Work

Towards efficient sorption-based heat harvesting via hierarchical pore structures tailored by novel salt–porous composites

Year: 2025

Type: article

Abstract: Sorption-based thermochemical energy storage presents a sustainable strategy for harvesting low-grade heat from ambient moisture. Salt-porous matrix composites are key materials for this application; however, their performance is often limited by low water uptake and slow sorption kinetics due to single type of pores (e.g., micropores or macropores). In this study, we explore the impact of pore structures on the sorption behaviour and heat storage capacity of such composites. A bimetallic ZIF-derived carbon matrix (C-BMZIF), integrated with LiCl to form LiCl@C-BMZIF, was tailored with multiple pore types to illustrate the structure-performance relationship. Experimental results indicate that the composite with hierarchical pore structure exhibited a good water sorption capacity of 0.527 g/g, a rapid sorption rate of 0.041 s⁻¹, and an impressive heat storage capacity of 1390 kJ/kg. LiCl@C-ZIF-8, a similar composite with single type pores, has much lower water sorption and energy storage capacity, which further confirms the critical role of meso- and macropores in enhancing sorption kinetics and overall performance. DFT and GCMC simulations further revealed that hierarchical pore size distribution in the composites promotes superior sorption characteristics on N-doped carbon and Co-N sites. Combing experimental and computational studies, our research confirms the critical role of hierarchical pores in enhancing thermochemical energy storage and provides insights for design the next-generation sorption materials.

Source: Chemical Engineering Journal

DOI: 10.1016/j.cej.2025.171025