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Heavy metals have been widely applied in industry, agriculture, and other fields because of their outstanding physics and chemistry properties. However, heavy metal pollution is inevitable in the process of mass production and emission. Heavy metal ions will cause irreversible harm to the human body and other organisms due to their nondegradable nature even at low concentrations of exposure and ingestion. Therefore, it is of great significance for human health and ecological environment to develop high accuracy and sensitivity as well as stable techniques for detecting heavy metal ions. In recent years, surface-enhanced Raman scattering (SERS) spectroscopy has been regarded as a promising new technique for the determination of trace heavy metal ions on account of its special fingerprint identification capability, high sensitivity, rapid detection ability, and simple operation. This review summarized in detail the basic principles and strategies for detecting mercury ions, copper ions, arsenic ions, zinc ions, cadmium ions, lead ions, and chromium (VI) ions as well as the current challenges and future trends for the determination of heavy metal ions based on SERS technology.

The separation and transfer of photogenerated electron–hole pairs in semiconductors is the key point for photoelectrochemical (PEC) water splitting. Here, an ideal TaON/BiVO4 heterojunction electrode was fabricated via a simple hydrothermal method. As BiVO4 and TaON were in well contact with each other, high performance TaON/BiVO4 heterojunction photoanodes were constructed. The photocurrent of the 2-TaON/BiVO4 electrode reached 2.6 mA cm−2 at 1.23 V vs. RHE, which is 1.75 times as that of the bare BiVO4. TaON improves the PEC performance by simultaneously promoting the photo-generated charge separation and surface reaction transfer. When a Co-Pi co-catalyst was integrated onto the surface of the 2-TaON/BiVO4 electrode, the surface water oxidation kinetics further improved, and a highly efficient photocurrent density of 3.6 mA cm−2 was achieved at 1.23 V vs. RHE. The largest half-cell solar energy conversion efficiency for Co-Pi/TaON/BiVO4 was 1.19% at 0.69 V vs. RHE, corresponding to 6 times that of bare BiVO4 (0.19% at 0.95 V vs. RHE). This study provides an available strategy to develop photoelectrochemical water splitting of BiVO4-based photoanodes.

Ultramicropores (size < 0.7 nm) are critically demanded to provide an efficient path for the penetration and transportation of electrolytes to achieve high-performance supercapacitors. Here, a self-sacrificial template approach is adopted, which introduces C8 alkyl chains with a kinetic diameter of 0.8-1 nm to occupy the cavity of a porous aromatic framework (PAF). During the heating process, the alkyl chains decompose from the dense architecture as the temperature increased from 500 to 600 °C, forming ∼1 nm micropores. The newly-obtained cavities provide sites for thermal-driven skeleton engineering (700-900 °C) to obtain ultramicropores. Based on the well-defined pore structure, the carbonized PAF solid revealed outstanding electrochemical performances, including high rate and long-term stability in a 6 M KOH electrolyte. Notably, the specific capacitance (294 F g-1) derived from the self-sacrificial template method exceeds the capability of all the other methods for the construction of ultramicropores including self-template strategy, carbonization of nanoparticles, and template-assisted strategy. The synthesis of ultramicroporous carbons via the self-sacrificial template route opens up a promising gate to adjust the porous structure for high-performance applications in supercapacitors.

Plasmon-assisted reactions have different reaction mechanisms than conventional chemical reactions occurring in solutions, and the hot electrons produced by plasmon decay play an irreplaceable role...

Gold nanoparticles have received widespread attention as surface-enhanced Raman scattering (SERS) detection active substrates. In this work, we used the nematic liquid crystal molecule N-(4-methoxybenzylidene)-4-butylaniline (MBBA) at room temperature to synthesize liquid crystal (LC)-Au nanoparticles in one step without adding any other reducing agents or stabilizers. Gold nanoparticles synthesized by this method have good sensitivity and stability as a SERS substrate. The nanoparticles can detect Rhodamine 6G (R6G) molecules with a concentration as low as 10−8 M, and the SERS signal does not decrease significantly in 30 days. Using this synthesis principle, we grew gold nanoparticles in a capillary in one step. We expect the proposed method to result in a highly efficient and portable SERS substrate after subsequent improvements.

In this study, zinc aluminum layered double hydroxide (ZnAl-LDH) with a Zn/Al molar ratio 8/1 was synthesized via a facile urea method, and the mixed metal oxide (MMO) was prepared using the corresponding LDH as a precursor. In order to improve the performance of electron transport layer, we introduced graphene into ZnAl-MMO to prepare new nanocomposites, ZnAl-MMO/graphene, as promising photoanodes for dye-sensitized solar cell (DSSC). The bare ZnAl-MMO and formed ZnAl-MMO/graphene nanocomposites were characterized by X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and UV–vis absorption spectrum, confirming the presence of graphene and the wurtzite type phase of ZnO. A series of DSSC were fabricated by the corresponding nanocomposites and a D205 as dye. The photovoltaic behavior of these cells based on different graphene concentration was further investigated by electrochemical method. It turned out that the introduced graphene facilitated the dye adsorption and light-scattering, which heightened the performance of DSSC. The DSSC based on ZnAl-MMO/0.2 wt.% graphene reached the best power conversion efficiency (PCE) of 0.51%, showing a rise of 25% approximately when compared with plain ZnAl-MMO.

