▎ 摘　　要

Small-sized Co3O4 hollow nanosphere/graphene (Co3O4-HNS/G) composites are fabricated via a cross-linking deposition. The Co3O4 hollow nanospheres with a diameter of around 15 nm are well-distributed on graphene sheets. The sensor based on the Co3O4-HNS/G (the optimal graphene content is 4.6 wt %) composite exhibits an excellent sensing response (30.6) to 50 ppm of H2S near room temperature of 50 degrees C, which is 3.3 times that of pristine Co3O4 (92 degrees C). The lowest H2S gas concentration that can be detected is 0.1 ppm. The composite-based sensor also shows excellent long-term stability, selectivity, and repeatability to H2S at 50 degrees C. The improved H2S-sensing properties may be attributed to a synergistic effect of unique small-sized Co3O4 mesoporous hollow nanosphere structures, large specific surface area, more chemically adsorbed oxygen, and isotype P-P heterojunctions.