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Core–shell Ni–Co(OH)F@NiCo2S4 nanorods with Ni doping and interface engineering have exhibited outstanding performances toward hydrazine-assisted hydrogen production.

Automatic obstacle detection is of great significance for improving the safety of train operation. However, the existing autonomous operation of trains mainly depends on the signaling control system and lacks the extra equipment to perceive the environment. To further enhance the efficiency and safety of the widely deployed fully automatic operation (FAO) systems of the train, this study proposes an intelligent obstacle detection system based on deep learning. It collects perceptual information from industrial cameras and light detection and ranging (LiDAR), and mainly implements the functionality including rail region detection, obstacle detection, and visual–LiDAR fusion. Specifically, the first two parts adopt deep convolutional neural network (CNN) algorithms for semantic segmentation and object detection to pixel-wisely identify the rail track area ahead and detect the potential obstacles on the rail track, respectively. The visual–LiDAR fusion part integrates the visual data with the LiDAR data to achieve environmental perception for all weather conditions. It can also determine the geometric relationship between the rail track and obstacles to decide whether to trigger a warning alarm. Experimental results show that the system proposed in this study has strong performance and robustness. The system perception rate (precision) is 99.994% and the recall rate reaches 100%. The system, applied to the metro Hong Kong Tsuen Wan line, effectively improves the safety of urban rail train operation.

Herein, a facile bottom–up approach for producing nitrogen-doped carbon quantum dots (N-CQDs) was carried out by the hydrothermal treatment of microcrystalline cellulose, in the presence of different nitrogen sources (blank/urea/ammonia water/ethanediamine(EDA)/Hexamethylenetetramine). The result showed that the fluorescence intensity and quantum yields (QYs) of N-CQDs with different nitrogen sources are all higher than that without nitrogen source. Compared with the other three nitrogen sources, N-CQDs prepared by EDA not only have the highest fluorescence intensity but also the largest QYs of 51.39%. Therefore, EDA was chosen as the nitrogen source to prepare N-CQDs. The obtained N-CQDs are uniform spherical particles with a diameter of 2.76 nm. The N-CQDs also exhibit excitation-dependent and long-wave emission properties. The emission range of N-CQDs is 470–540 nm. Moreover, N-CQDs as fluorescent agents successfully acted on purple LEDs (λem = 365 nm) to achieve white LEDs light emission. At the same time, a fluorescent thin layer chromatography plate was successfully prepared using N-CQDs, silica gel G and Sodium carboxymethylcellulose as raw materials. The separation trajectory of mixed sample of Sudan red III and kerosene on the fluorescent TLC plate is obviously clearer than that of the TLC plate.

In this paper, CoNi bimetallic nanoparticle decorated reduced graphene oxide (CoNi-RGO) was synthesized by a facile hydrothermal method. When applied this CoNi-RGO into counter electrode for dye-sensitized solar cells (DSSCs), it shows smaller charge-transfer resistance and better electrocatalytic activity than that of pure reduced graphene oxide (RGO). At the optimized conditions, the energy conversion efficiency of DSSCs based on CoNi-RGO counter electrode was 3.79%, indicating a higher photovoltaic performance of DSSCs based on CoNi-RGO counter electrode than that of DSSCs based on RGO counter electrode (1.37%), and comparable to the value of DSSCs based on Pt counter electrode as a reference (4.95%). Additionally, the photovoltaic performance of DSSCs based on CoNi-RGO counter electrode strongly depends on its composition. The molar ratio of Co/Ni and the weight ratio of CoNi/GO that used to prepare CoNi-RGO counter electrode are key factors to affect the performance of their cell devices. When both the molar ratio of Co/Ni and the weight ratio of CoNi/GO are 1:1, the CoNi-RGO counter electrode shows the best performance, indicating the potential of such bimetallic nanoparticle decorated RGO as low-cost and efficient counter electrode to replace noble metal Pt counter electrode for the practical application of DSSCs devices.

