▎ 摘　　要

We report a facile and environmentally benign approach to fabricate Co3O4 nanoparticles (NPs)/graphene oxide (G-O) composites by the use of supercritical fluid. With the aid of supercritical carbon dioxide, the ultrafine Co3O4 NPs are densely and homogeneously deposited on the supporting G-O sheets. Transmission electron microscope images revealed that the average size of Co3O4 NPs in Co3O4/G-O composites was 5.9 nm, much smaller than that of bare Co3O4 NPs, indicating that the graphene oxide sheets with Co3O4 NPs attached could hinder the growth and aggregation of Co3O4 crystals during synthesis. The layered graphite oxide sheets are exfoliated by the nucleation and growth of Co3O4 NPs. The composites exhibit a special catalytic effect for the thermal decomposition of ammonium perchlorate due to the combination of G-O sheets and Co3O4 NPs. This supercritical fluid method could be further extended to synthesize other G-O or graphene-based metal oxide composites using appropriate metal precursors.