A Photoactivated Gas Sensor of SnO2 Ordered Spherical Pore Array: Electrodeposition-Based Construction and Application in Room Temperature Detection of Ethanol Gas

The photoactivated semiconductor film gas sensor has received increasing attention in the room temperature detection of environmental gases, but the uncontrolled surface morphology and the associated light area still limit the application and the exploitation of the sensing response potential. Herein, a monolayer colloid crystal template strategy based on electrodeposition was introduced to in situ construct SnO2 ordered spherical macropore array (OSPA) sensors used for ethanol gas detection under a UV-LED. By adjusting the electrodeposition time, various OSPAs with regularly variable heights of pore-wall were obtained. The light area of the array could then be systematically regulated based on the spherical pore-walls' curve characteristics. The OSPAs showed a nearly 5-fold change in response in detection of 100 ppm ethanol gas under a 265 nm UV-LED, corresponding to the light area from small to large. The highest sensing response is even higher than that of almost all SnO2-based room temperature sensors that have previously been reported. Moreover, the sensor has excellent selectivity and linearity, a 1 ppm lower detection limit, and exceptional long-term stability. These finds are corroborated by analyses of the electrodeposition mechanism, the sensing mechanism, optical simulations, and various characterizations. The strategy provides an efficient way to tune and enhance the sensing response of a photoactivated gas sensor, and is beneficial for exploiting the sensing potential of a semiconductor.