With the increasing demand, synthesis of controllable morphology inorganic materials has been predicted for material science research owing to their primal optical, electrical and catalytic properties. The morphology has outstanding performance in several applications including electronics, catalysis, bio-sensing and energy storage. In particular 3D architecture, metal oxide was synthesized through bottom-up approach such as flower-like ZnO, Iron oxide film, cobalt oxide microstructure, NiCoO nanoneedles, a-MnMoO4 hierarchical architectures. Based on morphology, metal oxide have dramatic output in the field of application such as controlled morphology flower-like NiCo2O4 delivered higher specific capacitance compare to nanowires. Therefore, the focus on the material science research has inclined to engineering controllable morphology in order to boost efficiency in application field. However, the controlling morphology of inorganic materials requires intricate technique such as templet assisted, hydrothermal and sol-gel process. By observing high synthesis temperature and introducing surfactants amount as well as long process material preparation, the crystallinity and grain sizes may hinder while hydrothermal or sol-gel methods. Nevertheless, research of amiable and facile synthesis method for the construction of inorganic 3D flower-like inextricable structures without any surfactant and demanding construction along with mechanisms remain challenges in material science.
Recently, transition metal tungstate MWO4: M = bivalent (Ca, Ba, Mn, Co, Ni….etc.) have been sharply jumped in various application because of their extraordinary electronic, magnetic and catalytic properties. The MWO4 exist in tetragonal scheelite structure space group: I41/a, with Z = 4 and monoclinic wolframite structure space group: P2/c, with Z= 2, depends on M size. In the case of wolframite type structure, the divalent metal radii are smaller than 0.77 A (Mg2+, Fe2+, Co2+, Ni2+, and Zn2+). On the contrary, Scheelite type structure has greater ionic metals radius (0.77 A), the metal ion is as follow Ba2+, Ca2+, Sr2+, and Pb2+, where W atoms have six-fold coordination. Although there is an ample number of a report on wolframite structure metal tungstates such as MnWO4, FeWO4, CoWO4, NiWO4, and ZnWO4. Among them, a monoclinic wolframite structure nickel tungsten oxide (NiWO4) has remarkable attention owing to its widespread physicochemical properties. It has been reported in photocatalytic, supercapacitor, bio-sensor and in the electro-catalytic field. As stated in some previous report, the NiWO4 nano/microstructure including nano-bricks, fibers, nano-nests, and nanospheres was prepared through hydrothermal, solvothermal, electrospinning and solid-state reaction method for numerous application. For example, Shivakumar Mani et al successfully synthesized NiWO4 microcrystals completed octahedron structure by hydrothermal method, have stimulated excessive interest and significant bio-sensing activity towards glucose sensing. Shareen Fatima Anis et al reported electrospun NiWO4 composite fibers has good electrocatalyst hydrogen evolution performance compared with other metal oxide materials. Lengyuan Niu et al have studied asymmetric supercapacitor on NiWO4 nanostructure, have comparable electrochemical performance.
In this regards, surfactant-free self-growth assembly of the 3D NiWO4 may offer significant tool. This 3D flower-like structure of metal oxide have molded through continuous growth and Ostwald ripening, have shown significant electrochemical properties. Accordingly, we have reported an easy route chemical reduction method for the synthesis of 3D-NiWO4 micro flowers in an aqueous medium. Our optimization experimental condition have tuned the morphology evolution including nanoparticles, sheet, and micro flower. Therefore after analysis these critical issues, our aim to engineering controllable morphology of NiWO4 in 3D structure. We also elucidated growth mechanism and characterized as synthesized NiWO4 in detail by several techniques. In addition, the 3D NiWO4 microstructure has been applied to study electrochemical property for non-enzymatic glucose detection application.