Promotional effects of trace Ni on its dual-functional electrocatalysis of Co/N-doped carbon nanotube catalysts for ORR and OER

It is still a great challenge for developing efficient dual-functional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrocatalysts are critical to enhance the efficiency of metal-air cells and fuel cells. In this study, a one-pot vapor deposition method was used to realize the synchronously dope of N and Ni (trace) into Co/C to form Co-Ni (trace)/N-doped carbon nanotubes (Co-Ni (trace)/NCNTs). An interesting result is that injecting dicyandiamide (DCD) into Ni foam as a precursor led to the in situ formation of NCNTs, with synchronous doping of trace Ni into Co species. The cooperative effects of the Co-Ni (trace) and N-doped carbon nanotubes resulted in superior dual-functional electrocatalytic performance of Co-Ni (trace)/NCNTs for the ORR (half-wave potential E-1/2 vs. RHE: 0.83 V, electron transfer number n: 3.97) and OER (overpotential vs. RHE: 337 mV at 10 mA cm(-2), Tafel slope: 94.0 mV dec(-1)). Moreover, the Co-Ni (trace)/NCNTs catalyst showed excellent stability during 20,000 s of durability testing for both ORR and OER. This study provides a feasible strategy for designing efficient nonnoble metal-catalysts for renewable energy conversion devices. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, Co-Ni (trace)/NCNTs with superior dual-functional electrocatalytic performance for ORR and OER were successfully synthesized using a one-pot vapor deposition method. The catalyst showed excellent stability during durability testing and provides a feasible strategy for designing efficient nonnoble metal-catalysts for renewable energy conversion devices.