Surface modification of In2O3 porous nanospheres with Au single atoms for ultrafast and highly sensitive detection of CO

The growing concern on environmental issues has stimulated intensive research interest on the gas sensors based on metal oxide semiconductor (MOS) due to their superiority in monitoring gaseous pollutants. In this context, developing advanced MOS sensors that can realize fast and selective detection of various flammable and harmful gases is of greatly desired, but still remains challenging. Here, we propose an Au single-atom sensitization strategy to boost the CO sensing performance of In2O3. To expound it, Au single atom catalyst (Au1) was prepared from an iced photochemical reduction method and then modified on In2O3 porous nanospheres (PNSs) to obtain the hybrid Au1/In2O3 gas sensing material. Benefiting from the outstanding spillover and catalytic effects of Au1, the best Au1/In2O3-2 show superior CO sensing performances to the bare In2O3 counterpart, especially of lower optimal working temperature (OWT: 360 °C vs 380 °C), higher sensitivity (0.032/ppm vs 0.003/ppm to 10–100 ppm CO), and faster response/recovery speed (2/10 s vs 47/205 s). Besides, the Au1/In2O3-2 sensor also shows good selectivity and stability. These features make the present Au1/In2O3 PNS a promising candidate for fabricating high-performance CO sensor. Our research demonstrates that surface functionalization with single-atom metal catalyst is a promising strategy to develop advanced MOS sensor.