Highly Conductive Few‐Layer Graphene/Al 2 O 3 Nanocomposites with Tunable Charge Carrier Type

An ex situ strategy for fabrication of graphene oxide (GO)/metal oxide hybrids without assistance of surfactant is introduced. Guided by this strategy, GO/Al 2 O 3 hybrids are fabricated by two kinds of titration methods in which GO and Al 2 O 3 colloids are utilized as titrant for hybrids of low and high GO content respectively. After sintered by spark plasma sintering, few‐layer graphene (FG)/Al 2 O 3 nanocomposites are obtained and GO is well reduced to FG simultaneously. A percolation threshold as low as 0.38 vol.% is achieved and the electrical conductivity surpasses 10 3 Sm −1 when FG content is only 2.35 vol.% in FG/Al 2 O 3 composite, revealing the homogeneous dispersion and high quality of as‐prepared FG. Furthermore, it is found that the charge carrier type changes from p‐ to n‐type as graphene content becomes higher. It is deduced that this conversion is related to the doping effect induced by Al 2 O 3 matrix and is thickness‐dependent with respect to FG.