Amorphous cobalt phosphate porous nanosheets derived from two-dimensional cobalt phosphonate organic frameworks for high performance of oxygen evolution reaction

Abstract Two-dimensional cobalt phosphonate organic frameworks nanosheets were synthesized by a bottom-up chemical precipitation method. Different products were obtained by controlled calcination of the cobalt phosphonate organic frameworks. Results of products obtained at different temperatures were analyzed. The product obtained after calcination at 600 °C was amorphous, porous, and retains the original sheet-like structure of the two-dimensional cobalt phosphonate organic frameworks. The amorphous cobalt phosphate exhibited excellent reactivity in the oxygen evolution reaction. At 10 mA cm−2, the overpotential was only 278 mV, and the Tafel slope was 80 mV dec-1. The porous structure makes the amorphous cobalt phosphate have a large free space, increases the distribution of the active center, and facilitates the diffusion of hydroxide. The two-dimensional nanosheet structure has a high proportion of exposed metal atoms on the surface, and these coordinated unsaturated metal centers are important for electrocatalysis.