Stepwise dispersion of nickel species for efficient coupling of electrocatalytic redox reactions

Abstract

Advanced electrocatalysts are highly desirable to enhance energy conversion efficiency for properly coupling electrocatalytic redox reactions, but the fabrication of efficient bifunctional catalysts is still highly challenging. Herein, a self-feeding deposition strategy was demonstrated to disperse nickel species into single nickel atoms along with the growth of nitrogen-doped carbon nanotubes, thus inhibiting the thermal aggregation of nickel nanoparticles. The residual nickel nanoparticles are encapsulated among the bamboo-like carbon nanotubes and porous carbon matrix, which promotes the efficient electron transfer via the formation of heterojunctions. With the regulation of electronic and geometric structures between the single atom active sites and the isolated nickel nanoparticles, the unique nucleo- and electro-philic interfaces facilitate the targeted adsorption and activation of carbon dioxide and benzylamine molecules, respectively, thus narrowing the energy barriers to enhance electrocatalytic performances. The improved bifunctional electrocatalysis enables the carbon dioxide reduction into CO with an impressive Faraday efficiency (FE) up to 99.3 % and the highly efficient oxidation of benzylamine into benzonitrile (FE ∼ 98 %). This work not only reveals the fundamental understanding of the underlying structure–activity relationship, but also provides a new method for value-added chemicals production.