Scientists from the China University of Petroleum, Beijing make successful progress in the preparation of hydrogen evolution reaction (HER) catalysts using a simplified method.
The use of hydrogen as a fuel is well-known as a high energy density source and has lesser harmful impact on the environment compared to fossil fuels. The hydrogen evolution reaction (HER) is one of the most promising hydrogen production methods as a half-reaction of the electrolysis of water.
Currently, platinum-based compounds are used as the most active electrocatalysts for hydrogen evolution reactions. However, platinum is relatively scarce and expensive. Therefore, designing and synthesizing highly efficient, stable, and inexpensive catalysts is a major challenge in the field of water electrolysis.
Progress has been made in this area in a study published by Li Zhenxing and his team from the China University of Petroleum, Beijing. The team found a simple one-pot method to develop ultra-small hollow ternary alloy nanoparticles. During the synthesis process, the displacement reaction and oxidative etching were key in the formation of these hollow structures. One of the alloy nanoparticles, its average size is only five nanometres and contains only 10 percent of platinum.
The unique hollow structure and large specific surface area increase the degree of surface atom exposure, provide abundant active centres, and make the alloy nanoparticles exhibit excellent electrocatalytic activity and stability.
In alkaline electrolyte, the overpotential of hollow alloy nanoparticles was lower than those of commercial platinum-based compounds. In addition, its mass activity is higher than that of commercial platinum-based compound system. This effectively reduces the cost of platinum-based electrocatalysts and ensures that platinum atoms are used more efficiently.
By analysing the bonding and antibonding orbital filling, the density functional theory (DFT) calculations show that the Gibbs free energy of hydrogen adsorption is close to zero. In the hydrogen evolution reaction (HER) reaction process, the bonding strength of different metals to the hydrogen intermediate was in the order of platinum, cobalt, nickel, and copper. Thus, the excellent HER performance of hollow alloy nanoparticles can be attributed to moderately synergistic interactions between the three metals and the hydrogen intermediate. Combining theoretical calculations with experimental data, this work provides a new strategy for the design and preparation of low-cost and high-performance HER catalysts. [APBN]