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Abstract: Uniform and conformal coating of ultrathin molybdenum oxide (MoO3) thin film onto conducting MWCNTs was successfully synthesized through a facile, nontoxic and generally applicable precipitation method, followed by a simple heat treatment. The ultrathin MoO3 coating enables a fast and reversible redox reaction which improves the specific capacitance by utilizing the maximum number of active sites for the redox reaction, while the high porosity of the MWCNTs facilitates ion migration in the electrolyte and shorten the ion diffusion path. The ultrathin MoO3 coated MWCNTs electrodes show a very high specific capacitance of 1145 Fg−1 in 2M Na2SO4 aqueous solution when 5nm thick MoO3 was considered alone despite the low weight percentage of the MoO3 (16wt%). Furthermore, the ultrathin MoO3 coated MWCNTs supercapacitor electrodes exhibited excellent cycling performance of>97% capacitance retention over 1000 cycles. [Copyright &y& Elsevier]

Abstract: Tin oxide coated molybdenum oxide nanowires (SnO2/MoO3) are synthesized by a combination of hydrothermal and wet chemical routes. The electrochemical capacitance properties of the SnO2/MoO3 core shell composite nanowires are measured by cyclic voltammetry (CV) and galvanostatic charge–discharge method in 1M Na2SO4 aqueous solutions. The results showed that specific capacitance of SnO2/MoO3 core shell composite nanowires is 295Fg−1, which is much higher than the specific capacitance of pure individual MoO3 (69Fg−1) and SnO2 (96.6Fg−1). Moreover the synthesized core shell composite nanowires has also exhibited excellent long-term cycling stability (only 3% loss of its initial specific capacitance after 1000 cycles) which may lead to its multifarious usage in high-performance energy storage devices for future potential applications. [Copyright &y& Elsevier]

An efficient electrochemical urea oxidation reaction (UOR) could be used in energy production technology. Metallic nickel nano-particles (Ni NPs) are incorporated in cobalt hydroxide layered material to form Ni/Co(OH) 2. The synthesized material is utilized as an electrocatalyst in UOR. It has been revealed that the incorporation of Ni NPs into cobalt hydroxide significantly enhances their electrocatalytic activity toward UOR. Ni/Co(OH) 2 catalyzes UOR at a very low anodic potential of 1.15 V vs RHE with a peak current density of 14.2 mAcm−2 and Tafel slope of 75 mVdec−1. The current work is a step ahead towards use of transition metal hydroxide (TMH) as support in the electrocatalytic oxidation applications especially UOR. [ABSTRACT FROM AUTHOR]

Abstract The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction is a priority research area. Metal-organic frameworks (MOFs) have recently captured attention as heterogeneous water oxidation catalysts. In spite of their robustness and stability under specific pH conditions, the relatively low current density achieved is their main drawback. Herein, we explored a cobalt based framework [Co(bpy)(fa)] n (DMF) 0.25 (bpy) 0.25 (1) {bpy = 4,4ʹ-bipyridine, fa = fumarate, DMF = dimethylformamide} as an efficient electrocatalyst for the water oxidation reaction. Compound 1 exhibits excellent activity in a neutral phosphate buffer solution. Chronoamperometric studies show that 1 offers a current density of 10 mA cm−2 at only η = 382 mV. Onset over-potential of 248 mV is observed which holds a Tafel slope value of 84 mV dec−1. The catalyst showed a turnover frequency (TOF) of 2 × 10−3 s−1 for oxygen evolution reaction (OER) at 289 mV. Detailed electrochemical studies, including long-term electrolysis, indicates the potential of compound 1 to be utilized as heterogeneous catalyst toward the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

A ternary nanocomposite of molybdenum trioxide (α-MoO 3 ) nanowires coated with a thin layer of carbon, which is intertwined with graphene oxide is synthesized by hydrothermal and ultrasonication route. It is found that high conductivity of carbon coated MoO 3 nanowires is further increased by introducing the graphene sheets. The ternary nanocomposite (rGO/MoO 3 @C) exhibits high specific capacitance, excellent cyclic stability compared to the carbon coated MoO 3 (MoO 3 @C) and virginal MoO 3 nanowires due to the synergistic effect of carbon layer and graphene. The electrochemical impedance measurements show that rGO/MoO 3 @C nanocomposite have lower charge transfer resistance as compared to MoO 3 @C and MoO 3 nanowires electrodes. Two probe electrical conductivity ( I–V ) measurements confirm the enhanced conductivity of rGO/MoO 3 @C nanocomposite relative to MoO 3 @C and bare MoO 3 nanowires. The electrical and electrochemical measurements indicate that the rGO/MoO 3 @C nanocomposite is promising candidate for energy storage applications. [ABSTRACT FROM AUTHOR]

Novel graphitic material containing chromium oxide (Cr 2 O 3 ) nanoribbons is obtained by carbonizing a mixture of polyfurfuryl alcohol and MIL–101(Cr) at 900 °C. Morphological, structural, and chemical analysis of the product is carried out with HR–TEM, SEM, XPS, XRD, and BET surface area. The maximum BET surface area recorded for the nanocomposite is 438 m 2 g −1 . The nanocomposite exhibits a specific capacitance as high as 300 F g −1 at 2 mV s −1 and 291 F g −1 at 0.25 A g −1 , and presents 95.5% long–term cycling stability over 3000 cycles. The pseudo-capacitive role of Cr 2 O 3 nanoribbons is found to be important towards total capacitance of nanocomposite material. [ABSTRACT FROM AUTHOR]

High specific capacitance coupled with the ease of large scale production is two desirable characteristics of a potential pseudo-supercapacitor material. In the current study, the uniform and conformal coating of nickel-cobalt layered double hydroxides (CoNi0.5LDH,) nanoflakes on fibrous carbon (FC) cloth has been achieved through cost-effective and scalable chemical precipitation method, followed by a simple heat treatment step. The conformally coated CoNi0.5LDH/FC electrode showed 1.5 times greater specific capacitance compared to the electrodes prepared by conventional non-conformal (drop casting) method of depositing CoNi0.5LDH powder on the carbon microfibers (1938 Fg-1 vs 1292 Fg-1). Further comparison of conformally and non-conformally coated CoNi0.5LDH electrodes showed the rate capability of 79%: 43% capacity retention at 50 Ag- 1 and cycling stability 4.6%: 27.9% loss after 3000 cycles respectively. The superior performance of the conformally coated CoNi0.5LDH is mainly due to the reduced internal resistance and fast ionic mobility between electrodes as compared to non-conformally coated electrodes which is evidenced by EIS and CV studies. [ABSTRACT FROM AUTHOR]

Abstract: Ultrathin nanoflakes of Ni(OH)2 were synthesized onto multi-walled carbon nanotubes (MWCNTs) by simple low cost chemically precipitation method for high performance electrochemical supercapacitor applications. The synthesized ultrathin Ni(OH)2 exhibit high specific capacitance of 1735Fg−1 at a scan rate of 5mVs−1 with excellent rate capability. This high performance of Ni(OH)2 nanoflakes was attributed to its complete accessibility to the electrolyte and maximum utilization of metal hydroxides. Findings of this work suggest that synthesized electrodes offer low-cost and scalable solution for high-performance energy storage devices. [Copyright &y& Elsevier]