Exploration of cobalt phosphate as a potential catalyst for rechargeable aqueous sodium-air battery

•Co3(PO4)2 nanomaterial was synthesized by facile precipitation technique.•Bi-functional electrocatalytic activity of nano-Co3(PO4)2 was demonstrated.•The energy efficiency of Na-air cell was attained up to 83% by Co3(PO4)2 catalyst.•The Na-air cells were yielded low overpotential and good cycling stability.

Bifunctional catalysts are prominent to attain high capacity, maximum energy efficiency and long cycle-life for aqueous rechargeable Na-air batteries. In this work, we report the synthesis of bi-functional noble metal free, Co3(PO4)2 nanostructures by facile precipitation technique and evaluated its electrocatalytic activity. Co3(PO4)2 nanostructure was investigated as a potential electrocatalyst for rechargeable aqueous Na-air battery for the first time. The synthesized Co3(PO4)2 grain-like nanostructures showed better oxygen evolution activity compared to Pt/C catalyst. The fabricated Na-air battery with the Co3(PO4)2 catalyst as air-cathode delivered low overpotential and its round trip energy efficiency reached up to 83%. The Na-air battery exhibited stable cycle performance up to 50 cycles.

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