Insights on the Roles of Nitrogen Configuration in Enhancing the Performance of Electrocatalytic Methanol Oxidation over Pt Nanoparticles.

Abstract

Stabilization of the Pt in N-doped carbon materials is an effective method to improve the performance of electrocatalytic methanol oxidation reaction (MOR). Nevertheless, the roles of different N configurations (pyridinic N, pyrrolic N, and graphitic N) toward the electrochemical performance of Pt-based catalysts remain unclear. Herein, Density Functional Theory calculations are adopted to elucidate the synergistic promotion of MOR by different N-configurations with Pt nanoparticles (NPs). Guided by the theoretical study, a series of MOR electrocatalysts with different ratios of pyridinic N and pyrrolic N (denoted as Pt/N-CNT-X (500, 600, 700, 800, and 900)) are designed and synthesized. Surprisingly, the electrocatalytic activity of Pt/N-CNT-600 with a suitable ratio of pyrrolic-N and pyridinic-N for MOR reaches 2394.7mAmg-1 Pt and 5515.8mAmg-1 Pt in acidic and alkaline media, respectively, which are superior to the Pt/CNTs, commercial Pt/C, and the ever-reported Pt-based electrocatalysts. The strong metal-support interaction induced by the N-doping is the crucial reason for the superior electrocatalytic performance. More importantly, the ability of pyrrolic-N and pyridinic-N in promoting the adsorption and oxidation of CH3 OH and the oxidation of CO* is substantiated for the first time in methanol oxidation. This work provides new insights on the design of efficient electrocatalysts for MOR.