Nano-RuW Composites with Low Loading as High-Efficiency Electrocatalysts for Hydrogen Evolution in Acidic and Alkaline Solutions

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 Ru88W12 electrode not only exceeds that of Ru but also exceeds that of Pt/C, which is rarely reported in the previous literature. The Ru88W12 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 Ru88W12 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 H2SO4 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 Ru88W12 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.