In-situ construction of 2D β-Co(OH)2 nanosheets hybridized with 1D N-doped carbon nanotubes as efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions

It is crucial to develop highly active and durable bifunctional electrocatalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for rechargeable Zn-air batteries. Herein, we report a facile approach to synthesize 2D β-Co(OH) 2 nanosheets supported on 1D nitrogen-doped carbon nanotubes through a hydrothermal in-situ growth strategy of Co nanoparticles encapsulated N-doped carbon nanotubes and urea. The as-obtained Co(OH) 2 /NCNTs displays excellent bifunctional activity with a high half-wave potential of 0.85 V vs. RHE for ORR, a low overpotential of 312 mV at 10 mA cm −2 for OER, and a low potential gap of 0.69 V. Density function theory calculations show that the synergistic effort between doped carbon and β-Co(OH) 2 reduces the energy barriers of the rate determining steps for the former toward ORR and for the latter toward OER, contributing to the superior bifunctional catalytic performance. The assembled Co(OH) 2 /NCNTs- based battery performs a high specific capacity of 883 mAh g Zn -1 and remarkable cycle stability. This presented in-situ construction strategy provides an attractive rational design method for preparing carbon-based bifunctional electrocatalysts.