Tuning the Nanoparticle Interfacial Properties and Stability of the Core–Shell Structure in Zn-Doped NiMoO₄@AWO₄

The ability to tune the interfacial region in core–shell nanocomposites with a surface reconstruction as a source for surface energy (de)stabilization is presented. We consider Zn-doped nickel molybdate (NiMoO4) (ZNM) as a core crystal structure and AWO4 (A = Co or Mg) as a shell surface. Based on the density-functional theory method, the interfacial models of Zn-doped NiMoO4@AWO4 (ZNM@AW) core@shell structures are simulated and revealed to undergo surface reconstruction on the (−110) and (−202) surfaces of the AW shells, where the surface degradation of ZNM@MW(−110) is observed. The theoretical simulation is validated against the electrochemical performance of supercapacitor studies. To verify, we synthesize the hierarchical ZNM@AW core@shell semiconductor structured nanocomposites grown on a nickel foam conductive substrate using a facile and green two-step hydrothermal method. The morphology and chemical and electrochemical properties of the hierarchically structured nanocomposites are characterized in detail. The performance of the core@shell is significantly affected by the chosen intrinsic properties of metal oxides and exhibited high performance compared to a single-component system in supercapacitors. The proposed asymmetric device, Zn-doped NiMoO4@CoWO4 (ZNM@CW)||activated carbon, exhibits a superior pseudo-capacitance, delivering a high areal capacitance of 0.892 F cm–2 at a current density of 2 mA cm–2 and an excellent cycling stability of 96% retention of its initial capacitance after 1000 charge–discharge cycles. These fundamental theoretical and experimental insights with the extent of the surface reconstruction sufficiently explain the storage properties of the studied materials.