High Electrocatalytic Hydrogen Evolution Activity of an Anomalous Ruthenium Catalyst

Abstract

Hydrogen evolution reaction (HER) is a critical process due to its fundamental role in electrocatalysis. Practically, the development of high-performance electrocatalysts for HER in alkaline media is of great importance for the conversion of renewable energy to hydrogen fuel via photoelectrochemical water splitting. However, both mechanistic exploration and materials development for HER under alkaline conditions are very limited. Precious Pt metal, which still serves as the state-of-the-art catalyst for HER, is unable to guarantee a sustainable hydrogen supply. Here we report an anomalously structured Ru catalyst that shows 2.5 times higher hydrogen generation rate than Pt and is among the most active HER electrocatalysts yet reported in alkaline solutions. The identification of new face-centered cubic crystallographic structure of Ru nanoparticles was investigated by high-resolution transmission electron microscopy imaging, and its formation mechanism was revealed by spectroscopic characterization and theoretical analysis. For the first time, it is found that the Ru nanocatalyst showed a pronounced effect of the crystal structure on the electrocatalytic activity tested under different conditions. The combination of electrochemical reaction rate measurements and density functional theory computation shows that the high activity of anomalous Ru catalyst in alkaline solution originates from its suitable adsorption energies to some key reaction intermediates and reaction kinetics in the HER process.

Ruthenium-cobalt nanoalloys encapsulated in nitrogen-doped graphene as active electrocatalysts for producing hydrogen in alkaline media

“…For Pt cluster, even its calculated result was as good as our CoRu models; however, the measured activity was inferior to our S-4 sample. Similar results also existed in a recently published research59, Qiao and his co-workers have proved that, apart from the ΔG H* , the water dissociation kinetics would also affect the overall reaction rate, especially under basic electrolyte. According to their calculated results, when the kinetics of water dissociation from the Volmer step is considered, Pt exhibits a significant higher energy barrier than Ru and others, indicating sluggish water dissociation during catalytic process.…”

“…18a. Besides, recent researches report nano metallic Ru-based electrocatalysts with very active performance in basic media5960. Therefore, we synthesized nano-sized Ru nanoparticles (Supplementary Fig.…”

Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes: Mechanisms, Challenges, and Prospective Solutions

“…The Ru@C 2 N electrocatalyst exhibited high TOF at 25 mV (0.75 H 2 s −1 in 1.0 m KOH solution), low overpotentials at 10 mA cm −2 (17.0 mV in 1.0 m KOH solution) as well as superior stability. It is worth mentioning that recently reported anomalously structured Ru/C 3 N 4 /C catalyst also showed higher hydrogen generation rate than Pt and have been listed as the best HER electrocatalysts in alkaline medium 44. By structural identification, the Ru/C 3 N 4 /C catalyst shows a homogeneous dispersion of Ru NPs with an average size of 2 nm on g‐C 3 N 4 /C achieved by strong interaction between Ru and g‐C 3 N 4 /C phase.…”

“…In panel (a), the under potential hydrogen adsorption effect in the case of precious metals and the capacitance effect in the case of nanocarbons make that the current start points are not zero. Reproduced with permission 44. Copyright 2016, American Chemical Society.…”

“…Currently a plenty of catalysts have been developed that have comparable or even better catalytic activity than the benchmark PGMs‐based catalysts 44. Recently, it is also found that few catalysts have ability to perform better in alkaline medium than the acidic one, e.g., Hu and co‐workers prepared NiCo 2 P x as an active catalyst that can achieve current density of 10 mA cm −2 at 58 and 104 mV in alkaline and acidic mediums, respectively, where Ni modified the Co electronic atmosphere 45.…”