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High efficient hydrogen evolution over self-reproducible platinum photocatalyst
摘要： The current artificial photocatalysts often suffer from photocorrosion-induced irreversible damage and low efficiency. Here we report that under the UV irradiation of aqueous isopropanol solution, which photolysis to produce acetone and consume photoelectron in time and be oxidized to form acetone. And then the platinum nanoparticles can coordinate with product acetone on their surfaces to create a unique photocatalysis system for high efficient hydrogen evolution. In this system, the inherent close bonding between photoactive surface complexes and metallic platinum sites creates an efficient donor-acceptor system for charge transfer and leads to high efficiency, with hydrogen generation rate of 8.01 mmol? h?1. Furthermore, in the presence of isopropanol the photoactive acetonyl-platinum complexes are generated reproducibly via a continuous isopropanol-to-acetone conversion and thus work sustainably. This finding indicates the possibility of artificially creating self-reproducible systems to drive photocatalytic reactions efficiently and robustly.
关键词： Photocatalytic,Pt nanoparticles,Self-reproducible,Hydrogen
更新于2025-09-04 15:30:14
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Revisiting structural and photocatalytic properties of g-C3N4/TiO2: Is surface modification of TiO2 by calcination with urea an effective route to “solar” photocatalyst?
摘要： g-C3N4/TiO2 derived from the surface modification of TiO2 by calcination with urea has been widely studied as a “visible-light-active” photocatalyst for environmental purification applications. However, few attentions have been paid to the structure characterization and the photocatalytic properties of the resultant nanocomposite photocatalysts under a practical sunlight irradiation. Here we employ various characterization techniques, including TGA, XRD, TEM, XPS, UV-Vis spectrum, and N2-sorption analysis to characterize the evolutions in phase crystal structure, microstructure and optical properties of g-C3N4/TiO2 nanohybrids synthesized through calcining a mechanical mixture of urea and Evonik Aeroxide P-25 TiO2 (P25) at 350-500 oC. The thermal pyrolysis of urea leads to the surface decoration of TiO2 with graphitic carbon nitrate (g-C3N4) at temperatures above 400 oC. The photocatalytic properties of the resultant g-C3N4/TiO2 nanoparticles are evaluated through photocatalytic decoloration of methylene blue (MB) and reduction of Cr(VI) to Cr(III) under visible (420 nm), UV (365 nm), and simulated solar light irradiations. The nanohybrid photocatalysts, as most previous studies reported, show much higher photocatalytic activity under visible light irradiation than the single-component counterparts, i.e. P25 or g-C3N4. However, under solar and UV irradiation, no considerable improvements are found, which is caused by the decrease in redox potential upon interfacial charge carrier transfer between g-C3N4 and TiO2. Moreover, g-C3N4/TiO2 shows an ultralow photocatalytic activity in Cr(VI) reduction. The surface modification with organic g-C3N4 is assumed to tune the surface properties (e.g. hydrophilicity) of TiO2. Our results demonstrate that photocatalytic activity in UV range is as important as that in visible range, and developing efficient “solar” photocatalysts should balance both since they might be incompatible with each other.
关键词： graphitic carbon nitrate,dye degradation,TiO2 nanoparticles,Cr (VI) reduction,semiconductor photocatalysis,Aeroxide P25,charge carrier transfer
更新于2025-09-04 15:30:14
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Fabrication and characterization of pure and modified Co3O4 nanocatalyst and their application for photocatalytic degradation of eosine blue dye: a comparative study
摘要： The present work deals with the synthesis of cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles as a catalyst. The study is investigating the different factors in obtaining cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles. Photocatalytic degradation studies are carried out for water-soluble eosine blue (EB) dye using cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles in aqueous solution. Different parameters such as initial dye concentration, dose of catalyst, contact time and pH have been studied to optimize reaction conditions. It is observed that photocatalytic degradation is a more effective and faster mode of removing EB dye by cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles than work done before. The optimum conditions for the removal of the EB dye are initial concentration 40 mg/L, photocatalyst dose 0.8 g/L, and pH 7.5. The EDS technique gives the elemental composition of synthesised cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles. The TEM and XRD studies are carried for morphological feature characteristics of synthesized cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles. Pseudo-first-order kinetic has been investigated for both pure and doped cobalt oxide catalysts. Almost 95% dye degradation has been observed for doped cobalt oxide nanoparticles.
关键词： Photocatalytic degradation,Modified cobalt oxide nanoparticles,Eosine blue,EDS,SEM,XRD,TEM
更新于2025-09-04 15:30:14
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Confinement of Singlet Oxygen Generated from Ruthenium Complex-Based Oxygen Sensor in the Pores of Mesoporous Silica Nanoparticles
摘要： We synthesized mesoporous silica nanoparticles bearing ruthenium complexes in their pores (MSN-Ru) and characterized their photochemical properties. The ruthenium complexes that were immobilized in the pores showed oxygen-dependent phosphorescence, similar to the complexes that were not tethered to nanoparticles. Cellular imaging and in vivo experiments revealed that hypoxic cells and tissues could be visualized by monitoring the phosphorescence of MSN-Ru. Our most important finding was that the toxic effect of singlet oxygen (1O2), which was generated by excitation of the complexes, was effectively suppressed by the deactivation before leaking out from the pores. In addition, we observed a negligible toxic effect of the ruthenium complexes themselves due to the blockage of their direct interaction with intracellular biomolecules. Thus, MSN-Ru is a promising molecular probe of oxygen levels in living cells and tissues.
