Colloidal Co single-atom catalyst: a facile synthesis strategy and high catalytic activity for hydrogen generation

Developing highly active single-atom catalysts is one of the most significant issues for future renewable energy technologies. Here we present a facile but effective and efficient strategy for synthesizing colloidal Co single-atom catalysts with excellent catalytic activity using a copolymer, poly(isobutylene-alt-maleic anhydride) (ISOBAM-104), as a stabilizing agent. The catalytic activity of the as-prepared colloidal single-atom catalyst for hydrogen generation from hydrolysis of KBH4 in an alkaline solution was as high at about 14 300 mL-H-2 min(-1) g-Co-1, which was even higher than that of its Pt, Pd or Rh counterpart. Such a high catalytic activity of the colloidal catalyst was attributable to the in situ formed and well-stabilized Co single-atoms whose existence was confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy. Moreover, quantum chemical calculations reveal that ISOBAM-104 has a higher binding energy with the Co catalyst than with the well-known conventional protective agents, including poly(N-vinyl-2-pyrrolidone), starch, carboxymethylcellulose sodium, polyvinyl alcohol, sodium polyacrylate and polyethylene glycol. In addition, the use of as-prepared Co catalysts resulted in a much lowered barrier for the dissociation reaction of BH4- than in the cases of using Pt, Pd and Rh counterpart catalysts.