A New Facile Synthesis of Tungsten Oxide from Tungsten Disulfide: Structure Dependent Supercapacitor and Negative Differential Resistance Properties

Tungsten oxide (WO₃) is an emerging 2D nanomaterial possessing unique physicochemical properties extending a wide spectrum of novel applications which are limited due to lack of efficient synthesis of high‐quality WO₃. Here, a facile new synthetic method of forming WO₃ from tungsten sulfide, WS₂ is reported. Spectroscopic, microscopic, and X‐ray studies indicate formation of flower like aggregated nanosized WO₃ plates of highly crystalline cubic phase via intermediate orthorhombic tungstite, WO_3.H₂O phase. The charge storage ability of WO₃ is extremely high (508 F g^?1 at current density of 1 A g^?1) at negative potential range compared to tungstite (194 F g^?1 at 1 A g^?1). Moreover, high (97%) capacity retention after 1000 cycles and capacitive charge storage nature of WO₃ electrode suggest its supremacy as a negative electrode of supercapacitors. The asymmetric supercapacitor, based on the WO₃ as a negative electrode and mildly reduced graphene oxide as a positive electrode, manifests high energy density of 218.3 mWhm^?2 at power density 1750 mWm^?2, and exceptionally high power density, 17 500 mW m^?2, with energy density of 121.5 mWh m^?2. Furthermore, the negative differential resistance (NDR) property of both WO₃ and WO₃.H₂O are reported for the first time and NDR is explained with density of state approach.