A Co3O4-x/Co nanocomposite with synergistically enhanced electrochemical activity for reduction of nitrite to ammonia

Electrocatalytic reduction of nitrite (NO2- ) to ammonia (NH3) cannot only solve the problem of water pollution, but also produce high value-added ammonia. In practical applications, it is extremely important to develop high performance and cheap electrocatalysts. In this paper, a nano-electrocatalyst (Co3O4-x/Co) was prepared by combining cobalt trioxide (Co3O4-x) with cobalt nanoparticle (Co). The Co3O4-x is rich in oxygen vacancy. In neutral electrolyte, the composite electrocatalyst shows superior electrocatalytic activity for NO2 - reduction to ammonia (Faraday efficiency up to 97 % at -0.8 V vs. RHE, ammonia yield up to 0.628 mmol h-1 cm-2 at -1.1 V vs. RHE). This performance may result from synergistic enhancement between Co3O4-x and Co.