A first-principles study on the improved formaldehyde gas-sensing performance of Ni-doped ZnSnO₃

The ZnSnO3 and Ni-doped ZnSnO3 gas sensors have gained significant attention due to their high sensitivity in detecting hazardous gases, but the sensing mechanism for formaldehyde is still unclear. This study systematically analyzes the gas adsorption properties of ZnSnO3 and Ni-doped ZnSnO3 using first-principles calculations, focusing on structural characteristics, charge transfer, and band structure. The results show that Ni doping significantly enhances the formaldehyde adsorption capacity of ZnSnO3. This enhancement is attributed to a reduction in formation energy, increased electron mobility, and a narrower band gap, all of which improve conductivity and response speed. Calculations of the Density of States (DOS) and Projected Density of States (PDOS) show that the charge-transfer rate of Ni-doped ZnSnO3 is affected by formaldehyde adsorption, suggesting a chemisorption process. Additionally, frontier orbital theory calculations show that Ni doping has a minimal impact on the electronic structure of ZnSnO3 but reduces the band gap, thereby enhancing reactivity. In conclusion, Ni doping enhances the gas-sensing performance of ZnSnO3, especially for formaldehyde detection.