Conductometric room temperature ammonia sensor based on porous tin oxide

Abstract

Metal oxide based chemi-resistive sensors are widely accepted for detection of –pollutants in gaseous or aqueous form due to appealing selectivity and stability. Unfortunately, the high working temperature restrict their utilization in many field. Here, we present the room temperature self-recovered NH3 gas sensor based on porous tin oxide, synthesized by sequential elemental de-alloying technique. Interestingly, sensor is capable to detect the ammonia in wide range of concentration from 1 ppb to 10,000 ppm with fast, stable and reproducible response in fully humid (FH, > 90% relative humidity (RH)) atmosphere. Surprisingly, the sensor is ultra-selective towards ammonia as compared to other analytes like acetone, ethanol, toluene, methanol, chloroform and other gases, present in the atmosphere, in conjunction with long term stability, external stimuli free recovery and ultra-fast recovery time being 1.5 s for a concentration of 1 ppb and 4.5 s in highest concentration of 10,000 ppm. The self-recovery and ultra-fast response is due to its self-power generation capability. Overall, the results advocate the fabrication of porous metal oxide based NH3 sensor with high selectivity, reproducibility, ultra-fast recovery and stimuli free self-recovery for room temperature (RT) operation.