Transition Metal (Fe, Zn, Co, and Ni) Single-Atom Catalysts Anchored on N,S-Codoped Hybrid Nanocarbons for Oxygen Reduction Reaction
Dan Wei, Lixin Chen, Hui Zhao, Lidong Tian, Seeram Ramakrishna, Dongxiao Ji
Abstract
Atomically dispersed transition metal catalysts have served as promising candidates to substitute noble metals in energy conversion. A majority of carbon-supported transition metal single-atom catalysts (SACs) have been synthesized via the high-temperature sintering method, in which the complex heating and cooling processes are time- and energy-consuming. Herein, we have developed a simple and highly effective microwave-assisted heating method to prepare a series of isolated transition metal SACs anchored on a N,S-codoped nanocarbon matrix, which are denoted as M-NSC-MW, M = Fe, Zn, Co, and Ni. Among the various M-NSC-MW, Fe-NSC-MW possesses the highest ORR electrochemical activity in alkaline electrolytes. Its onset potential ( E onset ) is 0.955 V, and its half-wave potential ( E 1/2 ) can reach 0.852 V, both of which are the same as those of commercial Pt/C. Moreover, Fe-NSC-MW also exhibits much superior ORR catalytic efficiency than conventional pyrolysis samples. It is worth noting that Zn-NSC–MW is prepared for the first time, and it also shows a high ORR performance with an E onset of 0.945 V and an E 1/2 of 0.832 V. This work has revealed the general application of the microwave-assisted heating method to prepare well-dispersed transition metal SACs anchored on the N,S-codoped graphene/carbon hybrid matrix.