Novel tetracarboxylic zinc naphthalocyanine-graphene oxide (ZnNcC4-GO) and tetracarboxylic zinc naphthalocyanine-amino graphene oxide (ZnNcC4-NGO) hybrids have been prepared with a covalent functionalization method. A series of characterizations have been used to prove the structures of ZnNcC4-GO and ZnNcC4-NGO hybrids. The third order nonlinear optical properties were investigated using the Z-scan technique at 532 nm with 4 ns laser pulses. Either ZnNcC4-GO or ZnNcC4-NGO exhibited much larger nonlinear optical absorption coefficients than GO and ZnNcC4 as a result of the covalent link between GO and ZnNcC4. ZnNcC4-NGO hybrids perform the enhanced NLO properties than ZnNcC4-GO, attributed to the increased excited state absorption from the extended sp2 carbon configurations of the NGO moiety in ZnNcC4-NGO hybrids along with the partial reduction of NGO nanosheets, and the stronger PET/ET process between NGO and ZnNcC4. Moreover, the Z-scan curve of ZnNcC4-NGO shows a deeper RSA valley and the larger β value compared to that of ZnPcC4-NGO because the π-conjugated system of ZnNcC4 is larger relative to that of ZnPcC4.

In this work, an ultrathin nanocomposite films containing tetracarboxylic Nickel (Ⅱ) naphthalocyanine (NiNc) and titania nanoparticles are fabricated through electrostatic self-assembled layer-by-layer (LBL) technique. UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) are utilized to characterize the film. The optical limiting properties of the composite films are investigated through intensity-dependent transmittance measurements at 600 nm with 18 ps laser pulses. The results show that the composite films have notable optical limiting response (β ∼ 5.4 × 10−7 m/W), which is strongly enhanced compared to both TiO2 and NiNc-only samples. Our results suggest that the nanocomposite films possess the potential for optical limiting applications in the phototherapeutic window.

An efficient counter electrode material for dye sensitized solar cells (DSSCs) was synthesized by pyrolysis of melamine and graphene oxide. The synthesized samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electrode microscopy, which show that nitrogen doped reduced graphene oxide (NRGO) was obtained by this synthesis method. In the synthesized NRGO, graphitic structure was kept and the nitrogen was existence as pyrrolic, pyridinic, graphitic, and oxidized nitrogen species in the samples. After deposited as counter electrode films for DSSCs, it shows lower charge-transfer resistance at the electrode/electrolyte interface and higher electrocatalytic activity towards reduction of triiodide (I-₃) than that of reduced graphene oxide (RGO) prepared also by this method without adding melamine. Consequently, the DSSCs based on NRGO counter electrodes achieve an energy conversion efficiency of 4.60%, which is higher than that of RGO counter electrode (2.35%). Although the photovoltaic performance of NRGO counter electrode was lower than that of Pt counter electrode (5.70%), it is still a promising counter electrode to replace noble metal Pt due to its low cost and simple synthesis process.

Nanoparticles of the bimetallic alloy CoNi wrapped in nitrogen-doped graphite-like carbon shells and dispersed on nitrogen-doped graphite-like carbon sheets (CoxNi1−x@NC) were synthesized by calcining CoNi metal–organic frameworks that were prepared through a facile solvothermal reaction using various raw-material molar ratios Co:Ni and CoNi:ethylenedinitrilotetraacetic acid. After depositing CoxNi1−x@NC for use as a counter electrode film in dye-sensitized solar cells, it was found that the electrocatalytic activity of the CoxNi1−x@NC counter electrode towards triiodide reduction could be optimized by simply tuning the molar ratios (Co:Ni and CoNi:ethylenedinitrilotetraacetic acid) appropriately during CoxNi1−x@NC synthesis. Cells that utilized a CoxNi1−x@NC counter electrode exhibited strong chemical-composition-dependent photovoltaic performance. Under optimal conditions, the CoxNi1−x@NC counter electrode presented an impressive energy conversion efficiency of 3.58%, suggesting that it is a highly promising counter electrode for application in dye-sensitized solar cells. This counter electrode has the advantages that it is considerably less expensive than a Pt counter electrode and that it provides the basis for the design and preparation of other inexpensive and efficient counter electrodes to replace Pt.