The Ag+ is first adopted to oxidize PATP to DMAB. It could act as a SERS substrate and overcomes the drawbacks of the traditional metal sol. Compared with the traditional silver sol system, the intensity of the Raman peak is increased by 10 times.

The purpose of this study was to develop a flexible substrate methylcellulose-decorated silver nanoparticles (MC/Ag NPs) film and explore its application in fruits and vegetables by surface enhanced Raman spectroscopy (SERS) technology for rapid detection of pesticides. The performance of the MC/Ag NPs film substrate was characterized by Nile blue A (NBA), and the detection limit was as low as 10−8 M. The substrate also exhibited satisfactory Raman signal strength after two months of storage. The impressive sensitivity and stability were due to the excellent homogeneity of the silver nanoparticles that were grown in situ in the methylcellulose matrix, which generated “hot spots” between the silver nanoparticles without a large amount of aggregation, and resulted in the ultra-high sensitivity and excellent stability of the MC/Ag NPs film substrate. The MC/Ag NPs film substrate was used to detect thiram pesticides on tomato and cucumber peels, and the minimum detectable level of thiram was 2.4 ng/cm2, which was much lower than the maximum residue level. These results indicate that the MC/Ag NPs film is sensitive to rapid detection of multiple pesticides in food.

Multiple-twinned silver nanoparticles (Ag-NPs) supported on mesoporous graphene were prepared through a facile oxidative etching process. Firstly, the Ag-NPs are supported onto the traditional graphene (Ag-NPs/G) by the typical wetness impregnation method. Then, the mesopores with sizes ranging from 5 to 10 nm were successfully fabricated on the initial graphene support through the oxidative etching process assisted by the Ag-NPs. And the Ag-NPs with multiple-twinned structure were simultaneously generated on the mesoporous graphene (Ag-MtNPs/MpG) during the etching process. The synergistic effect of both the unique mesopores on the graphene and the as-prepared multiple-twinned Ag-NPs in the Ag-MtNPs/MpG sample dramatically enhanced the release rate of silver ions (Ag+) and resulted in robust antibacterial activity of against Escherichia coli, in comparison with that of single crystallized Ag-NPs supported on traditional graphene (Ag-NPs/G). The present method paves a feasible way to design novel Ag based antibacterial materials.

An integrated composite of meso-cellular silicate foam (MCF)-modified reduced graphene oxide (MCF@rGO) was designed and synthesized based on polyethylene oxide-polypropylene oxide-polyethylene oxide (P123)-modified rGO (P123-rGO). As the polymeric template for the fabrication of mesoporous silicates, modified P123 greatly improved the affinity between the nanosheet and the in situ formed MCFs, resulting in the formation of thin layers of MCFs on both sides of rGO. Therefore, the MCFs@rGO formed exhibited a unique sandwich structure with an inner skeleton of rGO and two outer layers of MCFs. The outer modification by MCFs, with the presence of large mesopores, not only shifted the surface property of rGO from hydrophobic to hydrophilic but also offered immobilized enzymes a favorable microenvironment to maintain their bioactivity. Meanwhile, the inner skeleton of rGO compensated for the weak conductivity of MCFs, providing a pathway for the direct electron transfer (DET) of various redox enzymes or proteins, such as hemoglobin (Hb), horseradish peroxidase, glucose oxidase (GOD), and cholesterol oxidase. It was found that the DET signal obtained from Hb-MCFs@rGO/glassy carbon electrode (GCE) was much larger than the sum of the signals from two components-based modified electrodes of Hb-P123-rGO/GCE and Hb-MCFs/GCE. A similar improvement in DET signal was also observed using GOD-MCFs@rGO/GCE. The significant enhancement of DET signals for both protein electrodes can be ascribed to the synergistic effects generated from the integration of the two components, one of which enhances biocompatibility and the other enhances conductivity. The bioelectrocatalytic performance of Hb and GOD electrodes was further investigated. As for Hb-MCFs@rGO/GCE, the GOD electrode displayed excellent analytical performance for the detection of hydrogen peroxide (H2O2), including a good sensitivity of 0.25 μA μmol-1 L cm-2, a low detection limit of 63.6 nmol L-1 based on S/N = 3, and a low apparent Michaelis-Menten constant (KMapp) of 49.05 μmol L-1. GOD-MCFs@rGO/GCE also exhibited good analytical performance for the detection of glucose, with a wide linear range of 0.25-8.0 mmol L-1. In addition, blood glucose detection in samples of human serum was successfully achieved using GOD-MCFs@rGO/GCE with a low quantification limit.

