Cobalt-based deep eutectic solvent modified nitrogen-doped carbon catalyst for boosting oxygen reduction reaction in zinc-air batteries

As an oxygen reduction reaction(ORR)catalyst,nitrogen-doped carbon(NC)is widely used in zinc-air batteries(ZABs).However,NC catalysts exhibit low conductivity and insufficient exposure of active sites.Therefore,a Co-based deep eutectic solvent(DES)was selected to modify NC catalyst(Co-NC)to improve ORR performances.Density functional theory(DFT)calculation shows that the modification of Co-based DES can change the electronic structure of NC and increase metallic active sites,which is beneficial to the desorption of reaction intermediates on Co-NC,further improving ORR performance.Co-NC shows excellent ORR performances and stability.Impressively,ZABs assembled with Co-NC manifest a high maximum power density of 177.4 mW cm^(-2),a high specific capacity of 726.12 mA h g^(-1)and a charge-discharge cycle life of 500 h.This study can provide practical reference for surface modified carbon-based electrocatalyst with DES to improve ORR performances.