Zinc phthalocyanine carrying sulfenyl and 6-sulfydryl linkers was firstly used to functionalize with sulfur vacancies MoS2. The synthesized MoS2/ZnPc composite was further prepared to be PVA (polyvinyl alcohol) thin films by a drop coating method. The microscopic structures and photophysical properties of novel MoS2/ZnPc composite were characterized. A series of analysis results indicate that zinc phthalocyanine with sulfenyl and 6-sulfydryl linkers is loaded to sulfur vacancies of MoS2 by ligand conjugation. The third order nonlinear optical properties of MoS2/ZnPc composite were studied by an open aperture Z-scan technique at 532 nm with 4 ns laser pulses width. In comparison with individual MoS2 or ZnPc, whether MoS2/ZnPc solution or MoS2/ZnPc/PVA film sample possesses larger third order nonlinear absorption coefficients (β) and lower limiting thresholds (F50). It can be ascribed to a combination of different NLO absorption mechanisms for MoS2/ZnPc composite, including one-photon absorption, two photon absorptions and nonlinear scattering of MoS2, triplet excited state absorption of ZnPc, nonlinear scattering of MoS2/ZnPc and the photo-induced electron transfer or energy transfer (PET/ET) process between MoS2 and ZnPc moieties.

Graphene has attracted a lot of attention because of its unique mechanical, thermal, electrical and optical properties. In this study, a double layered structured photoanode consisting of a graphene/TiO2 composite layer and a TiO2 nanoparticles (P25) underlayer was developed. The photoelectric properties of as-prepared double layer structured photoanode were studied with comparison of the anatase TiO2 photoanode. Graphene was prepared by reduction of graphene oxide (GO) under a hydrothermal conditions and graphenen/TiO2 composite semiconductor materials were prepared by mixing graphene into TiO2 paste. The effect of graphene contents in graphene/TiO2 composite layer was also investigated. After constructing double layer photoanode with proper amount of graphene, the photoanode displayed enhanced light and dye adsorption properties with higher light harvesting efficiency, lower internal resistances, faster electron transport and lower charge recombination rate, which resulted in high current density. At the optimum conditions, the DSSC exhibited a Jsc of 15.01 mA cm-2, a Voc of 0.72 V, and a FF of 0.66 with the energy conversion efficiency (η) of 7.08%, indicating a increase in Jsc and η respectively than that of DSSC based on pure TiO2 photoanode, which gives a Jsc of 13.25 mA cm-2, a Voc of 0.73 V, and a FF of 0.62 with a η of 5.94%. However, the addition of excess graphene in the composite layer led to the enhancement of charge recombination, the reduction of dye adsorption and the decrease of photoelectric conversion efficiency of DSSCs. The graphene/TiO2 composite layer in DSSCs could really enhance its efficiency after the amount of graphene was successfully optimized.

A series of tetra substituted phthalocyanines bearing 2-mercaptobenzimidazole or 2-mercaptobenzothiazole units with different central metals (Zn and In) were synthesized. Their photophysical properties including the parameters of fluorescence and triplet state were studied. The benzothiazole substituted phthalocyanines exhibit stronger third-order nonlinear optical properties (NLO) absorption effects, higher triplet quantum yield (ΦT) and faster intersystem crossing rate compared to the benzimidazole substituted phthalocyanines. With the same central metals, benzothiazole substituted phthalocyanine complexes have the lower fluorescence quantum yield (ΦF), the higher triplet quantum yield (ΦT) and the larger third-order NLO properties as a result of larger conjugated structure and spin-orbit coupling induced by sulphur atoms. The influences of the central metal atoms and the peripheral substituents on the third-order NLO properties are discussed using photophysical parameters.

In order to enhance the performance of the dye-sensitized solar cells (DSSCs), graphene oxide (GO) was introduced into the TiO2 photoanode to construct a GO-TiO2 composited photoanode. The photoelectric properties of the as-constructed photoanode were studied in comparison with those of the TiO2 photoanode and the effect of GO obtained by different methods on the performance of the GO-TiO2 composited photoanode was also compared. After constructed with GO, the photoanode displayed enhanced light and dye adsorption properties with a higher light harvesting efficiency, lower internal resistances, a faster electron transport, and a lower charge recombination rate, which resulted in a higher current density. At the optimal condition, the DSSCs based on the photoanode modified by GO obtained in our laboratory (GO1) exhibited a Jsc of 18.16 mA cm−2, a Voc of 0.68 V, and a FF of 0.59 with a energy conversion efficiency (η) of 7.30%, indicating an increased performance compared with that of the DSSCs based only on the pure TiO2 photoanode, which had a Jsc of 14.41 mA cm−2, a Voc of 0.66 V, and a FF of 0.60 with a η value of 5.67%. However, when GO that obtained from a production line in a factory (GO2) was used, the performance of the DSSCs was further improved, which showed a Jsc of 19.49 mA cm−2, a Voc of 0.68 V, and an FF of 0.59 with a η value of 7.83%. Different performances between GOs that obtained from the laboratory and the factory were mainly attributed to their distinct production processes, which distinguished their properties from each other. It is a potential method to enhance the performance of the DSSCs by constructing a GO-TiO2 photoanode with a suitable quality GO.

