From waste to functional materials: advances in porous material synthesis and applications derived from coal gasification slag.

Coal gasification slag (CGS) is a hazardous industrial byproduct generated during coal gasification process. Its large-scale accumulation leads to environmental pollution and wasting of land resources. Addressing these challenges, the development of high-value utilization strategies for CGS has become a critical priority in sustainable resource management. CGS has unique pore structure and high reactivity of alumina-silica components, enabling it to be transformed into porous materials, which offers the possibility for high-value utilization. This review systematically consolidates recent progress in designing and functionalizing CGS-based porous materials. First, we elucidate the microstructural and physicochemical properties of CGS, focusing on pore hierarchy, elemental distribution, and phase evolution. Next, we critically analyze mainstream synthesis methodologies, spanning acid/alkali etching, physical activation, and hybrid approaches for hierarchical structuring. Furthermore, we point out emerging applications across environmental and energy sectors, such as multifunctional adsorption (heavy metals, organics, CO), polymer nanocomposites, and electromagnetic shielding. Finally, we identify persistent challenges, including energy-intensive activation processes, synergistic utilization of different elements in CGS, and industrial scalability gaps, while proposing targeted solutions such as externally-coupled activation and full-component resource recovery. These insights aim to bridge fundamental research with industrial implementation, advancing CGS valorization toward a zero-waste paradigm.