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The HKUST-1@SBA-15 composites with hierarchical pore structure were constructed by in situ self-assembly of metal-organic framework (MOF) with mesoporous silica. The structure directing role of SBA-15 had an obvious impact on the growth of MOF crystals, which in turn affected the morphologies and structural properties of the composites. The pristine HKUST-1 and the composites with different content of SBA-15 were characterized by XRD, N adsorption-desorption, SEM, TEM, FT-IR, TG, XPS, and CO-TPD techniques. It was found that the composites were assembled by oriented growth of MOF nanocrystals on the surfaces of SBA-15 matrix. The interactions between surface silanol groups and metal centers induced structural changes and resulted in the increases in surface areas as well as micropore volumes of hybrid materials. Besides, the additional constraints from SBA-15 also restrained the expansion of HKUST-1, contributing to their smaller crystal sizes in the composites. The adsorption isotherms of CO on the materials were measured and applied to calculate the isosteric heats of adsorption. The HS-1 composite exhibited an increase of 15.9% in CO uptake capacity compared with that of HKUST-1. Moreover, its higher isosteric heats of CO adsorption indicated the stronger interactions between the surfaces and CO molecules. The adsorption rate of the composite was also improved due to the introduction of mesopores. Ten cycles of CO adsorption-desorption experiments implied that the HS-1 had excellent reversibility of CO adsorption. This study was intended to provide the possibility of assembling new composites with tailored properties based on MOF and mesoporous silica to satisfy the requirements of various applications.

The feasibility of the electrogeneration of H2O2 and degradation of an organic pollutant by a novel electro-Fenton (EF) process was demonstrated using dual rotating graphite felt disks to supply oxygen instead of the traditional aeration method, with methyl orange (MO) as the model pollutant. The effects of rotating speed, current density, and pH on the generation of hydrogen peroxide (H2O2) were investigated. At a current density of 50 A/m2, a rotating speed of 10 rpm, and a pH of 3, the concentration of H2O2 reached 116 mg/L in 1 h, which was much higher than that at 0 rpm (37 mg/L). The complete removal of 25 mg/L MO was achieved within 15 min, while the total organic carbon removal efficiency reached 58.7% at 2 h, which was almost 3-fold higher than that at 0 rpm (14.9%). The rotation of disk cathodes resulted in the efficient production of H2O2 without oxygen aeration, offering a potentially cost-effective EF method for degrading organic pollutants.

Chemically modified graphite felt as an efficient cathode in electro-fenton for p-nitrophenol degradation. (2014) Electrochimica Acta, 140. 376-383.

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