A reduced graphene oxide/TiO 2 (RGO/TiO 2 ) blocking layer in the photoanode of a dye sensitized solar cell (DSSC) was fabricated in a simple way by depositing a RGO/TiO 2 paste onto a FTO substrate through screen printing method. The RGO content in the RGO/TiO 2 blocking layer was optimized for better DSSC performance. The effect of the RGO/TiO 2 blocking layer on the performance of the DSSC was examined based on the electrochemical impedance spectral analysis, the photocurrent-voltage measurement, and the open-circuit voltage decay technology. After the introduction of RGO/TiO 2 blocking layer in the photoanode, direct contact between the electrolyte and the FTO glass surface was prevented. The electron transfer from the TiO 2 film to the FTO glass substrate was thus improved, the charge recombination rate suppressed, the electron transport rate enhanced, and the electron collection efficiency increased, resulting in higher current density. At the best level of RGO in the composite blocking layer, the DSSC has an energy conversion efficiency ( η ) of 7.48% with a J sc of 15.29 mA cm − 2 , a V oc of 0.74 V and a FF of 0.66, indicating a 29% and a 30% increase in J sc and η , respectively, compared to that of a DSSC based on pure TiO 2 photoanode, which exhibits a η value of 5.76% with a J sc of 11.85 mA cm − 2 , a V oc of 0.74 V, and a FF of 0.66. The introduction of the RGO/TiO 2 blocking layer in the photoanode could really enhance the efficiency of DSSC by preventing the direct contact between the electrolyte and the FTO glass surface.

Two kinds of metameric tetra-amino-phthalocyanine zinc (ZnTAPc) bearing peripherally and non-peripherally substituent groups connected to graphene oxide (GO) has been synthesized via covalent functionalized reaction. A series of characterizations including X-ray photoelectron spectroscopy, Fourier transform infrared spectra, Raman spectra, thermogravimetric analysis and ultraviolet–visible absorption confirm that the two kinds of ZnTAPc are grafted onto the GO nanosheets successfully. The fluorescence spectra show strong fluorescence quenching by the photo-induced electron transfer (PET) process between ZnTAPc moieties and GO nanosheets, and the possibility of the PET process has been further proved using the thermodynamic method. The nonlinear optical (NLO) properties of the two kinds of hybrid material were investigated using the Z-scan technique at the wavelength of 532 nm in the nanosecond scale. The GO-β-ZnTAPc hybrid possesses much stronger nonlinear absorption effect than GO-α-ZnTAPc hybrid, showing that the position of substituent have a significant influence on the NLO properties of aforementioned hybrids.

Rational regulation of localized sp2/sp3 hybrid carbon structure in graphene oxide systems plays a very important role in developing advanced carbon-based hybrid materials. Here, we report a simple ethanol solvothermal method toward precise control of the growth of the sp2 hybrid carbon configurations/clusters in the sp3 carbon matrix so as to regulate the structure of electronic energy bands in the graphene oxide system. The results of morphology observation, XPS, solid-state 13C MAS NMR, FT-IR and Raman spectroscopy proved that controllable generation of the sp2 hybrid carbon configurations/clusters can be achieved based on an executive oxidation/reduction strategy. Upon excitation by a 532 nm laser with 4 ns pulses, the obtained reduced graphene oxide (160-rGO-6) with a large number of sp2 hybrid carbon configurations displays greater nonlinear reverse saturable absorption response and a higher nonlinear absorption coefficient β of 560 cm GW−1 than graphene oxide with different oxidation degree (GO-X, X = 6, 8, 10 and 12), and reduced graphene oxide with relatively few sp2 hybrid carbon configuration ratios (Y-rGO-6, Y = 80, 100, 120, 140 and 180). The significantly enhanced nonlinear reverse saturable absorption of 160-rGO-6 is attributed to the two photon absorption and excited state absorption originating from the sp2 hybrid carbon configuration system.

