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A honeycomb-like NiMoO4 nanoporous network electrode was synthesized on nickel foam using an electrodeposition method and used for the fabrication of asymmetric supercapacitors (ASCs). The growth process of the NiMoO4 nanostructure was controlled by varying the number of electrochemical cycles. The evolution of the NiMoO4 nanoflakes with the electrochemical cycles was confirmed by field emission scanning electron microscopy. The supercapacitive properties of NiMoO4 nanostructure were measured by cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy. The well-grown NiMoO4 nanoporous network exhibited a highest specific capacitance of 1475 F g−1 at a current density of 1 A g−1 in an aqueous KOH electrolyte with a good rate capability of 72.8% when the current density was increased 20 fold. The nanoporous network also exhibited a capacitive retention of 87.9% after 5000 charge–discharge cycles at a fixed current density of 20 A g−1. A NiMoO4//reduced graphene oxide (rGO)-based solid state ASC was fabricated using a poly(vinyl alcohol)–KOH gel electrolyte. The NiMoO4//rGO ASC delivered a maximum energy density of 45 W h kg−1 and a power density of 14.5 kW kg−1 as well as an electrochemical stability of 84% after 5000 cycles, highlighting the potential of NiMoO4//rGO ASCs for portable electronic applications. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper, the different modes of electrodeposition such as PD (potentiodynamic), PS (potentiostatic) and GS (galvanostatic) have been successfully employed for the deposition of cobalt oxide and subsequently the effect of these modes on supercapacitive performance has been studied. The films were characterized for structural and morphological properties using XRD (X–ray diffraction), FTIR (fourier transform infrared spectroscopy), FT–Raman spectroscopy and SEM (scanning electron microscopy). The electrochemical performance of the films was tested using cyclic voltammetry, galvanostatic charge-discharge and EIS (electrochemical impedance spectroscopy) techniques. The cobalt oxide film deposited by potentiostatic mode showed maximum values of specific capacitance, specific energy and specific power as 248 F g–1, 2.3 Wh kg−1 and 3.5 kW kg−1. [Copyright &y& Elsevier]

Tungsten oxide/bismuth vanadate (WO 3 /BiVO 4 ) has emerged as a promising photoanode material for photoelectrochemical (PEC) water splitting owing to its facilitated charge separation state differing significantly from single phase materials. Practical implementation of WO 3 /BiVO 4 is often limited by poor stability arising from the leaching of V 5+ from BiVO 4 during PEC operations. Herein, we demonstrate that the synthesis of a tungsten oxide/bismuth vanadate/titanium oxide (WO 3 /BiVO 4 /TiO 2 ) heterostructure onto a fluorine-doped tin oxide-coated glass substrate through a combined simple hydrothermal-spin coating strategy will advance PEC performance while slowing water oxidation kinetics and improving photostability. We show that surface postmodification with a nanometer-thick layer of (1 0 1) monofacet-selective single-crystalline TiO 2 provides stable photocurrent density, up to 1.04 mA cm -2 at 1.23 V (compared to a reversible hydrogen electrode in 0.5 M Na 2 SO 4 ), with excellent quantum efficiency (45% at 460 nm) and long-term photostability (24 h). Interestingly, crystalline TiO 2 activation layers behave differently from previous TiO 2 amorphous layers, blocking surface defects while improving corrosion resistance, photostability, and the electron transfer process. These results indicate a ≈2.5 times enhancement in photoelectrocatalytic activity related to referenced WO 3 /BiVO 4 photoanodes, encouraging the use of single-crystalline TiO 2 modulations to develop a range of materials for PEC/photocatalytic applications.