Simple Synthesis of Amorphous NiWO₄ Nanostructure and Its Application as a Novel Cathode Material for Asymmetric Supercapacitors

This study reports a simple synthesis of amorphous nickel tungstate (NiWO₄) nanostructure and its application as a novel cathode material for supercapacitors. The effect of reaction temperature on the electrochemical properties of the NiWO₄ electrode was studied, and results demonstrate that the material synthesized at 70 °C (NiW-70) has shown the highest specific capacitance of 586.2 F g^–1 at 0.5 A g^–1 in a three-electrode system. To achieve a high energy density, a NiW-70//activated carbon asymmetric supercapacitor is successfully assembled by use of NiW-70 and activated carbon as the cathode and anode, respectively, and then, its electrochemical performance is characterized by cyclic voltammetry and galvanostatic charge–discharge measurements. The results show that the assembled asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a high specific capacitance of 71.1 F g^–1 at 0.25 A g^–1, which can deliver a maximum energy density of 25.3 Wh kg^–1 at a power density of 200 W kg^–1. Furthermore, this asymmetric supercapacitor also presented an excellent, long cycle life along with 91.4% specific capacitance being retained after 5000 consecutive times of cycling

Casein Phosphopeptide-Biofunctionalized Graphene Biocomposite for Hydroxyapatite Biomimetic Mineralization

Casein phosphopeptides (CPPs) with abundant phosphoserine clusters can mediate hydroxyapatite (HA) nucleation and growth. In this work, a new type of CPPs-biofuctionalized graphene composite was synthesized by amidation reaction between CPPs and carboxyalated graphene (CGO). When immersed in stimulated body fluid (1.5 × SBF) at 37 °C for different periods, the CPPs layer on the composite facilitated efficient interaction between the CGO surface and mineral ions, which promoted HA nanoparticle formation and shortened mineralization time in comparison with pristine CGO. The synthesis of the composite mimicked the natural biomineralization of bone, demonstrating that CPPs can effectively improve the bioactivity of graphene and be useful for HA formation. The presented biocomposite may have potential biomedical applications in different areas