The rational design and controllable preparation of the solid film with strong molecular coupled effect represents a long-standing challenge for developing advanced practical nonlinear optical (NLO) materials. Here, we report a general electrostatic self-assembled strategy toward fabricating tetracarboxylic Nickel(II) naphthalocyanine (NiNcC4) ultrathin film on solid substrate with an ordered molecular arrangement based on the controllable deposition of anionic NiNcC4 naphthalocyanine and cationic polydiallydimethyldiallylammonium chloride (PDDA). The 30-bilayer P/NiNcC4 film shows an ordered conformation of face-to-face molecular arrangement, ultrathin thickness (126.6 nm) and a Raman enhancement phenomenon, and exhibits a high second-order molecular hyperpolarizability γ of 7.0 × 10−27 esu, which is three orders larger than that of NiNcC4 aqueous solution, demonstrating the potential of strongly molecular coupling effects for advanced self-assembled systems.

The nonlinear refraction of tetrasodium salt of copper tetrasulfophthalocyanine in water was investigated by using Z-scan technique at 532 nm with different input energy and different pulse width. We reported the competition between the excited-state refraction and excited-state-thermal-induced refraction. The sign change of nonlinear refraction induced by thermal effect was observed and analyzed. In addition, we found that the excited-state refraction cannot counteract with excited-state-thermal-induced refraction due to different physical mechanism.

In this work a porous material, an MCM-49/MCM-41 composite molecular sieve, was synthesized via a microwave assisted hydrothermal process and characterized to observe its optimal properties for heavy metal chromate removal. The adsorption properties of chromate onto MCM-49/MCM-41 and the factors that influence its adsorption, such as chromate concentration and contact time, were investigated. It was found that MCM-49/MCM-41 is micro/mesoporous with a surface area of 372 m2 g−1 and average pore size of 2.9 nm. The adsorption capacity of MCM-49/MCM-41 was as high as 4.10 mg g−1 for chromate at a temperature of 298 K, when the initial concentration of chromate was 50 mg L−1. The adsorption isotherm data of chromate fit well with both Freundlich and Langmuir adsorption isotherm models and the adsorption kinetics was well fitted using a pseudo-second order kinetic model. Thermodynamic parameters such as the standard Gibbs free energy (ΔG), enthalpy change (ΔH) and standard entropy change (ΔS) were also evaluated. Thermodynamic analysis indicates that the adsorption of chromate onto MCM-49/MCM-41 is a spontaneous and exothermic process. These results suggest that MCM-49/MCM-41 could serve as a promising adsorbent for potential applications in the removal of chromate from wastewater.

Reduced graphene oxide (rGO) was prepared by reduction of graphene oxide (GO) under mild conditions and rGO/TiO2 composite semiconductor materials were prepared by mixing rGO into TiO2 paste and were used to deposit the photoanode films of dye sensitized solar cells (DSSCs). After preparation, the successful synthesis of rGO was confirmed using X-ray diffraction (XRD) and Raman spectroscopy analysis. The effect of rGO content on the performance of dye-sensitized solar cells was also investigated. After the addition of rGO, the photoanodes displayed enhanced dye adsorption properties with lower internal resistances, faster electron transport and lower charge recombination rate, which resulted in a high current density. At the optimum rGO concentration, the DSSC exhibited a Jsc of 15.23 mA cm−2, a Voc of 0.71 V, and a FF of 0.62 with the energy conversion efficiency (η) of 6.69%, indicating a increase in Jsc and η respectively with respect to that of a DSSC based on an unmodified TiO2 photoanode, which gives a Jsc of 13.56 mA cm−2, a Voc of 0.70 V, and a FF of 0.63 with a η of 5.97%. However, the addition of excess rGO weakened the crystallization of particles on the surface of the photoelectrodes, which led to the enhancement of charge recombination, the reduction of dye adsorption and the decrease of photoelectric conversion efficiency of DSSCs. The rGO modified TiO2 semiconductor materials could really enhance the efficiency of DSSCs after the optimal amount of rGO was successfully determined.

