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Different from typical circuit breakers, breakers used to switch AC filters in convertor stations have to operate frequently according to the real-time operation mode and daily load changes. Therefore, the performance of filter breakers decreases very quickly, which leads to frequent accidents. Both preinsertion resistors and controlled switching devices can suppress switching transients. In this paper, a comparative analysis of whether a controlled switching device and preinsertion resistor should be adopted is carried out using PSCAD. The transient is calculated as the combined result of the switching angle and preinsertion resistor value, and the optimal configurations are proposed. After determining the resistor value and whether a controlled switching device should be included, the reference voltage of the arrester should be reevaluated.

Relapse and drug resistance are the main causes of mortality in patients with small‑cell lung cancer (SCLC). Intratumoral heterogeneity (ITH) is a key biological mechanism that leads to relapse and drug resistance. Phenotypic plasticity is an important factor that leads to ITH in SCLC, although its mechanisms and key regulatory factors remain to be elucidated. In the present study, cell proliferation and cell switch assay were measured using trypan blue. Alamar Blue was used to test drug sensitivity. Differential genes were screened by RNA sequencing. Reverse transcription‑quantitative PCR and western blotting were performed to assess the expressions of CSF2/p‑STAT3/MYC pathway related molecules, neuroendocrine (NE)/non‑neuroendocrine (non‑NE), transcription factors and drug‑related targets. The present study found that SCLC cell line NCI‑H69 exhibited adherent (H69A) and suspensive (H69S) phenotypes, which could switch back and forth. The two phenotypic cells had significant differences in cellular NE and non‑NE characteristics, drug sensitivity and expression of drug‑related targets. RNA sequencing showed that granulocyte‑macrophage colony‑stimulating factor [i.e., colony‑stimulating factor 2 (CSF2)] was the main differentially expressed gene between the two phenotypes and that H69A cells highly expressed CSF2. The inhibition of CSF2 promoted the transformation from H69A to H69S, increased drug sensitivity and NE marker expression and decreased the non‑NE marker expression in H69A. The STRING, Pathway Commons and Reactome databases showed a potential regulatory relationship between CSF2 and phosphorylated signal transducer and activator of transcription 3 (p‑STAT3)/MYC. p‑STAT3 and MYC expression was higher in H69A cells than in H69S cells and CSF2 silencing inhibited their expression. Taken together, these results indicated that CSF2 may regulate the phenotypic plasticity of SCLC through the phosphorylated STAT3/MYC pathway, thereby limiting the transformation between cell clones with different phenotypes and changing the sensitivity of specific cell clones to targeted drugs. Targeting CSF2 may be a potential therapeutic strategy to overcome drug resistance in SCLC treatment by influencing ITH.

Increasing the electron density on the phthalocyanine (Pc) ring is an effective approach for ensuring an excellent third-order nonlinear optical (NLO) property. Herein, a series of axially substituted indium Pcs (axial substituent: ethyl, n-propyl, n-butyl, n-pentyl) were synthesized on the basis of tetra-[3-(2-ethoxy)ethoxy] indium phthalocyanine chloride (InClPc). The third-order nonlinear optical properties were investigated by the Z-scan technique at 532 nm with 4 ns laser pulses. All the axially alkyl substituted InPcs showed a better nonlinear absorption response than InClPc. The NLO properties of the axially substituted Pcs got better with the increased length of the alkyl chain. The effect of alkyl chain substituents on the nonlinear absorption of indium phthalocyanine was demonstrated through their optical physical parameters (ΦF, kST, ΦT, and τT).

At present, developing a simple, inexpensive, and scalable technology to fabricate an energy storage system remains a challenge. In this study, MWCNTs/FeNi3/PANI nanocomposites were prepared by means of in situ polymerization. The morphologies and structure were characterized by the application of various spectral and analytical techniques. When the newly fabricated MWCNTs/FeNi3/PANI-20 ternary composite was taken as supercapacitor electrode, the specific capacitance was 398.1 F g−1 at a current density of 0.5 A g−1. In addition, the assembled symmetric supercapacitors displayed not only an excellent cycling property (80.9% capacitance retention after 2000 charge/discharge cycles) but also a remarkable energy and power density (9.1 Wh kg−1 and 500 W kg−1). As revealed by the results, the electrochemical properties of MWCNTs/FeNi3/PANI composites can be improved by the synergistic action of various components through the rational selection of electrode materials.

