Mesoporous\nMetal–Nitrogen-Doped Carbon Electrocatalysts\nfor Highly Efficient Oxygen Reduction Reaction

Abstract

A family of mesoporous nonprecious\nmetal (NPM) catalysts for oxygen\nreduction reaction (ORR) in acidic media, including cobalt–nitrogen-doped\ncarbon (C–N–Co) and iron–nitrogen-doped carbon\n(C–N–Fe), was prepared from vitamin B12 (VB12) and the\npolyaniline-Fe (PANI-Fe) complex, respectively. Silica nanoparticles,\nordered mesoporous silica SBA-15, and montmorillonite were used as\ntemplates for achieving mesoporous structures. The most active mesoporous\ncatalyst was fabricated from VB12 and silica nanoparticles and exhibited\na remarkable ORR activity in acidic medium (half-wave potential of\n0.79 V, only ∼58 mV deviation from Pt/C), high selectivity\n(electron-transfer number >3.95), and excellent electrochemical\nstability\n(only 9 mV negative shift of half-wave potential after 10 000\npotential cycles). The unprecedented performance of these NPM catalysts\nin ORR was attributed to their well-defined porous structures with\na narrow mesopore size distribution, high Brunauer–Emmett–Teller\nsurface area (up to 572 m²/g), and homogeneous distribution\nof abundant metal–N_<i>x</i> active sites.