@article{Tang2026, 
author = {Leiqing Tang and Haoyu Jiang and Hongping Zhang and Zhangyi Huang and Haomin Wang and Qingyuan Wang and Jianqi Qi and Ruichong Chen},
title = {Spent coffee grounds as multifunctional modifiers for triple-synergistic enhancement of Li4SiO4 ceramic sorbents in high-temperature CO2 capture},
year = {2026},
journal = {Journal of Advanced Ceramics},
keywords = {Hierarchical porous structure, Oxygen vacancies, CO2 adsorption, Spent coffee grounds, Li4SiO4 ceramic sorbent, Potassium doping},
url = {https://www.sciopen.com/article/10.26599/JAC.2026.9221339},
doi = {10.26599/JAC.2026.9221339},
abstract = {Practical deployment of Li4SiO4 as a high-temperature CO2 sorbent requires pelletization, which inevitably densifies the microstructure and imposes severe CO2 diffusion limitations. Conventional sacrificial pore-forming agents address this issue but remain single-purpose, serving solely as structural templates without conferring chemical benefits. Here, we demonstrate that spent coffee grounds (SCG), an abundant food-industry waste, can serve as a single-source modifier that achieves three co-localized enhancements in Li4SiO4 pellets: hierarchical pore engineering, in-situ K-doping, and oxygen vacancy generation. The thermal decomposition of SCG creates an interconnected hierarchical macroporous network that effectively reduces intraparticle CO2 diffusion resistance. Meanwhile, the mineral-rich SCG ash provides in-situ potassium doping, generating a localized eutectic molten carbonate phase that accelerates liquid-phase ion transport. Crucially, the transient reducing atmosphere during biomass combustion introduces oxygen vacancies into the silicate lattice; Density Functional Theory (DFT) calculations reveal that these vacancies serve as highly active CO2 adsorption sites with a strongly exothermic adsorption energy of −0.914 eV. Benefiting from this triple-synergistic enhancement, the SCG-modified sorbent (LSO-50) achieves a CO2 adsorption capacity of 0.275 g/g at 650 °C under 15 vol% CO2, representing a more than fourfold improvement over unmodified pellets. When further combined with Na2CO3 co-doping to promote additional eutectic formation, the optimized sorbent (LSON-50) reaches 0.330 g/g, retains 0.284 g/g after 50 adsorption–desorption cycles, and exhibits robust mechanical stability (<10% attrition loss). By co-locating structural, chemical, and defect features within a single biomass-derived modifier, this work establishes a scalable waste-valorization route for high-performance, eco-friendly CO2 capture.}
}