Optimizing interfacial hydroxyl adsorption on an ordered Ru-Sn intermetallic compound for efficient hydrogen evolution

Abstract

Ruthenium (Ru)-based electrocatalysts have garnered considerable attention due to their low water dissociation barrier, exceptional H adsorption strength and relatively lower cost among the platinum-group metal catalysts. However, the strong oxyphilic property of Ru leads to the excessive adsorption of hydroxyl species (OH_ad) generated from the water dissociation process. It also remains challenging to introduce another oxophilic species to weaken the adsorption of OH_ad while avoiding the coverage of active sites and ensuring the subsequent re-adsorption and desorption of water. Herein, we report an ordered Ru₃Sn₇ intermetallic compounds (IMCs)/acetylene black (AB) electrocatalyst. The highly ordered structure exposed abundant Ru active sites and atomically adjacent Sn oxophilic sites, which enabled the uniform distribution of both H and OH adsorption sites and prevented the coverage of Ru sites. The prepared Ru₃Sn₇ IMCs/AB promoted interfacial water adsorption/dissociation by optimizing the OH adsorption ability. As a result, the Ru₃Sn₇ IMCs/AB catalyst delivered an exceptional HER performance, achieving a low overpotential of 9 mV at 10 mA cm⁻² and long-term durability for over 150 hours. CO-stripping tests, in situ electrochemical Raman spectroscopy and DFT calculations revealed that the synthesized ordered Ru₃Sn₇ IMC effectively modulated the OH adsorption and improved the adsorption/desorption of interfacial water.