Rapid preparation of mesopore-ultramicropore interconnected porous carbon for enhanced CO2 adsorption through tunable-energy-input microwave heating

Although constructing ultramicropore enhances CO 2 uptake, it simultaneously increases mass transfer resistance, resulting in ineffective ultramicropore utilization. To achieve both high CO 2 uptake and favorable kinetics, introducing interconnected mesoporous channels while increasing ultramicropores shows promising potential, but faces significant preparation challenges. Herein, we report a novel strategy for the rapid preparation of mesopore-ultramicropore interconnected porous carbon via tunable-energy-input microwave heating. By regulating the matching relationship between microwave power (200–400 W) and heating time (15–30 min), precise control of energy input density is achieved, thereby directionally regulating the interconnected structure of mesopores and ultramicropores. Under the same total energy input, the high energy input density enhances the outward release of volatiles, promoting the formation of mesopores. The reduction in heating time (50 %) weakens the etching of the carbon matrix by volatiles, limiting pore expansion. Moreover, the high energy input density rapidly drives the KOH activation into the high-temperature stage (>800 °C), enhancing gaseous potassium intercalation and K 2 O etching of the carbon matrix, thereby increasing the ultramicropore volume from 0.40 cm 3 /g to 0.67 cm 3 /g. Owing to the high microporosity (>60 %) and unique interconnected structure, the optimized MW400-15 exhibits high CO 2 uptake (3.90 mmol/g at 298 K, 1 bar, and 5.41 mmol/g at 273 K, 1 bar), good regenerability ( Q st of 36.58 kJ/mol), superior CO 2 /N 2 selectivity ( S ads of 82.45), and favorable kinetics. This work provides new insights into the directional regulation of mesopore-ultramicropore interconnected structure and rapid preparation of high-performance CO 2 adsorbents. • Rapid preparation of porous carbon by tunable-energy-input microwave heating. • High microwave energy input density promotes pore development while inhibiting pore expansion. • Porous carbon forms an interconnected structure with abundant ultramicropores and moderate mesopores. • Optimized sample exhibits both high S BET (2037 m 2 /g) and ultramicroporosity (63.81 %). • The CO 2 uptake reaches 3.90 mmol/g (298K, 1 bar) and 5.35 mmol/g (273K, 1 bar).