The green future where we break free from the shackles of fossil fuels is rapidly approaching. WIth each new development in energy technology, like improvements in solid-state battery tech for electric vehicles, we unveil more and more possibilities for circumventing a looming ecological and climatological disaster.
Part of the chase for energy innovation is the constant search and continuous efficiency upgrades for renewable energy sources, where explorations into solar cell technology and allied research fields have allowed scientists and engineers to develop even better ideas and methods into curbing one of our biggest sources of carbon emissions on the planet.
One of the most tantalizing fossil fuel alternatives being explored is hydrogen fuel, which takes advantage of the fact that hydrogen is, in essence, just a proton with an electron whizzing around it. Forcing the two components apart can free up the electron for power to a vehicle, and can also be recombined with the proton to simply form water and some heat.
Current technologies for sourcing hydrogen as fuel mostly resort to gathering hydrogen from refining fossil fuels themselves, ironically enough. Because of this,, alternatives are being sought after, such as the possibility of gathering hydrogen from the splitting of water molecules into hydrogen and oxygen gas—a process called, unsurprisingly enough, water splitting.
Water splitting involves the use of catalysts such as platinum (Pt) metal to facilitate the cleaving of water molecules; however, these metals often slowly become unstable over time, and are very expensive to source. Thus, the search is on for low-cost, effective measures that allow for the same water splitting effect.
Enter the nickel-cobalt single-atom dimer (NiCo-SAD), developed by the Center for Integrated Nanostructure Physics (CINP) at Korea’s Institute for Basic Science (IBS). IBS researchers led by CINP Associate DIrector Lee Hyoyoung managed to stabilize dimers of nickel (Ni) and cobalt (Co), effectively a pair of two and only two atoms, one of each element. These one-of-each dimers are stabilized on a nitrogen-doped carbon (NC) “support,” hence the novel material’s full acronym of NiCo-SAD-NC.
Said first author Ashwani Kumar: “We synthesized Ni-Co single atom dimer structure on [a] nitrogen-doped carbon support […]. We employed state-of-the-art transmission electron microscopy and x-ray absorption spectroscopy to successfully identify these NiCo-SAD sites with atomic precision.”
Lee and team also found that the process was not only capable of stabilizing Ni-Co dimer pairs onto the carbon support; they also found the process compatible with dimer pairs of cobalt and manganese (Mn), as well as cobalt and iron (Fe).
These dimer structures offer an advantage over standard water splitting catalysts, according to the team, as their very simple form maximizes the so-called atom utilization of the entire catalyst, as the functional surface of the catalyst is ultimately just two atoms sitting in tandem on an otherwise nonparticipatory support. These novel dimer systems are also remarkably stable, and were capable of driving reactions for up to 50 hours without much change in structure.
“We were very excited to discover that the novel NiCo-SAD structure dissociates water molecules with a much lower energy barrier and accelerates hydrogen evolution reaction […] with performances comparable to that of Pt, which addressed the shortcomings of the individual Ni and Co single-atom catalysts. The synthesis of such single atom dimer structure was a long-standing challenge in the field of single-atom catalysts,” said Lee in a statement. “This highly efficient and inexpensive hydrogen generation electrocatalyst will help us overcome long-term challenges of cost-competitive green hydrogen production: to produce high-purity hydrogen for commercial applications at a low price and in an eco-friendly manner.”
The findings by Lee and team were published in the journal Nature Communications.
References
- Fuel cells. (n.d.). Energy.Gov. Retrieved 23 November 2021, from https://www.energy.gov/eere/fuelcells/fuel-cells
- Institute for Basic Science. (2021, November 19). Two is better than one: Single-atom dimer electrocatalyst for green hydrogen production. EurekAlert! https://www.eurekalert.org/news-releases/935404
- Kumar, A., Bui, V. Q., Lee, J., Wang, L., Jadhav, A. R., Liu, X., Shao, X., Liu, Y., Yu, J., Hwang, Y., Bui, H. T. D., Ajmal, S., Kim, M. G., Kim, S.-G., Park, G.-S., Kawazoe, Y., & Lee, H. (2021). Moving beyond bimetallic-alloy to single-atom dimer atomic-interface for all-pH hydrogen evolution. Nature Communications, 12(1), 6766. https://doi.org/10.1038/s41467-021-27145-3
