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Covalent organic frameworks (COFs) possess extraordinary porosity, structural diversity, and good electrochemical performance, and have broad application prospects in the field of energy storage. However, the low conductivity of COFs limits its further development. In this paper, the electrochemical performance of triphenylamine-based COFs (TPA-COFs) was improved by compounding with highly conductive polyaniline (PANI) using solvothermal synthesis process. The highly conductive polyaniline fibers can act as conductive path in the composite to accelerate the charge transfer rate of TPA-COFs. The π-π interaction between TPA-COFs and PANI effectively decreases the agglomeration degree of PANI. The good dispersion of composite results in that the specific surface area of TPA-COFs/PANI-20 is high as 1233.9 m2 g−1, which provides rich diffusion channels for electrolyte ions. Moreover, the strong π-π structure in the composites ensures the stability of the material skeleton. Thus, TPA-COFs/PANI composite exhibits excellent rate characteristics and cycling stability.

As global warming continues, extreme precipitation events occur frequently in inland areas, seriously affecting human security and the ecological environment. Spatiotemporal evolution of extreme precipitation as well as response of extreme precipitation to climatic warming and its mechanism were investigated by considering the Weihe river basin in a monsoon transition zone of China as a research object. The results indicate that while the annual average temperature of the Weihe river basin increased with fluctuations from 1966 to 2017, except for the consecutive dry days (CDD) and simple daily intensity index that increased slightly, the other extreme precipitation indices (consecutive wet days, R25, and Rx5day) tended to decrease. Moreover, except for the CDD, the other four indices gradually increased from the northwest to the southeast, showing a similar trend to the temperature. The relationship between the 95th percentile threshold and temperature (hereinafter referred to as the P 95d–T relationship) in the Weihe river basin demonstrates the hook structure and its strength in terms of response is mainly dominated by the super-Clausius–Clapeyron (C–C) and C–C scaling. Furthermore, the peak temperature rises gradually from the northwest to the southeast. The results can provide important reference for the prediction of climate change and future studies of disaster risk in the Weihe river basin.

PtCu alloy supported on acid-treated multi-walled carbon nanotube (PtCu/MWCNT) catalysts were prepared through polyol reduction method. The prepared PtCu/MWCNT composites were annealed at different temperatures to study the effects of annealing temperatures on the particle size, structure, surface morphology, and the activity and stability of methanol oxidation reaction (MOR). X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) were used to study the structure and physical characteristics of the catalyst. These physical characterization analyses all confirmed the formation of PtCu alloy, and the particle size of the catalysts rose with the increase of annealing temperature. The activity and stability of catalysts were further measured by cyclic voltammetry (CV) and accelerated durability tests (ADTs), respectively. It was found after annealing at 400℃ that the PtCu/MWCNT catalyst has higher activity and longer durability toward MOR. This work demonstrated that PtCu catalysts after annealing in a H2 atmosphere will cause a change in the surface atomic configuration and degree of alloying of PtCu catalysts, which determines the activity and long-term durability of PtCu/MWCNT catalyst.

In this work, Ru-doped Ta2O5 was firstly synthesized as support for Pt nanoparticles by calcination and chemical precipitation. The prepared Pt/Ru-Ta2O5 catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These characterization methods confirm that Pt nanoparticles were successfully supported on Ru-doped Ta2O5 (Ru-Ta2O5). The TEM reveals that Pt nanoparticles with an average diameter of ca. 4.0 ± 0.5 nm were uniformly distributed on the Ru-Ta2O5. The further electrochemical characterizations including cyclic voltammograms (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) methods show that Pt/Ru-Ta2O5 catalysts have larger electrochemical surface area, better electrocatalytic activity, and higher stability toward the methanol oxidation reaction compared to the pure Ta2O5 supported Pt catalysts. The excellent electrocatalytic performance is mainly contributed to the improvement of Ru for the dispersion of Pt nanoparticles, the increased conductivity of Ta2O5, as well as the promotion of oxidation reactivity by Ru. This work demonstrated that Ru-Ta2O5 is a promising anode catalyst support for direct methanol fuel cells.

Free-standing flexible supercapacitive electrodes have practical application for wearable energy storage devices. In this paper, graphene paper (GP), a flexible electrode substrate, was prepared by one-step reduction of graphene oxide (GO) using HI solution. GP can be used independently as a flexible electrode with specific capacitance of 227 F/g. In order to make up for the shortage of GP specific capacitance storage, polyaniline (PANI) with high specific capacitance and good electrical conductivity was selected to composite with GP by electrochemical polymerization approach. This method to fabricate electrode material by direct electrochemical polymerization avoids the use of conductive binder and organic solvent. Owing to the specific capacitance contribution of PANI and GP, the PANI/GP composites exhibit higher specific capacitance when the polymerization time is 30 s and the polymerization voltage is 0.8 V. At 1 A/g current density, the specific capacitance of composite is up to 759 F/g, which is 3.34 times of neat GP.

