Modulated synthesis of chromium-based metal-organic framework (MIL-101) with enhanced hydrogen uptake

•High crystalline Cr-MOF with well-defined shape was prepared via modulated synthesis.•High reproducibility can be expected at certain optimized synthesis conditions.•It has good structure-stability in 80 °C H2O and DMF solutions for 5 days.•It has enhanced H2 storage capacity against the reported results.

Modulated synthesis of MIL-101(Cr) in high yield and with good reproducibility using formic acid as a modulator is reported. Higher molar ratio of formic acid/CrCl3 was found to form better shape-defined MIL-101(Cr) crystals with higher surface area, larger pore volume and better hydrogen uptake performance. The highly crystalline MIL-101(Cr), composed of crystals in the size range of 100–150 nm with multifaceted surface, could be obtained in an optimized molar regime of CrCl3·6H2O/H2BDC/100HCOOH/550H2O at 210 °C for 8 h. The MIL-101(Cr) obtained from the modulated synthesis also showed high thermal and moisture stabilities as well as enhanced hydrogen storage capacity, making this material particularly promising for practical hydrogen storage applications.