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V 2 O 5 nanobelt arrays (VNBAs) is fabricated on Ni foam by using an easy hydrothermal route and then NiO nanosheet arrays (NNSAs) is grown on VNBAs by using a simple chemical bath deposition approach to form VNBAs/NNSAs composite. It is found that the monocrystalline VNBAs with a lamellar structure is uniformly distributed on nickel foam and the polystalline NNSAs with a close packed structure is closely covered on the VNBAs. CV, GCD, EIS and CA electrochemical techniques are used to test the supercapacitive properties of the VNBAs/NNSAs composite. The single electrode displays a high specific capacity of 875 F g−1, a good cycling stability of 96.1%, a small charge transfer resistance of 1.32 Ω and a rapid ion diffusivity of 2.5 × 10−8 cm2 s−1. The symmetric supercapacitor combined by the VNBAs/NNSAs displays a large energy density of 120.1 W h kg−1 at 400 W kg−1 and it retains 68.3 W h kg−1 at 8000 W kg−1. The VNBAs/NNSAs composite with high electrochemical performance is a potential supercapacitor electrode material. [Display omitted] • The V 2 O 5 nanobelt arrays (VNBAs) is successfully prepared on a nickel foam. • The NiO nanosheet arrays (NNSAs) is compounded on the VNBAs to form a hierarchy. • The VNBAs/NNSAs shows a high specific capacitance of 875 F g−1 at 5 mV s−1. • The VNBAs/NNSAs has an energy density of 120.1 W h kg−1 at 400 W kg−1. • The high performance of the VNBAs/NNSAs are ascribed to its synergistic effect. [ABSTRACT FROM AUTHOR]

Abstract We report a heterojunction composite of V 2 O 5 nanobelt arrays/TiO 2 nanoflake arrays grown directly on nickel foam. The morphology evolution and growth mechanism of TiO 2 nanoflake arrays on V 2 O 5 nanobelt arrays are investigated in detail. The heterojunction composite nano-arrays have a large specific capacitance of 587 F g−1 at a current density of 0.5 A g−1, a high coulombic efficiency (>92%), an excellent cycle stability (92%) after 5000 cycles and a low charge transfer resistance of 2.6 Ω. When the heterojunction composite nano-arrays are assembled into symmetric supercapacitor, the device shows a high energy density of 100.8 W h kg−1 at a power density of 399 W kg−1. The high supercapacitive performance is attributed to their direct growth on conductive current collector and the synergistic effect of V 2 O 5 and TiO 2. Graphical abstract Image 1 Highlights • V 2 O 5 nanobelt arrays (VNBs) is prepared directly on a nickel foam. • TiO 2 nanoflake arrays (TNFs) is prepared on VNBs to form a heterojunction. • The VNBs/TNFs shows a high specific capacitance of 587 F g−1 at 0.5 A g−1. • The VNBs/TNFs exhibits a high energy density of 100.8 W h kg−1 at 399 W kg−1. • The high performance of VNBs/TNFs is ascribed to their synergistic effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • V 2 O 5 nanobelt arrays@RuO 2 nanosheet arrays (VNBs@RNSs) is prepared on a nickel foam. • The VNBs@RNSs electrode shows a specific capacitance of 971F g−1 at 5 mV s−1. • The VNBs@RNSs supercapacitor has an energy density of 174.2 W h kg−1 at 450 W kg−1. • The cyclic steadiness of the supercapacitor is retained at 80.4% after 10,000 cycles. • The high performance of VNBs@RNSs is ascribed to their synergistic effect. V 2 O 5 nanobelt arrays (VNBs) are directly synthesized on porous nickel as the primary structure, and then the VNBs are completely covered by RuO 2 nanosheets (RNSs) as the secondary structure to create a core–shell heterojunction. The as-prepared VNBs@RNSs core–shell heterojunction is systematically researched through SEM, EDS, XRD, XPS and TEM, and the growth process is investigated in detail by sampling at different time. The VNBs@RNSs has a superb specific capacitive value of 971F g−1 at a voltage scanning speed of 5 mV s−1, a better cyclic steadiness of 80.4 % after recycling 10,000 times, a small charge transferring resistance value of 1.8 Ω and a fast effective diffusion coefficient of 1.01 × 10−8 cm2 s−1 calculated by CV, GCD, AC impedance and CA electrochemical techniques in a three-electrode testing system. A symmetrical electrochemical capacitor assembled by the as-prepared VNBs@RNSs electrode material has a superior energy density of 174.2 W h kg−1 at a power density of 450 W kg−1 and still retains 95.9 W h kg−1 at 9000 W kg−1 in a two-electrode testing system. The improved supercapacitive performance makes the VNBs@RNSs as a superior electrode material for supercapacitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • V 2 O 5 nanobelt arrays@RuO 2 nanosheet arrays (VNBs@RNSs) is prepared on a nickel foam. • The VNBs@RNSs electrode shows a specific capacitance of 971F g−1 at 5 mV s−1. • The VNBs@RNSs supercapacitor has an energy density of 174.2 W h kg−1 at 450 W kg−1. • The cyclic steadiness of the supercapacitor is retained at 80.4% after 10,000 cycles. • The high performance of VNBs@RNSs is ascribed to their synergistic effect. V 2 O 5 nanobelt arrays (VNBs) are directly synthesized on porous nickel as the primary structure, and then the VNBs are completely covered by RuO 2 nanosheets (RNSs) as the secondary structure to create a core–shell heterojunction. The as-prepared VNBs@RNSs core–shell heterojunction is systematically researched through SEM, EDS, XRD, XPS and TEM, and the growth process is investigated in detail by sampling at different time. The VNBs@RNSs has a superb specific capacitive value of 971F g−1 at a voltage scanning speed of 5 mV s−1, a better cyclic steadiness of 80.4 % after recycling 10,000 times, a small charge transferring resistance value of 1.8 Ω and a fast effective diffusion coefficient of 1.01 × 10−8 cm2 s−1 calculated by CV, GCD, AC impedance and CA electrochemical techniques in a three-electrode testing system. A symmetrical electrochemical capacitor assembled by the as-prepared VNBs@RNSs electrode material has a superior energy density of 174.2 W h kg−1 at a power density of 450 W kg−1 and still retains 95.9 W h kg−1 at 9000 W kg−1 in a two-electrode testing system. The improved supercapacitive performance makes the VNBs@RNSs as a superior electrode material for supercapacitor. [ABSTRACT FROM AUTHOR]