A fluorinated greenhouse gas sensor based on N-doped tin oxide materials

Abstract

Compared with carbon dioxide, fluorinated greenhouse gases (F-type gases), such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF₆), have a stronger greenhouse effect, and their global warming potential can reach thousands or even tens of thousands of times that of carbon dioxide. Thus, the rapid online accurate detection of fluorinated greenhouse gases is highly desired and it can provide a basis for the evaluation of the greenhouse effect and a yardstick for the formulation of emission reduction measures. Unfortunately, these highly noble chemical gas molecules, especially at trace concentration levels, are extremely difficult to detect with conventional rapid screening methods. The use of the most common gas sensing techniques, semiconducting metal oxides, in the detection of HFCs and PFCs has not appeared within the scope of our knowledge. Herein, we report a novel N-doped tin oxide semiconducting metal oxide prepared by using a facile hydrothermal method. The experimental characterization results showed that the as-prepared materials were uniform spherical nanoparticles. The doping ratio of N-doped tin oxide was further optimized, and gas-sensing tests using these materials were carefully conducted. The results showed that the sensor had good detection performance for F-type gases, represented by SF₆, C₂F₆ and C₂H₂F₄, including low working temperature (200 °C), high selectivity, good repeatability, relatively high response, and low limit of detection (LOD ∼7 ppb). To the best of our knowledge, this is the first report on an F-type gas sensor based on semiconductor metal oxide. The ultra-fine particle size and uniform morphology of spherical particles, high concentration of oxygen vacancy defects and N doping contribute to the excellent performance of the sensor.