Platinum-based alloy catalyst can enhance methanol fuel cell efficiency and durability

Replacing traditional fossil fuels with clean, renewable energy sources is expected to solve environmental issues and alleviate the energy crisis. As a novel energy conversion device, fuel cells are capable of efficiently transforming chemical energy into electrical energy.

Methanol, a liquid fuel known for its high energy density, safety, and ease of transport, has long been seen as a promising candidate for fuel cells. However, a major challenge in methanol oxidation is the rapid deactivation of catalysts caused by poisoning species formed during the reaction. These species—especially carbon monoxide—stick to catalysts and keep them from working. Therefore, enhancing the activity and anti-poisoning performance of the catalyst is key to developing direct methanol fuel cells (DMFCs).

In response to this challenge, a research team led by Prof. Zhang Tierui from the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences (CAS) has developed a new catalyst that significantly enhances the efficiency and durability of methanol oxidation reactions. Composed of ultrafine platinum-based high-entropy alloy (HEA) octahedra, the catalyst marks a promising advance in DMFC efficiency and resistance to catalytic poisoning.

This breakthrough was published in Matter on April 8.

Due to the exposed crystal facets of Pt-based octahedral materials, they have shown good activity in various electrocatalytic reactions. However, the high surface energy of these nano-octahedra causes them to be unstable and prone to aggregation. As a result, it is difficult to efficiently use the catalyst’s active sites.

In this study, Prof. Zhang’s team addressed the challenge by engineering ultrafine HEA octahedra composed of multiple metal elements. By incorporating a diverse set of elements, the researchers successfully reduced the surface energy of platinum-based nano-octahedra, enabling the formation of stable structures with edge lengths under 3 nanometers—significantly smaller than those achieved in earlier efforts.

The experimental results show that as the number of metal elements increases, the size of the octahedra gradually decreases. For example, the average edge length of this senary alloy—one comprising six different metal elements—is only 2.8 nanometers.

Electrochemical tests and theoretical calculations indicate that the synergistic effect of multiple metal elements further modulates the electronic structure of platinum (Pt). In the methanol oxidation reaction, the senary alloy outperformed both ternary alloys—alloys comprising three metal elements—and commercial platinum-on-carbon (Pt/C) catalysts in terms of activity and resistance to poisoning.