Graphene field-effect transistors: Electrochemical gating, interfacial capacitance, and biosensing applications

Single-layer graphene has received much attention because of its unique two-dimensional crystal structure and properties. In this review, we focus on the graphene devices in solution, and their properties that are relevant to chemical and biological applications. We will discuss their charge transport, controlled by electrochemical gates, interfacial and quantum capacitance, charged impurities, and surface potential distribution. The sensitive dependence of graphene charge transport on the surrounding environment points to their potential applications as ultrasensitive chemical sensors and biosensors. The interfacial and quantum capacitance studies are directly relevant to the on-going effort of creating graphene- ased ultracapacitors for energy storage.