A strategy to promote hydrogen storage performance of porous carbon materials: Enriching micropore structure through mechanical pressure-assisted activation

Porous carbon materials (PCMs) with high specific surface area (SSA) exhibit significant potential for hydrogen storage applications but are severely limited due to the weak interactions of H2. In this work, polyvinylpyrrolidone (PVP) was employed to prepare PCMs with ultra-high SSA and high micropore ratio through applying mechanical pressure before activation. This approach resulted in an SSA exceeding 3100 m2/g and a maximum SBET/SMicro ratio above 90%. The increased microporosity significantly improved hydrogen storage performance, with a 62% increase in hydrogen uptake capacity per SSA at 77 K and 50 bar-H2, suggesting the strengthened interaction between PCMs and H2. This is further supported by the increased isosteric heat of hydrogen adsorption (Qst) values from 6.93 to 7.56 kJ/mol at near-zero hydrogen coverage, with SMicro/SBET increasing from 75.86% to 90.83%. Moreover, the increased microporosity enhances the volumetric and usable hydrogen storage capacity. Remarkably, the PCM with 84.35% microporosity and high SSA of 3116.58 m2/g exhibits a hydrogen uptake of 6.10 wt% (26.47 g/L) at 77 K under 50 bar-H2, and retains 1.26 wt% (5.52 g/L) even at 298 K and 130 bar-H2. This study provides a valuable reference for the large-scale preparation of PCMs with high SSA and microporosity for hydrogen storage.