关键词： ruthenium complexes,singlet oxygen,in vivo experiments,cellular imaging,oxygen sensor,mesoporous silica nanoparticles
更新于2025-09-04 15:30:14
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A highly efficient NiFe nanoparticles decorated Si photoanode for photoelectrochemical water oxidation
摘要： n-Si is a narrow band gap semiconductor that has been demonstrated as an excellent photo-absorber material for photoelectrochemical (PEC) water splitting. Depositing a thin layer of Ni film on n-Si can form a Schottky junction at the interface, which offers a simple and useful route toward light-driven water oxidation. However, the relatively low catalytic activity of the Ni layer and the presence of interface states limits the application of this structure. Herein, we prepared a high performance NiFe nanoparticles decorated Si photoanode for the efficient solar driven water oxidation to H2. NiFe nanoparticles were dispersed on a Si substrate surface homogeneously to form an inhomogeneous metal-insulator-semiconductor (MIS) junction, which increased the photovoltage of photoanode. In addition, the oxide/oxyhydroxide layer on the deposited NiFe layer formed during the evaporation deposition acted as a highly efficient electrocatalyst, which also contributed to the high PEC performance of the photoanode. The photoanode covered with 2 nm NiFe film exhibited the best PEC performance with a low onset potential of 1.09 V vs. RHE (the potential required to reach the photocurrent of 1 mA/cm2), a high photocurrent of 25.2 mA/cm2 at 1.23 V vs. RHE, and a stable output over 50 h under AM 1.5G illumination due to the high performance inhomogeneous MIS junction and a thick oxide/oxyhydroxide catalytic shell formed on NiFe nanoparticle via an aging process.
关键词： photoelectrochemical water oxidation,oxide/oxyhydroxide layer,Si photoanode,NiFe nanoparticles,MIS junction
更新于2025-09-04 15:30:14
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Bioconjugation strategy for cell surface labelling with gold nanostructures designed for highly localized pH measurement
摘要： Regulation of intracellular pH is critically important for many cellular functions. The quantification of proton extrusion in different types of cells and physiological conditions is pivotal to fully elucidate the mechanisms of pH homeostasis. Here we show the use of gold nanoparticles (AuNP) to create a high spatial resolution sensor for measuring extracellular pH in proximity of the cell membrane. We test the sensor on HepG2 liver cancer cells and MKN28 gastric cancer cells before and after inhibition of Na+/H+ exchanger. The gold surface conjugation strategy is conceived with a twofold purpose: i) to anchor the AuNP to the membrane proteins and ii) to quantify the local pH from AuNP using surface enhanced Raman spectroscopy (SERS). The nanometer size of the cell membrane anchored sensor and the use of SERS enable us to visualize highly localized variation of pH induced by H+ extrusion, which is particularly upregulated in cancer cells.
关键词： cancer cells,SERS,cell surface labelling,pH measurement,gold nanoparticles
更新于2025-09-04 15:30:14
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The Effects of Hydrostatic Pressure on the Surface Plasmon Resonance of Gold Nanocrystals
摘要： The surface plasmon resonances of gold nanospheres and nanorods have been measured as a function of hydrostatic pressure up to 17 GPa in methanol-ethanol 4:1 solvent and up to 10 GPa in paraffin. Both the sphere resonance and the longitudinal rod resonance exhibit redshifts while the transverse rod mode shows an extremely weak redshift or blueshift depending on the nanorod aspect ratio. Solidification of the solvent around 11 GPa causes some aggregation of the particles, readily identified through broadening of the SP band and further redshifting. Loading and unloading cycles show only minimal hysteresis in the spectra if the pressure remains below 11 GPa. The surface plasmon shifts are the result of two competing effects. Compression of the conduction electrons in the metals increases the bulk plasma frequency, which causes a blueshift. However, the increase in the solvent density under hydrostatic load leads to an increase in the solvent refractive index, which in turn leads to a redshift. We find that after accounting for the solvent contribution, we can spectroscopically determine the bulk modulus of the gold nanoparticles with a precision of 10%. The value obtained of K0 = 190 GPa is significantly higher than the value for bulk gold (167 GPa). Furthermore, we show that pressure-induced solidification causes a significant broadening and anomalous shift of the surface plasmon band that we attribute to aggregation and nanorod deformation.
