Size-Controllable High-Entropy Alloys Toward Stable Hydrogen Production at Industrial-Scale Current Densities.

Abstract

Efficient and stable electrocatalytic hydrogen evolution reaction (HER) at high current densities is highly desirable for industrial-scale hydrogen production, which is yet challenging, because of the electrocatalyst with short lifespans during the acidic HER process. Here, a controllable preparation technique is successfully developed to synthesize PdPtRuRhAu high-entropy alloys (HEAs) of various sizes, within the 3.14 nm particles (HEA-3.14) demonstrating exceptional catalytic performance and stable hydrogen production at current densities of -500 and -1000 mA·cm^-2 with negligible activity loss over 100 h. Theoretical calculations indicate that the bridge adsorption site of Pd-Au serves as an ideal location for HER, with HEA-3.14 possessing the highest proportion of such sites, reaching 18.97%. To further analyze the thermodynamic stability of HEAs, an element-encoding machine learning model is developed from over 300 000 preprocessed dataset of HEAs that achieving an impressively low RMSE of 58.6 °C and a high R² value of 0.98. By integrating thermodynamic modeling with machine learning methods, the melting point of the PdPtRuRhAu HEAs at 3.14 nm (366 °C) is predicted, which aligns well with the results obtained from differential scanning calorimetry tests. This work offers new insights and approaches for designing HEAs that reliably produce hydrogen at high current densities.