Acid-assisted hydrothermal synthesis and adsorption properties of high-specific-surface metal–organic frameworks

• Two kinds of novel aluminum–organic frameworks were synthesized via an acid-assisted hydrothermal method.
• The additional acid as coordinate modulation during the hydrothermal synthesis was beneficial for improving crystal quality, controlling crystal morphology and increasing surface areas of the metal–organic frameworks.
• The use of additive acids also enhanced the product yields and thermal stability of the frameworks.
• The high-specific-surface MIL-53(Al) displayed strong CO2-adsorption capacity.

In this work, we report on the controlled growth of trivalent metal–organic frameworks, MIL-53(Al), via an acid-assisted hydrothermal method. We demonstrated that some coordination modulation such as hydrochloric acid and acetic acid, could offer hydrogen ions or extra charge as well as competitive organic linkers during the hydrothermal synthesis, which was beneficial for improving crystal quality, controlling crystal morphology and increasing surface areas of the metal–organic frameworks. In addition, the use of additive acids also enhanced the product yields and thermal stability of the frameworks. The synthesized high-specific-surface MIL-53(Al) displayed strong CO2-adsorption capacity, indicating their potential applications as valuable adsorbent for low-concentration CO2 capture.