Phosphines as Efficient Dioxygen Scavengers in Nitrous Oxide Sensors

Abstract

A current challenge for development of amperometric sensors for the greenhouse gas nitrous oxide (NO) is their sensitivity toward dioxygen and trace water. The need for aqueous dioxygen scavengers in front of the sensor implies a background signal from penetrating water vapor. In this paper, we introduce substituted phosphines as dioxygen scavengers and demonstrate the application in a dioxygen-insensitive NO sensor. Suitably substituted phosphines have been synthesized to achieve good solubility properties in the electrochemically inert solvent propylene carbonate. Several sensors with and without physical separation of the sensing and dioxygen scavenging compartments were made and compared to current commercial sensors. The use of phosphines soluble in organic solvents as dioxygen scavengers yielded a higher sensitivity, albeit with longer response time. Proof-of-concept NO sensors without the physically separated dioxygen scavenger chamber showed a greatly enhanced sensitivity with a comparable response time, thus demonstrating the possibility for greatly simplified sensor construction.

Nitrous Oxide Is No Laughing Matter: A Historical Review of Nitrous Oxide Gas-Sensing Capabilities Highlighting the Need for Further Exploration

“…After testing different phosphine derivatives, Sveegaard et al reported diphenylphosphine in propylene carbonate as a good electrolyte for the compartment of O 2 reduction. 49 The two-compartment sensor using this electrolyte showed two times higher sensitivity and shorter response times in comparison to that using an alkaline ascorbate solution. The single-compartment sensors using diphenylphosphine were also successfully fabricated without sensitivity toward O 2 .…”

“…Also, an organic O 2 scavenger can possibly be used in a single-compartment sensor, which reduces the diffusion pathway simultaneously and corresponds to better performance of the sensor. After testing different phosphine derivatives, Sveegaard et al reported diphenylphosphine in propylene carbonate as a good electrolyte for the compartment of O 2 reduction . The two-compartment sensor using this electrolyte showed two times higher sensitivity and shorter response times in comparison to that using an alkaline ascorbate solution.…”

Electrochemical Filter To Remove Oxygen Interference Locally, Rapidly, and Temporarily for Sensing Applications

“…The detection of many analytes (N 2 O, , NO 2 – , NO 3 – , CO 2 , hydrazine, organic carbon content, and so on) is hindered by the presence of oxygen in the solution. A common method to eliminate dissolved oxygen in laboratory experiments is the purge of the solution with an inert gas such as nitrogen or argon.…”

“…For sensing applications, oxygen scavengers have been tested for several analytes. For example, phosphines 1 and ascorbic acid 8 can consume oxygen in N 2 O sensors and sodium thiosulfate was applied to H 2 O 2 sensing. 9 Plumeŕéet al proposed an enzymatic oxygen scavenger using glucose, galactose, or pyranose 2-oxidase as effective catalysts for O 2 reduction, 4 and the efficiency of the system was evaluated for the biosensing of nitrate.…”