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Visible light assisted photocatalytic reduction of CO2 to ethane using CQDs/Cu2O nanocomposite photocatalyst
摘要： CO2 reduction through photocatalysis is considered a promising way to mitigate the abundance of this greenhouse gas in the earth’s atmosphere. In this work, blue-fluorescent carbon quantum dots (CQDs) were synthesized via a facile top-down hydrothermal method using biochar as the carbon source. The as-synthesized CQDs were incorporated together with commercial copper (I) oxide (Cu2O) nanoparticles to form CQDs/Cu2O nanocomposite. The CQDs, Cu2O and CQDs/Cu2O nanocomposite were then applied for gas phase photocatalytic reduction of CO2. The experiments were performed under visible light irradiation in a self-designated photoreactor which was connected to an online Gas Chromatography (GC). High resolution transmission electron microscopy (HRTEM) confirmed the uniform deposition of CQDs with size ranging from 2.5 to 6.0 nm on the surface of Cu2O nanoparticles. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy further revealed the presence of CQDs on the surface of Cu2O. The CQDs/Cu2O nanocomposite photocatalyst showed a considerable improvement in the CO2 photoreduction with an enhancement of 54% compared to the pure Cu2O. In addition, the band alignment of CQDs/Cu2O, charge carriers transfer and separation as well as possible reaction pathways for CO2 photoreduction was proposed. Finally, the photostability test revealed the CQDs/Cu2O nanocomposite was able to retain its photostability of up to ~90% under five cycles of photoreaction.
关键词： copper (I) oxide,carbon quantum dots,CO2 photoreduction,photocatalyst
更新于2025-09-23 15:21:01
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Dependence of the photocatalytic reduction of bicarbonate to formic acid by Aua??TiO2 on Au morphology and its plasmonic vibrational mode
摘要： The effect of Au morphology and its plasmonic vibration mode on the photoactivity of Au-TiO2 nanostructures was evaluated. Here, Au nanoparticles with three distinct morphologies, i.e., nanooctahedra, nanocube, and nanorod, were successfully prepared and integrated into TiO2 nanoparticles. The nanocatalysts were used for photocatalytic conversion of bicarbonate to formic acid for solar fuel generation. Based on the result, it is found that the integration of Au and TiO2 resulted in a synergistic effect on the production of formic acid due to the presence of Au’s SPR phenomenon. Results also demonstrated that the shape of Au nanoparticles plays a pivotal role in the improvement of Au-TiO2 activity. From the photocatalytic experiment, Au NR-TiO2 was found to be the most active nanocatalyst with a formic acid yield of 5.14 mmol/g cat. By using spectroscopy techniques and near-field enhancement simulation, it is believed that the photocatalytic enhancement was due to non-radiative (hot electron transfer and storage) and radiative (near-field enhancement and far-field scattering) effects. However, the additional shape-dependent variation on activity was most likely due to the radiative effects instead of non-radiative ones.
关键词： heterostructures,bicarbonate,Plasmonic,TiO2,photoreduction,Au nanoparticles
更新于2025-09-23 15:21:01
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On the Role of Plasmonic Nanoparticles on the Photocatalytic of TiO <sub/>2</sub> Nanoparticles for Visible-Light Photoreduction of Bicarbonate
摘要： The potential application of anatase titanium dioxide (TiO2) nanoparticles for solar fuel generation has been recently attracting many attentions due to its excellent chemical stability. Nevertheless, the fast charge recombination during photoexcitation process may often reduce the photocatalytic activity. This work presents the role of plasmonic Au nanoparticles on enhancing the photocatalytic activity of TiO2 nanoparticles for a visible-light-driven conversion of bicarbonate to formate. Here, two types of nano-sized Au and TiO2 heterostructures, i.e., Au-TiO2 Janus nanostructures and core-shell Au@TiO2 nanostructures were successfully prepared and characterized using UV-Vis and HR-TEM. Results demonstrated that Au-TiO2 Janus nanostructures had a superior photocatalytic activity compared to TiO2 nanoparticles and core-shell Au@TiO2 nanostructures. This photocatalytic enhancement is believed due to the presence of surface plasmon resonance (SPR) phenomenon in Au nanoparticles that provides a Fermi energy level, which could prevent the charge recombination process during photoexcitation.
