Low coordination states in Co3O4/NiOx heterostructures by atomic layer deposition for enhanced gas detection

•NiO/Co3O4 nanoparticles are synthesized by atomic layer deposition (ALD).•Low coordination atoms are created in NiO/Co3O4 nanoparticles.•Oxygen vacancies are regulated by optimizing the NiO ALD cycles.•The NiO/Co3O4 sensor shows improved response for triethylamine detection. Oxygen vacancy is crucial to modulate the electronic structure and chemical properties of functional materials. However, a general and elegant method that is capable of manipulating the surface defects of materials is still missing. Herein, we propose an efficient strategy based on atomic layer deposition (ALD) to create low coordination atomic states in Co3O4/NiOx heterostructures, which allows for controllable regulation of oxygen vacancies, as well as the electronic and band structure of the materials. Consequently, the sensor device based on optimized Co3O4/NiOx sensing layer exhibits significantly enhanced performance to detect triethylamine (TEA) compared to pristine Co3O4, including lower operating temperature, higher sensitivity and lower limit of detection. Considering the generality of the ALD process, the proposed strategy is expected to be useful to design efficient nanomaterials for surface-oriented applications.