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Plasmonic and non-plasmonic contributions on photocatalytic activity of Au-TiO2 thin film under mixed UVa??visible light
摘要： A highly photocatalytic Au-TiO2 hybrid thin film was prepared by the photocatalytic deposition of Au nanoparticles (NPs) on reactive sputtered TiO2 thin film. By altering the ratio of the visible (Vis) and ultra-violet (UV) light (Vis/UV) we investigated plasmonic and non-plasmonic contributions of Au NPs to the overall photocatalytic activity. While, a gradual increase of Vis/UV (≤0.24/1) led to a steady enhancement of the photocatalytic performance of Au-TiO2 hybrid structures, further increase in Vis/UV (≥0.30/1) did not foster the enhancement further. At high Vis/UV, plasmon excited electrons seem to start promoting electron-hole recombination in TiO2, which significantly reduces the photocatalytic performance.
关键词： plasmonic,Au,TiO2,nanoparticles,photocatalyst,photoreduction
更新于2025-09-19 17:13:59
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3D-printed, home-made, UV-LED photoreactor as a simple and economic tool to perform photochemical reactions in high school laboratories
摘要： In the paper we present the simple manufacturing of an easy and economical UV-A photoreactor using a desktop 3D printer and its application in chemical transformations. PLA (polylactic acid) was used as inexpensive and not toxic polymer for the 3D printing process, while commercially available decorative ultraviolet LEDs (UV-A) have been employed as a light source. With this device, the photoreduction of benzophenone was performed in high yield and short times, compatible with the duration of a typical laboratory experiment in a high school program.
关键词： UV-LEDs,benzophenone,photoreduction,photoreactor,3D printing
更新于2025-09-16 10:30:52
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Hydrogen Production System by Light‐Induced α‐FeOOH Coupled with Photoreduction
摘要： Solar driven catalysts on semiconductors to produce hydrogen are considered as a means to solve environmental issues. In this study, H2 production coupling with oxygen consumption by noble metal-free α-FeOOH was demonstrated even though the conduction band edge was lower than the reduction potential of H+ to H2. For activation of α-FeOOH, an electron donor, Hg-Xe irradiation, and low pH (~5) were indispensable factors. The H2 production from H2O was confirmed by GC-MS using isotope-labeled water (D2O) and deuterated methanol. The α-FeOOH synthesized by coprecipitation method showed 25 times more active than TiO2. The photocatalytic activity was stable for over 400 h. Our study suggests that α-FeOOH known as rust can produce H2 by light induction.
关键词： α-FeOOH,Photocatalyst,photoreduction
更新于2025-09-12 10:27:22
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Photo-induced generation of size controlled Au nanoparticles on pure siliceous ordered mesoporous silica for catalytic applications
摘要： A versatile in situ photochemical reduction approach was used to generate a composite of gold nanoparticles and pure siliceous SBA-15 silica support with regular mesopores. The mesoporous silica support was first synthesized and, after calcination, was suspended in a solution of gold bromide (EtOH or H2O) containing a free radical generator activated by UV irradiation and used for the photochemical reduction of gold precursor. The influence of gold precursor concentration, light intensity and nature of the solvents on the formation and properties of gold nanoparticles (size, dispersion, stability) on the mesoporous SBA-15 support have been studied with the aim of optimizing the dispersion of the gold nanoparticles in the mesoporous network and their chemical stability. The catalytic activity of the resulting AuNPs@SBA-15 nanocomposite was successfully evaluated for the oxidation of benzyl alcohol reaction in liquid-phase.
