As the cleanest renewable energy, hydrogen energy has attracted special attention in research. Yet the commercialization of traditional proton exchange membrane fuel cells (PEMFCs), which consume hydrogen and produce electricity, is seriously restricted due to the fact that the chemical reaction of PEMFCs cathode largely relies on expensive platinum-based catalysts.

One solution is to change the acidic electrolyte of PEMFCs to alkaline. Such fuel cells are called anion exchange membrane fuel cells (AEMFCs), and they allow for the use of cheaper metal elements like Co, Ni or Mn to design electrocatalysts.

The research team led by Prof. GAO Minrui from University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), inspired by this solution, developed a practical and scalable way to manufacture a novel Ni-W-Cu alloy, Ni_5.2WCu_2.2, as the cathode for AEMFCs. The study was published in Nature Communications.

The researchers first grew Cu(OH)₂ nanowires from a three-dimensional foam copper skeleton by anodic oxidation. The obtained nanowires were then immersed in a solution containing Ni and W elements. After hydrothermal synthesis and annealing, the Ni-W-Cu alloy was produced.

The ternary Ni_5.2WCu_2.2 alloy can catalyze the oxidation of hydrogen in alkaline medium 4.31 times more efficient than the benchmark platinum/carbon anode. It has an oxidation potential as high as 0.3V in comparison with the reversible hydrogen electrode, and can maintain high activity for up to 20 h under such overpotential, exceeding anodes based on non-platinum-group metals.

Besides, the alloy catalyst showed excellent resistance to CO poisoning, and maintained high activity in 20000 ppm CO/H₂ mixed atmosphere.

Analysis showed that the projected density of states of Ni_5.2WCu_2.2 alloy lies in the lowest at Fermi level, which indicates that the alloy has the optimal hydrogen binding energy. The multiple-element alloying effect rendered the Ni-based alloy a high activity catalyst and explained its oxidation resistance.

This work sheds light on the exploration of multiple-element alloys composed of cheap metals, thereby promoting the development of more efficient hydrogen oxidation catalysts for AEMFC anodes.