A Poly (3, 4-dioxyethylthiophene)–Carbon Nanotubes (PEDOT–CNT) composite electrochromic material, connected by interfacial covalent bonds, was successfully synthesized by electrochemical copolymerization of 3, 4-dioxyethylthiophene with thiophene-2-methylamine functionalized CNT. The molecular and aggregate structures of PEDOT–CNT were investigated by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The electrochemical behavior and electrochromic properties of PEDOT–CNT were measured by CV (cyclic voltammetry), UV–Vis (ultraviolet visible spectroscopy) and EIS (electrochemical impedance spectroscopy). The test results show that the electrochromic performance of PEDOT–CNT is better than that of neat PEDOT. As the percentage of carbon nanotubes increases, the contrast and response speed of the composites increase accordingly. The PEDOT film has a contrast under square-wave potential of 0.54, a coloring time of 6.42 s, and a fading time of 2.54 s. Compared with PEDOT, the contrasts of PEDOT–CNT-3%, PEDOT–CNT-5% and PEDOT–CNT-7% are increased by 31%, 33%, and 89%, respectively. The response speeds of PEDOT–CNT-5% increase to coloring time of 3.51 s and fading time of 1.37 s.

In this paper, we prove an efficient and facile synthesis method for preparing PtRu nanoparticles (NPs)/graphene nanosheets (GNS) catalysts for methanol electrooxidation. Our approach employed carboxylated-graphene nanosheets (C-GNS) as the support which prepared by the Friedel-Crafts reaction between succinic anhydride and GNS. The reaction conditions are mild without cumbersome pretreatment of GNS. The morphology and component of PtRu NPs/C-GNS catalysts were characterized by transmission electron microscopy (TEM) and inductively coupled plasma-atom emission spectroscopy (ICP-AES), respectively. The TEM observation reveals that PtRu NPs with an average diameter of ca. 4.0 ± 0.5 nm uniformly distributed on the edges and wrinkles of C-GNS. The further electrochemical characterizations including cyclic voltammograms (CV) and chronoamperometry (CA) methods show that PtRu NPs/C-GNS catalysts have significantly higher electrocatalytic activity and stability toward methanol electrooxidation compared to the PtRu catalysts supported on the unmodified GNS. This provides an easy approach to synthesize GNS-based electrode materials for high-performance energy conversion devices in the future.

Polyaniline nanotubes (PANI-T) and graphene oxide (GO) have been compounded by a postcomposition method with the assistance of electrostatic adsorption. Using this so-called postcomposition method, both the electric double-layer capacitance of the GO and the pseudocapacitance of the conducting polymer can be utilized. PANI-T prepared by a rapid mixing method was positively charged by pretreatment with (3-aminopropyl)triethoxysilane (APTES). PANI/GO composites were obtained by mixing the positively charged PANI-T and negatively charge GO with the assistance of electrostatic attraction. Charge–discharge measurements in 1 mol L−1 H2SO4 aqueous electrolyte revealed that the specific capacitance of PANI-T/GO-10% could reach 1220 F g−1 at a current density of 0.5 A g−1, being much higher than the value of 648 F g−1 for PANI-T. After 500 cycles of charge–discharge testing, the composite retained 97% of its capacitance. These enhanced supercapacitive properties can be attributed to the two types of energy storage mechanism and the electrostatic interaction between GO and PANI-T. Preparation of such PANI-T/GO composite electrode materials by electrostatic adsorption thus provides an efficient approach for improvement of the supercapacitive properties of conducting polymers or metal oxides.

In this paper, water-dispersible and covalently bonded polyaniline-carbon nanostructures, including polyaniline-reduced graphene oxide (PANI-rGO), polyaniline-single-walled carbon nanotubes (PANI-SWCNTs), and polyaniline-reduced graphene oxide/single-walled carbon nanotube (PANI-rGO/SWCNTs) nanocomposites, were synthesized by grafting PANI onto p-phenylenediamine (PPD)-functionalized graphene oxide (GO) or single-walled carbon nanotubes (SWCNTs) using polystyrene sulfonate (PSS) as a macromolecular dopant agent. The structures and morphologies of the PANI, PANI-rGO, PANI-SWCNTs, and PANI-rGO/SWCNTs nanocomposites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The cyclic voltammetry and UV–vis spectra were performed on an electrochemical workstation and a UV–vis spectrometer, respectively. The results show that the electrochromic and electrochemical properties of nanocomposites can benefit from the high conductivity of SWCNTs and the abundant active sites of rGO. When SWCNTs and rGO work together, their respective shortcomings are overcome, allowing the nanocomposite to exhibit the best electrochemical and electrochromic properties. The optical contrast increased from 0.38 for PANI to 0.52 for PANI-rGO/SWCNTs. The coloring and bleaching times decreased from 2.59 s and 2.39 s, respectively, for PANI to 1.33 and 0.78 s, respectively, for PANI-rGO/SWCNTs. The charge transfer resistance (Rct) decreased from 135 Ω for PANI to 30 Ω for PANI-rGO/SWCNTs. The synergistic effect of PANI, rGO, and SWCNTs can significantly improve the electrochromic ability of PANI. Electrochromic properties of covalently bonded polyaniline-reduced graphene oxide/single walled carbon nanotubes nanocomposites. A high performance electrochromic material was prepared using polyaniline (PANI) and two different dimensional carbon nanostructures, single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) as the components. The covalent bond was introduced to interface between PANI and two carbon nanostructures to form a three-dimensional conductive network. Owing to the high electron conduction through directly connected covalent bond and loose molecular chain aggregation brought by two various dimensional carbon nanostructure, PANI-rGO/SWCNTs nanocomposites exhibit superior electrochemical and electrochromic properties (high optical contrast and short switching time) compared with PANI.

