Developments in two-atom catalysts make renewable energy sources more efficient

The rapidly developing field of green energy is constantly seeking improvements, and recent advances in two-atom catalysts could potentially revolutionize energy conversion technologies.

In the search for sustainable alternatives to carbon-based energy sources, the need for fast, efficient and scalable technologies is crucial. Water separation systems (WWS), based on solar batteries, offer a promising solution. However, the complex and slow reaction steps inherent to WWS limit their scalability for widespread use.

Researchers at the Qingdao Institute of Bioenergy and Bioprocess Technology of the Chinese Academy of Sciences sought an improved design to increase the speed and stability of the main half-reactions required for the operation of high-caliber WSS: reactions of oxygen reduction, oxygen evolution reactions and hydrogen evolution reactions.

Dual-atom catalysts, bridging single-atom catalysts and metal/alloy nanoparticle catalysts, are found to provide more opportunities to improve the kinetics and multifunctional performance of oxygen reduction/evolution reactions and hydrogen release.

Their results were published in Natural communications.

“Oxygen reduction/evolution and hydrogen evolution reactions are the main reactions, involving multiproton-electron coupling processes, which are kinetically slow, so there is an urgent need to develop efficient, stable and inexpensive electrocatalytic materials to improve their conversion efficiency,” said Jiang Heqing, corresponding author of the study.

Double-atom catalysts (DAC), unlike single-atom catalysts (SAC), which have only one metal atom per active site, play a central role in the field of energy catalysis due to their catalytic activity advantageous multifunctionality, their higher atomic utilization efficiency, and more efficient disruption of the linear relationship with the reaction intermediates.

Additionally, the application of SACs to energy conversion systems will significantly limit the energy conversion efficiency due to higher reaction barriers.

DACs benefit from the synergistic effect between their double metal atoms, allowing efficient modulation of cooperative effects between the two active sites and a substantial reduction in the energy barriers required for the reaction.

Considering the advantages of DACs, it is crucial to explore their synthesis mechanism through high-temperature sintering strategies to advance their preparation and facilitate commercial applications.

“We reported a new atomization/sintering strategy to synthesize and tune the configurational states of cobalt (Co) species at the atomic level, from nanoparticles to single atoms to double atoms,” said Huang Minghua, a other author and researcher who contributed to the study.

The atomization/sintering strategy involves the conversion of cobalt into nanoparticles (atomization), which are then used to form single-atom (SA) and two-atom (DA) species through the sintering process.

One of the most impressive features of this strategy and the results of this research is the applications that atomization/sintering can have in manufacturing 21 other DACs. This is all due to observing how these DACs form via the atomization/sintering process. The more DACs there are, the more opportunities there are to explore other ways to better harness energy in a sustainable way.

Testing the capabilities of double-atom Co₂NOT₅ in zinc-air batteries have shown promising results. The Zn-air batteries had a stability of 800 hours and allowed continuous water separation for 1,000 hours at a time, demonstrating the potential for uninterrupted operation even overnight.

Work on DACs is underway. “This universal and scalable strategy provides opportunities for the controlled design of efficient multifunctional dual-atom catalysts in energy conversion technologies,” said Jiang Heqing.

Further developments can be made to continue improving the capabilities of bimetallic catalysts. Seeing how they perform in different circumstances can also be informative, such as how the water distribution system handles cold temperatures or seawater. Placing these systems in unfavorable conditions can highlight difficulties to be resolved which may constitute an obstacle to large-scale or commercial use.