Synthesis of nitrogen and phosphorus co-doped graphene as efficient electrocatalyst for oxygen reduction reaction under strong alkaline media in advanced chlor-alkali cell

Abstract

Development of low-cost electrocatalyst for oxygen reduction reaction (ORR) is the main requirement for advanced chlor-alkali (ACA) cell. Herein, we report a simple and economical one-pot microwave assisted synthesis of nitrogen and phosphorus co-doped graphene (NPG) from graphene oxide in presence of ammonium dihydrogen phosphate. The optimized NPG showed well exfoliated graphene oxide with few layers of graphene and the XPS assured that about 6% of nitrogen and 4% of phosphorus co-doping into the graphene lattice through the various active forms of nitrogen and phosphorus. The large N and P content in the catalyst with all the active forms could facilitate faster ORR kinetics as well as it stability. The oxygen depolarized cathode containing electrocatalyst was fabricated and utilized in ACA cell. According to the result, the minimum cell voltage (2.01 V) was found under conditions: brine concentration 300 g/L, temperature 80 °C, pH 2 and current density 1.0 kA/m2.