N-doped graphene (N-graphene) confined Pt nanoparticles (NPs) with core-shell structure supported on carbon nanotubes (CN@Pt/CNTs) are prepared by a facile two-step process. The obtained N-graphene nanoshell ranging from 2 to 4 graphene layers and the Pt NPs covered within N-graphene are uniformly dispersed on the CNTs. The as-prepared CN@Pt/CNTs exhibits much higher styrene selectivity and robust recycle ability in selective hydrogenation of phenylacetylene, compared with that of traditional CNTs supported Pt NPs (Pt/CNTs). DFT calculation reveals that the high styrene selectivity is derived from the confinement effect of N-graphene, which facilitates desorption of styrene from Pt NPs surface, avoiding the over hydrogenation of styrene to benzylethane. The present method paves a new way to design high selective Pt based hydrogenation catalyst.

The development of convenient assays for the determination of hydrazine (N2H4) has drawn significant attention due to the high toxicity of this substance. Herein, we developed a concise, rapid and ultrasensitive surface-enhanced Raman scattering (SERS) sensor for N2H4 detection based on alpha-cyclodextrin-silver nanoparticles (α-CD-AgNPs) modified by 4-mercaptobenzaldehyde (4-MBA). The 4-MBA molecules can specifically capture the N2H4 molecules and undergo a Schiff base reaction. As a result, this induces the aggregation of nanoparticles and generates a new characteristic peak at 1529 cm–1 that is attributed to C N and C C vibrations. Compared with noble metal nanoparticles, 4-MBA not only formed Ag S bonds but could also be fixed in the cavity of cyclodextrin to produce a more stable and stronger SERS signal. The SERS intensity at 1529 cm–1 and the logarithm of the concentration of N2H4 presented a good linear relationship from 10–9 to 10–7 M with an unprecedented limit of detection (LOD) of 38 pM. The proposed SERS sensor exhibited satisfactory selectivity and reproducibility and was applied to detect N2H4 in real and complex water samples. We expect this assay to be a promising alternative tool for the on-site detection of N2H4.

Noble metal-semiconductor nanocomposites have received extensive attention in Surface Enhanced Raman Scattering (SERS) due to their unique properties. In this paper, the Ag–ZnO nanocomposites are prepared by hydrothermal growth and simple chemical reduction immersion. The synthesized nanocomposite material simultaneously integrates the individual enhancement effects of the two materials in the SERS, such as the electromagnetic enhancement of silver nanoparticles and the chemical enhancement of ZnO semiconductor materials. Using this substrate, Rhodamine 6G molecules with a concentration as low as 10−8 M can be detected, and the coupling reaction of PATP can be effectively promoted. The nanocomposite materials prepared by selecting appropriate semiconductor materials and metal materials combined, could be potentially applied, as SERS substrates, in certain catalytic reactions.

A facile and efficient strategy is described in this communication for preparing a molecular catalyst/semiconductor hybrid photoanode by immobilizing a cobalt cubane water oxidation catalyst onto a porous BiVO4 electrode via electrochemical polymerization. With the introduction of Vpa as the anchoring linkage, the poly-1/Vpa/Al2O3/BiVO4 photoanode exhibits high performance as well as stability for photoelectrochemical water oxidation.

PdZn alloy nanoparticles encapsulated within a few layers of graphene supported on ZnO nanowires (PdZn@C/ZnO) exhibit enhanced catalytic performance and robust long-term stability in semi-hydrogenation of acetylene to ethylene. The enhanced ethylene selectivity of PdZn@C/ZnO originates from the confining environment of the graphene cover, which can promote desorption of ethylene from the PdZn surface, avoiding the over-hydrogenation of ethylene to ethane.

Modification of the semiconductor surface by cobalt-rich catalysts is an effective strategy to improve the photoelectrochemical (PEC) water oxidation kinetics and migration of photogenerated electr...

A new type of graphene-based catalyst with rewriteable function was designed and synthesized based on poly(1-vinyl-3-ethylimidazolium bromide) modified and reduced graphene oxide (denoted as poly[ViEtIm]Br-rGO). The modified polymeric ionic liquid poly[ViEtIm]Br not only acted as interlink between the polar catalytic anion and the non-polar graphene substrate, but also endowed the favorable dispersibility of poly[ViEtIm]Br-rGO in ionic liquid, leading to the adequate exposure of immobilized catalytic sites during the process of desulfurization. Moreover, due to the reversible anion-exchange property of the modified poly[ViEtIm]Br, various anions of Bronsted acids or heteropolyacids could be sequentially ‘written in’ or ‘erased’ on the nanosheets of rGO for desulfurization, thus establishing a green model for screening suitable catalysts based only on the limits of the same carrier. Such a rewriteable cycle was confirmed and monitored by characterization of TEM, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). Based on this catalyst screening process of a rewriteable cycle, poly[ViEtIm][PW 12 O 40 ]-rGO, a heteropolyanoin modified rGO, was selected as the optimized catalyst. Benefiting from the synergistic effects between rGO and acidic anions, together with the large surface area and open two-dimensional structure of rGO, poly[ViEtIm][PW 12 O 40 ]-rGO was found to exhibit an excellent catalytic performance toward various sulfur-containing compounds. Furthermore, the outstanding reusability of poly[ViEtIm][PW 12 O 40 ]-rGO was also displayed owing to its structural stability. It was found that the sulfur removal efficiency of DBT could still reach 98.0% after the catalyst poly[ViEtIm][PW 12 O 40 ]-rGO had even been recycled eight times.

