CoOx/CoNy nanoparticles encapsulated carbon-nitride nanosheets as an efficiently trifunctional electrocatalyst for overall water splitting and Zn-air battery

A novel and efficient trifunctional electrocatalyst composed of cobalt oxide (CoOx) and cobalt nitride (CoNy) embedded in carbon–nitride nanosheets (CNz, represented by CoOx/CoNy@CNz) has been developed by calcining the composite of cobalt phthalocyanine (CoPc) and melamine–cyanuric acid complex at high temperatures. Multiple active sites of Co, CoOx, CoNy, and CNz containing in hybrids resulted in superior catalytic activities toward hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction in an alkaline medium. Among different catalysts, the CoOx/CoNy@CNz,700 catalyst not only displayed outstanding electrocatalytic ability for overall water splitting but also showed a high power density as high as 204.8 mW cm−2, high gravimetric energy density of 1008.6 W h kg−1, low charge–discharge polarization, and excellent reversibility after 86 h at 10 mA cm−2 in a Zn-battery system. This work presents a feasible strategy for developing multifunctional metal–carbon–nitride electrocatalysts for clean energy and energy transfer.