Thermal, structural, and morphological features of Zea mays husk activated carbon for low pressure hydrogen physisorption

Plant-sourced biomass is a natural, renewable material that has proven to be a good substitute for fossil fuels in energy. Activated carbon (AC) is a carbonized porous material often synthesized from plant biomass for different energy applications, including hydrogen storage. Considering the components of the corn stover, the potency of corn husk (CH) AC for hydrogen storage via physisorption needs to be evaluated. Two different conventional activation reagents, potassium hydroxide (KOH) and sodium hydroxide (NaOH), are made to interact with carbonized corn husk biochar. Characterizations through scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA) show that the properties of these two ACs are comparable. However, their porous structures as analyzed via Brunauer–Emmett–Teller (BET) technique clarify the difference, as activation with KOH (AKNH) possesses a higher microporous surface area (S _BET ) and volume of 904.76 m ² /g and 1.00 cm ³ /g, respectively; 704.80 m ² /g and 0.36 cm ³ /g are characterized by NaOH-activated CH biochar (ANCH). At 77 K and 1.2 bar, 2.84 wt.% hydrogen is adsorbed by AKCH, while the uptake capacity for ANCH is 1.48 wt.%. The higher S _BET and micropore volume displayed by AKCH are attributed to its better hydrogen uptake.