New insights into the structure-property relation in ZnCo2O4 nanowire and nanosheet arrays

Fractal geometry is a powerful and novel tool for material characterization, but it has been rarely applied in the field of electrochemistry. In this contribution, the structure-property relation in the ZnCo2O4 nanowire and nanosheet arrays was initially investigated with the aid of fractal geometry. The fractal properties of ZnCo2O4 were explored by scanning electron microscopy imaging and nitrogen adsorption analysis. It was found that ZnCo2O4 nanosheet arrays exhibited lower inner fractal dimension but higher surface fractal dimension than nanowire arrays, revealing their complex microstructures. The better Na-ion storage capacity of ZnCo2O4 nanosheet arrays recorded thereafter confirmed that the reactions involved were surface-dominated processes. Further kinetic analysis of the electrochemistry was conducted, and the outcomes obtained were also in well accordance with those from fractal analysis. As a result, the employment of fractal geometry had led to new dimension of understanding the relationship between microstructure and electrochemical properties of ZnCo2O4.