Temperature-dependent formaldehyde and xylene dual selectivity in ZnCo2O4 sphere-like architectures

The gas selectivity of gas sensing materials based on oxide semiconductors is an important parameter for evaluating their functions. Revealing the dominant factor of sensing selectivity is a prerequisite for optimizing gas sensing performance. Herein, the temperature-dependent gas sensing selectivity is achieved in ZnCo2O4 sphere-like architectures via simple solvothermal-annealing treatments instead of noble metal loading or heterojunction construction. The ZnCo2O4 sphere-like architectures after two solvothermal-annealing treatments show superior selectivity to formaldehyde at 100 ℃ and simultaneously present high xylene selectivity at 180 ℃. However the as-prepared ZnCo2O4 sphere-like architectures without treatments merely exhibit high selectivity to formaldehyde at 100 ℃. Such gas sensing behaviors prominently stem from the catalytic promotion discrepancy induced by oxygen vacancies at different working temperatures. The feasible gas sensing selectivity regulation strategy holds great promise for other oxide semiconductor materials.