Catalysts sit at the core of industrial chemistry, powering the reactions that produce everything from everyday plastics to life-saving medicines. Despite their pivotal role, traditional catalysts can be expensive, hard to recycle and prone to inefficiencies when scaled up for mass manufacturing—limitations that restrict their use in complex processes.
Shibo Xi from A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE2) highlighted how the structure of catalysts affects their performance.
Heterogeneous catalysts, which are solid and have fixed active sites, are easier to separate from the final products. However, their rigidity limits their effectiveness in reactions requiring multiple active sites. In contrast, homogeneous catalysts are more flexible at the molecular level in enhancing efficiency, but they are far more difficult to separate from the final product.
“Our research aimed to develop a geminal active site catalyst that is both easily separable from the product, while providing the necessary mobility for efficient catalysis,” said Xi.
In collaboration with researchers from the National University of Singapore; Shaanxi University of Technology, Peking University and Tsinghua University in China; and ETH Zurich, Switzerland; Xi’s team worked to design a more efficient, scalable and eco-friendly solution. Their approach involved placing single-atom catalysts close together to boost their performance, improving the efficiency of key reactions such as cross-coupling in organic synthesis.
The team developed geminal-atom catalysts (GACs) by anchoring pairs of copper atoms onto a polymeric carbon nitride (PCN) framework. This arrangement created a stable yet flexible environment for catalysis. To closely examine how these copper atoms behaved, the researchers used advanced techniques like X-ray absorption fine structure (XAFS) to monitor electronic changes and theoretical simulations to understand how the atoms interact on a molecular level.
“By combining XAFS data with theoretical calculations and first-principles simulations, we identified the true structure of these catalysts and tracked their transformations during the catalytic process,” Xi explained.
The study showed that GACs greatly enhanced the efficiency of critical cross-coupling reactions, such as C-N and C-C bond formation, providing better control and faster reaction times. After testing the catalysts across 90 reactions, including pharmaceutical synthesis, the team demonstrated their scalability in continuous flow systems, opening avenues for further development with other metals and configurations.
The team’s research also resolved long-standing misconceptions about PCN’s structure, revealing new insights that can lead to more versatile and efficient catalyst designs. The team now plans to explore the photocatalytic potential of GACs, investigating their ability to respond to light and drive reactions.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Sustainability for Chemicals, Energy and Environment (ISCE2).