Opioid addiction is a complex phenomenon with genetic, social, and other components. Due to such complexity, it is difficult to interpret the outcome of clinical studies, and thus, mutations found in individuals with these addictions are still not indisputably classified as opioid addiction-causing variants. Here, we computationally investigated two such mutations, A6V and N40D, found in the mu opioid receptor gene OPRM1. The mutations are located in the extracellular domain of the corresponding protein, which is important to the hetero-dimerization of OPRM1 with the delta opioid receptor protein (OPRD1). The hetero-dimerization of OPRD1–OPRM1 affects the signaling pathways activated by opioids and natural peptides and, thus, could be considered a factor contributing to addiction. In this study, we built four 3D structures of molecular pathways, including the G-protein signaling pathway and the β-arrestin signaling pathway of the heterodimer of OPRD1–OPRM1. We also analyzed the effect of mutations of A6V and N40D on the stability of individual OPRM1/OPRD1 molecules and the OPRD1–OPRM1 heterodimer with the goal of inferring their plausible linkage with opioid addiction. It was found that both mutations slightly destabilize OPRM1/OPRD1 monomers and weaken their association. Since hetero-dimerization is a key step for signaling processes, it is anticipated that both mutations may be causing increased addiction risk.

Polyaniline is one of the most common electrode materials for supercapacitors. The morphology of polyaniline directly affects the properties of polyaniline. In this paper, a new method for preparing hollow polyaniline nanospheres is described. Polyaniline-S with solid and hollow structures are successfully synthesized by the hydrothermal method, through varying the amounts of the catalyst and oxidant. The prepared hollow nanospheres have uniform particle size, a smooth surface, and uniform wall thickness. The hollow structure provides rapid permeability to the material, facilitating the transfer and transport of charges and ions in the electrolyte, and it can also act as an ion storage tank to increase the accumulation of ions inside. The specific capacitance of polyaniline-S is high at 235 F g-1 at 0.5 A g-1. To reduce the aggregation of polyaniline-S and improve the electrochemical activity, polyaniline-S, and graphene oxide are composited using the interfacial electrostatic interaction. The content of graphene oxide has a significant influence on the electrochemical performance of the composites. The specific capacitance of the polyaniline-S/ graphene oxide composite with a 10% loading amount of graphene oxide reaches 535 F g-1 at 0.5 A g-1, increase of nearly 128% compared to representing a significant polyaniline-S. The specific capacitance retention rate is 93.6% after 10,000 cycles.

Intravesicular pH plays a crucial role in melanosome maturation and function. Melanosomal pH changes during maturation from very acidic in the early stages to neutral in late stages. Neutral pH is critical for providing optimal conditions for the rate-limiting, pH-sensitive melanin-synthesizing enzyme tyrosinase (TYR). This dramatic change in pH is thought to result from the activity of several proteins that control melanosomal pH. Here, we computationally investigated the pH-dependent stability of several melanosomal membrane proteins and compared them to the pH dependence of the stability of TYR. We confirmed that the pH optimum of TYR is neutral, and we also found that proteins that are negative regulators of melanosomal pH are predicted to function optimally at neutral pH. In contrast, positive pH regulators were predicted to have an acidic pH optimum. We propose a competitive mechanism among positive and negative regulators that results in pH equilibrium. Our findings are consistent with previous work that demonstrated a correlation between the pH optima of stability and activity, and they are consistent with the expected activity of positive and negative regulators of melanosomal pH. Furthermore, our data suggest that disease-causing variants impact the pH dependence of melanosomal proteins, this is particularly prominent for the OCA2 protein. In conclusion, melanosomal pH appears to affect the activity of multiple melanosomal proteins.

In this study, polyaniline (PANI) nanostructures with different morphologies (nanofibers, nanotubes, and nanospheres) were obtained via interfacial polymerization, rapid mixing reaction, and hydrothermal method. The influences of the synthesis methods on the morphologies and supercapacitive properties of PANI nanostructures were investigated. The chemical structures of materials were characterized by Fourier-transform infrared and Raman spectroscopies. Scanning electron microscopy and transmission electron microscopy images were used to explore the morphologies of PANI nanostructures. N2 adsorption–desorption isotherm, cyclic voltammetry, charge–discharge test, and electrochemical impedance spectroscopy were used to characterize the pore distribution, electrochemical, and supercapacitive properties of PANI nanostructures. The results show that PANI nanotubes (PANI-T) exhibit the best electrochemical performances among three kinds of PANI nanostructures. The PANI-T exhibits high specific capacitances of 648 and 290 F g−1 at current densities of 0.5 and 10 A g−1, respectively, indicating its good supercapacitive property and rate capability. The enhanced electrochemical and supercapacitive performances can be attributed to its hollow nanotube structure.