A series of metal-doped α-MnO2 catalysts (M-MnO2, M = Ni, Cu, Co) were synthesized via a novel ethylene glycol (EG) reduction strategy for the first time, based on initial reduction of KMnO4 with EG and subsequent heteroatom doping at room temperature, and used for catalytic toluene combustion. The obtained catalysts have been full characterized by XRD, XRF, N2 adsorption, SEM, TEM, XPS, H2-TPR, O2-TPD, and C7H8-TPSR. It was found that the catalytic properties of α-MnO2 can be significantly improved by nickel doping, a remarkable low-temperature performance (T90 = 199 °C) has been achieved over Ni-MnO2 catalyst, which is among the best reported values. Meanwhile, Ni-MnO2 has also exhibited high catalytic stability with strong water tolerance (5 vol%) in the oxidation of toluene. Herein, the relationship between catalyst structure and catalytic activity has been elucidated. The outstanding catalytic properties can be related to the synergistic effect between Mn and doped Ni species for the adsorption and activation of toluene. Significantly, the substitutional doping of Ni2+ into octahedra MnO6 frameworks could not only improve the redox properties, lattice oxygen mobility and the formation of more active lattice oxygen, but also promote the toluene adsorption. Additionally, a potential catalytic reaction process base on the Mars and van Krevelen mechanism was also proposed. Hence, this work paves a new way for the design and synthesis of high efficient catalysts for the elimination of volatile organic compounds.

A nitrogen-doped reduced graphene oxide (N-RGO) nanosheet was synthesized by a simple hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electrode microscopy. After being deposited as counter electrode film for dye-sensitized solar cells (DSSCs), it is found that the synthesized N-RGO nanosheet has smaller charge-transfer resistance and better electrocatalytic activity towards reduction of triiodide than the reduced graphene oxide (RGO) nanosheet. Consequently, the DSSCs based on the N-RGO counter electrode achieve an energy conversion efficiency of 4.26%, which is higher than that of the RGO counter electrode (2.85%) prepared under the same conditions, and comparable to the value (5.21%) obtained with the Pt counter electrode as a reference. This N-RGO counter electrode offers the advantages of not only saving the cost of Pt itself but also simplifying the process of counter electrode preparation. Therefore, an inexpensive N-RGO nanosheet is a promising counter electrode material to replace noble metal Pt.

Graphene has attracted a lot of attention because of its unique mechanical, thermal, electrical and optical properties. In this study, a double layered structured photoanode consisting of a graphene/TiO2 composite layer and a TiO2 nanoparticles (P25) underlayer was developed. The photoelectric properties of as-prepared double layer structured photoanode were studied with comparison of the anatase TiO2 photoanode. Graphene was prepared by reduction of graphene oxide (GO) under a hydrothermal conditions and graphenen/TiO2 composite semiconductor materials were prepared by mixing graphene into TiO2 paste. The effect of graphene contents in graphene/TiO2 composite layer was also investigated. After constructing double layer photoanode with proper amount of graphene, the photoanode displayed enhanced light and dye adsorption properties with higher light harvesting efficiency, lower internal resistances, faster electron transport and lower charge recombination rate, which resulted in high current density. At the optimum conditions, the DSSC exhibited a Jsc of 15.01 mA cm-2, a Voc of 0.72 V, and a FF of 0.66 with the energy conversion efficiency (η) of 7.08%, indicating a increase in Jsc and η respectively than that of DSSC based on pure TiO2 photoanode, which gives a Jsc of 13.25 mA cm-2, a Voc of 0.73 V, and a FF of 0.62 with a η of 5.94%. However, the addition of excess graphene in the composite layer led to the enhancement of charge recombination, the reduction of dye adsorption and the decrease of photoelectric conversion efficiency of DSSCs. The graphene/TiO2 composite layer in DSSCs could really enhance its efficiency after the amount of graphene was successfully optimized.

Multilayer films containing α-CoPc(QnSO3Na)4 (CoPc), polydiallydimethyldiallylammonium chloride (PDDA) and graphene oxide (GO) were fabricated through electrostatic self-assembled layer by layer (LBL) technique. UV-Vis spectroscopy was used to characterize the assembly process. Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were utilized to explore the microstructure of the film. The third-order nonlinear properties of the film were studied by Z-scan measurements at 532 nm with 4 ns pulses. When excited by laser with the input intensity of 1.16 μJ, the 25 bilayer CoPc/GO film exhibits strong reverse saturable absorption (RSA) effect. The nonlinear absorption coefficient β value is 1.6 × 10−5 m W−1, which is 5 and 3 orders larger than that of CoPc solution sample and grapheme oxide solution sample, and 1.5 times larger than that of the 35 bilayer CoPc/PDDA film. And also, combination of UV-Vis spectroscopy with Raman spectroscopy was adopted to analyze the enhancement mechanism of nonlinear optical absorption of the film.

