oxygen vacancy pair sites are demonstrated by X-ray photoelectron spectroscopy and electron paramagnetic resonance spectra. In situ Fourier transform infrared spectroscopy monitors the *CH 3 O intermediate, a key intermediate for CH 4 production, during the CO 2 photoreduction in oxygen-deficient Nb 2 O 5 nanosheets. Importantly, the built metal-vacancy pair sites regulate the *CH 3 O formation step as a spontaneous process, making the reduction of CO 2 to CH 4 the preferred method. Therefore, the oxygen-deficient Nb 2 O 5 nanosheets exhibit a CH 4 formation rate of 19.14 μmol g –1 h –1, with an electron selectivity of ∼94.1%.