Promising supercapacitor electrodes based immobilization of proteins onto macroporous Ni foam materials

Abstract

Immobilizing biocomponents on solid surfaces is a critical step in the development of new devices for future biological, medical, and electronic applications. Therefore, numerous integrated films were recently developed by immobilizing different proteins or enzymes on electrode surfaces. In this work, hemeproteins were safely immobilized onto macroporous nickel-based electrodes while maintaining their functionality. Such modified electrodes showed interesting pseudo-capacitive behavior. Among hemeproteins, hemoglobin (Hb) film has a higher electrochemical performance and greater charge/discharge cycling stability than myoglobin (Mb) and cytochrome C (CytC). The heme group in an alkaline medium could induce the formation of superoxides on the electrode surface. These capacitive features of hemeprotein-Ni electrode were related to strong binding sites between hemeproteins and porous Ni electrode, the accumulation of superoxide or radicals on the Ni surface, and facile electron transfer and electrolyte diffusion through the three-dimensional macroporous network. Thus, these new protein-based supercapacitors have potential use in free-standing platform technology for the development of implantable energy-storage devices.