Scalable synthesis of hcp ruthenium-molybdenum nanoalloy as a robust bifunctional electrocatalyst for hydrogen evolution/oxidation

The hydrogen evolution reaction (HER) is the cathodic process of water splitting, and its reverse, the hydrogen oxidation reaction (HOR), is the anodic process of an H2-O2 fuel cell; both play important roles in the development of hydrogen energy. The rational design and scalable fabrication of low-cost and efficient bifunctional catalysts for the HER/HOR are highly desirable. Herein, ultrasmall Mo-Ru nanoalloy (Mo0.5Ru3 and MoRu3) particles uniformly distributed on mesoporous carbon (MPC) were successfully synthesized by a simple method that is easy to scale up for mass production. After the incorporation of Mo atoms, the as-prepared Mo0.5Ru3 and MoRu3 nanoalloys maintain a hexagonal-close-packed crystal structure. In acidic media, Mo0.5Ru3 exhibits excellent Pt-like HER and HOR activity, as well as good stability. Density functional theory (DFT) calculations reveal that the H adsorption free energy (DGH*) on the Mo0.5Ru3 (0 0 1) surface (-0.09 eV) is much closer to zero than that of metallic Ru (-0.22 eV), which contributes to the enhanced catalytic activity. In alkaline media, Mo0.5Ru3 also presents outstanding HER and HOR activity, even significantly outperforming Pt/C. The DFT results confirm that optimal binding energies with H* and OH* intermediate species, and low energy barriers in the water dissociation and formation steps, efficiently accelerate the alkaline HER/HOR kinetics of Mo0.5Ru3. This study provides a new avenue for the scalable fabrication of high-efficiency bifunctional electrocatalysts for the HER and HOR in both acidic and alkaline media. (c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, low-cost and efficient catalysts for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) were synthesized using ultrasmall Mo-Ru nanoalloys on mesoporous carbon. The Mo0.5Ru3 catalyst exhibited excellent activity and stability in both acidic and alkaline media, outperforming Pt-based catalysts. The results suggest that Mo0.5Ru3 has great potential as a bifunctional electrocatalyst for HER and HOR in hydrogen energy applications.