Photocatalytic CO2 conversion over single-atom MoN2 sites of covalent organic framework

Single-atom MoN2 site was introduced into COF to construct Mo-COF materials for photocatalytic conversion of CO2 at atmosphere concentration to high added value hydrocarbons products (CxHy), such as CH4 and C2H4. [Display omitted] •COF with single-atom MoN2 site was successfully prepared.•Single-atom MoN2 site COF with showed excellent performance of photocatalytic reduction of CO2.•The mechanism of single-atom MoN2 site improving performance was revealed. The application of covalent organic framework (COF) for photocatalytic CO2 conversion has received more and more attention. However, it is still a challenge for photocatalytic conversion of CO2 with atmosphere concentration to high added value hydrocarbons products (CxHy) such as CH4 and C2H4. Here, integrating the advantages of micropore structure and single atom catalysis, we introduced single- atom MoN2 sites into COF to construct Mo-COF materials. The aberration-COrrected high-angle annular dark-field scanning transmission electron microscopy (HAADF- STEM) confirms that Mo single atom on COF. Mo-COF can reduce CO2 to CxHy under visible light with a selectivity of 42.92 % and C2H4 product was found for the the first time. In-situ fourier transform infrared spectrometer (In situ FT-IR) and theoretical calculation showed that the introduction of single-atom MoN2 sites is the key to improving the catalysis performance. It also provides a new idea for converting CO2 into high added value CxHy products.