Comparative study of hydrogen storage in green synthesized porous biocarbon and N/S doped biocarbon

Abstract

The present work reports the green synthesis and hydrogen storage capacities of porous biocarbon (CK-700) and, N/S doped biocarbon (ACK-1) prepared by green and sustainable carbonization methods from pistachio shells. The hydrogen uptake capacity of CK-700 and ACK-1 were investigated at −196 °C and in the pressure range of 5–50 bar. A green and sustainable route is described for the synthesis of N/S doped biocarbon (ACK-1) by using a combined hydrothermal carbonization and chemical activation process in which Na2S2O3 applied as an activating agent. The characterization of N/S doped biocarbon and raw biocarbon were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyses. The hydrogen storage capacities of the green synthesized CK-700 and ACK-1 were measured by IGA dynamic gas adsorption analyzer. The hydrogen adsorption capacity of CK-700 and ACK-1 were measured and, the highest hydrogen adsorption capacity of ACK-1 was obtained to be 4.55 wt% under pressure of 50 and at 73 K, while the lowest hydrogen uptake capacity of CK-700 was obtained to be 2.24 wt% under pressure of 5 bar and at 73 K in raw biocarbon. HIGHLIGHTS Hydrogen storage capacity of the green synthesized porous biocarbon and N/S doped porous biocarbon were studied. Biocarbon nanoparticles were prepared via green and sustainable method. The addition of sodium thiosulfate as a nontoxic agents plays a synergetic catalytic role. Increase of pore sizes around 765 m2/g in porous N/S doped biocarbon essential for the enhanced hydrogen adsorption.