Basiru O. Yusuf,Sulayman A. Oladepo,Saheed A. Ganiyu,Abdul Malik P. Peedikakkal
Metal-organic frameworks (MOFs) are excellent for immobilizing guest active species due to their high surface area and porosity. In this study, CuO/UiO-66 catalysts with varying amounts of CuO were successfully synthesized and used for converting waste cooking oil (WCO) to biodiesel. The catalysts were characterized using N 2 adsorption-desorption, XRD, NH 3 -TPD, SEM, TEM, TGA and FTIR. The biodiesel was characterized using NMR and GC–MS. The results showed that CuO/UiO-66 displayed high catalytic activity due to the synergistic effect between UiO-66 and copper oxide in the composite. Under optimum reaction conditions, we achieved a 90.1 % conversion with the 7 %CuO/UiO-66 catalyst. This catalyst also displayed good stability and reusability with a conversion of 81.06 % after three cycles. Our kinetic studies revealed a pseudo-first-order kinetics, with 32.26 kJ/mol in activation energy, consistent with a chemically controlled reaction.
A novel nanocomposite of CuO nanoparticle-modified Zr-MOF (CuO/UiO-66) was synthesized and developed as a fluorescence nanoplatform for H 2 O 2 and adenosine triphosphate (ATP) via the “turn-on–off” mode in the presence of terephthalic acid (TA). The structure of CuO/UiO-66 was thoroughly characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and other techniques. The CuO/UiO-66 with enhanced peroxidase-like (POD) activity obtained due to the Zr 4+ in UiO-66 is beneficial to the aggregation of CuO NPs on its surface. As a result, the strengthened fluorescence at 425 nm with the excitation of 300 nm was found due to the highly fluorescent species of TAOH. This is produced by the oxidation of TA by ·OH that came from the catalysis of H 2 O 2 via the peroxidase mimic of CuO/UiO-66. Hence the modification of CuO NPs on porous UiO-66 can provide a friendly and sensitive physiological condition for H 2 O 2 detection. However, upon addition of ATP, the fluorescence intensity of TAOH at 425 nm effectively declined owing to the formation of complexation of Zr 4+ -ATP and the interaction of CuO to ATP which hampers the catalytic reaction of CuO/UiO-66 to H 2 O 2 . The specific interaction induced “inhibition of the peroxide-like activity” endows the sensitive and selective recognition of ATP. The detection limits were 16.87 ± 0.2 nM and 0.82 ± 0.1 nM, and linear analytical ranges were 0.02–100 μM and 0.002–30 μM for H 2 O 2 and ATP, respectively. The novel strategy was successfully applied to H 2 O 2 and ATP determination in serum samples with recoveries of 97.2–103.8% for H 2 O 2 and 97.6–101.7% for ATP, enriching the avenue to design functional MOFs and providing new avenue of multicomponent bioanalysis. Graphical abstract
To address the issue of limited degradation efficiency due to rapid carrier recombination in piezoelectric catalysis, this study designed a ternary heterojunction structure of ZnO/CuO@UiO-66-NH 2 . A ZnO/CuO heterointerface was constructed on the surface of UiO-66-NH 2 via a hydrothermal method, forming a composite piezoelectric catalytic system with abundant active sites and enhanced built-in electric fields. Theoretical analysis indicated that UiO-66-NH 2 , as a carrier, not only significantly increased the specific surface area of the material but also cooperatively regulated the charge distribution in the heterojunction region. Under ultrasonic vibration, the piezoelectric potential generated by the ZnO/CuO heterojunction effectively drove carrier separation, thereby significantly enhancing the redox reaction efficiency. Under dark conditions, the 30-minute degradation rate of RhB by this material reached 99.7%, with a rate constant of 0.09435 min⁻¹, far superior to the pure ZnO/CuO system. Additionally, ZnO/CuO@UiO-66-NH 2 demonstrated excellent catalytic performance and cycling stability in the degradation of methyl orange and methylene blue. Band structure and radical trapping experiments confirmed that hydrogen radicals (·H) and superoxide radicals (·O 2 ⁻) were the main active species in the degradation process. This research provides new material ideas for the development of efficient and stable heterojunction piezoelectric catalysts and offers potential pathways for the construction of integrated systems for dye wastewater treatment and energy conversion. Graphical
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