Controllable construction of CoP nanoparticles anchored on a nitrogen-doped porous carbon as an electrocatalyst for highly efficient oxygen reduction in Zn-air batteries
Exploring cost-efficient and highly-efficient noble metal-free catalysts for the oxygen reduction reactions(ORRs)in-volved in sustainable energy devices remains a great challenge.Transition-metal phosphides supported on heteroatom-doped carbons have shown potential as alternative candidates for precious metals because of their tunable electronic structures and higher catalytic performance.Phosphating was used to construct CoP nanoparticles(NPs)anchored on a nitrogen-doped porous carbon framework(CoP@NC)from Co NPs loaded on NC,using PH3 gas released from NaH2PO2 during heat treatment.The dodecahedral structure of Co NPs was retained in their transformation to CoP NPs.The CoP@NC electrocatalyst shows a remarkable ORR activity with a half-wave potential up to 0.92 V under alkaline conditions,which is attributed to the combined coupling between the well dispersed CoP nanoparticles on the nitrogen-doped carbon and the efficient mass transport in the porous structure.Zinc-air batteries assembled with the CoP@NC electrocatalyst as a cathode have a high open-circuit voltage of 1.51 V and power density of 210.1 mW cm-2.This work provides a novel strategy to develop low-cost catalysts with an excellent ORR performance to promote their practical use in metal-air batteries.
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