Polarization-induced NO2 sensing and amine generation using Sb single-atoms embedded in few-layered MnPS3 flatlands

Abstract

Catalytic conversion of NO_x into ammonia is a significant step towards sustainable energy, requiring efficient materials for environmental NO_x detection and its subsequent reduction to amines. While chemiresistive sensing has been realized as technically distinct from the conventional oxygen reduction reaction (ORR), the development of smart catalytic materials which can detect trace-level NO_x and also demonstrate efficient ORR capabilities is crucial. In this proof-of-concept work, Sb single atoms (SAs) have been monodispersed on a nitrobenzene-intercalated few-layered MnPS₃ crystal-surface, for efficient room-temperature NO₂ detection. The sensing properties have been found to be influenced by polarized-monochromatic light and SA loading, with the response being maximum at an ∼50° polarization angle for green light and 3.5% SA content. Under controlled experimental conditions of humidity and pressure, the abovementioned novel composition exhibited ORR response, with ammonia generated at a weight hourly space velocity of 40 000 ml g_cat⁻¹ h⁻¹ and a rate of 4700 μmol g⁻¹ h⁻¹. X-ray absorption spectroscopy revealed the atomic environment of Sb SAs. Quasi-operando micro-photoluminescence combined with Raman spectroscopy identified the role of the MnPS₃ network in facilitating surface NO₂ adsorption. Theoretical calculations delineated the selective and energetic role of Sb SAs in sensing and initiating the ORR, elucidating the reaction pathway in terms of a reduction in Gibbs energy.