There is much evidence that surface plasmon photocatalytic reactions can occur on organic molecules on metal surfaces. In this paper, we focus on the photocatalytic reaction of 4-ethynylaniline (PEAN) on silver nanoparticles (Ag NPs) in a liquid environment by surface-enhanced Raman spectroscopy (SERS). Our experiments used SERS to characterize p,p′-diynylazobenzene produced from PEAN via a selective catalytic coupling reaction on Ag NPs. This discovery not only achieved the expected results but also broadens the known plasmon-driven surface catalytic reaction system. In our work, we also regulated the photocatalytic coupling reaction conditions of PEAN on Ag NPs by laser power-dependent and time-dependent SERS spectra.

Photoelectrochemical (PEC) water splitting is a promising method for the conversion and storage of solar energy. A combination of catalysts with photoelectrodes is generally required for the development of active photoanodes in PEC devices. In this work, we present two BiVO4 photoanodes modified with cobalt salophen (Co(salophen)) complexes for PEC water oxidation. The resulting photoanodes show significantly enhanced PEC performance. Under simulated sunlight illumination (AM 1.5G, 100 mW cm−2), high photocurrents of 3.89 mA cm−2 and 4.27 mA cm−2 were obtained for Co1/BiVO4 and Co2/BiVO4, respectively at 1.23 V (vs. the reversible hydrogen electrode (RHE)) in a neutral solution, an almost three-fold enhancement over that of the unmodified BiVO4. Intensity-modulated photocurrent spectroscopy (IMPS) analysis shows that the Co(salophen) complexes not only accelerate the water oxidation reaction but also reduce the surface recombination. The half-cell solar energy conversion efficiencies for Co1/BiVO4 and Co2/BiVO4 were 1.09% and 1.18% at 0.7 V, respectively. Due to their hydrophobic nature, the Co(salophen) complexes can bind strongly to the surface of BiVO4. When the Co2 complex featuring four hydrophobic tert-butyl groups in a salophen ligand was anchored to BiVO4, an extremely stable photocurrent of more than 3.5 mA cm−2 at 1.23 V vs. RHE is sustained for at least 3 h without decay. Such a stable and robust photoanode based on a molecular WOC surpasses those attained by most of the state-of-the-art heterogeneous catalysts.

Constructing heterojunctions by coupling dissimilar semiconductors is a promising approach to boost charge separation and charge transfer in photoelectrochemical (PEC) water splitting. In this work, we fabricated a highly efficient TiO2/BiVO4 heterojunction photoanode for PEC water oxidation via a simple hydrothermal method. The resulting heterojunction photoanodes show enhanced PEC performance compared to the bare BiVO4 due to the simultaneous improvements in charge separation and charge transfer. Under simulated sunlight illumination (AM 1.5G, 100 mW cm−2), a high photocurrent of 3.3 mA cm−2 was obtained at 1.23 V (vs. the reversible hydrogen electrode (RHE)) in a neutral solution, which exceeds those attained by the previously reported TiO2/BiVO4 heterojunctions. When a molecular Co–cubane catalyst was immobilized onto the electrode, the performance of the TiO2/BiVO4 heterojunction photoanode can be further improved, achieving a higher photocurrent density of 4.6 mA cm−2 at 1.23 V, an almost three-fold enhancement over that of the bare BiVO4. These results engender a promising route to designing an efficient photoelectrode for PEC water splitting.

The development of a facile, rapid, precise, and ultrasensitive assay for the detection of mercury ions (Hg2+) is an urgent problem to be solved because excessive Hg2+ poses a great threat to human health and the ecological environment. Herein, a novel surface-enhanced Raman scattering (SERS) sensor which employed phenylacetylene (PA) as a label-free probe was established. The PA functionalized silver nanoparticles (PA-AgNPs) produced an intense SERS signal in the Raman-silent region, which effectively avoided the interference of solvent and overcame the signal overlap problem. In the presence of Hg2+, the PA molecules separated from the Ag surface due to the strong coordination between the alkynyl group and Hg2+, which resulted in a significant SERS signal attenuation. Basing on the proposed SERS platform, a linear relationship with a wide range from 10–10 to 10–8 M and a low detection limit of 87.6 pM were obtained. Besides, the selectivity and reproducibility of the SERS system were also investigated. What’s more, we applied the SERS sensor to analyze Hg2+ in lake water with high accuracy and excellent recovery. The obtained results demonstrated that the established SERS platform is expected to be a promising alternative tool for the determination of Hg2+ in practical application.

We have developed a label-free, concise, time-efficient, ultrasensitive, and selective strategy for the determination of Fe2+ ion based on surface-enhanced resonance Raman scattering (SERRS) spectroscopy. There was no Raman signal because of the weak adsorption of 2,2′-bipyridine (Bpy) on silver nanoparticles (AgNPs). Upon the addition of Fe2+, Bpy quickly formed [Fe(Bpy)3]2+ complexes with Fe2+ and produced an intense Raman signal through inducing the aggregation of AgNPs, which provided a theoretical foundation for quantitative analysis of Fe2+. The proposed SERRS platform displayed a wide linear range from 10–11 to 10–7 M with an unprecedented detection limit of 5.73 pM. The whole process can be completed in 3 min and provided a new universal route for practical detection in various water samples.

