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A synthesis of graphene quantum dots/hollow TiO2 nanosphere composites for enhancing visible light photocatalytic activity
摘要： Given the versatility and value of the semiconductor composites for photocatalysis, we reported a new, friendly environment, high specific surface area material of the graphene quantum dots/hollow titanium dioxide nanosphere (GQDs/H-TiO2) composites which are synthesized through a simple hydrothermal method. GQDs (~ 5 nm) exhibit highly photoluminescent and widely visible light absorption properties. H-TiO2 has high surface area and abundant exposed active sites for photocatalysis. The research demonstrates that GQDs coupled on H-TiO2 can effectively enlarge the light absorption of the H-TiO2 to visible region (~ 650 nm) and enhance the electron–hole pair separation efficiency of GQDs/H-TiO2 composites owing to GQDs acting as an electron repository and electron transport bridge. In our delight, the photocurrent enhancement of newly prepared GQDs-3.0/H-TiO2 composite electrode was almost 3.5 times higher in comparison with that in pure H-TiO2 electrode at an applied voltage of 0.5 V using Na2SO4 (0.5 M) solution as the electrolyte. In addition, the photocatalytic activity of the prepared GQDs-3.0/H-TiO2 (96.9%) on the degradation of Rhodamine B (RhB) was also significantly enhanced compared with that of pure H-TiO2 (33.3%) after 180 min. The protocol is suitable not only for the GQDs-modified semiconductors photocatalysts but also provides further insights to apply GQDs to other energy conversion devices.
关键词： composites,graphene quantum dots,hollow TiO2 nanosphere,visible light photocatalytic activity
更新于2025-09-12 10:27:22
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Fabrication of highly efficient and hierarchical CdS QDs/CQDs/H-TiO2 ternary heterojunction: Surpassable photocatalysis under sun-like illumination
摘要： Highly efficient and durable visible-light utilized nanocomposites have a vital role in environmental pollutants remediation. Hence, in this study, we have fabricated CdS QDs co-sensitized CQDs/H-TiO2 (Hollow Titania) ternary heterostructures (CdS QDs/CQDs/H-TiO2) in a facile region-selective deposition route. The as-fabricated nanocomposites were evidently characterized by physicochemical techniques. CdS QDs were uniformly distributed on the smooth surface of hierarchical CQDs/H-TiO2 heterojunction. The as-fabricated CdS QDs/CQDs/H-TiO2 nanocomposite has high-performances for efficient degradation efficacy of phenol, MB and RhB which exhibited enhanced degradation activities with rate constants (k) of 0.03, 0.051 and 0.045 min-1, respectively. All these superior photocatalytic activities obviously attributed to the effect of calcination temperature, enhanced photocurrent, minimized recombination of photo-induced charges in the photocatalysis and optimum content of CdS QDs have the distinct basis for the close interfacial connection developing. In addition, evidenced on the arguable results of electron spin resonance and radical-trapping experiments, the primary reactive-oxygen species and a plausible reaction-mechanism for organic pollutants degradation over CdS QDs/CQDs/H-TiO2 were proposed. This creative work is strategically considered an important step to potentially enhance the utilization of TiO2 in various fields as visible light-induced heterojunction.
关键词： Hollow TiO2,CdS QDs/CQDs/H-TiO2,Visible-light photocatalysis,CQDs/H-TiO2,Environmental remediation
更新于2025-09-04 15:30:14