Interfacial Self-Assembly of Silk Fibroin Polypeptides and α-NiCo(OH)₂ Nanocrystals with Tunable Energy Storage Applications

There is an increasing interest in the self-assembly process from a bottom-up approach to synthesize functional structures for engineering applications. Silk fibroin is a protein extracted from the cocoons of silkworm Bombyx mori that can be processed into various materials generally stabilized by the induction of β-sheet formation through the use of solvents or by physical stretching. In our study, the introduction of cobalt-substituted nickel hydroxide nanoparticles on silk fibroin presented a dual effect causing the stabilization of the α polymorph of nickel hydroxide and promoting a highly connected network of the β-sheet crystalline domain in the fibroin chains. Electrochemical measurements were performed to examine silk fibroin (SF)/NiCo(OH)2 hybrid materials. The optimized sample exhibits a high specific capacity of 362 mA h g–1 at a current density of 1 A g–1, maintaining steady electrochemical performance >75% of the initial value at higher current densities. The presented assembly provides a route for preparing monodisperse inorganic nanoparticles in the presence of SF as an organic matrix with potential energy storage properties.