Fluorophosphates as Efficient Bifunctional Electrocatalysts for Metal-Air Batteries

An efficient bifunctional catalyst still remains a stupendous challenge for the use of energy storage devices such as rechargeable metal-air batteries and fuel cells as the current electrocatalysts are either oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) selective and suffer from cost and stability issues. Co-phosphate-based bifunctional materials can be a plausible option owing to the enhanced stability imparted by the phosphate group. Inspired by the possibility, we report solution combustion synthesized porous Na2CoPO4F as a bifunctional electrocatalyst. Comparable to the existing conventional electrocatalysts, porous Na2CoPO4F exhibits robust bifunctional (ORR/OER) properties. Having F-based chemistry, the dissolution is minimal in an aqueous medium, paving a way for its use as a cathode for the aqueous rechargeable hybrid Na-air battery. Thus, based on the bifunctional catalytic performances and stability in an aqueous medium, this material can be envisaged as a cheap and an efficient catalyst for fuel cell as well as a cathode for metal-air batteries.