Bimetallic MOFs-derived core-shell structured mesoporous Sn-doped NiO for conductometric ppb-level xylene gas sensors

Mesoporous metal oxides have proven to be one kind of promising sensitive materials for semiconductor gas sensors that have shown great potential in detection of volatile organic compounds (VOCs) pollutants in air. Here we demonstrate core-shell structured mesoporous Sn-doped NiO derived from the bimetallic metal organic frameworks (MOFs) that synthesized by a combination strategy of hydrothermal and ion-exchange processes for the construction of high-performance xylene gas sensors. The MOFs-derived mesoporous structure can cause the increased amount of sensing reactive sites and improved gas adsorption capacity, as well as provide permeation channel for gas diffusion. In addition, the in-situ substitution of Sn4+ ions for Ni2+ ions can achieve the regulation of charge carrier concentrations. As a consequence, the synthesized core-shell mesoporous 2.64 at% Sn-doped NiO based xylene sensors operating at 250 °C exhibit high sensitivity, excellent selectivity, low detection limit (63 ppb), rapid recovery kinetic and well long-term stability. This work will open up a new pathway toward the development of mesoporous oxides semiconductor gas sensors.