Synthesis of rational nanostructure design of hybrid materials including uniformly growing, stable and highly porous structures have received a great deal of attention for many energy storage applications. In this study, the positive electrode of the uniform distribution of NiCo 2 O 4 nanorods anchored on carbon nanofibers has been successfully prepared by in-situ growth under the hydrothermal process. Whereas, the activated multichannel carbon nanofibers (AMCNFs) have been fabricated via electrospinning followed by alkaline activation as the negative electrode. The crystal phase, morphological structure for the proposed electrode materials were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, the electrochemical behaviors were investigated using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Compared to the neat CNFs and the pristine NiCo 2 O 4 , the NiCo 2 O 4 @CNFs hybrid electrodes showed better electrochemical performance and achieved a high specific capacitance up to 649 F g −1 at a current density of 3 A g −1 . The optimized NiCo 2 O 4 @CNFs//AMCNFs asymmetric device achieved a high energy density of 38.5 Wh kg −1 with a power density of 1.6 kW kg −1 and possessed excellent recyclability with 93.1% capacitance retention over 6000 charging/discharging cycles. Overall, the proposed study introduces a facile strategy for the robust design of hybrid structured as effective nanomaterials based electrode for high-performance electrochemical supercapacitors.

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Thin films from copper sulfide (CuxS) are the most commonly used electrocatalyst counter electrodes (CEs) for high-efficiency quantum dot sensitized solar cells (QDSSCs) because of its superior electrocatalytic activity in the presence of polysulfide electrolytes. In addition to the stability issues, the CuxS CEs are usually prepared by complicated, costly, time consuming, and less productive methods, which are inadequate for practical applications of QDSSCs. In this work, we present a simple approach for fabricating an efficient and stable CE for QDSSCs using pure covellite phase CuS nanoparticles (NPs) pre-prepared via a cheap, fast, and scalable chemical method. The catalyst ink was obtained by mixing the as-prepared CuS NPs with polyvinylidene fluoride, as a polymeric binder, which was then directly applied to a conductive fluorine-doped tin oxide substrate without any further high temperature post treatment. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization measurements were used to investigate the electrocatalytic activity of the CuS NPs CE. The power conversion efficiency of 2.6% was achieved from CdS QDSSC assembled with CuS NPs CE, which was higher than 1.57% for conventional Cu2S/brass and 1.33% for Pt CEs under one-sun illumination. The CdS QDSSC with CuS NPs CE was also able to supply a constant photocurrent value without any obvious decrease under light soaking test, in contrast to the devices with Cu2S/brass and Pt CEs, which showed inferior stability. This remarkable photovoltaic performance was attributed to the nanoporous morphology and the excellent electrocatalytic activity of CuS NPs CE.

Polyaniline (PANI) is a potential candidate for n‐type thermoelectric (TE) materials owing to its intrinsic electrical conductivity, low thermal conductivity, and facile synthesis techniques. However, its low Seebeck coefficient and power factor have limited its widespread usage. In this study, nitrogen‐doped, and sulfur‐nitrogen co‐doped reduced graphene oxide (rGO) were used for tuning the TE properties of PANI. Doped rGO and PANI/doped‐rGO nanocomposites were prepared via hydrothermal technique and chemical oxidative polymerization respectively and thereafter characterized. The TE properties of the nanocomposites were also studied and an optimized Seebeck coefficient, power factor and zT value of −1.75 mV K−1, 95 μW m−1 K−2 and 0.06, respectively were reported for the PANI nanocomposite containing 1 wt% sulfur‐nitrogen co‐doped rGO. These results suggest that PANI/heteroatom‐doped rGO can serve as promising candidates for n‐type based TE applications.

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