  In this chapter, semi-analytical models for the calculation of the quantum
capacitance of both monolayer and bilayer graphene and its nanoribbons, are
presented. Since electron-hole puddles are experimental facts in all graphene
samples, they have been incorporated in our calculations. The temperature
dependence of the quantum capacitance around the charge neutrality point is
also investigated and the obtained results are in agreement with many features
recently observed in quantum capacitance measurements on both monolayer and
bilayer graphene devices. Furtheremore, the impact of finite-size and edge
effects on the quantum capacitance of graphene nanoribbons is studied taking
into account both the edge bond relaxation and third-nearest-neighbour
interaction in the band structure of GNRs.