The development of effective methods for synthesizing and stabilizing ultrafine supported metal catalysts is not only advantageous but significantly recommendable in electrocatalytic water splittin...

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.

Anodizing and post-treatment of aluminium alloys can effectively improve their surface corrosion resistance. In this work, we demonstrate the effectiveness a potassium permanganate sealing (M-S) treatment of tartaric‑sulfuric anodized 2024 aluminium alloy. This post anodic oxidation process was performed by immersing samples in the electrolyte solution at 70 °C for 30 min. Immersion and salt spray tests show such a M-S sealing processing can result in much improved corrosion resistance. The M-S treated samples can resist 240 h of salt spray test without corrosion pitting. Detailed morphological, microstructural and chemical analyses have been used to reveal mechanistic effects of the M-S retreatment. Interfacial electrochemical impedance measurements were performed to directly compare the corrosion behaviors of Al alloys after different post-treatments.

The AC filter is one of the important parts of HVDC transmission system. In order to compensate for reactive power and eliminate harmonics on the AC side, the AC filter needs to be installed. And the A C filter needs to be frequently put in and removed as the DC power changes. When the filter is put into the circuit, because the voltage on the capacitor and the bus voltage are not completely in phase, a closing inrush current will be generated, which will cause an impact on the system. This paper uses EMTDC/PSCAD to establish a simulation model, the effect of pre-insertion resistor, pre-insertion resistor insertion duration and closing target angle on closing inrush current and energy absorption by pre-insertion resistor is calculated. Simulation calculation shows that combining the pre-insertion resistor and the phase selection closing device to accurately control the input time and exit time of the resistor, it can avoid pre-breakdown, and limit the closing inrush current and the energy absorbed by the pre-insertion resistor to the minimum at the same time.

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.

The dielectric spectrums properties of silicone oil and mineral oil with different aging status were experimentally studied for comparison in this paper. Frequency domain spectroscopy as a non-destructive diagnosis method to evaluate the insulation status of oil-immersed paper insulation. Study the dielectric spectroscopy difference between thermal aged silicone oil and mineral oil can provide principles for evaluating the insulation status of silicone oil. Samples are conditioned to the same initial conditions through the heating at a temperature of 100 °C for 24 hours at first. Then silicone oil samples and mineral oil samples were thermal aged at 140°C in hermetical bottles with paper insulation sheets inside. Dielectric measurement was done after aging time of 0 hour, 500 hours and 1000 hours. The results show that the relative permittivity of the silicone oil is a little lager than that of mineral oil, which can improve the electric distribution inside the power apparatus with oil-impregnated paper insulation system. With the increasing of aging duration, the relative permittivity of silicone oil almost remains constant, while the mineral oil's relative permittivity shows low frequency dispersion phenomenon and becomes higher. The thermal stability of silicone oil is obviously better than that of mineral oil.

Surface charging phenomena on DC GIL spacers is a complicated process affected by lots of factors, among which surface conductivity is an important dielectrics parameter. In this study, experimental and theoretical research are carried out to investigate the effects of non-uniform surface conductivity on surface charge accumulation behaviours of downsized HVDC GIL spacers. A SiC/epoxy layer is partially coated on alumina/epoxy spacers to form a non-uniform surface conductivity. The coating patterns include sector-shaped coating and ring-shaped coating. The applied stress is DC voltage. The accumulated surface charges show a rising first and then decreasing trend with the increase of $S$ iC contents in coated area. When surface conductivity is high enough, there is almost no charge accumulation. Bipolar charges, which are generally observed on raw alumina/epoxy spacers, are found to be preferable to accumulate at interface region between high and low surface conductivity. The orientation of bipolar charges is determined by the distribution of inhomogeneous surface conductivity. The corresponding mechanism is revealed on the basis of experiment and simulation results which would be helpful for designing highly reliable and stable HVDC GIL.

