Xanthine-derived 3D porous iron–nitrogen-carbon catalysts for enhanced oxygen reduction reaction

Iron-nitrogen-carbon (Fe-N-C) catalyst has emerged as highly promising contender for oxygen reduction reaction (ORR), yet challenges such as limited active site accessibility and intricate synthesis procedures impede their commercialization as a replacement for the benchmark Pt/C catalyst. Herein, we present an innovative approach to in situ fabricate a unique iron and nitrogen co-doped 3D porous carbon material. The material is synthesized through a straightforward one-step pyrolysis of xanthine, oxidized carbon nanotubes and iron nitrate nonahydrate mixture. During the high temperature pyrolysis, the nucleobase xanthine undergoes gradually transformation into an efficient N-doped graphene-like material. Simultaneously, it assembles with carbon nanotubes (CNTs), resulting in the formation of a unique 3D graphene-CNTs composite structure composed of graphene and CNTs. This exceptional 3D porous structure serves as an excellent scaffold, ensuring firm anchoring, uniform dispersion, and optimal exposure of numerous FeNx active sites. Leveraging this well-engineered framework, the optimized Fe-N-C catalyst (NC/CNT/Fe0.04) shows excellent ORR performance with an onset potential of 1.03 V vs. RHE, a half-wave potential of 0.87 V vs. RHE, and a diffusion-limited current density of −5.59 mA cm−2, even better than those of the commercial Pt/C catalyst. This work provides valuable insights into the design of efficient electrocatalysts with 3D channel.