In this work, a series of zinc titanium mixed metal oxides obtained from the zinc titanium layered double hydroxides as precursor were prepared as the photoanode material of the CdS quantum dot-sensitized solar cells. CdS quantum dots were deposited on photoanodes by the successive ionic adsorption and reaction method. It was investigated that the effects of photoanode based on different Zn–Ti molar ratios on the photovoltaic performance of solar cells. The essential parameters of samples were investigated by UV–vis absorption spectrum, incident photon-to-current conversion efficiency, photoelectric conversion efficiency and electrochemical impendence spectrum. The varying Zn–Ti ratios influence adsorption properties and charge mobility. As a result, the cells based on Zn–Ti MMOs achieved an optimum power conversion efficiency of 2.71% when the Zn–Ti ratio is 7:1.

Constructing a heterojunction photoelectrode is an effective way to promote the photogenerated charge separation in photoelectrochemical (PEC) water oxidation. In this work, we successfully fabricated C3N4/BiVO4 hybrid electrodes by integrating g-C3N4 onto the nanoporous BiVO4 via a simple in-situ synthesis method. The as-prepared C3N4/BiVO4 photoanodes were systematically studied by Electrochemical Impedance Spectroscopy, steady-state surface photovoltage (SPV), transient SPV, Open circuit potential and Photoluminescence measurements. With an optimal loading of g-C3N4, the 2-C3N4/BiVO4 electrode showed a high photocurrent density of 4.06 mA/cm2 at 1.23 V (vs. RHE) for water oxidation, a 2.8 times enhancement over that of the BiVO4. It is found that g-C3N4 improved the PEC performance of the photoanodes by simultaneously promoting the charge separation and surface reaction kinetics. When a NiOOH co-catalyst was immobilized onto the 2-C3N4/BiVO4 electrode, both the PEC property and stability of the photoanode were enhanced. An extremely high photocurrent density of 5.44 mA/cm2 at 1.23 V was achieved. The largest half-cell solar energy conversion efficiency for NiOOH/2-C3N4/BiVO4 was 1.43% at 0.78 V, corresponding to 8.4 times that of unmodified BiVO4 (0.17% at 0.97 V). This work brings new insight into the development of C3N4-based devices for application in solar to fuel conversion.

CH3NH3PbI3 (MAPbI3)-based perovskite solar cells (PSCs) with special hole and electron transport layers (HTL and ETL) were prepared to study their light-induced degradation. Obvious degradation was observed under initial light exposure not only at the device level but also at the film morphology and electronic structure level. Device performance parameters, such as short-circuit current (JSC), power conversion efficiency, fill factor, and hysteresis effect, were aggravated with an initial light exposure of less than ∼8 h at 1 sun intensity. Meanwhile, the deteriorated crystallinity and electronic structure of the MAPbI3 film were also detected with x-ray diffraction, ultraviolet photoelectron spectroscopy, and UV-Visible absorption spectroscopy. The observed degradation is rationally related to the light-induced decomposition of MAPbI3. However, the degradation can be partly recovered with the following light exposure resulting in self-healing of the devices and MAPbI3 films. The self-healing behavior should be ascribed to the conversion of decomposition products back to MAPbI3, because the intermediates are wrapped tightly in the photoactive layer by the compact coverlayers of HTLs and ETLs and some reversible reactions occur consequently. The mechanism of self-healing is discussed by introducing the trapped states derived from ion migration. The PSCs prepared here imply a good optical stability and thus a good performance facilitated by tight wrapping of the active MAPbI3.

The surface passivation strategy is one of the effective ways to improve the power conversion efficiency (PCE) of quantum dots-sensitized solar cells (QDSSCs). In this work, a novel ZnS/SiO2 coating serves as the passivation layers for the CdS/CdSe co-sensitized solar cells based on zinc titanium mixed metal oxides (MMOs) obtained from layered double hydroxides (LDHs) precursor. The incorporation of passivation layers effectively improved the performance of the corresponding CdS/CdSe quantum dots co-sensitized solar cells and the best PCE of 4.91% has been achieved, which represents an over 55% improvement than that of devices without passivation. The effects of ZnS/SiO2 double passivation layers were systematically investigated, especially by 2D time-resolved fluorescence imaging and electrochemical impedance spectroscopy technique. It was revealed that the existence of ZnS/SiO2 outer layers caused the suppression of charge recombination, higher electrons collection efficiency, and superior surface quality.

In general, a colloidal method employing polyvinylpyrrolidone (PVP) as the stabilizer has been proven particularly suitable for preparing Pd nanoparticles (Pd-NPs) with controlled morphology and size. However, this surfactant will seriously cover the Pd-NP surface, which is detrimental for catalytic activity. In this paper, we reported a method to remove PVP from the carbon nanotube (CNT) supported Pd nanocubes (Pd-NCs) and Pd nanooctahedra (Pd-NOs) by steam treatment in a lab-made reactor. We found that this method can not only efficiently remove PVP from the Pd-NP surface, but also can well maintain the original structure of Pd-NCs and Pd-NOs, dramatically enhancing the catalytic performance. The present approach may promote potential applications of Pd-NPs prepared by colloidal methods in catalytic fields.