In this article, a high specific capacitance biomass carbon/MnO2 nanocomposites electrode materials were prepared by hydrothermal method. The porous sugarcane bagasse based biomass carbon was used as the host to load MnO2 nanospheres. The final obtained nanocomposites exhibit high specific capacitance. Besides, the effects of different electrolytes on the electrochemical properties of sugarcane bagasse carbon (SBC)/MnO2 nanosphere composites (SBC/MnO2) were also investigated. In comparison with MnO2 nanospheres, the specific capacitances of the SBC/MnO2 composite materials are improved whether in alkaline electrolyte or neutral electrolyte. Especially, in 1 M Na2SO4 electrolyte, the specific capacitance of SBC/MnO2 composite is up to 747 F·g−1 at a current density of 1 A·g−1, which is much higher than the MnO2 nanospheres at the same current density. At the same time, after 1000 cycles of charge–discharge process in a neutral electrolyte, the specific capacitance retention of SBC/MnO2 composite reaches 77%.

In view of the poor electronic conductivity and inferior structural stability, the direct application of Metal-Organic Frameworks (MOFs) as an electrode material is limited. Herein, the carboxylated multi-wall carbon nanotubes (MWCNT) are utilized as a substrate for the in-situ growth of bimetallic NiCo-based MOFs (NiCo-MOF). The flower-string-like NiCo-MOF/MWCNT composites are successfully synthesized using 4, 4′-biphenyldicarboxylic acid (BPDC) as a ligand via a simple solvothermal approach. In the composites, MWCNT is wrapped with 2D NiCo-MOF nanosheets through some bonds or affinity between MWCNT and NiCo-MOF. Meanwhile, the MWCNT presence does not affect the formation of the NiCo-MOF crystals. Compared with the hydrangea-like NiCo-MOF microspheres, the flower-string-like composite structures are more loosely assembled by NiCo-MOF nanosheets. Owing to the guiding effect of MWCNT on the NiCo-MOF growth, many well-dispersed flower-string-like structures can be achieved by adjusting MWCNT dosages. Due to the unique hierarchical structure and good synergistic effect, the NiCo-MOF/MWCNT composites exhibit excellent capacitance performances. The optimal composites demonstrate a large specific capacitance of 1010 F g−1 at 0.5 A g−1, a good rate capability (760 F g−1 even at 10 A g−1), a good cycling stability and reversibility with the capacitance retention of 828 F g−1 (100% of the initial capacitance) and coulombic efficiency of approximate 98% at 5 A g−1 after 3000 cycles, a low internal resistance and charge transfer resistance. The asymmetric supercapacitor assembled by NiCo-MOF/MWCNT composites as electrode materials has high energy density even at high power density, good rate capability, excellent cycling stability and reversibility. Hence, the as-synthesized NiCo-MOF/MWCNT composites are a promising high-performance electrode material for supercapacitors.

In this article, polyaniline nanofibers (PANI-NF)/manganese dioxide composites (PANI/MnO2) were synthesized through an interfacial polymerization approach. The PANI-NF and MnO2 were obtained by in situ oxidation of aniline by potassium permanganate and in situ reduction of potassium permanganate by aniline, respectively. During the interfacial polymerization, the monomer aniline can only be oxidized to PANI after it diffuses into the water phase. This diffusion-control feeding process of the monomer results in nanofiber structure. The morphologies and crystal structures of the prepared PANI/MnO2 composites were measured by scanning electron microscopy and x-ray diffraction. The supercapacitive behaviours of these composites were analysed by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) tests. The CV and GCD tests indicate that the PANI/MnO2 composites possess better electrochemical activity and higher capacitive properties compared to neat PANI nanofibers. The specific capacitance of PANI/MnO2 composites and PANI-NF are 751 F g−1 and 180 F g−1 at 0.2 A g−1 in Na2SO4 solution, respectively. We believe that the enhanced capacitive properties are related to the special nanostructure and strong interaction between PANI and MnO2 that resulted from the interfacial synthesis method.

Polyaniline nanowires (PANI NWs) were synthesized under different temperatures through a facile hydrothermal method and used as electrodes for high-performance pseudocapacitor. The resulting samples were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron micrographs, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Electrochemical properties of these PANI electrodes are studied by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy in 0.5M H2SO4 aqueous solution. The highest specific capacitance is obtained on the PANI NWs synthesized under 80°C (PANI-80) with 540.0 F g−1 at current density of 0.5 A g−1 accompanied with 82% specific capacitance retention after 1000 charge discharge cycles at 5 A g−1 current density.

