Coupling electron donors with proton repulsion via Pt-N3-S sites to boost CO2 reduction in CO2/H2 fuel cell

A fuel cell involving CO2/H2 is an appealing energy system to convert CO2 into synthetic fuels as well as to generate electricity using only waste heat. However, overcoming the inherent activation barrier of CO2 to improve the CO2 conversion rate in CO2/H2 fuel cell is still challenging. Herein, we report a synergistic electron-donor and proton-repulsion group composed of Pt-N3-S-C sites to simultaneously modulate the electronic structure and CO2-protonation ability of Ru nanoclusters (RuNC) in RuNC/Pt-N3-S-C catalyst. Experiments combined with theoretical calculations indicate that Pt-N3-S sites not only function as electron donors to Ru nanoclusters to cooperatively induce the orbital hybridization of Ru 3d and the antibonding orbitals of CO2, affording the dissociation of CO bonds in CO2, but also as electronic structure “modulator” to create new active sites on the surface of RuNC to effectively activate molecular CO2. More importantly, an internal polarization field between Pt-N3-S-C and RuNC additionally makes single atom Pt sites repel protons while Ru atoms serve as proton capturers via hydrogen spillover effect, resulting in accelerated protonation of CO2. Consequently, the catalyst exhibits highly improved catalytic activities for CO2 reduction with a conversion rate of 559.1 μmol gcat−1 h−1. This approach helps with fine tuning the electronic structures and catalytic CO2 protonation ability of catalysts for thermal-coupled electrocatalysis. [Display omitted] •A CO2/H2 fuel cell to reduce CO2 and generate electricity was developed.•Pt-N3-S sites can modulate the electronic structure and CO2-protonation ability of Ru.•The featured catalysts exhibited excellent catalytic performance for CO2 reduction.•The catalytic mechanism of catalyst was investigated and revealed in depth.