Facile preparation of high-capacity hydrogen storage metal-organic frameworks: A combination of microwave-assisted solvothermal synthesis and supercritical activation

The Cu3(BTC)2 Metal—oragnic frameworks (MOFs) are synthesized by four different processes, i.e. solvothermal method (sample 1), microwave-assisted solvothermal method (sample 2), a combination of solvothermal method and supercritical carbon dioxide (Sc-CO2) activation (sample 3) and a combination of microwave-assisted solvothermal method and Sc-CO2 activation (sample 4). By comparing the N2 adsorption isotherms of the four samples, it is found that the sample 4 displays the greatest N2 uptake. Due to the best performance of sample 4 in N2 adsorption, we further study H2 adsorption in the sample 4. Results indicate that the excess and absolute hydrogen uptakes of this material reach 4.12 and 4.49 wt% at T=77 K and P=18 bar, respectively, which is the largest one among all these reports on Cu3(BTC)2 for H2 storage at the same condition. Therefore, it is believed that a combination of the two technologies of microwave-assisted method and supercritical Sc-CO2 activation provides a new approach for chemical engineers rapidly and efficiently preparing MOFs for high-capacity H2 storage.