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Due to the numerous challenges related to selectivity, sensitivity, stability, and operation at standard room temperature, improving the environmental detection of nitrogen oxide presents a considerable defy in the development of novel promising structures in chemical detection. In this study, a new series of p‐type heterojunction nanocomposites based on electrodeposited polypyrrole (PPy) doped with n‐dodecylbenzene sulphonate and either reduced graphene oxide (PPy/RedGO) or reduced graphene oxide functionalized using aryl 4‐carboxybenzene diazonium salt (PPy/RedGO‐arylCOOH) was synthetized using a one‐step chronoamperometric process. The influence of functionalized graphene incorporation on the structural, morphological, and sensory performances of the PPy film was investigated. Its sensitivity and reactivity to NO2 sensing were studied. The structural data confirms that PPy/RedGO‐arylCOOH film is a homogeneous nanocomposite with improved crystalline ordering. It shows optimal NO2 sensing properties compared to the PPy/RedGO composite in terms of sensitivity (0.87 ppm−1), detection limit (2 ppm), response time of 29 s, recovery time of 40 s and reproducibility at room temperature. [ABSTRACT FROM AUTHOR]

Due to the difficult access of the electrolyte into the nanoconfined space of nanoporous reduced graphene oxide (rGO) electrodes, achieving the optimal electrochemical performance of these devices becomes a challenge. In this work, the dynamics of interfacial‐governed phenomena are investigated during a voltage‐controlled electrochemical activation of nanoporous rGO electrodes that leads to an enhanced electrochemical performance in terms of areal capacitance and electrochemical impedance. In situ/operando characterization techniques are used to reveal the dynamics of the irreversible material changes introduced during the activation process, including ionic diffusion and water confinement within the nanopores, along with the reduction of oxygenated groups and the decrease of the rGO interlayer distance. Furthermore, operando techniques are used to uncover the origin of the complex polarization‐dependent dynamic response of rGO electrodes. The study reveals that the reversible protonation/deprotonation of remaining functional groups and the cation electro‐adsorption/desorption process in the graphene basal plane govern the pseudocapacitive performance of nanoporous rGO electrodes. This work brings new understanding of the complex interplay between surface chemistry, ion confinement, and desolvation processes occurring during electrochemical cycling in nanoporous rGO electrodes, offering new insights for designing high‐performing electrodes based on nanoporous rGO. [ABSTRACT FROM AUTHOR]

To boost the energy storage of microsupercapacitors (MSCs), a nanocomposite electrode combining carbonaceous materials with metal oxides was developed, i.e. combining capacitive and faradaic currents. Our method involves a one-step hydrothermal process, the initial components being graphene oxide, dopamine and Co2+ ions, resulting in a reduced graphene oxide–polydopamine–Co3O4 composite. Dopamine acts as a reducing agent and prevents graphene oxide agglomeration. Co2+ ions are expected to be chelated by polydopamine, likely leading to uniform dispersion of Co3O4 particles on the graphene surface. Using this composite as an active material, thin film electrodes were prepared, thoroughly characterized via various chemical techniques, and their electrochemical properties were tested in KOH. In situ electrochemical quartz crystal microbalance was used to elucidate the charge storage process, which showed the presence of a "point of maximum mass" separating a dominant anionic contribution due to the pseudocapacitive response of Co3O4 and a cationic contribution reflecting the electroadsorption/desorption of cations on the rGO surface. Lastly, we extended our study to the fabrication of a current collector-free microsupercapacitor device, composed of interdigitated rGO–PDA–Co3O4 electrodes, which demonstrates excellent cycling stability over 3000 cycles at a scan rate of 50 mV s−1 and remarkable energy density of 12.25 mW h cm−3 at a power density of 0.26 W cm−3. [ABSTRACT FROM AUTHOR]

