Researchers from the Hong Kong University of Science and Technology (HKUST) have made a significant breakthrough in understanding how carbon dioxide (CO2) reacts in supercritical water, identifying pyrocarbonate ions as crucial intermediates.

Notably, the research highlights the role of nanoconfinement in chemical reactions, showing that pyrocarbonate (C2O52-) can be a stable intermediate in confined environments, despite its known instability in aqueous solutions.

Professor Ding Pan noted that their innovative method employs unsupervised learning techniques to emphasize the significance of large oxocarbons in extreme aqueous reactions and the regulatory potential of nanoconfinement.

This study, led by Associate Professor Ding Pan and published in the Proceedings of the National Academy of Sciences at the end of December 2024, enhances our understanding of CO2 mineralization and sequestration processes.

Utilizing first-principles Markov models, the research team explored CO2 reactions in both bulk and nanoconfined water, discovering that carbonation reactions involve collective proton transfer along transient water chains.

The findings reveal that under bulk conditions, proton transfer occurs concertedly, while in nanoconfined environments, it proceeds stepwise, illustrating how spatial constraints affect reaction kinetics.

Prof. Chu Li emphasized that their computational approach autonomously uncovers new pathways for CO2 dissolution, operating without reliance on prior knowledge or human bias.

The research was supported by the Hong Kong Research Grants Council, the Croucher Foundation, and the Excellent Young Scientists Fund of the National Natural Science Foundation of China, with computational work conducted on the Tianhe-2 supercomputer in Guangzhou.