An effective porous Co-N-C electrocatalyst deriving Prussian-blue-analog for oxygen reduction of zinc-air battery

Abstract

The exploration of advanced carbon electrocatalysts derived from Prussian-blue-analog (PBA, Co₃[Co(CN)₆]₂) to replace precious metals such as Pt and Pd for the oxygen reduction reaction (ORR) has attracted significant attention. In this study, a porous Co-N-C carbon electrocatalyst (PBA-p-CoNC) was derived from PBA and developed for application in rechargeable zinc-air batteries (ZABs). Notably, the as-prepared PBA-p-CoNC exhibits a large surface area (1105.0 m² g⁻¹) and good ORR activity, with a half-wave potential (E_1/2) of 0.901 V, surpassing that of commercial 20 % Pt/C (0.865 V). Importantly, after 2500 cycles, the E_1/2 loss of PBA-p-CoNC is only 29.0 mV, which is remarkably lower than that of Pt/C (75.7 mV after 1000 cycles). In the chronoamperometry test, the current decay rate of PBA-p-CoNC is 17.6 % for 50,000 s, also superior than Pt/C (18.4 %). And the ZAB assembled with PBA-p-CoNC has a high capacity per unit of 848.8 mAh g_zn⁻¹ at a current density of 10 mA cm⁻², with good charge-discharge capability and stability over the long term (more than 159 h). These performances outperform commercial Pt/C + RuO₂ cathodes, underscoring the potential of PBA-derived carbon materials in future energy conversion applications.