Two BODIPY‐C60‐peptide assemblies were synthesized by CuAAC reactions of BODIPY‐C60 dyads and a helical peptide functionalized with a terminal alkyne group and an azide group, respectively. The helical peptide within these assemblies was functionalized at its other end by a disulfide group, allowing formation of self‐assembled monolayers (SAMs) on gold surfaces. Characterizations of these SAMs, as well as those of reference molecules (BODIPY‐C60‐alkyl, C60‐peptide and BODIPY‐peptide), were carried out by PM‐IRRAS and cyclic voltammetry. BODIPY‐C60‐peptide SAMs are more densely packed than BODIPY‐C60‐alkyl and BODIPY‐peptide based SAMs. These findings were attributed to the rigid peptide helical conformation along with peptide‐peptide and C60‐C60 interactions within the monolayers. However, less dense monolayers were obtained with the target assemblies compared to the C60‐peptide, as the BODIPY entity likely disrupts organization within the monolayers. Finally, electron transfer kinetics measurements by ultra‐fast electrochemistry experiments demonstrated that the helical peptide is a better electron mediator in comparison to alkyl chains. This property was exploited along with those of the BODIPY‐C60 dyads in a photo‐current generation experiment by converting the resulting excited and/or charge separated states from photo‐illumination of the dyad into electrical energy. [ABSTRACT FROM AUTHOR]

Herein, the development and the characterization of an all‐solid‐state symmetrical and current collector‐free microsupercapacitor based on a new reduced graphene oxide‐polydopamine (rGO‐PDA) composite are reported. The rGO‐PDA composite is synthesized by a facile, eco‐friendly and scalable hydrothermal approach in the presence of dopamine which can not only contribute to the oxygen functional groups removal from graphene oxide but also polymerize onto the rGO sheets reducing their restacking and improving the wettability of the electrode. The optimized rGO‐PDA composite material exhibits excellent capacitance and cycling stability as well as an improved rate capability compared to the pristine rGO in Na2SO4 solution. This performance enhancement can be linked to the higher transfer kinetic and lower transfer resistance values of the ions involved in the charge storage process of rGO‐PDA, as determined by ac‐electrogravimetry. Furthermore, an all‐solid‐state microsupercapacitor was prepared employing the optimized rGO‐PDA composite as electrode material. Interdigitated electrodes were obtained thanks to a CO2 laser and a Na2SO4/PVA hydrogel was employed, no current collector was used. This device achieves a noteworthy energy density of 6.2 mWh ⋅ cm−3 at a power density of 0.22 W ⋅ cm−3. Moreover, it exhibits exceptional cycling stability, retaining 104 % of its initial capacity even after undergoing 10,000 cycles at 2 V ⋅ s−1. [ABSTRACT FROM AUTHOR]

The consistent rise in current density within electrical wires leads to progressively more substantial heat losses attributed to the Joule effect. Consequently, mitigating the electrical resistivity of copper wires becomes imperative. To attain this objective, the development of a composite material that incorporates a more conductive reinforcement, like graphene, holds great promise. The conception of a copper/graphene composite using a powder metallurgy-based approach is presented. An optimum graphene quantity of 0.06 vol.% was obtained by calculation in order to limit the phenomenon of overlapping layers. This synthesis technique enables the dispersion of graphene and the meticulous control of the interface through the growth of CuO(Cu) nanoparticles that are tightly bonded to the reinforcement. The increase in the hardness of the various materials with separation of the graphene sheets by ultrasonic treatment (55.3 to 67.6 HV) was obtained. It is an indicator of the correct distribution of the reinforcement. The influence on the electrical properties of dendritic copper (ρe = 2.30 µΩ.cm) remains limited, resulting in a modest reduction in electrical resistance of around 1.4%. Nevertheless, for flake copper (2.71 µΩ.cm) and brass (7.66 µΩ.cm), we achieved a more substantial reduction of 2.7% and 10%, respectively. With the improvement of graphene quality, there exists a greater potential for further enhancing the electrical properties. [ABSTRACT FROM AUTHOR]