High-Temperature Pyrolysis Unlocks Multilevel Pore Hierarchy in Biochar for Enhanced Atmospheric Carbon Capture

New research shows larger biochar pores actively capture carbon dioxide, with high-temperature biochar achieving 3.82 mmol/g capture capacity.

By: AXL Media

Published: Mar 14, 2026, 6:13 AM EDT

Source: Information for this report was sourced from Biochar Editorial Office, Shenyang Agricultural University

Revisiting the Mechanics of Biochar Sequestration

Biochar has gained international attention as a low-cost, carbon-negative material capable of removing $CO_{2}$ directly from the atmosphere. Historically, the scientific community believed that carbon capture was almost exclusively the domain of micropores—microscopic openings less than one nanometer in diameter. However, new research from Shenyang Agricultural University suggests that the internal architecture of biochar is far more complex. The study indicates that the entire structural hierarchy, including larger mesopores and macropores, actively participates in the adsorption process rather than serving as simple transit tunnels for gas molecules.

The Impact of Pyrolysis Temperature on Capture Capacity

The research team analyzed sawdust-derived biochar produced at temperatures ranging from 300°C to 1000°C, finding a dramatic correlation between heat and capture efficiency. Biochar synthesized at the highest temperature (1000°C) exhibited a capture capacity of 3.82 mmol/g, nearly triple the 1.26 mmol/g capacity of the 300°C samples. This increase is attributed to the thermal decomposition process, which clears out volatile matter and carves out a more intricate internal landscape, allowing the material to hold significantly more carbon within its solid framework.

Beyond Passageways: The Active Role of Large Pores

The study’s most significant theoretical shift is the redefined role of mesopores and macropores. Previously dismissed as passive channels, these larger structures possess a specific internal surface roughness and fractal geometry that directly influences molecular interaction. By developing advanced mathematical models to describe these surfaces, researchers found that the irregular folds and "rough" structures within large pores can slow down $CO_{2}$ molecules. This increased residence time enhances the probability of the molecules being captured by physical adsorption forces before they can escape back into the atmosphere.