In this article, polyaniline nanofibers/reduced graphene oxide (PANI-NFs/rGO) nanocomposites were prepared by a one-pot hydrothermal method. Under the condition of high temperature and high pressure, graphene oxide (GO) was reduced to rGO and aniline was in-situ polymerized to form PANI-NFs using ammonium persulfate as oxidant. The morphologies and structures of PANI-NFs/rGO nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and Raman analysis. The results show that PANI-NFs uniformly grow on the surfaces of rGO sheets, which can act as spacers to prevent the aggregation of rGO. Combining with FTIR and Raman analysis, it can be concluded that PANI-NFs/rGO nanocomposites are successfully prepared. The electrochemical performances of PANI-NFs/rGO nanocomposites were tested by cyclic voltammetry and galvanostatic charge–discharge. The PANI-NFs/rGO nanocomposites exhibit superior electrochemical performances compared to the PANI-NFs. With 10 wt% of GO loaded, the PANI-NFs/rGO nanocomposite exhibits highest specific capacitance of 942 F g−1 at a current density of 1 A g−1. The PANI-NFs/rGO nanocomposites also demonstrate good rate capacity and high cycling stability under the high discharging current density (10 A g−1), the specific capacitance can still reach to 680 F g−1. After 1000 charge–discharge cycling at a current density of 5 A g−1, 78% of specific capacitance can be retained. The enhanced capacitive performances can be attributed to the facile electron conduction pathway brought by the even distribution of highly conductive rGO nanosheets.

NiCo-based bimetal-organic frameworks (NiCo-MOF) are synthesized via a hydrothermal approach, using 4,4′-biphenyldicarboxylic acid (BPDC) as a ligand. Structural characterizations find that NiCo-MOF is composed of one-dimensional micro-nanorods and regular three-dimensional cuboids assembled by one-dimensional micro-nanorods，possessing a good crystalline structure, in which nickel and cobalt ions have been coordinated to the BPDC ligands. Moreover, NiCo-MOF can be stable below 300 °C in air. The electrochemical measurements show that GCD activation at a high current density can significantly increase the capacity of NiCo-MOF due to decreasing the charge-transfer resistance and ion diffusion impendence. The specific capacitance of NiCo-MOF reaches 990.7 F/g from 156.5 F/g at 1 A/g, and the coulombic efficiency increases to 98.0% from 77.6% after the CV-GCD activation. Activated NiCo-MOF exhibits prominent pseudocapacitive behaviors, high specific capacitances at different current densities and a good cycling stability after 1000 cycles. The capacity of NiCo-MOF is up to 405.0 F/g when the current density increases to 20 A/g, and remains 553.2 F/g at 1 A/g after 3000 cycles. Compared with monometallic Ni-MOF and Co-MOF, bimetallic NiCo-MOF possesses a much higher capacity at different current densities due to the lower intrinsic resistance, charge-transfer resistance and ion diffusion impendence.

Two-dimension covalent organic frameworks (2D COFs) are porous materials with the interlayer π-π interaction and excellent optoelectronic properties. Their adjustable porous structure and designable molecular structure endow them unlimited possibilities in the field of optoelectronic materials and other functional materials. In this paper, 2D COF electrochromic films were prepared by solvothermal synthesis method with different amounts of functionalized carbon nanotubes (FCNT) loading to improve their conductivity. The morphology characterization of COFDAAQ-TFP reveals its intertwined nanofiber structure. The electrochromic performance of COFDAAQ-TFP film shows that the color of COFDAAQ-TFP and FCNT-COFDAAQ-TFP have a reversible transformation from orange to dark brown during the redox process. When the loading amount of FCNT is 1%, FCNT-COFDAAQ-TFP exhibits best electrochromic properties, which has a contrast of 0.358 and coloring time of 5.7 s. Relative to COFs, FCNT-COF has enhanced contrast and stability, which is a potential electrochromic material in many fields such as smart window and smartphone back case.

Using coal-based polyaniline as a carbon and nitrogen source, N-doped porous carbon (NPC)/nickel cobalt oxides (NixCoyOz)/carbon micro–nanotubes (CMNT) composites possessing rich nanoscale meso–macropores, spinel NiCo2O4 sheets and multi-walled CMNT are successfully synthesized by the first pyrolysis and the second wet oxidation process. Therein, CMNT owning a diameter of 10–200 nm and a length of several micrometers is grown by a two-stage furnace process in a hydrogen-free atmosphere, using nickel acetate as a growth catalyst precursor. CMNT exhibits polymorphic features, including most curved tubes, a few vertical tubes, some bamboo-like tubes and some Chinese-sugar-gourd-skewer-like tubes, resulting from the diversity and low hydrogen content of gaseous cracking products from coal-based polyaniline. Carbon in CMNT mainly exists in the graphitic state while carbon in NPC mainly presents in the amorphous state. Nitrogen in CMNT mainly exists in the form of graphitic N while nitrogen in NPC (0.89 wt% in composites) mainly presents in the form of pyrrolic N (74.4 at.%) and oxidized N (25.6 at.%). The intercalated Ni and Co impurity in NPC and CMNT are transformed to most NiCo2O4 and a few NiO. The BET specific surface area and average pore width of composites are 169.3 m2/g and 8.4 nm. CMNT incorporation obviously improves capacitance properties of NPC/NixCoyOz/CMNT composites. The composites demonstrate a higher specific capacitance of 598.4 F/g at 1 A/g, and a good cycling stability retaining a high capacity of 190.1 F/g (81.1% retention) at 5 A/g after 5000 charge–discharge cycles. It is attributed to the nitrogen incorporation of porous carbon, high conductivity and large specific surface area of CMNT, and high electrochemical activity of NixCoyOz, especially, the synergistic effects of NPC, CMNT and NixCoyOz. This study has developed a polygeneration process for coal pyrolysis, which also enables the combined utilization of coal pyrolysis products.

