Ultrathin cobalt pyrophosphate nanosheets with different thicknesses for Zn-air batteries.

Two dimensional (2D) ultrathin nonprecious metal based catalysts show excellent electrocatalytic activities, due to the larger surface areas, more catalytic sites and more interconnected electron-transfer access than their bulk counterparts. Here, we synthesized cobalt pyrophosphate (CoPO) nanosheets with different thickness by a simple and efficient one-step hydrothermal process. The catalytic performance of the obtained CoPO was investigated via diverse electrochemical measurement. Due to the unique 2D structure and the flexible coordination of pyrophosphate group, the as-prepared CoPO catalyst had excellent electrocatalytic performance and good stability, which could rank among the most active nonprecious metal catalysts for oxygen evolution reaction and oxygen reduction reaction. In addition, the ultrathin CoPO nanosheets exhibited good performance as the air cathode catalyst for zinc air batteries.