V2O5@RuO2 core–shell heterojunction nano-arrays as electrode material for supercapacitors

Abstract

V2O5 nanobelt arrays (VNBs) are directly synthesized on porous nickel as the primary structure, and then the VNBs are completely covered by RuO2 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.