Efficient Electrocatalytic Hydrogen Evolution Using HEAs

High-entropy alloys (HEAs) have become promising candidate materials for hydrogen evolution reaction (HER) electrocatalysts due to their unique cocktail electronic effect and lattice distortion effect.

In this study, ultra-small (less than 2 nanometers) nanoparticles of PtRuCoNiCu HEA were highly dispersed on hierarchical nitrogen-doped carbon nanocages (hNCNC) through a low-temperature thermal reduction method, referred to as us-HEA/hNCNC. The optimal us-HEA/hNCNC exhibited excellent HER performance in 0.5 M H₂SO₄ solution, achieving an ultra-low overpotential of 19 mV at 10 mA·cm⁻² (without iR compensation) and a high mass activity of 13.1 A·mgₙₒₙₑₗₑ ₘₑₜₐₗₛ⁻¹ at -0.10 V, with only a 3 mV increase in overpotential after 20,000 cyclic voltammetry scans, demonstrating outstanding stability, far superior to commercial Pt/C (20 wt.%).

Combined experimental and theoretical studies reveal that Pt and Ru serve as the main active sites for HER, while CoNiCu species modulate the electronic density of the active sites to facilitate H* adsorption and achieve optimal M-H binding energy. The hierarchical porous structure and nitrogen doping of the hNCNC support also play a key role in enhancing HER activity and stability.This study presents an effective strategy to significantly enhance noble metal HER performance by developing HEAs on a unique hNCNC support.

01 Catalyst Design and Synthesis

Synthesis of ultra-small HEA nanoparticles: By precisely controlling the types and amounts of metal sources, ultra-small HEA nanoparticles were successfully synthesized.

Hierarchical porous nitrogen-doped carbon nanocages (hNCNC) as support material: hNCNC not only provides abundant active sites but also promotes electrolyte wetting and mass transfer through its hierarchical porous structure.02 Catalyst Characterization

Characterization of physical and chemical properties: Various characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed for detailed analysis of the catalyst’s physical and chemical properties.

Characterization of electrochemical properties: Electrochemical methods, including cyclic voltammetry (CV) testing and linear sweep voltammetry (LSV) testing, were used to evaluate the catalyst’s HER activity, electrochemical active surface area (ECSA), and charge transfer resistance (Rct).

03 Optimization of HER Performance

Optimization of active sites: The synergistic effect between HEA nanoparticles and hNCNC support material optimized the structure and electronic density of active sites, thereby enhancing HER activity.

Optimization of pore structure: The hierarchical porous structure of hNCNC facilitated electrolyte wetting and mass transfer, further improving HER performance.

04 Performance Comparison and Mechanistic Discussion

Comparison of performance with other catalysts: The prepared catalyst was compared with other recently reported HER catalysts, demonstrating its superior HER activity.

Discussion of HER mechanism: Combining theoretical calculations and experimental data, the HER mechanism of the catalyst was discussed, including the formation of active sites, electronic density modulation, and the hydrogen evolution process.

05 Visual Guide

06 Assessment of Catalyst Stability

Long-term stability testing: Long-term HER tests were conducted to evaluate the stability of the catalyst, and the results indicate that the prepared catalyst exhibits excellent stability.

07 Conclusion and Outlook

Research conclusions: This study successfully prepared a high-performance HER catalyst, significantly enhancing its HER activity through the optimization of active sites and pore structure.

Future outlook: Future research will further explore the structure-activity relationship of the catalyst and how to enhance its HER performance through more refined synthesis strategies.

08 Experimental Section

Detailed experimental procedures: The paper describes in detail the synthesis steps of the catalyst, characterization methods, and electrochemical testing conditions, providing a reproducible experimental scheme for other researchers.

• This paper reveals the preparation methods and performance optimization mechanisms of high-performance HER catalysts through carefully designed experiments and in-depth theoretical analysis, providing strong support for the development of hydrogen energy.

▲ Programmable high-precision membrane electrode coater