4-Aminothiophenol (PATP) and 4-aminophenyl disulfide (APDS) in contact with silver will form H2N-C6H4-S-Ag (PATP-Ag), and under the conditions of surface-enhanced Raman spectroscopy (SERS), a coupling reaction will generate 4,4-dimercaptoazobenzene (DMAB). DMAB is strongly Raman-active, showing strong peaks at ν ≈ 1140, 1390, and 1432 cm–1, and is widely used in surface-plasmon-assisted catalysis. Using APDS, PATP, p-nitrothiophenol (PNTP), and p-nitrodiphenyl disulfide (NPDS) as probe molecules, Raman spectroscopy and imaging techniques have been used to study the effect of intermolecular distance on surface-plasmon-assisted catalysis. Theoretically, PATP-Ag formed from APDS will be bound at proximal Ag atoms on the Ag surface due to S–S bond cleavage. The results show that APDS is more prone to surface-plasmon-assisted catalytic coupling due to the smaller distance between surface PATP-Ag moieties than those derived from PATP. Therefore, APDS has a higher reaction efficiency, better Raman activity, and ...

A novel graphene nanocomposite, functionalized by polymeric ionic liquids (PILs) and poly(sodium-p-styrenesulfonate) (PSS), was successfully prepared and exhibited excellent conductivity, favourable biocompatibility and good film-forming properties as an electrode material. TEM showed that the nanocomposite possessed an individual nanosheet-like structure. Owing to the surface modification of graphene, PSS/PILs–GP can not only be well dispersed in aqueous solution, but also possesses a strong negative charge. Due to electrostatic interactions, positively charged cholesterol oxidase (ChOx) can be immobilized onto the surface of PSS/PILs–GP to form the ChOx/PSS/PILs–GP/GC electrode material. UV-vis and FT-IR spectroscopy were used to monitor the assembly process of the nanocomposite. Due to the conductivity and biocompatibility of PSS/PILs–GP, the immobilized ChOx exhibited enhanced direct electron transfer (DET) at a glassy carbon (GC) electrode. Furthermore, the ChOx/PSS/PILs–GP/GC electrode displayed excellent catalytic performance with a wide linear range of 10.5 × 10−6 to 10.4 × 10−3 mol L−1, and a low detection limit of 3.5 μmol L−1 for the detection of cholesterol.

Based on the time-dependent density functional theory (TDDFT), the excited state intramolecular proton transfer (ESIPT) mechanism of a new compound 1 chromophore synthesized and designed by Liu et al. [Journal of Photochemistry and Photobiology B: Biology., 138 (2014), 75-79] has been investigated theoretically. The calculations of primary bond lengths, angles and the IR vibrational spectra verified the intramolecular hydrogen bond was strengthened. The fact that reproducing the experimental absorbance and fluorescence emission spectra well theoretically demonstrates that the TDDFT theory we adopted is reasonable and effective. In addition, intramolecular charge transfer based on the frontier molecular orbitals demonstrated the indication of the ESIPT reaction. The constructed potential energy curves of ground state and the first excited state based on keeping the O-H distance fixed at a serious of values have been used to illustrate the ESIPT process. A little barrier of 2.45 kcal/mol in the first excited state potential energy curve provided the transfer mechanism. Further, the phenomenon of fluorescence quenching has been explained reasonably based on the ESIPT mechanism. PACS: 31.25.Jf; 82.39.Jn

4-Aminophenyl disulfide (APDS) forms on the surface of silver nanoparticles due to chemical adsorption and disulfide bond breakage. This leads to the formation of new silver chemical bonds to result in the new compound NH2-C6H6-S-Ag. This novel material produces enhanced Raman spectra under weak laser light irradiation. When irradiated a plasma-assisted catalytic coupling reaction of NH2-C6H6-S-Ag occurs leading to the formation of 4,4-dimercaptoazobenzene (DMAB). Raman spectroscopy was used to monitor this reaction process, showing clear spectral changes associated with each step after addition of Ag nanoparticles onto the APDS powder. This method clearly shows the mechanism of the plasma-assisted catalytic reaction and may also be useful for spectral imaging purposes.

Both dual responsive and thermal responsive reduced graphene oxide (rGO) with a strategically inbuilt function have been successfully synthesized by utilizing non-covalent modified poly(NIPAm-co-ViEtImBr) combined with anion exchange.

We report the remote excited Raman optical activity (ROA) of adenine along Ag plasmonic waveguide. First, the surface plasmons that propagate along Ag nanowire is demonstrated experimentally. Second, the Raman spectra of adenine are measured experimentally. Third, the remote exited ROA by plasmonic waveguide are measured and compared. It is found that the plasmon chirality strongly influenced the molecular ORA by the local surface plasmon and remote plasmon waveguide. The plasmon chirality of nanostructures and the chirality plasmon waveguide should be considered in the experiments for the local and remote measurement.