关键词： Benzyl alcohol,Photoreduction,Gold nanoparticles,Mesoporous silica,SBA-15,Oxidation
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Photoreduction in Optofluidic Hollow-Core Photonic Crystal Fiber
摘要： Optofluidic hollow-core photonic crystal fiber (HC-PCF) uniquely allows light to be guided at the centre of a microfluidic channel. The system maximizes the interaction of light with infiltrated chemicals and (nano)particles, offering unique opportunities for in-situ optical monitoring of a range of photochemical and catalytic reactions [1,2]. Our current goal is to extend this work to hybrid colloidal systems comprising a particulate light absorber and a molecular catalyst for photocatalytic fuel production [3]. Here we use HC-PCF microreactors to study novel light-absorbing particles for such systems: graphitic, N-doped, and amorphous carbon-nanodots (CNDs) that offer a unique combination of scalability, biocompatibility, water solubility, and stable optical properties [4]. To test the CNDs’ absorption- and electron-transfer properties, we combine them with the redox-active heterocycle methyl viologen dichloride (MV2+·2Cl-). Upon absorption of UV light, CNDs can transfer an electron to MV2+, whose reduction to the radical cation (MV?+) creates a strong optical absorption peak around 600 nm (Figs. 1(a,c)). An electron donor (EDTA) is added to the solution to quench the photo-induced holes in the CNDs [4]. The mixture was infiltrated into the core of a 30 cm long liquid-filled kagomé style HC-PCF (Fig. 1(b)), designed to guide in the wavelength range of the MV?+ absorption peak. To ensure a homogeneous excitation of the CNDs, a 5 cm long section of the fiber was side-illuminated by a UV lamp (λ = 365 nm). A supercontinuum source, launched into a guided mode, was used to monitor the absorption spectrum. Despite sample volumes of less than 50 nL, we obtain highly-reproducible time traces of the MV?+ absorption (Fig 1(d-e)). Unexpectedly, a significant initial time-delay of 135 s was observed in the reduction of MV2+, revealing the presence of a previously unknown activation process of the CNDs. The initial delay was found to depend on the functionalization of the CNDs, with delays for a -COOH group (81 s) being ca. three times shorter than those for NH2 (176 s) and NMe2 (204 s) groups. The subsequent reaction rate was found to be independent of the surface-group. Our unexpected results highlight the scope for urgently needed in-situ analysis of photocatalytic systems. Future experiments will include the use of surface-sensitive higher-order modes [5] to selectively probe the diffusion of reaction products within the optofluidic reactor.
关键词： Carbon-Nanodots,Photoreduction,Hollow-Core Photonic Crystal Fiber,Optofluidic,Photocatalytic
更新于2025-09-12 10:27:22
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Simultaneous Photoreduction and Nitrogen Doping of Graphene Oxide for Supercapacitors by Direct Laser Writing
摘要： Graphene-based supercapacitors have attracted tremendous attention owing to their outstanding electrochemical performance. In terms of material, nitrogen(N)-doped graphene(NDG) displays enhanced specific capacitance and rate performance compared with bare graphene used as a supercapacitor electrode. However, it still remains a challenge to develop a facile and simple method of NDG in cost-effective manner. Here, we used a simple direct laser writing technique to accomplish the simultaneous photoreduction and N-doping of graphene oxide(GO) using urea as a N source. The N content of the resultant reduced N-doped graphene oxide(NGO) reached a maximum value of 6.37%. All reduced NGO(NRGO)-based supercapacitors exhibited a higher specific capacitance than those based on pure reduced GO(RGO). Interestingly, the electrochemical performance of NRGO-based supercapacitors varied with different contents of N species. Therefore, we can control the properties of the obtained NRGOs by adjusting the doping ratios, an important step in developing effective graphene-based energy storage devices.
关键词： Simultaneous photoreduction and nitrogen-doping,Direct laser writing,Graphene based supercapacitor
更新于2025-09-11 14:15:04
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Photocatalytic reduction of CO2 to methane over PtOx-loaded ultrathin Bi2WO6 nanosheets
摘要： Solar CO2 photoreduction into hydrocarbons is promising and significative. However, many conventional catalysts reported usually suffer from poor photocatalytic activities. Herein, ultrathin Bi2WO6 nanosheets with a thickness of about 4.8 nm have been synthesized by hydrothermal method, which exhibited a CH4 production rate of 19 ppm g?1 h?1 under a low CO2 concentration of 400 ppm. PtOx nanoparticles with a size of about 2 nm were then loaded on the Bi2WO6 nanosheets as excellent co-catalysts by photoreduction in aqueous solution, and an optimal CH4 yield of 108.8 ppm g?1 h?1 was achieved, which was about 5.7 times than that of pristine Bi2WO6 nanosheets. Further analyses of photocurrent curves, electrochemical impedance spectroscopy and polarization curves of water oxidation indicated that the improved photocatalytic activity was suggested to result from the enhanced carrier separation and accelerated water oxidation by PtOx nanoparticles. The work will likely give a deeper insight of PtOx nanoparticles and provide a new idea to design catalysts for CO2 photoreduction to CH4.
