Intermolecular hydrogen bond modulating the selective coupling of protons and CO2 to CH4 over nitrogen-doped carbon layers modified cobalt

Photocatalytic reduction of CO 2 with H 2 O to CH 4 is a promising route to migrate CO 2 emission and complete the carbon neutrality goal. Nevertheless, one of the biggest challenges for this elegant strategy is that the coupling of the protons and CO 2 to form CH 4 is fiercely competed with proton-proton coupling to form H 2 , leading to extremely low CH 4 selectivity. Herein, we designed and fabricated the nitrogen-doped carbon layers modified cobalt (N-C@Co) photocatalyst achieving the selective coupling of protons and CO 2 to CH 4 during photocatalytic reduction of CO 2 . The successful formation of intermolecular hydrogen bonds between the as-prepared N-C@Co and H 2 O molecule was found to suppress the mass transfer of the generated protons and promote the adsorption and activation of the CO 2 molecule. More crucially, it was conducive to suppressing the desorption of the CO intermediate, which was typically deemed as the decisive species for CH 4 generation. As a result, the H 2 selectivity (9.0 %) and activity (17.3 µmol g −1 ) of the as-prepared N-C@Co were reduced by a factor of 9.3 and 17.6, respectively, as compared to that of bulk Co. The CH 4 selectivity of N-C@Co was boosted 6.1 times from 13.3% of bulk Co to 81.3 % of N-C@Co with the generation rate of 155.7 μmol g −1 in 23 h. This work provides a new insight into the photocatalyst design for improving CH 4 selectivity and suppressing the competing H 2 and CO generation.