Review of Emerging Strategies and Progress in Transition Metal-Modified Activated Carbons for Hazardous Gas...

Hazardous gas emissions, including volatile organic compounds (VOCs), nitrogen oxides (NO _x ), sulfur dioxide (SO₂), elemental mercury (Hg⁰), carbon dioxide (CO₂), and chemical warfare agents (CWAs), pose severe threats to human health and the environment, driving the need for efficient, cost-effective removal technologies. Activated carbon (AC), renowned for its high surface area, tunable porosity, and economic viability, serves as an ideal support for transition metal modification (e.g., Mn, Fe, Co, Ni, Cu, Zn), which imparts enhanced catalytic activity and selectivity through redox and acid-base functionalities. This review systematically summarizes recent advances in transition metal-modified ACs for hazardous gas elimination, covering preparation methodologies (impregnation, doping, sol-gel, and composites), adsorption mechanisms (physisorption vs chemisorption, and diffusion processes), key influencing factors (pore structure, surface chemistry, metal dispersion, gas properties, and operational conditions), and practical applications across diverse pollutants. Key insights highlight the synergistic roles of metal loading in bridging physical adsorption and catalytic conversion, while addressing challenges such as pore blockage, humidity interference, and multipollutant competition. Future perspectives prioritize operando mechanistic studies, scalable engineering processes, and precision synthesis to bridge the gap between fundamental research and industrial application, achieving scalable, high-performance solutions for real-world environmental remediation.