Background: The fabella is a sesamoid bone having anatomical variations and it is more common in patients with primary keen osteoarthritis (KOA). The purpose of this study was to classify the fabellae and discuss the relationship between the classification of fabellae and the severity of KOA in Chinese. Material and methods: 136 patients were measured and classified using CT three-dimensional reconstruction. According to the CT imaging characteristics, the fabellae were divided into 5 types: type Ⅰ, a fabella on the lateral femoral condyle; type Ⅱ, a fabella on the medial femoral condyle; type Ⅲ, a fabella on the lateral femoral condyle and a fabella on the medial femoral condyle; type Ⅳ, two fabellae on the medial femoral condyle and type Ⅴ, two fabellae on the lateral femoral condyle. The severity of KOA was assessed on the Recht grade by MRI. The data were analyzed with SPSS 24.0. Results: The classification of fabellae were correlated with KOA grades (c 2 =35.026, P

A sensitive electrochemical sensor for ascorbic acid (AA) is designed and synthesized via the following steps. The novel tetra-β-isoheptyloxyphthalocyanine cobalt(II) (PcCo) spontaneously adsorbs on the surface of acid-treated multi-walled carbon nanotubes (aMWCNTs). Then, the aMWCNT/PcCo composite was immobilized on the glassy carbon electrode (GCE). The results of UV-vis, FT-IR, TG, XPS, SEM and TEM revealed the successful self-assembly between PcCo and aMWCNTs via the π–π stacking interaction, and the aMWCNT/PcCo composite appears to have a uniform network-like structure on the GCE surface due to the four peripheral isoheptyl substituents of PcCo. Such a structure can effectively increase the electrode area, facilitate the mass transport of analytes and provide continuous conducting pathways for the transportation of electrons. Synchronously, benefitting from the synergistic effect between PcCo and aMWCNTs, the obtained electrochemical sensor has a high current and low potential for the oxidation of AA. The linear range for the AA detection is from 10 μM to 1.2 mM and the detection limit is as low as 4.0 μM. The developed biosensor exhibited good reproducibility and acceptable stability, providing a simple method for the analysis of AA.

A novel naphthalocyanine 2,11,20,29-tetrabromo-2,3-naphthalocyanine iron was synthetized. Its optical nonlinearity was investigated using the Z-scan technique. Reverse saturable absorption and high-order optical nonlinear refraction were detected. The absorption cross sections of the ground state, the singlet first excited state and the triplet first excited state were fitted to be 3.2 × 10[Formula: see text] cm[Formula: see text], 6.2 × 10[Formula: see text] cm[Formula: see text] and 4.6 × 10[Formula: see text] cm[Formula: see text], respectively. Fits also gave 1.17 × 10[Formula: see text] cm[Formula: see text] for the refractive volume of the ground state, 0.6 for the ratio of the refractive volume of the singlet first excited state to the ground state and 2.7 for the ratio of refractive volume of the first triplet excited state to the ground state.

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.

WSe2/reduced graphene oxide (WSe2/rGO) composite has been synthesized by a facile solvothermal reaction and all the polyvinyl alcohol (PVA) films were prepared by simple drop casting method. The third order nonlinear optical (NLO) properties and optical limiting (OL) responses of WSe2/rGO solution and WSe2/rGO/PVA film were investigated using the Z-scan technique at 1064 nm and its second harmonic of 532 nm with 4 ns laser pulses. The results demonstrate that the third order NLO and optical limiting responses of the WSe2/rGO composite are significantly enhanced compared with WSe2, rGO and WSe2/GO composite, whether in the solution or in the PVA film. It can be attributed to the contribution of charge transfer process and synergistic effect between WSe2 and rGO moieties. Besides, the optical nonlinearity of WSe2/rGO/PVA film was larger than that of the WSe2/rGO solution. The WSe2/rGO/PVA film exhibits much larger nonlinear absorption coefficient (3.5 × 105 cm/GW) and much lower threshold value (0.25 J/cm2) with the input energy of 27 μJ at 532 nm. The results pave the way for the nonlinear optical properties with transition metal dichalcogenides (TMDs)/graphene composite in the optical limiting devices.

