Facile one-pot synthesis of 3D graphite–SiO2 composite foam for negative resistance devices

Abstract

In this study, we successfully prepare a porous graphite–SiO₂ composite foam via a facile glucose-foaming-based method. The foam was characterized by XRD, XPS, SEM, Raman, and soft X-ray absorption spectroscopy of the carbon and oxygen K-edges and by silicon K-edge X-ray absorption near edge structure (XANES) spectroscopy. The electrical properties of the sample were evaluated using current–voltage measurements. The synthesized graphite–SiO₂ composite foam showed negative resistance effect, i.e. an increase in the applied voltage led to a decrease in current. This negative resistance effect can be explained by two possible mechanisms: (1) the existence of defect states and (2) a change in the charge shifting amount.