A series of nano PdFe alloy film electrodes with different ratios were prepared by high-vacuum magnetron sputtering under the action of high-strength magnetic field. Among them, the Pd 3 Fe alloy film electrode possesses the best hydrogen evolution activity, which significantly changes the properties of hydrogen adsorption (H ad ) and absorption (H abs ) of Pd. Pd 3 Fe is a nanoassembled film, which consists of many tiny nanosheets connected together. The electrochemical surface area of Pd 3 Fe electrode is 13 and 7 times that of the Pd/C and Pd electrode, respectively. At the same time, Pd and Fe had formed an alloy structure. The (111) plane of the Pd 3 Fe alloy is an obvious positive shift, and the crystal cell is compressed. The electron is transferred from Fe to Pd through XPS analysis, which has proven the electronic relationship between Pd and Fe. DFT calculations have also shown that the ΔG H* of the Pd 3 Fe surface is significantly reduced compared to that of Pd. Reducing the desorption energy of H on the Pd surface is beneficial to improve the electrocatalytic performance. It is noteworthy that the HER activity of Pd 3 Fe electrode has exceeded that of Pd/C, Pd, and Pt/C in both 0.5 M H 2 SO 4 and 1.0 M KOH. The HER activity of Pd 3 Fe electrode is 20, 1.9, and 3.1 times that of Pd/C, Pd, and Pt/C in 1.0 M KOH at −0.2 V. In 0.5 M H 2 SO 4 , the HER activity of the Pd 3 Fe electrode is 6, 3.5, and 1.6 times that of Pd/C, Pd, and Pt/C. The Pd 3 Fe film electrode has the most favorable reaction kinetics, with Tafel slopes of 44.7 and 38.7 mV dec −1 in acidic and alkaline solutions, respectively. The values of the Tafel slope indicate that the mechanism of HER on the Pd 3 Fe film electrode is consistent with the Volmer−Heyrovsky pathway, and the Heyrovsky step is a rate-determining step. In this paper, the Pd alloy electrode has exceeded the commercial Pt/C in both acidic and alkaline solutions, which makes it more practical.
Electrolysis of water is an effective way to produce high-purity hydrogen. Also, it is of great significance to develop an efficient electrocatalyst for hydrogen evolution reaction (HER), which is suitable for both acidic and alkaline solutions. In this work, a series of nano-RuW composite electrodes with different proportions were prepared by high-vacuum magnetron sputtering with a metal Ru loading of 78 μg cm −2 . Among them, both in acidic and alkaline solutions, the HER activity of a Ru 88 W 12 electrode not only exceeds that of Ru but also exceeds that of Pt/C, which is rarely reported in the previous literature. The Ru 88 W 12 electrode is composed of a number of small-sized nanoparticles arranged in sequence, which has improved the ECSA of the electrode. The ECSA of the Ru 88 W 12 electrode is 3.2 times that of Ru. At the same time, when W is doped into a Ru cell, the cell volume increases and electrons are transferred from W to Ru metal, thereby changing the electronic structure of Ru. The change of the Ru valence electron structure and the increase of ECSA greatly improve the electrochemical activity of the electrode. The HER activities of nano-RuW composite electrodes are 6.5, 1.7, and 1.1 times those of Ru/C, Ru, and Pt/C electrodes in 0.5 M H 2 SO 4 at −0.2 V. In 1.0 M KOH, the HER activities of nano-RuW composite electrodes are 3.6, 1.6, and 4.1 times those of Ru/C, Ru, and Pt/C electrodes. The Ru 88 W 12 electrode has the most favorable reaction kinetics, with Tafel slopes of 40.8 and 59.1 mV dec −1 in acidic and alkaline solutions, respectively. These results demonstrate that the strategy of nano-RuW composite electrodes could open an avenue for designing non-Pt efficient electrocatalysts with high activity in both acidic and alkaline solutions.
The optimized RuO2/Co3O4–RuCo-EO electrode with Ru loading of 0.064 mg cm−2 exhibits the excellent oxygen evolution activity with an overpotential of 220 mV at the current density of 10 mA cm−2 and a Tafel slope of 59.9 mV dec−1.
A nano AuTiO2−x composite with the electrochemical characteristics of under-potential deposition of H has exhibited excellent activity for hydrogen evolution.
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