ZnO Nanoparticles Modified by Carbon Quantum Dots for the Photocatalytic Removal of Synthetic Pigment Pollutants

Abstract

Synthetic pigment pollutants caused by the rapid development of the modern food industry have become a serious threat to people's health and quality of life. Environmentally friendly ZnO-based photocatalytic degradation exhibits satisfactory efficiency, but some shortcomings of large band gap and rapid charge recombination reduce the removal of synthetic pigment pollutants. Here, carbon quantum dots (CQDs) with unique up-conversion luminescence were applied to decorate ZnO nanoparticles to effectively construct the CQDs/ ZnO composites via a facile and efficient route. The ZnO nanoparticles with a spherical-like shape obtained from a zinc-based metal organic framework (zeolitic imidazolate framework-8, ZIF-8) were coated by uniformly dispersive quantum dots. Compared with single ZnO particles, the obtained CQDs/ZnO composites exhibit enhanced light absorption capacity, decreased photoluminescence (PL) intensity, and improved visible-light degradation for rhodamine B (RhB) with the large apparent rate constant (k app ). The largest k app value in the CQDs/ZnO composite obtained from 75 mg of ZnO nanoparticles and 12.5 mL of the CQDs solution (∼1 mg•mL −1 ) was 2.6 times that in ZnO nanoparticles. This phenomenon may be attributed to the introduction of CQDs, leading to the narrowed band gap, an extended lifetime, and the charge separation. This work provides an economical and clean strategy to design visible-light-responsive ZnObased photocatalysts, which is expected to be used for the removal of synthetic pigment pollutants in food industry.

Tandem FRET: A Robust Mechanism for Efficient Fabrication of WLED Using an Organic–Inorganic Hybrid Mixture

“…For instance, Zhang et al have grown ZnO nanowires on the glass substrate using the hydrothermal method, and the average lifetime exhibited by ZnO nanowires is 13.9 ns. Xu et al reported the synthesized ZnO nanoparticles with an average size of 80 nm, exhibiting an average lifetime of 5.642 ns . In a study by Sunandan and coworkers, ZnO nanoparticles were prepared by the hydrolysis and microwave methods, where the ZnO nanoparticles prepared by hydrolysis method exhibited an average lifetime of 26.8 ns and particles prepared by the conventional method exhibited 25.2 ns.…”

“…Xu et al reported the synthesized ZnO nanoparticles with an average size of 80 nm, exhibiting an average lifetime of 5.642 ns. 49 In a study by Sunandan and coworkers, 50 ZnO nanoparticles were prepared by the hydrolysis and microwave methods, where the ZnO nanoparticles prepared by hydrolysis method exhibited an average lifetime of 26.8 ns and particles prepared by the conventional method exhibited 25.2 ns. Sonmez et al have prepared a ZnO thin film using a spray pyrolysis technique, 47 which exhibited nanorod morphology, and the fluorescence lifetime of ZnO nanorods was estimated to be 1.56 ± 0.05 ns.…”

Photocatalytic Degradation, Anticancer, and Antibacterial Studies of Lysinibacillus sphaericus Biosynthesized Hybrid Metal/Semiconductor Nanocomposites

“…Thus, the band gap modification of ZnO through silver doping extends the absorption of light at the visible wavelength. The high intensity and broad absorption peak of Ag/ZnO through the entire solar spectrum can also facilitate enhanced light absorption capacity both in the UV and visible regions for photocatalytic activities [ 40 ]. The band gap energy of Ag/ZnO is lower than that of ZnO.…”

The Influence of Carbon Quantum Dots Addition on the Photoluminescence Performance of ZnO Nanoparticles

“…The use of Zinc oxide (ZnO) has garnered considerable interest due to its high photoluminescence in visible regions, low cost, and biocompatibility [16][17][18][19][20]. The use of ZnO nanoparticles as photocatalysts [21][22][23][24][25][26], anti-bacterial agents [27], sensor components [28,29], drug delivery agents [30], and others have been reported in recent studies.…”