| dc.description.abstract | With the rapid advancement of technology, the consumption of energy sources such as fossil fuels and the resulting environmental pollution have garnered increasing attention. Due to its high energy density and zero-carbon combustion characteristics, hydrogen is considered a promising alternative to traditional fossil fuels. Consequently, hydrogen production via electrocatalytic water splitting is seen as a promising solution. However, the slow kinetics of the hydrogen evolution reaction (HER) poses a significant limitation. To accelerate the overall hydrogen production rate, the design of highly active electrocatalysts plays a decisive role in the HER process.
This study is divided into two parts. The first part introduces palladium (Pd) as an alternative material to high-cost platinum-based catalysts. Two strategies are employed to modify the catalytic activity of Pd： alloying with the iron, and incorporating hydrogen as interstitial atoms into the Pd lattice. These strategies aim to address the low activity of Pd catalysts caused by their strong affinity for hydrogen. Inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) were used to analyze the catalysts, obtaining material properties such as elemental composition, crystal structure, and valence state composition. Electrochemical analysis was conducted to evaluate the HER performance of the catalysts.
In this study, carbon-supported Pd-Fe alloy hydride nanoparticles were successfully synthesized using the oleylamine method. To understand the relationship between the Pd/Fe ratio and HER activity, three Pd-Fe alloy hydride catalysts with different ratios (1:1, 3:1, 9:1) were designed. Compared to the pure Pd catalyst used as a control, the Pd-Fe alloy hydride exhibited superior activity and stability in acidic media. Among them, Pd3FeH demonstrated the best HER performance, with an overpotential of 41 mV at 10 mA cm-2 and a Tafel slope of 17 mV dec-1. After 5000 cycles of accelerated degradation tests, the overpotential at 10 mA cm-2 remained at 41 mV, and the Tafel slope was 14 mV dec-1. The comparison revealed that an optimal Pd/Fe ratio could maximize the enhancement of both the activity and stability of the catalysts.
The second part of the study focuses on the regeneration of deactivated Pd-Fe alloy hydride catalysts through appropriate heat treatment. It compares the effects of different heat treatments on the Pd-Fe alloy hydride catalysts and explores the optimal heat treatment conditions for catalyst regeneration. After heat treatment at 200°C in a H2 atmosphere for 300 minutes, the overpotential degradation rate of the accelerated degradation tests (ADT) decreased from 160% to 35%, and the Tafel slope degradation rate decreased from 276% to 28%.
This study successfully combines the advantages of hydrides and transition metal alloying, designing a Pd3FeH catalyst for the HER in acidic media. The catalyst exhibits high activity and excellent electrochemical stability, and the deactivated catalyst can be regenerated, restoring its activity for continued use. | en_US |