Co-MOF-74 derived Co3O4/graphene heterojunction nanoscrolls for ppb-level acetone detection

For the first time, Co-MOF-74 derived Co3O4/graphene heterojunction nanoscrolls (Co3O4/GNS) structure is synthesized by a simple one-step hydrothermal strategy and subsequent calcination process. Theoretically, the growth mechanism of Co3O4/GNS is revealed by molecular dynamic simulation, demonstrating that a high loading of Co-MOF-74 nanoparticles is needed for effective rolling of GO. The sensor based on Co3O4/GNS exhibits high response of 58.1 (34-fold enhancement compared with that of Co3O4), short response/recovery time of 12 s/66 s (157 s/200 s for Co3O4) toward 1 ppm acetone at 190 degrees C and superior selectivity, which are much better than those of most reported acetone sensors. Moreover, the Co3O4/GNS can even detect as low as 50 ppb acetone with a notable response (1.24). The appreciable response together with rapid response/recovery of Co3O4/GNS is attributed to the large heterojunction interface between Co3O4 and graphene nanoscroll and high-speed gas transfer pathways provided by nanoscroll. This unique structure design is believed to offer guidance for generalizable synthesis of metal oxide/GNS that can be effectively applied in the fields of ppb-level gas detection.