Hierarchical Pd/UiO-66-NH₂-SiO₂ nanofibrous catalytic membrane for highly efficient removal of p-nitrophenol

Catalytic membranes are attractive for treating persistent pollutants. The key limitation is the trade-off between permeate flux and catalytic efficiency. Herein, a series of hierarchical Pd/UiO-66-NH₂-SiO₂ nanofibrous catalytic membranes were fabricated, where SiO₂ nanofibrous membranes were prepared by electrospinning and calcination and then UiO-66-NH₂ nanoparticles were grown on the SiO₂ nanofibrous membranes by a solvothermal method. Interestingly, adding a bit of water during the solvothermal, smaller UiO-66-NH₂ nanoparticles with micropores and mesopores are fabricated on the membrane, which provides more surface areas for loading Pd, thereby enhancing active sites. The corresponding catalytic membrane Pd/UiO-SiO2-3.75 shows more 3 times higher catalytic activity as compared to Pd/SiO2 in the removal of p-nitrophenol by conversion to the valuable product p-aminophenol. Furthermore, Pd/UiO-SiO2-3.75 almost has the same permeate flux as that of Pd/SiO2. The as-fabricated Pd/UiO-SiO2-3.75 has good recyclability during five reaction cycles. This work provides a new insight in the design and preparation of catalytic membranes with high permeate flux and catalytic efficiency.