The vibrational spectra have been investigated for revealing the comprehensive structure of diferrocenyl-oligothienylene-vinylene complex, stimulated by the excellent experimental reports [group of Casado J. Am. Chem. Soc. 2012, 134, 12, 5675]. The IR and Raman spectra were simulated. It is found that the change of charge distribution and bond length are associated with the variation in the frequencies of specific vibration in infrared spectra for the neutral and radical oxidation states. The theoretical simulation of charge difference density indicate that charge transfer mechanism for neutral and dication states are significant different. The results can offer hints for the rational design of novel and interesting oligomer semiconductor.

A very simple method for preparation of high SERS-active silver films was reported in the paper. The process is performed by reduction of silver nitrate with glucose on a borosilicate cover glass in an aqueous solution of 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4). The silver film shows excellent SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 nm, and the enhancement factor reaches ∼3 × 105. Moreover, there exists a synergistic effect on SERS signals for BMIMBF4 and NaCl. The synthetic method reported here suggests a very promising route for preparation of sensitive SERS-active substrates.

Hollow spheres with nanometer to micrometer dimensions have been of great interest in many areas of science and technology due to their special structure and properties such as large specific area, surface permeability and low density. In this work, hollow copper microspheres were employed as a catalyst to degrade dyes. The microspheres show good catalytic activities in degradation reactions of dyes and maintain their catalytic activity when reused multiple times. The reaction rate of eosin Y (EY) and methylene blue (MB) degradation was enhanced by 7.5–15 times by hollow copper microspheres compared with the control test. Copper is particularly attractive as a catalyst, since it is orders of magnitude cheaper than any noble metal; so the hollow copper microspheres are expected to play an important role in the fields of catalysis and environmental remediation.

A new, well-designed type of micron-sized hollow copper spheres was synthesized in this article. The process was performed using ZSM-5 molecular sieve as a template. It has the prominent advantage in that the various stages of pretreatment for the core material can be omitted because of the inherent nature of the ZSM-5 molecular sieve. The surface of the sieve consists entirely of negatively charged oxygen sites such that free Cu2+ ions can easily be adsorbed and reduced there, acting thereafter as a seed and self-catalyst for electroless plating of copper so as to lead to the formation of interconnected Cu particles around the external surface of the ZSM-5 molecular sieve. Moreover, there are many holes with a size of more than 5 × 5 A2 on the surface of the ZSM-5 molecular sieve, which can act as concavities that the reduced Cu can ‘rivet’ into, resulting in the link between the molecular sieve and the reduced Cu being stronger. In addition, the ZSM-5 molecular sieve has the merits of ease of removal, low cost, and less aggregation owing to its micrometer size, and it avoids the use of nonvolatile surfactants, which may be adsorbed onto the reduced Cu and then interfere with the possible application of the hollow copper spheres in catalysis and in analytical devices based on surface-enhanced Raman scattering (SERS) spectroscopy. The copper spheres obtained show enhanced Raman scattering in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 nm, and the enhancement factor reaches ∼7 × 103. The new micron-sized hollow copper spheres are produced in a simple and cost-effective method; so they are expected to play an important role in the fields of catalysts, fillers, and engineering, and in the development of SERS-based analytical devices. The synthetic method may represent a novel route to prepare hollow metal spheres, which is a subject of intense interest. Copyright © 2009 John Wiley & Sons, Ltd.

A well-designed and new type of sensitive surface-enhanced Raman scattering (SERS)-active substrate is reported in the paper. The process, which is performed by using 5 A molecular sieves as templates and final removal of the templates, has considerable virtue of enormously enlarging the amount of contact spots between every pair of particles due to the formation of inner planar nanostructures. First, the ammine complexes of silver ions appear to adsorb on the molecular sieves, then reduced and coalescenced to form closed silver layers, and the 5 A molecular sieves are subsequently removed by using HF to produce nanostructure aggregations. It has the prominent advantages that the SERS peak intensity of the ∼1076 cm−1 band of 4-mercaptophenol (4-MPH) adsorbed on Ag nanoaggreates is about 60 and 30 times greater than when it is adsorbed on silver nanoparticles coated on a glass substrate or on commercially available 2 μm-sized silver (μAg) powders, respectively. The new SERS-active substrate is produced simply and cost-effectively, so it is expected to play a great role in the development of SERS-based analytical devices.

The dilational viscoelastic properties of interfacial films containing fibrous crystals were investigated by means of two methods: the interfacial tension response to sinusoidal area variations and the relaxation of an applied stress. The results obtained show that fibrous crystals (length > 50 μm) could increase the dilational modulus of interfacial films on a jet kerosene/water interface. The dilational modulus increased with time due to the increase of sedimenting quantities and decreased with concentration after 15 h of pre-equilibrium time due to the enhancement of particle exchange between the bulk and the interface. The nature of films containing solid particles strongly depends on their shape. The ethyl metal phosphates, which are short and rigid, may pack tightly at the interface and form long-range ordered structure. As a result, interfacial films containing ethyl metal phosphates had higher dilational modulus and showed more elastic behaviour. The results obtained by interfacial tension relaxation measurements show that there exist two main relaxation processes in all films: the fast relaxation process with a characteristic relaxation time of several seconds, which may correspond to the exchange of alkyl metal phosphates between the bulk and the interface, and the slower relaxation process with a characteristic relaxation time of several tens of seconds, which may correspond to the interparticle interaction. However, only the films containing ethyl metal phosphates have the third relaxation process, which is the slowest process with a characteristic time of several hundreds of seconds. This slowest process may correspond to the reorganization of whole interfacial film. Our results may be used to account for the ability of solid particles in stabilizing emulsions.

