Quasi-one-dimensional Mo chains for efficient hydrogen evolution reaction

Structural modulation of catalytic nanostructures and fundamental understanding of their active sites at the atomic scale are important for predicting and improving the catalytic properties of nanostructures. Here, we prepared quasi-one-dimensional (1D) metal molybdenum (Mo) chains confined in atom-thick molybdenum disulfide (MoS2), referred henceforth as Mo/MoS2 nanosheets, and evaluated their hydrogen evolution reaction (HER) properties. The experiment and theoretical calculations show that the quasi-1D Mo chain with unsaturated coordination exhibits high HER activity. The unsaturated Mo sites in the chains increase the carrier density and facilitate the diffusion of hydrogen along the chains, mimicking an atomic scale reactor which leads to an experimentally observed enhanced catalytic performance. Within the framework of Volmer-Tafel model, the calculated kinetic barrier for H-2 evolution is only 0.48 eV for Mo/MoS2, which is significantly lower than that for the Pt (111) surface (similar to 0.8 eV). In particular, Mo/MoS2 nanosheets supported on reduced graphene oxide (Mo/MoS2/RGO) outperformed commercial Pt on glassy carbon (Pt/C) in the practically meaningful high-current region (> 140 mA cm(-2)) in 0.5MH(2)SO(4) solution and (15 mA cm(-2)) in 1.0 M NaOH solution, demonstrating that the Mo/MoS2/RGO could potentially replace Pt catalysts in practical HER systems. Additionally, this study provides crucial insights into the role of active centers in catalysis through a model-structure-performance relationship, thus pointing the way to a commercially viable technology for HER.