Abstract View
Rapid and Selective Ammonia Sensing by Porous CuBr at Room Temperature Made by Flame-deposited and In-situ Annealed, Reduced and Brominated CuO Nanoparticles
ANDREAS GUENTNER, Nicolay Pineau, Markus Wied, Sotiris Pratsinis, ETH Zurich, Switzerland
Abstract Number: 141
Working Group: Nanoparticles and Materials Synthesis
Abstract
Ammonia (NH3), a major industrial commodity, is toxic as well as a tracer for food spoilage and putative breath marker for impaired kidney and liver function (e.g. cirrhosis, hepatic encephalopathy or injury). So there is strong interest in developing reliable sensors over a wide range of NH3 concentrations: from 250 to 2900 ppb in mouth-exhaled breath down to few ppb in indoor air at high relative humidity (RH). Also, ammonia is present in gas mixtures containing a myriad of compounds demanding high selectivity.
So fast and selective detection of NH3 at ppb concentrations with inexpensive and low-power sensors represents a long-standing challenge. Here, a room temperature, solid-state sensor is presented consisting of nanostructured porous (78%) CuBr films. These are prepared by flame-aerosol deposition and in-situ annealing of CuO onto sensor substrates followed by in-situ dry reduction and bromination that are continuously monitored in situ through the film resistance [1] affording excellent process control. Such porous CuBr films feature an order of magnitude higher NH3 sensitivity and five times faster response times than conventional denser CuBr films. That way, rapid sensing of even the lowest (e.g. 5 ppb) ammonia concentrations at 90% RH is attained with outstanding selectivity (30 - 290) over typical confounders including ethanol, acetone, H2, CH4, isoprene, acetic acid, formaldehyde, methanol and CO, superior to state-of-the-art sensors [2]. This sensor is ideal for hand-held and battery-driven devices or integration into wearable electronics as it does not require heating.
[1] C.O. Blattmann, A.T. Güntner, S.E. Pratsinis, In Situ Monitoring of the Deposition of Flame-Made Chemoresistive Gas-Sensing Films, ACS Appl. Mater. Interf., 9, 23926-23933 (2017).
[2] A.T. Güntner, M. Wied, N. Pineau, S.E. Pratsinis, Rapid and selective NH3 sensing by porous CuBr, Advanced Science, 1903390 (2020).