▎ 摘　　要

A facile hydrothermal strategy to synthesize borate cross-linked reduced graphene oxide (B-RGO) sheets with good optical and electrical properties is proposed by using graphene oxide (GO) sheets, boric acid and sodium hydroxide as precursors in one pot without any polymer or surfactant. The resulting B-RGO sheets can be assembled into a highly conductive B-RGO paper by simple filtration. Moreover, the atomic percentage of boron (B) in the B-RGO sheet can be readily controlled, as when it reaches to a maximum of 3.33 at%, about 30.0 mA current passes through the resulting single-layer B-RGO sheet and B-RGO paper at an applied bias of 2.0 V. This current value is much higher than that of the annealed GO paper (similar to 1.2 mA) and very close to that of the single-layer graphene sheet (similar to 60.0 mA) synthesized by a chemical vapour deposition method under the same test conditions. The resulting highly conductive B-RGO sheet and B-RGO paper offer a promising transparent conductive material for electronic or optoelectronic applications.