Silk Fibroin-Regulated Biomimetic Mineralization of Ni(OH)2 for Energy Storage Applications

Understanding and controlling biomimetic hybrid materials is essential to obtain novel hierarchical structures and expand the range of potential applications. Here, the biomineralization approach was applied as a rational integration method of silk fibroin and nickel hydroxide. Under protein-directed self-assembly conditions, hollow structures of hierarchical hybrid nickel hydroxide microflowers were systematically formed due to structural disorders such as stacking faults. Notably, the uniform, well-dispersed, and tunable morphology of biomineralized hybrid nickel hydroxides hollow microflowers is achieved by controlling the concentration of silk fibroin and nickel (II) chloride. The effects of organic solvents and nickel precursors on the morphology of nickel hydroxides were also elucidated. The fibroin/Ni(OH) ₂ hybrid material exhibits good charge storage performance, rate capability, proton diffusion coefficient, and outstanding cyclic stability owing to its high ionic conductivity and the presence of β-sheet crystallites.