Experimental data are presented to show the influence of solid particles on demulsification. It was found that the solid particles could effectively resist demulsification. Compared with conventional heating, microwave radiation can enhance the demulsification rate by an order of magnitude and increase the demulsification effectiveness. The demulsification effectiveness of the emulsions stabilized by graphite powder can reach 82%-89% in a very short time under microwave radiation, whilst that of the emulsions stabilized by barium sulfate can attain 100% under similar conditions.

Experimental data are presented to show the influence of alkyl metal phosphates, Shengli resin fraction, and NaCl, on the shear viscosity of interfacial films and the stability of emulsions. It was found that the alkyl metal phosphates and the Shengli resin fraction could enhance the shear viscosity of interfacial films and the stability of emulsions. NaCl (0.01-0.03 mol L-1) could change the shear viscosity of interfacial films containing alkyl metal phosphates and the Shengli resin fraction. The shear viscosity of interfacial films containing ethyl iron phosphate and the Shengli resin fraction decreased with the increase of the concentration of NaCl. On the other hand, NaCl could decrease the stability of the emulsions. (C) 2004 Elsevier B.V. All rights reserved.

Experimental data are presented to show the influence of a very small amount of inorganic salt on the demulsification of water-in-oil emulsions. It was found that some inorganic salts could effectively enhance the demulsification efficiency and increase the light transmittance of the water separated from the emulsions. The demulsification efficiency may reach 100% in a very short time under microwave radiation.

A well-designed type of micron-sized hollow silver sphere was successfully synthesized by a simple hard-template method to be used as substrates for surface-enhanced Raman scattering. 4 Å molecular sieves were employed as a removable solid template. [Ag(NH3)2]+was absorbed as the precursor on the surface of the molecular sieve. Formaldehyde was selected as a reducing agent to reduce [Ag(NH3)2]+, resulting in the formation of a micron-sized silver shell on the surface of the 4 Å molecular sieves. The micron-sized hollow silver spheres were obtained by removing the molecular sieve template. SEM and XRD were used to characterize the structure of the micron-sized hollow silver spheres. The as-prepared micro-silver spheres exhibited robust SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 nm, and the enhancement factor reached ~1.5 × 106. This synthetic process represents a promising method for preparing various hollow metal nanoparticles.

A well-designed type of ultrathin carbon shell coating a silver core was prepared for the first time through an alternate adsorption and carbonization method. The obtained ultrathin carbon shell shows prominent advantages, including sufficient uniformity, better chemical stability than silica or alumina, biocompatibility, being free of pin-holes and low cost.

A sensitive silver substrate for surface-enhanced Raman scattering (SERS) spectroscopy is synthesized under multimode microwave irradiation. The microwave-assisted synthesis of the SERS-active substrate was carried out in a modified domestic microwave oven of 2450 MHz, and the reductive reaction was conducted in a polypropylene container under microwave irradiation with a power of 100 W for 5 min. Formaldehyde was employed as both the reductant and microwave absorber in the reductive process. The effects of different heating methods (microwave dielectric and conventional) on the properties of the SERS-active substrates were investigated. Samples obtained with 5 min of microwave irradiation at a power of 100 W have more well-defined edges, corners, and sharper surface features, while the samples synthesized with 1 h of conventional heating at 40 degrees C consist primarily of spheroidal nanoparticles. The SERS peak intensity of the approximately 1593 cm(-1) band of 4-mercaptobenzoic acid adsorbed on silver nanoparticles synthesized with 5 min of microwave irradiation at a power of 100 W is about 30 times greater than when it is adsorbed on samples synthesized with 1 h of conventional heating at 40 degrees C. The results of quantum chemical calculations are in good agreement with our experimental data. This method is expected to be utilized for the synthesis of other metal nanostructural materials.

Experimental data are presented to show the influence of asphaltenes and resins on the stability and demulsification of emulsions. It was found that emulsion stability was related to the concentrations of the asphaltene and resin in the crude oil, and the state of dispersion of the asphaltenes and resins (molecular vs colloidal) was critical to the strength or rigidity of interfacial films and hence to the stability of the emulsions. Based on this research, a possible emulsion minimization approach in refineries, which can be implemented utilizing microwave radiation, is also suggested. Comparing with conventional heating, microwave radiation can enhance the demulsification rate by an order of magnitude. The demulsification efficiency reaches 100% in a very short time under microwave radiation.

This communication reports a remarkably simple templating method for the preparation of Pt nanorods enclosed by high-index {311} facets. Due to the existence of the high-index facets, the as-prepared Pt nanorods exhibit significantly enhanced catalytic properties toward a methanol selective oxidation reaction, compared with that of 3 nm Pt nanoparticles.