Manipulating the morphology and protonic acid doping of polyaniline (PANI) is significant for optimizing its NH3-sensing. Herein, tetra-β-carboxyphthalocyanine cobalt(II) (TcPcCo) acted as the dopant and structure-directing agent simultaneously to fabricate the uniform fibrous network-like PANI (PANI-TcPcCo hybrids) by a one-step polymerization at low temperature. During the reaction process, the protonic acid groups in TcPcCo not only induced the aniline monomers polymerizing into one-dimensional nanofibers (consist of both solid and hollow cylinders) with abundant tiny protuberances on the surface but also successfully doped into PANI. The resulting PANI-TcPcCo hybrids displayed the enhancement in terms of the good conductivity, the large gas adsorption capacity, and the unobstructed channels for the electron and gas transport. The central metal atoms of TcPcCo present the strong and selective affinity to NH3. Meanwhile, the deep-seated conversion of PANI’s molecular structure after exposure in NH3 coul...

Herein, a series of tetra-α-isopentyloxyphthalocyanine copper, nickle, lead (CuPc-3, NiPc-3, PbPc-3) have been successfully bonded on the surface of acidified multi-walled carbon nanotubes (MWCNTs) by using a solution self-assembly method based on π–π stacking interaction facile reaction. The obtained MPc-3/MWCNTs (M = Cu, Ni, and Pb) hybrids display good dispersibility in DMF, which is beneficial to construct uniform sensing devices. The MPc-3/MWCNTs sensors exhibit excellent sensing performance, in terms of sensitivity, reversibility, reproducibility, selectivity and stability, especially CuPc-3/MWCNTs sensor in detail, the response is about 40.5% (80 ppm), the limit of detection is as low as 75 ppb, and the recovery time is about as fast as 180 s at room temperature. The enhanced NH3-sensing performance is mainly due to the synergistic effect between MPc-3 and MWCNTs, e.g. the stronger adsorption interaction of MPc-3 with NH3, the high electrical conductivity of MWCNTs, and the fast charge transfer between MPc-3 and MWCNTs. The systematic study developed here provides a valid way to fabricate high-efficient NH3 sensors.

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.

The development of innovative methods for the integration of carbon nanotubes (CNTs) and polyaniline (PANI) that preserve their exceptional quality, while robustly enriching their gas-sensing features, is still rare and remains challenging for the realization of rapid and sensitive gas detection. Herein, due to the advantages in its structure, tetra-β-carboxyphthalocyanine cobalt(II) (TcPcCo) acts not only as a sensing promoter, but also as an efficient mediator to couple multi-walled CNTs (MCNTs) with PANI, resulting in MCNT@PANI hybrids with a uniform 3D network; the planar 18π-electrons in TcPcCo allow it to closely conjugate on the surface of MCNT by π–π interactions; moreover, the outer –COOH groups in TcPcCo prompt it to link with the aniline monomers based on acid–base interactions. During the subsequent polymerization process, TcPcCo also serves as a protonic acid doped into PANI, increasing the electronic conductivity of PANI. Due to the specific selectivity of TcPcCo, high sensitivity of PANI towards NH3, and good conductivity and stability of the MCNTs, the obtained core–shell MCNT@PANI hybrids demonstrate radically enhanced NH3-sensing performance, especially in terms of response/recovery duration (∼5.0 s/12.0 s to 100 ppm NH3) and selectivity, outperforming the single components and previously reported materials at room temperature. In addition, the MCNT@1.0PANI hybrid shows a superior sensing sensitivity (140.99% to 100 ppm NH3) as well as remarkable stability over 60 days. The proposed strategy, TcPcCo-mediated non-covalent coupling of MCNT with PANI, is of potential importance towards the design and construction of ideal materials for future sensing devices, as well as many other applications.

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.

Cost-efficient, highly sensitive, selective and stable sensing materials play a key role in developing NH3 sensors. Herein, a series of tetra-β-aminephthalocyanines metal(II) (aPcMs M = Cu, Ni, Co, Fe) have been successfully covalently bonded on the surface of graphene oxide (GO) by a facile amidation reaction. The obtained aPcM–GO hybrids display good dispersibility, which is beneficial to construct uniform sensing devices. The aPcM–GO sensors exhibit excellent sensing performance in terms of sensitivity, reversibility, reproducibility, selectivity and stability, especially the aPcCo–GO sensor which exhibited a response of about 11.6% (50 ppm), a limit of detection as low as 800 ppb, and a recovery time of about as fast as 350 s at room temperature. The enhanced NH3-sensing performance is mainly due to the synergistic effect between aPcM and GO, e.g. the stronger adsorption interaction of aPcM with NH3, the high electrical conductivity of GO, and the fast charge transfer between aPcM and GO. By comparison, the response of aPcM–GO hybrids to ammonia decreases gradually in the following order of Co > Cu > Ni > Fe ≫ GO, indicating that the central metals play a critical role in gas sensitivity toward NH3, which is further confirmed by first-principle density functional theory.

