Sustainable fabrication of metal-organic frameworks for improved hydrogen storage

As greenhouse gas emissions become serious, the need for sustainable and efficient hydrogen storage solutions to replace traditional fuel energy becomes increasingly urgent. This study focuses on enhancing the hydrogen storage performance of CuBTC, a metal-organic framework (MOF) via green synthesis, aligning with the green circular economy principles of reducing energy consumption and chemical solvent waste. By applying the Design of Experiments methodology, we systematically explored the impact of different synthesis conditions on CuBTC properties, offering valuable insights for mechanochemical synthesis and hydrogen storage applications. Identified optimal conditions significantly increased CuBTC hydrogen uptake to 3.2 wt% at 20 bar, comparable to solvothermal CuBTC at 3.37 wt% and 10% higher than prior studies. This optimal CuBTC also possesses a comparable hydrogen adsorption rate to solvothermal CuBTC and an accelerated adsorption rate compared to smaller CuBTC crystal samples. A notable achievement of this work is the drastic reduction of the CuBTC synthesis time to just minutes while eliminating the need for chemical solvents. This breakthrough consumes less than 2% of the energy required for traditional solvothermal synthesis and completely avoids chemical solvent waste, marking a significant environmental and efficiency improvement. In addition, the CuBTC formation mechanism was explored in this research, shedding light on the intricate process of crystal structure development. Our findings demonstrate that the ball-milling technique can significantly enhance the hydrogen storage capabilities of CuBTC while reducing energy consumption and chemical solvent waste during the synthesis process.