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.