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.

An ultrathin composite films containing cobalt phthalocyanine (CoPc) and poly(diallydimethyl ammonium chloride) (PDDA) were fabricated through layer-by-layer assembly technique. The resulting films were characterized by UV-Vis spectroscopy and atomic force microscopy. Their third-order nonlinear optical properties and photo-excitation dynamics were investigated with 20 ps laser pulses at 532 nm. The results demonstrate that the ultrathin films have notable third order optical nonlinearities (χ(3)∼4.7 × 10−9 (esu)) and fast excited-state relaxation (τ∼67 ± 6 ps), indicating their potential applications in future nonlinear optical devices.

Bismuth telluride/reduced graphene oxide (Bi2Te3/rGO composites) was prepared by solvent-thermal method, and Bi2Te3/rGO-PVA (Polyvinyl alcohol) thin film was synthesized from drop coating method. The third-order nonlinear optical properties (NLO) and optical limiting (OL) performances of the solution samples and the film samples were studied using Z-scan test at the laser wavelength of 532 nm and 1064 nm with 10 Hz repetition frequency and 4 ns pulse width. In comparison with Bi2Te3, rGO and Bi2Te3+rGO (Bi2Te3 and rGO are mechanically stirred together), whether Bi2Te3/rGO solution sample or Bi2Te3/rGO-PVA film sample possess larger third order nonlinear absorption coefficients (β) and lower limiting thresholds due to the charge transfer and synergistic effect between Bi2Te3 and rGO. The limiting thresholds of Bi2Te3/rGO-PVA thin film samples (~0.19 J/cm2 at 532 nm and ~0.52 J/cm2 at 1064 nm) are lower than that of Bi2Te3/rGO solution due to much higher concentration in the film at the same level of linear transmission. The Bi2Te3/rGO-PVA thin film could be the promising optical limiting materials.

4-Nitrophenol (4-NP) sensors with high sensitivity and reproducibility are desirable for biosafety and environmental monitoring. Herein, cationic tetra-β-(N,N,N-trimethylaminoethoxy) phthalocyanine cobalt(II)/acid-treated carbon nanotubes multilayer films, marked as (tmaePcCo/CNT)n films (n represents the bilayer number), were successfully constructed on glassy carbon electrode (GCE) by a facile, effective layer by layer (LBL) electrostatic assembly method without the assistant of polyelectrolyte. Because CNTs within the multilayer films are beneficial to collect and transfer charges, and polyelectrolyte-free assembly ensures active sites exposing, the obtained (tmaePcCo/CNT)10/GCE exhibits excellent 4-NP electrocatalytic performance with good reproducibility and acceptable stability, a wide linear calibration range over 3 orders of magnitude of 4-NP concentrations (1 μM–1.8 mM) and a low detection limit of 0.2 μM (S/N = 3), and it can be applied to the quantification analysis of 4-NP under optimum conditions. This work shows that the LBL multilayer films fabricated without polyelectrolyte can provide a valid way to improve the sensitivity and reproducibility of 4-NP sensors.

