Study of the mechanism of nitrogen doping in carbon supports on promoting electrocatalytic oxygen reduction reaction over platinum nanoparticles

Abstract

Nitrogen-doped carbons (Nano-NC) are often employed as functional supports for boosting oxygen reduction reaction (ORR) over Pt-based catalysts, however, the mechanism of N doping on the adsorption and activation of molecular oxygen on Pt active sites is still not clear. Herein, Nano-NCs as the supports were prepared by a facile NH3 antipyretic method, which allowed to tune the kinds of nitrogen species in carbon matrix and their contents by adjusting the NH3 antipyretic temperatures. With such an exquisite control, the Pt nanoparticles loaded on the as-obtained Nano-NC showed an optimal Pt particle size (2.10 nm), a higher content of Pt0, a large electrochemically active surface area, and fast electron transport ability. As a consequence, the Pt/Nano-NC-800 catalyst with the optimal N-doping showed an outstanding ORR performance with half-wave potential of 0.80 V vs. RHE, limit diffusion current of 5.37 mA/cm2 and improved methanol/CO anti-poisoning, which is superior to the commercial Pt/C catalyst (20%, JM), and most of previously reported Pt-based catalysts. This work may pave a way for the design of the advanced supports for Pt-based catalysts for the ORR applications.