关键词： Visible-Light Photoreduction,Bicarbonate,Plasmonic Nanoparticles,Photocatalytic,TiO2 Nanoparticles
更新于2025-09-23 15:19:57
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Plasmonic Electronsa??Driven Solara??toa??Hydrocarbon Conversion over Au NR@ZnO Corea??Shell Nanostructures
摘要： This work demonstrates the long-range redox reactivity of gold plasmon-generated hot electrons for solar-driven CO2 conversion. A series of Au NR@ZnO core-shell photocatalysts with a tunable shell thickness are rationally designed to achieve the solar-to-CH4 conversion, where the hot plasmonic electrons-induced photoreduction takes place on the polar oxide moiety. The shell thickness-independent activity implies that the core, gold nanorods, plays a dominant role in the CH4 generation. The ZnO metal oxide semiconductor shell is beneficial to prolong the lifetime of hot electrons, thereby enhancing the photocatalytic efficiency. However, the thickness of ZnO shell is not relevant to the production rate. Both of these two parts are co-excitated by solar light and synergetic enhance the photocatalytic activity.
关键词： gold nanorod,core-shell nanostructure,ZnO,photocatalysis,CO2 photoreduction,plasmon resonance
更新于2025-09-23 15:19:57
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Direct Ultraviolet Laser-Induced Reduction of Disulfide Bonds in Insulin and Vasopressin
摘要： Ultraviolet (UV) light has been shown to induce reduction of disulfide bonds in solution. The photoreduction is proposed to be a result of electron donation from excited Tyr or Trp residues. In this work, a powerful UV femtosecond laser was used to generate photoreduced products, while the hypothesis of Tyr/Trp mediation was studied with spectroscopy and mass spectrometry. With limited irradiation times of 3 min or less at 280 nm, the laser-induced reduction in arginine vasopressin and human insulin led to significant yields of ～3% stable reduced product. The photogenerated thiols required acidic pH for stabilization, while neutral pH primarily caused scrambling and trisulfide formation. Interestingly, there was no direct evidence that Tyr/Trp mediation was a required criterion for the photoreduction of disulfide bonds. Intermolecular electron transfer remained a possibility for insulin but was ruled out for vasopressin. We propose that an additional mechanism should be increasingly considered in UV light-induced reduction of disulfide bonds in solution, in which a single UV photon is directly absorbed by the disulfide bond.
关键词： mass spectrometry,photoreduction,disulfide bonds,Tyr/Trp mediation,femtosecond laser,Ultraviolet light
更新于2025-09-23 15:19:57
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High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse
摘要： Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties, which, however, is usually restricted by the disadvantages of the current fabrication methods. Here, by exploiting cylindrical focusing of a femtosecond laser on graphene oxide (GO) films, we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process. Strikingly, the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations. The proposed model and simulations reveal that the structure formation is based on the transverse electric (TE) surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior, which eventually results in interference intensity fringes and spatially periodic interactions. Further experiments prove that such a regular structured surface can cause enhanced optical absorption (>20%) and an anisotropic photoresponse (~0.46 ratio) for the reduced GO film. Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography, with the prospect of expansion to other two-dimensional materials for novel device applications.
关键词： graphene oxide,photoreduction,anisotropic photoresponse,femtosecond laser,plasmonic lithography
更新于2025-09-23 15:19:57
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Eosin?Y‐Functionalized Conjugated Organic Polymers for Visible‐Light‐Driven CO <sub/>2</sub> Reduction with H <sub/>2</sub> O to CO with High Efficiency
摘要： Visible-light-driven photoreduction of CO2 to energy-rich chemicals in the presence of H2O without any sacrifice reagent is of significance, but challenging. Herein, Eosin Y-functionalized porous polymers (PEosinY-N, N = 1–3), with high surface areas up to 610 m2 g@1, are reported. They exhibit high activity for the photocatalytic reduction of CO2 to CO in the presence of gaseous H2O, without any photosensitizer or sacrifice reagent, and under visible-light irradiation. Especially, PEosinY-1 derived from coupling of Eosin Y with 1,4-diethynylbenzene shows the best performance for the CO2 photoreduction, affording CO as the sole carbonaceous product with a production rate of 33 mmol g@1 h@1 and a selectivity of 92 %. This work provides new insight for designing and fabricating photocatalytically active polymers with high efficiency for solar-energy conversion.