Cost-efficient, highly sensitive and stable sensing materials play a key role in developing H2S sensors. Herein, tetra-β-carboxyphenyloxyphthalocyanine cobalt(II) (cPcCo) has been successfully bonded on the surface of acidified multiwalled carbon nanotubes (aCNTs) by a facile two-step condensation reaction in the presence of N,N′-dicyclohexylcarbodiimide (DCC), using hydroquinone (HQ), p-aminophenol (PAP), and p-phenylenediamine (PPD) as linking molecules, respectively. The obtained cPcCo–B–aCNT (B= HQ, PAP, and PPD) hybrids display good dispersibility in ethanol, which is beneficial to construct uniform sensing devices. The cPcCo–B–aCNT sensors, with a loose network-like structure, present abundant exposed sensing sites, oriented transmission of charges, and unimpeded pathways for H2S diffusion, which endow the cPcCo–B–aCNT hybrids with excellent sensing performance, in terms of sensitivity, reliability, reproducibility, and detection limit. The detection limit of the sensors composed of cPcCo–B–aCNT hybrids towards H2S reaches the ppb-level at room temperature, which is about the same as the odor threshold level for humans. For the cPcCo–HQ–aCNT sensor, the response to H2S varies linearly with respect to its concentration from 20 to 160 ppb and from 320 to 2560 ppb, with the highest gas response of 2.5% to 80 ppb H2S and a low detection limit of 5 ppb. Furthermore, the linking molecules play a critical role in the sensitivity of H2S, as evidenced from the current–voltage characteristics. The systematic study developed here provides a valid way to fabricate other high-efficient H2S sensors.

As vital biological mediators, the accurate detection of nitrite (NO2−) and hydrogen peroxide (H2O2) is desirable for clinical monitoring and diagnosis. Herein, cationic 2,9,16,23-tetra[4-(N-methyl)pyridinyloxy]phthalocyanine cobalt(II) ([TMPyPcCo]4+) and acid-treated multiwalled carbon nanotubes (aCNTs) were alternately self-assembled on the glassy carbon electrode (GCE) by means of the electrostatic interaction, leading to a 3D loose and interconnected assembly of [TMPyPcCo/aCNTs]n multilayer films. In the [TMPyPcCo/aCNTs]n films, [TMPyPcCo]4+ is anchored onto the surface of aCNTs without any inert polymer binders, which is beneficial to expose more active sites for electrocatalysis. The effective combination of [TMPyPcCo]4+ and aCNTs brings many advantages in electrochemical detection, involving the fast oriented transmission of charges, permeable channels for ion adsorption and transport, and more sensing sites, thus the [TMPyPcCo/aCNTs]n films display excellent electrochemical sensitivity towards both NO2− and H2O2. The responses of NO2− and H2O2 vary linearly with respect to the concentration from 5 µM to 30 mM and 10 µM to 9 mM. Furthermore, the superior cycling stability, reproducibility, and selectivity make [TMPyPcCo/aCNTs]n films suitable for the real samples.

2,9,16,23-tetra-(6-mercaptohexylthio) phthalocyanine (MPc(THdT), M = Zn, In)-graphene oxide (MPc(THdT)-GO hybrids) and 2,9,16,23-tetra-(6-hydroxyhexyloxy) phthalocyanine (MPc(THdI), M = Zn, In)-graphene oxide (MPc(THdI)-GO hybrids) have been prepared with a covalent functionalization method. A series of characterizations revealed that phthalocyanine is covalently attachment on graphene oxide sheets. The third order nonlinear optical properties were investigated using the Z-scan technique at 532 nm with 4 ns laser pulses. The four kinds of MPc-GO hybrids exhibited much larger nonlinear optical absorption effects than that GO and Pc, respectively. Energy diagrams show that the PET process from Pc molecules to GO nanosheet exists. In the process of PET/ET, thioester bond between GO and MPc(THdT) make process of PET/ET easier, and the nonlinear absorption coefficient β values of MPc(THdT)-GO hybrids are higher than those of MPc(THdI)-GO hybrids.

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.

A highly efficient catalyst is a key challenge for developing electrochemical sensors for p-aminophenol (4-AP), which widely exists in the environment. In this paper, we describe a feasible synthesis for a tetra-β-[3-(dimethylamine)phenoxy] phthalocyanine cobalt(II) (aPcCo) and acid-treated multiwalled carbon nanotube (CNT) hybrid using a strong π–π stacking interaction. The combination of aPcCo and CNT can improve the conductivity of aPcCo and the dispersion of CNT simultaneously, which benefits formation of uniform electrodes, and provides unimpeded pathways for matter diffusion, as well as accelerating charge-transfer kinetics. As a result, the aPcCo/CNT hybrid we produced can serve as an efficient electrochemical catalyst for 4-AP oxidation and provide more sensitive detection. The oxidation current of 4-AP is linear at concentrations from 0.5 μM to 300 μM and 300 μM to 800 μM. The detection limit is as low as 0.3 μM (S/N = 3). This development offers an attractive catalyst material for electrochemical sensors.

