Ultrathin atomic Mn-decorated formamide-converted N-doped carbon for efficient oxygen reduction reaction

Abstract

It is of great importance to control the thickness of catalytic components to enable maximum catalyst utilization and strong catalyst–substrate interaction since electrocatalytic reactions occurring at the interface of catalysts involve a one or two-atom thick active layer. Herein, we achieved an ultrathin deposition of a 2.5 ± 0.2 nm active layer containing atomically dispersed Mn–nitrogen–carbon (Mn–NC) materials on conductive carbon nanotubes (CNTs) via a solvothermal treatment of formamide and Mn salt, and applied the as-made Mn–NC/CNT composite without pyrolysis directly as a catalyst for the oxygen reduction reaction (ORR). The atomic dispersion of Mn species in multiple nitrogen surroundings has been confirmed by combining high-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photon spectroscopy. The as-prepared formamide-converted Mn–NC/CNT composite, used for catalyzing the ORR, exhibited a highly comparable performance in alkaline media relative to that of 20 wt% Pt/C by achieving a high onset potential and a half-wave potential (E_1/2) of 0.91 V and 0.83 V (vs. RHE), respectively. Density functional theory (DFT) calculations further suggested that Mn–N moieties were capable of efficiently accelerating the release of *OH intermediates under a high reduction potential, thus exhibiting advanced ORR performance.