Relationship between hydrogen binding energy and activity for hydrogen evolution reaction by palladium supported on sulfur-doped ordered mesoporous carbon

The performance of a heterogeneous catalyst is determined by the interaction between the support and the metal active site of the catalyst. To investigate the effect of the interaction between sulfur in sulfur-doped ordered mesoporous carbon (SOMC) and palladium (Pd) on hydrogen evolution reaction (HER) activity, a catalyst was prepared with low Pd content supported on SOMC (Pd/SOMC). Sulfur was expected to serve as an anchor for Pd to form smaller nanoparticles. Transmission electron microscopy confirmed that the Pd particle size in Pd/SOMC was smaller than that of Pd supported on pristine ordered mesoporous carbon (Pd/OMC), indicating the improvement of Pd dispersion by the anchoring of sulfur to Pd. HER activity of these catalysts was analyzed from 0.1 V to -0.3 V with a scan rate of 1 mV/s in N-2-saturated 0.1 M HClO4 electrolyte. Despite the smaller Pd particle size in Pd/SOMC, Pd/OMC showed better HER activity (7.38 mA/cm(2) at -0.15 V) than Pd/SOMC (2.71 mA/cm(2)). Moreover, overpotential at -10 mA/cm 2 for Pd/OMC was 90 mV lower than that for Pd/SOMC. Density functional theory calculations proved that the increase in the binding energy of hydrogen on the Pd in the Pd/SOMC is related to the decrease in HER activity. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.