Exploring Active Sites in Multi‐Heteroatom‐Doped Co‐Based Catalysts for Hydrogen Evolution Reactions

Abstract

Today, metal-N- as well as metal-S-doped carbon materials are known to catalyze the hydrogen evolution reaction (HER). However, especially N- and S-co-doped catalysts reach highest activity, but it remains unclear if the activity is related to MN_x or MS_y (M=metal) sites. In this work we apply a simple method for multi-heteroatom doping and investigate the effect of cobalt content on the HER in acidic medium. The CoN_x and CoS_y sites were evidenced on the basis of structural characterization by Raman, X-ray induced photoelectron spectroscopy, and TEM. The presence of sulfur enables the formation of a larger number of CoN_x sites. Structure-performance relationship proves that the HER activity is dominated by CoN_x rather than CoS_y sites. The most active catalysts also exhibit an excellent stability under galvanostatic conditions making them of interest for electrolyser application.