关键词： optical absorption,refractive index,hydrostatic pressure,surface plasmon resonance,bulk modulus,gold nanoparticles
更新于2025-09-04 15:30:14
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Enhanced Photoinduced Electrocatalytic Oxidation of Methanol Using Pt Nanoparticle-Decorated TiO <sub/>2</sub> –Polyaniline Ternary Nanofibers
摘要： Herein, perylene-3,4,9,10-tetracarboxylic acid-doped polyaniline (PTP) nanofibers with/without photoreactive anatase TiO2 (TiO2?PTP and PTP, respectively) have been successively synthesized and subsequently decorated by Pt nanoparticles (Pt NPs) to prepare Pt?PTP and Pt?TiO2?PTP composites. High-resolution transmission electron microscopy confirms the presence of ～3 nm spherical-shaped Pt NPs on both the composites along with TiO2 on Pt?TiO2?PTP. Pt loading on the composites is deliberately kept similar to compare the methanol electro-oxidation in the two composites. The Pt nanocomposites along with the precursor polyanilines are characterized by optical characterization, X-ray diffraction study, X-ray fluorescence spectroscopy, and Raman spectroscopy. The ternary composite-modified (Pt?TiO2?PTP) electrode demonstrates high electrocatalytic performance for methanol oxidation reaction in acid medium than Pt?PTP and Pt?TiO2. The higher electrochemical surface area (1.7 times), high forward/backward current ratio, and the higher CO tolerance ability for Pt?TiO2?PTP make it a superior catalyst for methanol oxidation reaction in the electrochemical process than Pt?PTP. Moreover, the catalytic activity of Pt?TiO2?PTP is further enhanced significantly with light irradiation. The cooperative effects of photo- and electrocatalysis on methanol oxidation reaction in Pt?TiO2?PTP enhance the methanol oxidation catalytic activity approximately 1.3 times higher in light illumination than in dark. Therefore, the present work will be proficient to get a light-assisted sustainable approach for developing the methanol oxidation reaction activity of Pt NP-containing catalysts in direct methanol fuel cells.
关键词： photo-assisted,TiO2 nanofibers,methanol oxidation,electrocatalysis,Pt nanoparticles
更新于2025-09-04 15:30:14
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Optical coupling between resonant dielectric nanoparticles and dielectric nanowires probed by third harmonic generation microscopy
摘要： Localized electromagnetic modes and negligible Ohmic losses dictate the growing interest to subwavelength all-dielectric nanoparticles. Although an exhaustive volume of literature dealt with interaction of all-dielectric nanostructures with free-space electromagnetic fields, they received little attention as integrated photonic elements. We present an experimental and numerical study of optical coupling between a resonant subwavelength silicon nanodisk and a silicon nanowire, as probed by third harmonic generation microscopy and full-wave simulations. First, by placing the nanodisks at different distances from the nanowire, we observed third harmonic intensity modulation by a factor of up to 4.5. This modulation is assigned to changes in the local field enhancement within the nanodisks caused by their coupling to the nanowires and subsequent shifting and broadening of their magnetic-type resonances. Interestingly, although the nanowire presents an additional loss channel for the nanodisk, we observed an increase in the local field strength within the nanodisk, as verified by rigorous full-wave simulations. Inversely, for the gap sizes that are smaller than ≈ 200 nm, we observe the influence of the nanoparticles on the propagation properties of the fundamental waveguide modes of the nanowire. The better understanding of the mutual influence of the Mie-resonant nanoparticles and waveguiding structures heralds integration of the former on photonic chips.
关键词： dielectric nanowire,third harmonic generation microscopy,silicon nanoparticles,Optical coupling
更新于2025-09-04 15:30:14
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AN ALGORITHM TO DETERMINE THE NANODOSIMETRIC IMPACT OF GOLD NANOPARTICLES ON CELL MODELS
摘要： High-Z nanomaterials, e.g. gold nanoparticles (GNPs), are being investigated worldwide for potential application in radiation imaging and therapy. Photon irradiation of cells containing GNP was shown to produce enhanced DNA damage which is believed to be related to the increased secondary electron (SE) yield and ionization density. In this work, an algorithm was developed for simulating the physical radiation damage inside the nucleus of a spherical cell model for the case of uniformly distributed GNPs within the cytoplasm. Previously calculated energy spectra of SE emerging from a single NP irradiated with different photon sources are used as input to obtain the SE energy spectrum at the surface of the cell nucleus. In a second step, the SE transport inside the cell nucleus is simulated with a track structure Monte Carlo code to obtain the spatial distribution of ionizations. The preliminary results presented here show that the developed algorithm allows for a fast calculation of the SE spectra at the cell nucleus surface, thus enabling a more realistic assessment of the ionization density inside the cell nucleus than that obtained by the simulation of a single GNP. Furthermore, the algorithm can be easily adapted to investigate both the effect of GNP clustering and the impact of GNP–GNP interactions on SE spectra.
关键词： radiation therapy,secondary electrons,gold nanoparticles,Monte Carlo simulation,ionization density
更新于2025-09-04 15:30:14