A comparative study of depositing Cu-BTC metal-organic framework onto cellulosic filter paper via different procedures

Cellulose-based material has been increasingly used as a suitable substrate for depositing metal-organic frameworks (MOFs) in recent years. In this work, MOFs (Cu-BTC) were deposited onto carboxymethylated filter paper (CMP) using four different preparation procedures: one-pot, two-step, layer-by-layer-organic (LbL-org), and layer-by-layer-water-organic (LbL-wtr-org). The products (Cu-BTC@CMP) were comparatively characterized by SEM, ATR FT-IR, XRD, and BET specific surface area analyses. The Cu-BTC crystals were immobilized on the CMP surface, where different deposit ratios (1.31% for one-pot, 4.23% for two-step, 31.49% for LbL-org, and 39.38% for LbL-wtr-org, respectively) were obtained when different preparation procedures were used under the precondition of the same chemical dosage and reaction time. The Cu-BTC crystals were found to grow in the main solution rather than on the substrate surface and the layer-by-layer method would contribute to a remarkable quantity of MOFs depositing onto the substrate surface. The crystals on Cu-BTC@CMP surface prepared by LbL-wtr-org procedure presented a much larger particle size and rougher surface compared to those prepared by the LbL-org procedure due to the aqueous solution of copper precursor. Depositing more Cu-BTC onto CMP surface also endowed the composite prepared by LbL-wtr-org procedure with the highest gas adsorption capacity (1.59 x 10(2) m(2)/g of BET specific surface area). Hence, the LbL-wtr-org procedure will be an optimal pathway for depositing metal-organic frameworks onto cellulose-based materials with the advantages of saving organic solvents and best gas adsorption ability.