If you compare metal thin films to a canvas, scientists have long tried to punch dense, uniform "nanoholes" into them, drastically increasing their surface area and turning them into honeycomb-like, highly active materials that excel in chemical production and energy conversion (Fig. 1). This structure is known as "mesoporous (2-50nm)".
Figure 1. Learning from nature.
For nearly two decades of research, mesoporous metals were considered a luxury reserved only for "nobles"—precious metals like gold, platinum, and rhodium could be synthesized using micelle self-assembly, but non-precious metals could not.
We kept thinking: Is it possible to extend this strategy to non-precious metals like iron, nickel, and cobalt, which are much cheaper and more functional but more difficult?
Finding a New Path from Failure
The difficulty lay in the fact that traditional heat-driven nucleation and growth methods do not work for non-precious metals. They need more negative reduction potentials (Fig. 2). My first successful attempt came in 2018, when I realized traditional heating methods were ineffective.
Instead, I tried a chemical-driven strategy, artificially introducing tiny crystal nuclei to successfully achieve precise control over reduction kinetics and customized mesoporous morphology, but with a spherical shape (DOI: 10.1002/smll.201906707).
Figure 2. The standard reduction potentials of different metals.
Not Just Pores, But Direct Usability
Once we had mesoporous structures, the next question was how to make them practical. Traditional powder materials typically require additives like active carbon or binders (such as Nafion) to fix them onto electrodes, which is cumbersome and blocks precious active sites.
To solve this, we wanted to directly fabricate thin films. Thin films can be used directly as electrodes without extra supports and binders, and 2D films can maximize the utilization of metal active sites. Therefore, we pioneered an electro-driven nucleation strategy: electrons reduce metal ions so that metal atoms nucleate on the electrode surface, and after nucleation, they grow through a self-catalyzed process coupled with surfactant self-assembly, ultimately forming a mesoporous film (Fig. 3).
Figure 3. Our new design strategy for mesoporous NiCoFeB film.
Looking Forward: Beyond Catalysis
This research has been officially published in Nature Communications. Looking at these thin, nano-honeycomb-structured amorphous alloy films, we know this is not only a breakthrough in preparation technology, but also opens up a versatile platform and mechanistic insights for designing high-performance non-precious and amorphous alloy materials.
Scientific exploration's joy often lies in questioning and trying conventional ideas. From "noble exclusive" to "affordable universal", we have finally brought these abundant, earth-abundant metals into the spotlight.