Co3O4 Hollow Nanosphere-Decorated Graphene Sheets for H2S Sensing near Room Temperature

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 °C, which is 3.3 times that of pristine Co3O4 (92 °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 °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.