Regulating the metal-support interactions of Ru on hollow nitrogen-doped carbon to enhance the hydrogen evolution reaction activity

The metal-support interactions (MSIs) play a significant role in regulating the electronic structure of metal species on oxide; however, they are often overlooked on carbon-based supports. In this work, hollow nitrogen-doped carbon (H-NC) supported Ru nanoparticles catalyst (Ru/H-NC) was prepared by a solvothermal method using H-NC as support and RuCl 3 as precursor. Subsequently, Ru/H-NC was annealed at different temperatures (Ru/H-NC t °C) to adjust the effect of MSIs between H-NC support and Ru nanoparticles. The X-ray photoelectron spectroscopy results showed that the MSIs between Ru species and H-NC support increased with the increase of temperature, and more electrons were transferred from Ru species to H-NC support, thus regulating the valence state of Ru. In hydrogen evolution reaction (HER), the as-synthesized Ru/H-NC 300 °C merely requires overpotential of 35.45 mV to achieve 10 mA/cm 2 at low Ru mass loading of 24.03 µg/cm 2 on the glassy carbon electrode. The cyclic voltammetry test revealed that the electrochemically active surface area increased first and then decreased with the increasing MSIs. Moreover, electrochemical impedance spectroscopy results showed that HER kinetics of Ru/H-NC t °C catalysts increased first and then decreased with the MSIs enhancement. The density functional theory calculations confirmed that the MSIs effectively optimize the adsorption strength of the key intermediates (H*, HO*) on Ru clusters, and thus greatly improve the catalytic performance of Ru/H-NC in HER.