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.

Room temperature operation, high sensitivity, low detection limit, fast response/recovery, and excellent selectivity are desirable for a wide range of NH3-sensing application. In this report, well-dispersed 2,9,16,23-tetrakis(2,2,3,3-tetrafluoropropoxy) metal(II) phthalocyanine/multi-walled carbon nanotube hybrids (TFPMPc/MWCNT, M = Co, Zn, Cu, Pb, Pd, and Ni) were prepared by using a solution self-assembly method based on π–π stacking interactions. The as-prepared TFPMPc/MWCNT hybrids show a sensitivity response/recovery and excellent selectivity for NH3 at room temperature, especially TFPCoPc/MWCNT sensor. The sensitivity of TFPCoPc/MWCNT to 50 ppm NH3 is about 26%, and the limit of detection is as low as 60 ppb. The enhanced NH3-sensing performance is mainly due to the synergistic effect between TFPMPc and MWCNT, e.g. the stronger adsorption interaction of TFPMPc with NH3, the high electrical conductivity of MWCNT, and the fast charge transfer between TFPMPc and MWCNT. By contrast, the response of various TFPMPc/MWCNT sensors decreases in the order of Co > Zn > Cu > Pb > Pd ≈ Ni, implying that the central metals play a critical role in the sensitivity of NH3. Such results are further evidenced by the binding energies and charge transfers of MPc-NH3 system calculated by the first-principle density functional theory.

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.

The development of effective approaches for preparing large-area, self-standing, ultrathin metal-based nanosheets, which have proved to be favorable for catalytic applications such as water electrolysis, is highly desirable but remains a great challenge. Reported herein is a simple and versatile strategy to synthesize ultrathin Co3 O4 and CoP NSs consisting of close-packed nanoparticles by pyrolyzing cobalt(II) phthalocyanine/graphene oxide (CoPc/GO) assemblies in air and subsequent topotactic phosphidation while preserving the graphene-like morphology. The strong π-π stacking interactions between CoPc and GO, and the inhibiting effect of the tetrapyrrole-derived macrocycle for grain growth during the catalytic carbon gasification contribute to the NSs forming. The resulting homologous Co3 O4 and CoP NSs display outstanding catalytic activity in alkaline media toward the oxygen evolution reaction and the hydrogen evolution reaction, respectively, ascribed to the richly exposed active sites, and the expedited electrolyte/ion transmission path. The integrated asymmetrical two-electrode configuration also presents a superior cell voltage of 1.63 V at 10 mA cm-2 for overall water splitting, accompanied with the excellent durability during long-term cycling. Further evidences validate that this strategy is appropriate to fabricate graphene-like ultrathin NSs of many other metal oxides, such as Fe2 O3 , NiO, MoO3 , and mixed-metal oxides, for various applications.

A novel hybrid material composed of reduced graphene oxide (RGO) and 1,8,15,22-tetra-iso-pentyloxyphthalocyanine copper (3-CuPc) derivative was obtained. The resultant RGO/3–CuPc hybrid was characterized by Fourier transform infrared, Ultraviolet-visible, X-ray photoelectron and Raman spectroscopy, transmission electron microscopy and scan electron microscopy. The results indicated that 3-CuPc molecules were successfully anchored on the surface of the RGO sheets by the π–π stacking interaction. The NH3 sensing behaviors of the RGO/3–CuPc hybrids were also investigated and compared with the sensors based on pristine RGO. The results showed that the response of the RGO/3–CuPc hybrid sensor is five times more sensitive than that of pristine RGO, and the recovery time is 10 times faster than that of pristine RGO. The RGO/3–CuPc hybrid sensor exhibited excellent response, reversibility and selectivity, indicating a remarkable accumulation effect as a result of 3-CuPc functionalized graphene. An innovative method for the application of RGO/MPc hybrids in the gas sensing field was provided.

