Chemical Vapor Deposition for Atomically Dispersed and Nitrogen Coordinated Single Metal Site Catalysts

Atomically dispersed and nitrogen coordinated single metal sites (M-N-C, M=Fe, Co, Ni, or Mn) are the popular platinum group-metal (PGM)-free catalysts for many electrochemical reactions. Traditional wet-chemistry catalyst synthesis often requires complex procedures with unsatisfied reproducibility and scalability. Here, we report a chemical vapor deposition (CVD) strategy to synthesize the promising single metal site (M-N-C) catalysts. The deposition of gaseous 2-methylimidazole onto ZnO substrates doped with M, followed by an in-situ thermal activation, was proved effective in generating single metal sites well dispersed into porous carbon. In particular, an optimal CVD-derived Fe-N-C catalyst is featured with atomically dispersed FeN4 sites with increased Fe loading relative to other catalysts from wet-chemistry synthesis. The catalyst exhibited outstanding oxygen-reduction activity in acidic electrolytes, which was further studied in proton-exchange membrane fuel cells with encouraging performance. The CVD synthesis sheds some light on the mass production of single metal site catalysts towards advanced electrocatalysis.