In this article, we reported a biomass carbon/MnO2 nanocomposite electrode material prepared by a hydrothermal method. Sugarcane bagasse and KOH were the carbon source and activation agent, respectively. The obtained sugarcane bagasse carbon is rich in pore structure, so it can act as the host for MnO2. The biomass carbon/MnO2 nanocomposite electrode was prepared by a hydrothermal method. The morphologies of materials were observed by scanning electron microscopy. Raman spectra and x-ray diffraction were utilized to characterize the molecular and crystal structures of samples, respectively. The electrochemical and capacitive performances of materials were tested by electrochemical workstation. By calculation, the specific capacitance of sugarcane bagasse carbon, MnO2 and composite electrode are 280 F g−1, 163 F g−1 and 359 F g−1, respectively. Compared with pure sugarcane bagasse carbon and MnO2, the specific capacitance of the composite increases by 28% and 120%, respectively. After 2000 cycles of charge and discharge, the capacitance retention of the composite is 94%, which is higher than 91% of sugarcane bagasse carbon and 45% of MnO2.

A facile method was developed for preparation of PtRu nanoparticles/multiwalled carbon nanotubes (MWCNTs) electrocatalysts for methanol oxidation. Starting from pristine MWCNTs, high dispersion of PtRu nanoparticles was directly assembled on the side wall of MWCNTs by using p-phenylenediamine (PPDA) as the inter-linker. FTIR and Raman spectroscopy examinations show that PPDA can be immobilized on pristine MWCNTs by π-π stacking, and the integral structure of MWCNTs was preserved after modification. TEM and XRD investigations show that the face-centered cubic (fcc) Pt structure of PtRu alloy nanoparticles with average diameter 3.5 ± 0.5 nm are uniformly supported on the surface of PPDA-functionalized MWCNTs (PPDA-MWCNTs). The resulting PtRu/PPDA-MWCNTs catalyst exhibits a more negative onset potential (0.15 V) than PtRu/MWCNTs (0.33 V), showing the higher electrocatalytic activity towards methanol oxidation, while its forward peak current density (731.6 mAmg−1 of Pt) is 1.66 times higher than that of PtRu/MWCNTs (440.5 mAmg−1 of Pt). The PtRu/PPDA-MWCNTs catalyst also shows significantly enhanced steady-state current and long-term stability. The smaller size, better dispersion, and higher electrochemical surface area (73.5 m2 g−1) of the PtRu nanoparticles on PPDA-MWCNTs result in superior electrocatalytic performance towards methanol oxidation. This work may provide an efficient method to fabricate MWCNTs-supported superior noble metal catalysts for broad applications in energy systems and sensing devices.

A 4-aminobenzensulphonate (p-ABS)-assisted strategy has been proposed to separate the aggregations of carbon nanotubes (CNTs) and deposit PtRu nanoparticles on them with holonomic graphitic structures. In this work, as an efficient dispersing agent, 0.5 wt% of p-ABS in isopropanol/water solution can drastically separate CNTs aggregations. Meanwhile, under the help of p-ABS, high dispersion of PtRu nanoparticles is anchored on CNTs surface with small average diameter (3.0 ± 0.5 nm). It is clear that p-ABS acts as dispersant, stabiliser and linker in the proposed strategy. The obtained PtRu/p-ABS-CNTs nanohybrids were applied as electrocatalysts for methanol oxidation and showed enhanced catalytic activity and stability. Due to the introduction of the amino (−NH2) and sulphonic acid (−SO3H) groups onto CNTs by non-covalent method, it ensures PtRu nanoparticles with the advantages of high dispersion, small particle size, locating in triple-phase zones to increase Pt utilisation and reduces the electrochemical corrosion of p-ABS-CNTs, which result in the improved catalytic performance. This work demonstrates an alternative approach to fabricate CNTs supported superior noble metal catalysts for broad applications in fuel cells and chemo/biosensors.

A novel ferrocene-containing hybrid electrochromic material was synthesized via copolymerization of aniline with p-phenylenediamine functionalized acetyl ferrocene in the presence of poly (styrene sulfonate) dopant in an aqueous medium, and neat polyaniline (PANI) was prepared for comparison. The polymerization characteristics and the structure of the copolymer were systematically studied by Fourier-transform infrared, meanwhile, their electrochromic properties and electrochemical behaviors were tested by UV–vis spectra, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). It was found that the strong covalent bond and large conjugated system between PANI and ferrocene enhance the electron transfer rate and electron delocalization in the ferrocene-polyaniline (Fc-PANI) hybrid. In particular, the electrochromic device with Fc-PANI as the active layer shows significant enhancement in optical contrast over the PANI-based device.

