Nafion-based amperometric H2S sensor using Pt-Rh/C sensing electrode

In this paper, an amperometric gas sensor based on proton exchange membrane (Nafion) was fabricated for H 2 S detection at room temperature . Pt-Rh nanoparticles loaded on carbon fibers, as sensing electrode , was prepared by chemical reduction method, and membrane electrode assemble (MEA) was fabricated using hot-pressing method. X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM) were used to analyze the structure and morphology of the fabricated electrode material. The effect of the weight ratio of Pt to Rh on the performance of the sensor was investigated and the results showed that the sensing performance was best when the ratio of Pt to Rh was 1:1. Moreover, the sensitivity had been significantly improved due to the use of carbon fibers pretreated by nitric acid, increasing from 0.158 μA/ppm to 0.191 μA/ppm. The present sensor could detect H 2 S at levels as low as 0.1 ppm with a −20 nA response and had a good linear relationship in the range of 0.1 to 200 ppm H 2 S. In addition, this amperometric H 2 S sensor displayed fast response-recovery rate as well as excellent selectivity and stability.