Two kinds of graphene oxide–zinc phthalocyanine (GO–ZnPc) hybrid materials have been prepared by the covalent functionalization method. The morphologies and structures of the two kinds of GO–ZnPc hybrids are characterized by a series of methods, such as scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, ultraviolet-visible absorption and fluorescence spectroscopies. From the fluorescence spectra, the two kinds of GO–ZnPc hybrids display strong fluorescence quenching by the photo-induced electron transfer (PET) process from ZnPc moieties to the GO. Energy diagrams show that a PET process from ZnPc molecules to GO nanosheets exists. The third order nonlinear optical (NLO) properties of GO–ZnPc hybrids are investigated by the Z-scan technique at 532 nm with 4 ns laser pulses. The nonlinear absorption coefficient β value of GO–ZnPc(DG)4 is larger than that of GO–ZnPc(TD)4 because GO–ZnPc(DG)4 possesses peripheral substituents with a stronger electron-donating effect compared to GO–ZnPc(TD)4.

Reduced graphene oxide-metal(II) phthalocyanine (RGO-MPc, M = Cu, Zn and Pb) hybrid materials have been prepared by the covalent functionalization method. The resultant RGO-MPc hybrids are characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, ultraviolet-visible absorption and fluorescence spectroscopy. The RGO-MPc hybrids exhibit strong fluorescence quenching by means of the photo-induced electron transfer or the energy transfer (PET/ET) process between the RGO and MPc moieties. The PET/ET process particularly depends on the fluorescence quantum yield of MPc molecules with different central metals. The nonlinear optical (NLO) properties of the RGO-MPc hybrids are investigated by using the Z-scan technique at 532 nm with 4 ns laser pulses. The results show that the NLO properties of MPc molecules increase in the order of ZnPbCu, but the RGO-MPc hybrids exhibit NLO performance in the inverse sequence of ZnPbCu, implying that the NLO response arising from the efficient PET/ET process between RGO and MPc may play a more important role in the NLO properties of RGO-MPc hybrids than that originating from the MPc moiety.

A reduced graphene oxide–zinc phthalocyanine (RGO–ZnPc) hybrid material with good dispersibility has been prepared by covalent functionalization method, based on the initial covalent linkage of ZnPc to GO and subsequent in situ reduction of GO moiety to RGO during mild thermal treatment in DMF solvent. The microscopic structure, morphology and photophysical properties of resultant RGO–ZnPc hybrid are characterized. The nonlinear optical (NLO) properties of the RGO–ZnPc hybrid are also investigated using the Z-scan technique at 532 nm with 4 ns laser pulses. The results show that the efficient functionalization and reduction of GO make RGO–ZnPc hybrid possess much larger NLO properties and optical limiting performance than those of individual GO, ZnPc and the GO–ZnPc hybrid. It can be ascribed to a combination of different NLO absorption mechanisms for RGO–ZnPc hybrid, including two-photon absorption originating from the sp3 domains, saturable absorption from the sp2 carbon clusters and excited state absorption from numerous localized sp2 configurations in RGO moiety, reverse saturable absorption arising from ZnPc moiety and the contribution of efficient photo-induced electron transfer or energy transfer process between ZnPc and RGO.

Tetracarboxylic Zn(ii) phthalocyanine-amino functionalized graphene oxide (ZnPcC4-NGO) hybrid materials have been prepared by a covalent functionalization method. The characterizations indicate that the amino-functionalization of GO has an important influence on the structure and photophysical properties of the ZnPcC4-NGO hybrid. The ZnPcC4-NGO hybrid exhibits enhanced photo-induced electron transfer or energy transfer (PET/ET), compared to the ZnPcC4 covalent functionalized GO (ZnPcC4-GO), owing to the presence of the extended sp(2) carbon configurations, along with the partial reduction of the NGO nanosheets and the introduction of electron-donating ethylenediamine. The nonlinear optical (NLO) properties of the hybrids were investigated using the Z-scan technique at 532 nm with 4 ns laser pulses. The results show that the efficient covalent functionalization and partial reduction of NGO cause the ZnPcC4-NGO hybrid to possess evidently larger NLO properties than the individual NGO, ZnPcC4 and the ZnPcC4-GO hybrid. The enhanced NLO performance can be attributed to the increased excited state absorption from the extended sp(2) carbon configurations of the NGO moiety, reverse saturable absorption arising from ZnPcC4 moiety, and the contribution of the efficient PET/ET process between the ZnPcC4 and NGO moieties in the hybrid.

