Efficient Electrochemical Hydrogenation of Toluene by Relay Catalysis Over a Ru Single Atom/Nanoparticle Dual‐Site Catalyst

The methylcyclohexane-toluene-hydrogen (MTH) cycle is one of the most promising liquid organic hydrogen carrier (LOHC) systems. Despite the good performance of carbon-supported Pt nanoparticles, the drawbacks of noble metals, such as high cost and limited availability, hinder the industrial applications of these catalyst technologies. Herein, a ruthenium single-atom/nanoparticle (Ru SA/NP) dual-site electrocatalyst is developed with low metal loadings and notable electrochemical hydrogenation (ECH) efficiency of toluene (TL) to methylcyclohexane (MCH) in an electrochemical microreactor. The results reveal that within a wide potential window (∆V = 500 mV), the optimal catalyst Ru4-CN exhibits ≈100% Faraday efficiency (FE), high MCH selectivity, and significant inhibition of the hydrogen evolution reaction (HER). At a cell voltage of 2.0 V, the yield of MCH reaches 657.12 µmol h^-1 mg_Ru ^-1, which is ≈28 times higher than that of commercial Ru/C catalyst. Experimental and theoretical analyses indicate that TL preferentially adsorbs on Ru NP, while hydrogen atoms adsorb on Ru-SA to form H^*, which is then delivered to Ru-NP to hydrogenate TL. This work brings forth a special design of Ru SA/NP dual-sites on the electrochemical hydrogenation of organic substrates and sheds light on the structure-activity relationships for future studies.