Effect of exposed facet determined the room-temperature ammonia gas sensing of Cu2O nanoparticles

Cu2O nanoparticles have received extensive attention due to their superior gas sensing properties, but the effect of their exposed crystal facet on gas interaction has not been studied. Here, Cu2O concave octahedrons, do-decahedrons, and cubes with different exposed crystal facets were synthesized based on a simple hydrothermal reaction, and ammonia gas sensing experiments showed that the Cu2O concave octahedron responded to 10 ppm ammonia gas by 5.29 and 1.40 times that of dodecahedron and cubes, respectively. Ammonia gas adsorption calculations based on density functional theory revealed significant differences in the gas interactions between different exposed crystal facets of Cu2O, confirming the positive effect of the high-index facet {511} of Cu2O on ammonia gas sensing. This work not only shows the great potential of Cu2O concave octahedron as a room temperature ammonia gas sensing material, but also discusses the intrinsic relationship between the exposed crystal facet and the gas sensing performance of Cu2O nanoparticles for the first time, which is expected to provide a reference for the development of gas sensors based on metal oxide semiconductors.