The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions.

An ultrathin composite film with alternating layers containing anionic octacarboxylic copper phthalocyanine [CuPc(COONa)8] and cationic polyethylenimine (PEI) has been prepared by the electrostatic layer-by-layer self-assembly technique. The alternating multilayer assemblies of CuPc(COONa)8/PEI were characterized by UV–Vis spectroscopy, showing the regularly consecutive adsorption process. The film surface was smooth and homogeneous as indicated by atomic force microscopy. The closely packed nanoparticles, with the average diameter of 36 nm and the mean interface roughness of 2.984 nm, can be easily seen on the film surface uniformly. Further structure investigation was carried out by using small angle X-ray diffraction. Third-order nonlinear properties of the film and CuPc(COONa)8 aqueous solution were studied by Z-scan measurements at 532 nm with 8 ns pulses. The ultrathin film depicted strong nonlinear reverse saturable absorption and excellent self-defocusing performance. The second-order molecular hyperpolarizability γ value of the film was 68 times larger than that of solution sample.

Smart antenna technology is a key technology adopted in TD-SCDMA communication system. There are two main functions of smart antenna, including DOA estimation and beamforming. It is usually difficult to implement the function of smart antenna directly in TD-SCDMA system simulation in OPNET, which is a network simulation tool suited for system level simulation. In this paper, two simulation methods by integrating OPNET with MATLAB are surveyed. Then the uplink and downlink beamforming processes of smart antenna in TD-SCDMA system are implemented during system level simulation with these two methods respectively. An example is also given to verify the function of smart antenna by implementing uplink and downlink beamforming in the system level simulation. Simulation results show the performance improvement caused by smart antenna in the whole system.

Smart antenna technique is one of the most important techniques used in TD-SCDMA system. Setting up a methodology to implement smart antennas based on TD-SCDMA system level simulation platform is useful for analyzing the influences of smart antennas on the whole communication system. Generally speaking, smart antennas can be divided into two kinds, one is fixed multi-beam switching antenna and the other is adaptive antenna. This paper proposes a methodology to implement adaptive antenna in TD-SCDMA simulation platform by establishing the node model of Node B, raising the orientation methodology of the adaptive antenna array, and giving the detailed process of downlink beam forming implementations as well. Theoretically, statistics such as SNR (signal to noise ratio) at UE (user equipment) and throughput at Node B are larger for systems adopting adaptive antenna than isotropic antenna. Through running simulations and collecting statistics of SNR and throughput, the proposed methodology is verified to be feasible and appropriate.

The effect of hydrofluoric acid (HFA) on the upgrading and structure of oil shale from Yilan county, Heilongjiang province, China was investigated by the ultrasonic treatment of the shale in a mild water bath. The oil shale samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron (SE) microscopies, as well as Fourier transform infrared (FTIR) spectroscopy, and densimetry. The results of the study indicate that the HFA-based ultrasonic treatment exhibited a better performance in upgrading oil shale than the ordinary mechanical stirring method. It was also found that the concentration of HFA significantly influenced upgrading performance and the separation degree of inorganic minerals. The kerogen content in oil shale increased with increasing con- centration of HFA. The total content of C, H, O and N in oil shale reached 98.2% when 40% HFA was used. Oil shale is composed mainly of a chainlike cyclic saturated organic material called kerogen, and inorganic minerals such as quartz, kaolinite, illite, siderite and pyrite. These materials integrate into a smooth lithified sandwich by the hydrogen bond and intermolecular forces. Via the ultrasonic treatment under mild conditions, kaolinite and siderite can be removed from oil shale with the use of a weak HFA, while a stronger HFA is needed to leach illite and quartz. Then kerogen with a loose porous structure is obtained.