Work

Alcohol-assisted hydrothermal synthesis of facet-engineered MgO: Molecular structure effects on CO2 adsorption at high temperature

Year: 2026

Type: article

Abstract: High-temperature CO2 capture is essential for hydrogen production and carbon-neutral energy systems. Magnesium oxide (MgO) is a promising adsorbent due to its thermal stability and strong basicity, yet controlling the exposure of its active (111) planes remains challenging. Herein, a green, one-pot alcohol-assisted hydrothermal method was developed to synthesize MgO nanosheets with highly exposed (111) facets, eliminating the need for toxic surfactants or complex steps. Systematic comparison of various alcohols revealed that alcohol molecular structure strongly influences crystal growth, surface basicity, and CO2 adsorption. Ethanol-assisted MgO achieved the highest adsorption capacities of 1.32 mmol g−1 at 300 °C and 0.44 mmol g−1 at 600 °C, outperforming commercial MgO. CO2-TPD and XPS analyses confirmed enhanced strong basic sites and increased low-coordinated O2− species, while DFT calculations demonstrated that alcohol molecules direct Mg(OH)2 growth via preferential adsorption on (001) planes, promoting (111) facet formation after calcination. The findings elucidate how molecular configuration governs surface energy modulation and facet exposure, offering a scalable and sustainable route to engineer MgO-based adsorbents for efficient high-temperature CO2 capture.

Source: Chemical Engineering Journal