Sacrificial template induced interconnected bubble-like N-doped carbon nanofoam as a pH-universal electrocatalyst for an oxygen reduction reaction

Abstract

Developing highly efficient, environmentally friendly and cost-effective electrocatalysts for oxygen reduction reactions is crucial for electrochemical energy conversion devices such as metal/air batteries and fuel cells. In this regard, metal-free porous carbons with their high activity, good stability and low cost show promising properties as a candidate for replacing expensive Pt-based electrocatalysts. However, it remains a major challenge to establish a template-free and green method for the synthesis of highly active metal-free carbon materials with outstanding performance over a wide pH range. In this paper, a controllable and scalable method to synthesize porous N-doped carbon nano-foams with interconnected bubble-like structures is presented. These as-prepared N-doped carbon catalysts, which were obtained by spray pyrolization and the subsequent heat treatment in the presence of NH3, possess activities which are well comparable to the commercial Pt/C. In addition, systematic electrochemical analyses were performed with a detailed explanation of the pore formation induced by the activation of Zn and NH3. In brief, this work is of great importance for the development of relevant electrochemical energy devices, particularly fuel cells and metal–air batteries.