关键词： PtOx nanoparticles,Carrier separation,Water oxidation,CO2 photoreduction,Bi2WO6 nanosheets
更新于2025-09-10 09:29:36
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Application of thermal lens microscopy (TLM) for measurement of Cr(VI) traces in wastewater
摘要： In this work, we demonstrate for the ?rst time that Thermal Lens Microscopy technique (TLM) can be applied to monitor the dynamics of a photocatalytic process in-situ. The photocatalytic reduction of hexavalent chromium -Cr(VI)- in aqueous solution using CdS and irradiated with visible light is monitored by TLM. Since the values of Cr(VI) concentration obtained after the photocatalytic process were close to those imposed by the international regulations for drinking water, the use of TLM allowed its measurement with a better reliability than with UV spectroscopy, usually used in this kind of analysis.
关键词： Cr(VI),Photocatalysis,Photoreduction,Thermal lens microscopy,Photothermal,CdS photocatalyst
更新于2025-09-10 09:29:36
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Construction of Z-scheme MoSe2/CdSe Hollow Nanostructure with Enhanced Full Spectrum Photocatalytic Activity
摘要： For better use of solar energy, the development of full-spectrum photocatalysts has attracted most attentions. In this research, uniform hollow MoSe2/CdSe nanospheres (250 nm) were prepared by one-pot solvothermal strategy. It is the first time to synthesize hollow MoSe2 based nanostructure without any template/surfactant assistance. By varying reaction time, the formation mechanism was investigated, illuminating that the novel hollow structure is derived from the Kirkendall Effect. Both experimental and density functional theory (DFT) calculations reveal the Z-scheme mechanism of the charge transfer in the heterostructure. The hollow MoSe2/CdSe nanospheres (MC2) possess the remarkable photocatalytic activity in degradation of Cr(VI) (125 mg g-1, simulated sunlight), owing to the high harvest of full spectrum, porous hollow structure and effective charge separation/transfer. Furthermore, the photocatalytic process was further studied in detail, showing that the Langmuir single-layer adsorption behavior, low pH value condition, and thermal effect also benefit to the high photoreduction performance. Benefiting from the Z-scheme mechanism, the high redox activity make sure the water splitting capacity of MC2 (7120.0 and 348.0 μmol·h-1·g-1 of H2 and O2 evolution) under simulated sunlight irradiation and its AQY for H2 evolution at 670 nm reaches up to 27.2% (50 mg MC2).
关键词： Z-scheme,Water splitting,Cr(VI) photoreduction,Hollow MoSe2/CdSe nanospheres,Full Spectrum photocatalysis
更新于2025-09-10 09:29:36
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Enhanced activity of β-Ga2O3 by substitution with transition metal for CO2 photoreduction under visible light irradiation
摘要： Gallium oxide semiconductors have been developed as effective photocatalysts for water splitting driven by UV light irradiation, but there is no relevant study for the CO2 photoreduction application. Herein, we report the first investigation of β-Ga2O3 applying to photocatalytic CO2 reduction under visible light irradiation by doping transition metal ions (M = V, Cr, Mn, Fe, Co, Ni and Cu) onto the framework. Using sol-gel method, a series of transition metal ions incorporated β-Ga2O3 have been successfully obtained, in which the transition metal substitution content is 2 mol %. The β-Ga2O3:M photocatalysts are characterized completely by diverse tests (e.g., XRD, XPS, UV-Vis DRS, SEM). The effective replacement of Ga3+ ion by M ions significantly expands the scope of spectral response from UV light to visible light, and Fe3+, Co2+, Ni2+ significantly enhance the photocatalytic activity under visible light irradiation. In these cases, CO and H2 are evolved as the reduction products from CO2 and H+ by the generated electrons, respectively. Among these effective catalysts we prepared, β-Ga2O3:Ni exhibits the most substantial CO formation rate of 14.3 μmol/h at 30 °C, and the selectivity for CO evolution exceeds 60.9 %. Furthermore, the CO formation rate increases to 24.6 μmol/h after loading of Ag as the co-catalyst. The stability of the Ag/β-Ga2O3:Ni are verified after five cycle of CO2 photoreduction under visible light.
关键词： transition metal substituted,visible light irradiation,CO2 photoreduction,gallium oxide
更新于2025-09-10 09:29:36