Recent progress in nitrogen-doped activated carbon: Microstructural regulation and enhanced gas adsorption

N-doped activated carbon (NAC) adsorption research—especially for CO₂, SO₂, and some volatile organic gases (VOCs)—is a major focus in adsorption studies. This review covers recent NAC preparation methods, including novel approaches like microwave activation and Joule flash technique. The review also examines how activating and nitrogen doping agents affect activated carbon's pore development, surface chemistry, and underlying mechanisms. Crucially, it discusses how resultant structural and chemical alterations impact gas adsorption performance. Key factors—activating agents, temperature, and nitrogen dopants—govern pore development and surface modification: activating agents develop porous structures. Nitrogen doping agents facilitate surface chemical structure development. Temperature enhances the interaction between activating agents and the carbon precursor. Notably, precise control over the micropore volume proportion in the modified carbon significantly enhances its gas adsorption capacity under conditions of 1 bar pressure and low temperatures (e.g., 0 °C and 25 °C). In terms of surface chemistry, nitrogen-containing functional groups, specifically pyridinic nitrogen (N-6) and pyrrolic nitrogen (N-5), enhance the affinity of the modified carbon towards acidic gas molecules like CO₂、 SO₂ and some volatile organic gases. This enhanced affinity improves the material's selectivity for adsorbing these acidic gases.