Acetone Sensing and Catalytic Conversion by Pd-Loaded SnO2

Abstract

Noble metal additives are widely used to improve the performance of metal oxide gas sensors, most prominently with palladium on tin oxide. Here, we photodeposit different quantities of Pd (0–3 mol%) onto nanostructured SnO2 and determine their effect on sensing acetone, a critical tracer of lipolysis by breath analysis. We focus on understanding the effect of operating temperature on acetone sensing performance (sensitivity and response/recovery times) and its relationship to catalytic oxidation of acetone through a packed bed of such Pd-loaded SnO2. The addition of Pd can either boost or deteriorate the sensing performance, depending on its loading and operating temperature. The sensor performance is optimal at Pd loadings of less than 0.2 mol% and operating temperatures of 200–262.5 °C, where acetone conversion is around 50%.

Embedding Pd into SnO2 drastically enhances gas sensing

“…This is consistent with the literature showing that sensors with low Pd contents (0.1-0.2 mol%) exhibit higher response than those with higher Pd loadings (0.5-3 mol% Pd). 9,11,33,36 When the above sensors were exposed to 1 ppm of CO (Fig. S17 in the ESI †), they gave similar results: hardly any response by those containing surface and embedded Pd (blue triangles), which is lower than that of pure SnO 2 (green square and diamonds) and a much higher response by the sensor containing only embedded Pd (red circles) that reached a 125fold amplication for the largest -18 nm -SnO 2 crystals (C = 1.5 M).…”

“…As our focus is on understanding the partitioning of Pd between the surface and interior of SnO 2 and the subsequent impact on gas sensing, we benchmarked the sensitivity, the most basic property of gas sensors, at a commonly employed temperature, humidity and concentration of acetone and CO. Other sensor characteristics such as selectivity, stability and response and recovery times have not been investigated as they largely follow those of pure and Pd-containing SnO 2 sensors. The effect of sensing temperature, humidity and analyte concentration on the performance of SnO 2 -based sensors has been documented extensively for acetone 13,[15][16][17][18] and CO 11,16,[19][20][21][22] as summarized in Table S1 in the ESI. †…”

“…Fig.5The response to 1 ppm of acetone at 350 °C in 50% RH by pure (green square,13 diamondsresponses from Fig.4) and 1 mol% Pdcontaining SnO 2 sensors before (blue triangles) and after leaching and removal of surface Pd (red circles) made at various FSP precursor solution concentrations (starting from the left C = 0.1, 0.5, 1, 1.5 M) and i/D = 5/5 as a function of SnO 2 crystal size. The star shows the response of a sensor that contained 1 mol% photodeposited Pd onto SnO 2 particles by FSP at C = 0.5 M and same P/D 11. …”

Facile Modification of Flexible Electrodes via Laser Transfer

“…Therefore, due to our continued interest in the development of sensors by applying LIFT and modifications of LIFT, in this work, we have transferred different SnO 2 and Pd-SnO 2 pixels onto flexible and low-cost electrochemical sensors and tested them for their ability to detect Cu ions. We have chosen Pd-SnO 2 due to the fact that noble metal additives are frequently used to improve the performance of metal oxide gas sensors [ 39 ]. The novelty of the paper is twofold: on one hand, we focus on the promotion of LIFT as a viable method to decorate electrodes for sensors, and, on the other hand, we aim at improving and developing new flexible sensors by a low-cost, solvent free, environmentally friendly method.…”

Special Issue “Advanced Materials for Gas Sensors”

“…An enhanced catalytic conversion process of acetone with Pd-loaded SnO 2 was proved by the work of Gschwend et al [6]. Knowing that Pd addition to SnO 2 may enhance or downgrade the sensing performances of based SnO 2 is of crucial importance to tune the desired amount in such a way that maximum sensitivity is attained.…”