Mechanism difference between nanoparticles and single-atom sites on aqueous formic acid dehydrogenation over coblat catalyst

Various Co-N-C catalysts including nanoparticles and single-atom sites were prepared using a low-temperature synthetic strategy by vacuum calcining with high exposure of the active sites and low energy consumption. When used in the formic acid (FA) dehydrogenation reaction, the obtained single-atom sites catalyst displayed high catalytic activity with a high H 2 production rate of 27,361 mL·g −1 ·h −1 . Moreover, the single-atom sites catalysts can still exhibit astonished catalytic performance in 88% FA (cheapest commercially available grade of FA) due to their super stability and special mechanism of reaction. From TEM, XRD, HAADF-STEM, XPS, and XANES characterization, the atomically dispersed active sites in the single-atom sites catalysts caused by strong metal-nitrogen coordination is believed to be the key to the success of this reaction. Moreover, the mechanism difference between nanoparticles and single-atom sites on aqueous formic acid dehydrogenation over coblat catalyst was illustrated. The mechanism of SAC and NP catalyst were both discussed through contrast experiment and isotope effect experiment. Finally confirmed the reaction proceeds through the HCO 2 − dehydrogenation path on NP catalyst and HCO 2 H dehydrogenation path on SAC.