关键词： photoreduction,CO2 reduction,H2O oxidation,porous organic polymer,CO
更新于2025-09-19 17:15:36
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Phenyl-grafted carbon nitride semiconductor for photocatalytic CO2-reduction and rapid degradation of organic dyes
摘要： Molecular engineering of graphitic carbon nitride (g-C3N4) is achieved by the copolymerization of π-conjugated phenyl urea, melamine, and urea. Integration of aromatic phenyl rings into the heptazine network of g-C3N4 alters its structural, optical and electronic properties. The fusion of polymeric g-C3N4 core with aromatic phenyl groups induces band gap tuning, greatly improves the separation and lifetime of charge-carriers. As a result, CO2 photoreduction experiments conducted by using phenyl grafted g-C3N4 afford methane and formic acid in high yields. Furthermore, a selective model organic pollutant rhodamine B dye is rapidly decomposed under visible light irradiation. This work suggests that pyrolysis of a suitable aromatic π-deficient molecular dopant such as phenyl urea can drastically alter the photo-response of carbon nitride photocatalyst and may enhance its photocatalytic activity. Hence, the present work is expected to be of significant value in sustainable energy production and environmental remediation.
关键词： CO2 photoreduction,photocatalysis,Carbon nitride,Phenyl grafted g-C3N4,dye degradation
更新于2025-09-19 17:15:36
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New Understanding of Crystal Control and Facet Selectivity of Titanium Dioxide Ruling Photocatalytic Performance
摘要： Engineering crystals of titanium dioxide (TiO2) to expose with the most reactive facet has been proved to significantly improve the photocatalytic performance. While most of TiO2 with facets reported in the past were in a particle form, herein we directly grow TiO2 with arbitrarily tunable facets onto the transparent conductive substrate. This could reduce interparticle boundaries, and thus suppress charge recombination and facilitate more efficient charge transport compared to particle-assembled films. Combined systematic experimental and theoretical (Density Function Theory, DFT) studies reveal that fluoride ions (F-) and protons (H+) could play a synergistic role in controlling TiO2 crystals in the way that F- ions change the crystal phase of TiO2 to anatase with low-indexed facets, while H+ ions increase of {001}/{101} ratio. Moreover, the reductive and oxidative sites of facets are clearly elucidated by a selective photodeposition of noble metal and metal oxide. Different photocatalytic tests manifested that {001} facet, which is conventionally believed as the highest reactive facet, does not always show highest performance. On the other hand, the facets reactivity appeared to depend on the types of reactions (reduction or oxidation) and the co-existing synergy of facets. These findings would clarify the ambiguous understanding about the true factors controlling facets, the true order of reactivity of each facet that has still been controversial, and pave a way to improve both efficiency and selectivity of TiO2 in a wide variety of photocatalytic applications in the future.
关键词： Facet Control,CO2 Photoreduction,TiO2,Crystal Growth,PEC Water Splitting
更新于2025-09-19 17:15:36
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Simultaneous photoreduction and Raman spectroscopy of red blood cells to investigate the effects of organophosphate exposure
摘要： Simultaneous photoreduction and Raman spectroscopy with 532 nm laser has been used to study the effects of organophosphate (chlorpyrifos) exposure on human red blood cells. Since in red blood cells, auto-oxidation causes oxidative stress, which, in turn, is balanced by the cellular detoxicants, any possible negative effect of chlorpyrifos on this balance should results in an increased level of damaged (permanently oxygenated) hemoglobin. Therefore, when 532 nm laser, at a suitable power, was applied to photoreduce the cells, only common oxygenated form of hemoglobin got photoreduced leaving the permanently oxygenated hemoglobin detectable in the Raman spectra simultaneously excited by the same laser. Using the technique effects of chlorpyrifos to build up oxidative stress on red blood cells could be detected at concentrations as low as 10 ppb from a comparison of relative strengths of different Raman bands. Experiments performed using simultaneously exposing the cells, along with chlorpyrifos, to H2O2 (oxidative agent) and/or 3-Aminotriazole (inhibitor of anti-oxidant catalase), suggested role of chlorpyrifos to suppress the cellular anti-oxidant mechanism. Since the high level of damaged hemoglobin produced by the action of chlorpyrifos (at concentrations > 100 ppm) is expected to cause membrane damage, atomic force microscopy was used to identify such damages.
关键词： atomic force microscopy,Photoreduction,optical trap,Raman spectroscopy,red blood cells,chlorpyrifos
更新于2025-09-19 17:15:36