In this paper, we designed a novel organic-inorganic nanohybrid electrochromic material through tethering polyaniline and gold colloids with an interfacial coordinate bond. The enhanced electrochemical and electrochromic properties were expected owing to the high conductivities of the gold colloids and strong interfacial interaction between the organic phase and inorganic phase. The water-dispersible polyaniline-gold (PANI-Au) nanohybrids were synthesized successfully through grafting copolymerization of aniline with p-aminothiophenol (PATP) functionalized gold colloids in an aqueous system using a macromolecular acid, poly(styrene sulfonate) (PSS) as the dopant agent. The structures, morphologies, and electrochemical and electrochromic properties of PANI-Au nanohybrids were characterized by the UV–vis, FTIR, Raman spectrometers, SEM, and electrochemical working station, respectively. The results show that through incorporating gold nanoparticles into the PANI matrix with the interfacial coordinate bond, PANI-Au nanohybrids possess uniform nanoparticles morphologies with diameter ~180 nm. The electrochemical activity and the charge transfer process of PANI were enhanced, which is proved by the CV test and EIS analysis. As the results, the PANI-Au nanohybrids can switch at relatively lower potentials and give a higher optical contrast as comparison with neat PANI: PSS. With ~1.4 wt% Au loading amount, the contrast of PANI-Au nanohybrid is 0.97, which is much higher than 0.76 of PANI: PSS. The coloration and bleaching time are also shortened from 13.4 s and 8.9 s for PANI: PSS to 8.3 s and 7.6 s for PANI-Au-c, respectively.

Inspired by hydrothermal synthesis of inorganic crystallites, we apply one-step hydrothermal polymerization to directly grow polyaniline on fluorine-doped tin oxide (FTO) substrate. In contrast to classical procedure that requires long reaction times and low temperature, hydrothermal polymerization allows for only 3 h under hydrothermal condition. Investigation of the morphology via SEM suggests that PANI fiber aggregates uniformly on FTO substrate. The PANI film was used as electrochromic layer in an electrochromic device and the obtained PANI film shows high electrochromic performance. We believe that this study provided a novel way to directly grow PANI on FTO substrate and, thus, has some impact on the applications of other conjugated polymers in electrochromic and electrochemical devices.

Conjugated covalent organic frameworks (COFs) with redox properties can be considered as conductive polymers with ordered porous structures and can be designed for photoelectric materials application. In this paper, 2,6-diaminoanthraquinone and 1,3,5-triformylresorcinol (DAAQ-TFP) COF with anthraquinone active unit was synthesized by solvothermal method for electrochromic application in a Teflon-lined autoclave. Functionalized graphene oxide (FGO) was covalently bonded with COF to improve its electrical conductivity and photoelectric properties. After the addition of FGO, the impedance of COF was reduced, and the optical contrast and cyclic stability of COF were increased. At potential windows of 2.5 V to -3.8V, the COF-FGO-2% can be switched reversible from orange to dark brown. Stability test shows that the contrast retention is 109.1% after 1800s switching, which is much higher than COF (75%). Considering the abundance of COF building units with redox activity available, it is possible to develop novel COF based electrochromic materials with rich colors.

The molecular architecture of conducting polymers has a significant impact on their conjugated structure and electrochemical properties. We have investigated the influence of star-shaped structure on the electrochemical and electrochromic properties of polyaniline (PANI). Star-shaped PANI (SPANI) was prepared by copolymerization of aniline with triphenylamine (TPA) using an emulsion polymerization method. With addition of less than 4.0 mol.% TPA, the resulting SPANI exhibited good solubility in xylene with dodecylbenzenesulfonic acid (DBSA) as doping acid. The structure and thermal stability of the SPANI were characterized using Fourier-transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis, and the electrochemical behavior was analyzed by cyclic voltammetry (CV). The electrochromic properties of SPANI were tested using an electrochemical workstation combined with an ultraviolet–visible (UV–Vis) spectrometer. The results show that, with increasing TPA loading, the thermal stability of SPANI increased. With addition of 4.0 mol.% TPA, the weight loss of SPANI was 36.9% at 700°C, much lower than the value of 71.2% for PANI at the same temperature. The low oxidation potential and large enclosed area of the CV curves indicate that SPANI possesses higher electrochemical activity than PANI. Enhanced electrochromic properties including higher optical contrast and better electrochromic stability of SPANI were also obtained. SPANI with 1.6 mol.% TPA loading exhibited the highest optical contrast of 0.71, higher than the values of 0.58 for PANI, 0.66 for SPANI-0.4%, or 0.63 for SPANI-4.0%. Overdosing of TPA resulted in slow switching speed due to slow ion transport in short branched chains of star-shaped PANI electrochromic material. Long-term stability testing confirmed that all the SPANI-based devices exhibited better stability than the PANI-based device.

