Researchers from IMDEA Materials Institute have demonstrated improved and more affordable catalytic materials used to produce green hydrogen.

In a recent study, published in ACS Catalysis, intermetallic thin films made from three low-cost alloys: silver and indium (Ag₃In), nickel and iron (Ni₃Fe) and nickel and tin (Ni₃Sn), showed significant gains in catalytic efficiency for the hydrogen evolution reaction (HER) when subjected to controlled elastic strains.

The findings point to elastic strain engineering as a promising avenue to develop affordable catalysts that could replace platinum-group metals in industrial hydrogen production.

Unlocking Green Hydrogen: looking beyond high-cost platinum

Hydrogen generated from renewable-powered electrolysis is currently considered central to the global transition toward carbon-free energy.

However, its efficiency depends heavily on the catalysts that accelerate the splitting of water molecules: water electrolysis. This produces almost 100% pure hydrogen and can be scaled industrially.

In order to facilitate the required HER as part of this process, platinum remains the benchmark material, prized for its activity and durability. However, its high cost and limited supply pose major barriers to large-scale deployment.

“Consequently, there is a strong drive to discover affordable alternatives that can rival Pt-group metals in catalytic performance”, the study emphasises.

Putting materials under strain to boost catalytic performance

Rather than trying to develop entirely new materials with equivalent or superior characteristics to platinum, the IMDEA Materials research team aimed to show how the catalytic properties of the three existing intermetallic alloys: Ag₃In, Ni₃Fe and Ni₃Sn, could be improved via Elastic Strain Engineering. 

These materials were selected because of their availability and price, absence of toxic and hazardous elements and chemical stability in alkaline environments.

The team investigated whether introducing elastic strain, either tensile (stretching) or compressive (squeezing), could alter how catalytic surfaces bind to hydrogen atoms, a key step in the HER process.

Promisingly, the results demonstrated that elastic strains of the order of 1% led to significant changes in the surface activity that can be used to tune the catalytic performance for the HER.

According to the publication, “tensile strains improved catalytic activity (and reduced the Tafel slope and the charge transfer resistance) on Ag₃In, while compressive strains have similar effects in Ni₃Fe and Ni₃Sn, and Pt.”.

In one notable case, one Ni₃Sn alloy sample stretched by 1.26% achieved 71% of the efficiency of platinum.

A blueprint for strain-optimised hydrogen catalysts

The study, from current or former IMDEA Materials researchers: Jorge Redondo, Dr. Jayachandran Subbian, Dr. Miguel Monclús, Dr. Valentín Vassilev Galindo, Prof. Jon Molina and Prof. Javier LLorca, provides one of the first experimentally isolated and quantified demonstrations of how elastic strain, without defects or cracking, can tune a material’s catalytic properties.

“This work builds on our previous work at IMDEA Materials and the Technical University of Madrid confirming that elastic strains imposed by shape memory alloys can improve the catalytic efficiency in Au thin films,” says Redondo, one of the authors behind both papers.

“This time the group went further to develop serious intermetallic candidates to replace platinum catalysts,” he adds.

The work offers a platform that may accelerate the discovery of new hydrogen-producing catalysts. This is especially relevant as researchers continue to explore nonprecious metals and intermetallic compounds suggested by machine-learning screening studies.