Nickel Phosphonate MOF Derived N-Doped Carbon-Coated Phosphorus-Vacancies-Rich Ni2 P Particles as Efficient Bifunctional Oxygen Electrocatalyst.

The design of non-noble metal bifunctional electrocatalysts with outstanding performance and remarkable stability for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most essential issues to the realization of rechargeable zinc-air battery, and transition metal phosphides (TMPs) have emerged as robust candidates for oxygen electrocatalysts. Herein, N-doped carbon-coated phosphorus-vacancies-rich Ni2 P particles (Vp -Ni2 P@NC) is proposed via simple carbonization and following Ar plasma treatment from a single nickel phosphonate metal-organic framework (MOF) without extra phosphine and nitrogen sources. The facile and rapid plasma treatment can achieve phosphorus vacancies which could modulate the electronic structure to enhance the inherent active and electrical conductivity. Meanwhile, the pyridine-N and graphitized-N produced during calcination also could provide more active sites and increase the electrical conductivity. The resultant Vp -Ni2 P@NC catalyst shows excellent bifunctional electrocatalytic activity (OER/ORR) based on synergistic effect of introducing P vacancies into Ni2 P and N-doped carbon. Vp -Ni2 P@NC catalyst shows more advantageous ΔE value (0.70 V) compared to Pt/C+RuO2 (0.73 V) and most reported catalysts. Additionally, the zinc-air bbatterie (ZAB) employing Vp -Ni2 P@NC as air cathode shows excellent performance. The maximum power density of 203.48 mW cm-2 , the cycling stability of more than 150 h at 10 mA cm-2 .