In this paper, we demonstrate a simple approach to improve the electrochromic performances of polyaniline (PANI) by incorporating PANI nanofibers (PANI-NFs) synthesized by interfacial polymerization into water-soluble PANI:poly(styrene sulfonate) (PANI:PSS). The one-dimensional PANI-NFs endow spin-coated PANI film high electrochemical activities and electrochromic properties. The structures and morphologies of PANI-NFs were characterized by FTIR spectroscopy and SEM observation. The electrochemical behaviors of PANI/PANI-NFs composites were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochromic properties of composites were tested using electrochemical working station combining a UV-Vis spectrometer. The results show that the PANI-NFs with even diameter of ~ 30 nm can be synthesized easily using interfacial polymerization method. With the increasing of feeding amount of PANI-NFs, the oxidation peaks of CV curves shift to low potential direction, indicating enhanced electrochemical activities. The electrochromic test confirms that the PANI/PANI-NFs composites films have higher electrochromic contrast of 0.67 as comparison to 0.49 of PANI:PSS film. The PANI/PANI-NFs also exhibit excellent electrochromic stability. After 2000 cycles switching, only less than 4% contrast decay is observed. The enhanced electrochromic properties can be attributed to the small charge-transfer resistance and facile ion diffusion process brought by PANI-NFs. The EIS tests exhibit that with incorporating of highly conductive PANI-NFs, the PANI/PANI-NFs composites possess relatively lower charge-transfer resistance of 76 Ω as comparison to 94 Ω of neat PANI:PSS.

Electrochromic properties of organic or inorganic materials can be improved through preparing organic/inorganic electrochromic nanocomposites. In electrochromic nanocomposites, the interfacial interactions between the organic and inorganic phases play three important roles in preparation and application of the nanocomposites. Firstly, the interfacial interactions result in stable molecular structures. Secondly, they also improve the electron conduction and ion transport process in the nanocomposites. Thirdly, they enhance the electrochemical and electrochromic properties of the nanocomposites. In this paper, we review the common interfacial interactions including covalent bond, coordination bond, electrostatic interaction, hydrogen bond and π-π stacking interaction between the organic and inorganic phases in the electrochromic nanocomposites. The preparation method, the relationship between the structure and properties, and the mechanism of modulation of electrochromic effect in the nanocomposites with various interfacial interactions are surveyed. The strong interfacial interaction, e.g., covalent bond, is helpful for obtaining electrochromic nanocomposites with high electron conduction and high structural strength. However it is very complicated to construct covalent bond between the organic and inorganic phases. Another strong interfacial interaction, the coordination bond is mainly confined to preparation of electrochromic complex of metal ion and pyridine derivative. While, the weak interfacial interactions, e.g., electrostatic interaction, hydrogen bond and π-π stacking interaction, exist widely between the organic and inorganic phases in the electrochromic nanocomposites. Relative to single strong interaction, the multiple weak interactions may be a development direction for achieving high performance electrochromic effect in the organic/inorganic nanocomposites, owing to their integrated effect and various adjusting mechanisms of electrochromic properties.

In this paper, the covalently bonded polyaniline (PANI) nanofiber/multi-walled carbon nanotubes (MWCNT) composites were synthesized via interfacial polymerization of aniline with para-phenylenediamine functionalized MWCNT at the interface of oil/water system. Owing to the diffusion-controlled growth process of PANI, PANI with uniform fiber structure were obtained. The morphology analysis showed that the diameter of PANI nanofiber decreased with the increasing of MWCNT loading amount. Impedance analysis showed that the charge-transfer resistances of the composites were reduced also with the increasing of MWCNT loading amount. The decreasing of charge-transfer resistances and change of morphology resulted in enhanced capacitive properties. Electrochemical tests showed that the specific capacitance of PANI, PANI/MWCNT-10% and PANI/MWCNT-20% were 405, 641 and 764 F·g-1, respectively. As comparison with pure PANI nanofiber, the specific capacitance of the composites increased by 58% and 88.6%, respectively.

Helical hinges are common in transmembrane (TM) proteins. Hinging motions of TM helices are associated with the functional dynamics of many important membrane proteins such as various G-protein-coupled receptors and potassium channels. Although coarse-grained (CG) simulations are useful for studying membrane proteins, they are limited in describing accurately the hinge-related protein dynamics. In this study, we have overcome this limitation through a further development of the MARTINI CG model. The key improvement lies in implementation of additional local structural types and parameterization of the model against a structural library of TM helices obtained from the Protein Data Bank. Through simulations of 12 membrane proteins, we have demonstrated that the improved model not only accurately describes the local hinge structures of these proteins but also reproduces the overall structures of TM domains better than the original MARTINI is able to do. Furthermore, we show that the improved model, when combined with an elastic network, can now be used to explore the deactivation of the human β2 adrenergic receptor and the gating motions of the KcsA potassium channel. The important details of these hinge-associated transitions captured in our simulations agree well with previous experiments and all-atom simulations, and it was concluded that the improved model shows promise as a useful tool for the study of functional dynamics of membrane proteins.