Hierarchical growth of nickel oxyhydroxide on bacterial cellulose hydrogel: role of water channels in hydrogel to form hierarchical structure

Abstract

Bacterial cellulose (BC) hydrogel was used as a three‐dimensional scaffold for the hierarchical formation of nickel oxyhydroxide (NiOOH). The formation was completed, without the need of any external energy utilization, special apparatus, and surface modification at room temperature. A solution‐process method is utilized through controlled reaction conditions. The proposed mechanism ascribed that the abundant water channels in the BC hydrogel play a pivotal role in the formation of hierarchical NiOOH nanocoating on individual fiber while preserving the open three‐dimensional structures of BC. The composite structures in both hydrogel and freeze‐dried forms were compared using optical microscopy, scanning electron microscopy, and powder X‐ray diffractions. Furthermore, the formation mechanism was explained on the basis of spectroscopy analysis. As a final step, the formed aerogels (BC‐NiOOH) were annealed at 300°C for a particular time to transform NiOOH to hierarchical nickel oxide (NiO) on the surface of BC without any structural deformation.