Construction of ZnO/MnO2 heterostructure for enhanced ammonia sensitive performances at room temperature

ZnO/MnO₂ nanostructures, including nanosheets and nanotubes, were synthesized by hydrothermal and annealing method. The carefully designed ZnO/MnO₂ heterostructure significantly enhances ammonia gas sensing performance at room temperature (RT). By integrating heterojunction formation with structural optimization, this approach facilitates faster charge carrier transport and increases the surface area compared to pure ZnO. The incorporation of nanosheet- and nanotube-structured ZnO/MnO₂ heterojunctions leads to a substantial reduction in response/recovery time, which decrease to 6 s and 3 s, accordingly. Furthermore, first-principles calculations are employed to elucidate the potential sensing mechanism by analyzing the electronic density of states, electrostatic potential, charge transfer, population analysis, and adsorption energy between the sensing materials and ammonia molecules.