Composite film with alternating layers containing anionic 1,8,15,22-tetrakis (8-quinolineoxy-5-sulfonic acid)-phthalocyanine copper and cationic polydiallydimethylammonium chloride was fabricated by electrostatic self-assembled layer-by-layer (LBL) technique. The microstructure of the film was characterized by a series of techniques. The third-order nonlinear optical properties of the film were measured using 4f coherent imaging system with phase object (NIT-PO) with laser duration of 20 ps at the wavelength of 532 nm. The film exhibited excellent nonlinear absorption and self-focusing effect. The second-order molecular hyperpolarizability γ value of the film reaches as high as 1.54 × 10−29 esu.

Two kinds of novel hybrid materials were prepared by noncovalent functionalized single wall carbon nanotubes (SWCNT) with tetra-α-iso-pentyloxyphthalocyanine copper (CuPcTIP) and tetra-α-(2,2,4-trimethyl-3-pentyloxy) metal phthalocyanines (CuPcTTMP) and characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and scan electron microscopy. The results revealed that the CuPc derivatives had been successfully anchored on the surface of nanotubes through π–π stacking interaction. The gas sensing behaviors of the SWCNT/CuPcTIP and SWCNT/CuPcTTMP hybrid were investigated with respect to NH3 at room temperature. The response and recovery properties of SWCNT sensor to NH3 are improved due to the synergetic behavior between CuPc and SWCNT. Moreover, the SWCNT/CuPcTIP and SWCNT/CuPcTTMP hybrids to NH3 exhibit excellent reversibility, reproducibility and selectivity. The advantages of combining CuPc derivatives with SWCNT in enhancing the gas sensing properties of the final product were presented, and an innovative method for the application of SWCNT/CuPc hybrids in the gas sensing field was provided.

The carbazole derivatives are suitable for two-photon absorption optical storage and photoluminescence material. Two carbazole derivatives, asymmetrical and symmetrical type molecules containing quinoline rings as electron acceptors and an N-ethylcarbazole group as electron donor, 9-ethyl-3-(2-quinolin)viny-carbazole ( 4 ) and 9-ethyl-3,6-bis(2-(quinolin)vinyl)-carbazole ( 5 ), had been synthesized by the Vilsmeier reaction of formylation and Knoevenagel condensation. The one-photon properties including absorption, fluorescence emission spectra, fluorescence quantum yields and fluorescence decay behaviors were investigated in N,N-dimethylformamide. Meanwhile, these compounds were theoretically surveyed by the density functional theory (DFT) and the time-dependent functional theory (TD-DFT). The two-photon excited fluorescence and two-photon absorption cross-sections were measured for the compounds by 120 fs pulse at 800 nm Ti: sapphire laser operating at 1 kHz repetition rate. The results showed that both of the two compounds 4 and 5 had higher fluorescence quantum yield ( Φ ) of 0.77 and 0.81 comparing with carbazole. Compounds 5 with symmetric π conjugated structure possessed longer fluorescence lifetime ( τ ) of 21.4 ns and larger two-photon absorption cross-sections ( δ TPA ) of 364 × 10 −50 cm 4 s/photon than those of compounds 4 with asymmetric π conjugated structure ( τ = 10.03 ns and δ TPA = 81 × 10 −50 cm 4 s/photon). It was indicated that the one and two-photon optical properties of carbazole derivatives are influenced strongly by the symmetry and length of π conjugated structure.

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.

Two kinds of novel carbon nanotubes hybrids were prepared by noncovalent hybridization of the acidified multi wall carbon nanotubes (MWCNT-COOH) and single wall carbon nanotubes (SWCNT-COOH) with lead 2,9,16,23-tetra-iso-pentyloxyphthalocyanine (PbPc) and characterized by FTIR, absorption spectra and scanning electron microscopy. The results revealed that the PbPc derivatives had been successfully anchored on the surface of nanotubes through π–π stacking. The gas sensing behaviors of the MWCNT-COOH, PbPc/MWCNT-COOH, SWCNT-COOH and PbPc/SWCNT-COOH films were investigated with respect to NH 3 at room temperature. The synergetic behavior between PbPc and CNTs allows an excellent sensitivity to NH 3 . We present the advantages of combining metallophthalocyanine (MPc) with CNTs in enhancing the gas sensing properties of the final product, and pave a new way for the application of MPc/CNTs hybrids in the gas sensing field.