Enhanced Gas Sensing Performance Based On Crystal Facets Effect Of Co₃O₄ And Graphene Composite

P-type and N-type gas sensors based on metal oxide semiconductor（MOS）are widely used in various gas detection and identification fields.These sensors are not only sensitive,but also have the advantages of low cost and easy to use.The sensor material,the core part of gas sensor,affects the key performance of the sensor.In recent years,how to prepare high performance gas sensitive materials has become the research focus of researchers.In order to improve the gas-sensitive performance of MOS,from the perspective of the synergistic effect of crystal surface engineering and graphene composite,Co₃O₄nanocrystalline heterostructures coated with{112}and{100}crystal faces by two-dimensional reduced graphene oxide（r GO）nanosheet network were prepared by a simple hydrothermal reaction.The gas-sensitive properties of Co₃O₄/10%rGO heterostructures were investigated.It is found that Co₃O₄{112}crystal plane alone has significantly better triethylamine sensing performance than{100}crystal plane,showing obvious crystal plane effect.Further studies show that the triethylamine sensing performance of Co₃O₄{112}crystal surface is further improved after r GO modification.On this basis,the gas-sensitive stability,selectivity and other properties of Co₃O₄/10%r GO nanoheterojunction materials were systematically studied.We further investigate the gas-sensitive mechanism of the heterojunction by first principles calculation.We found that the Co₃O₄{112}crystal plane contains more active Co³⁺vacancies and chemisorbed oxygen vacancies than the{100}crystal plane,thus promoting the adsorption of triethylamine and the subsequent sensing reaction.In addition,strong electrons between the Co₃O₄{112}crystal plane and rGO interact through the heterogeneous interface to promote effective charge transfer,further improving the sensing performance.This paper not only provides a new way to improve the gas-sensitive performance of Co₃O₄,but also deepens the understanding of the crystal face effect of MOS gas sensor and the interaction of heterogeneous interfaces in MOS/graphene heterogeneous structures.This provides a new research idea for the development of gas sensors,and will contribute to the further design of high performance gas sensors based on MOS.