Thin Film Gas Sensors Based on Planetary Ball-Milled Zinc Oxide Nanoinks: Effect of Milling Parameters on Sensing Performance

Abstract

Planetary ball-milled zinc oxide (ZnO) nanoparticle suspensions (nanoinks) were used to produce thin film chemiresistive gas sensors that operate at room temperature. By varying milling or grinding parameters (speed, time, and solvent) different thin film gas sensors with tunable particle sizes and porosity were fabricated and tested with dry air/oxygen against hydrogen, argon, and methane target species, in addition to relative humidity, under ambient light conditions. Grinding speeds of up to 1000 rpm produced particle sizes and RMS thin film roughness below 100 nm, as measured by atomic force and scanning electron microscopy. Raman spectroscopy, photoluminescence, and X-ray analysis confirmed the purity and structure of the resulting ZnO nanoparticles. Gas sensor response at room temperature was found to peak for nanoinks milled at 400 rpm and for 30 min in ethylene glycol and deionized water, which could be correlated to an increased film porosity and enhanced variation in electron concentration resulting from adsorption/desorption of oxygen ions on the surfaces of ZnO nanoparticles. Sensor response and dynamic behavior was found to improve as the temperature was increased, peaking between 100 and 150 °C. This work demonstrates the use of low-cost PBM nanoinks as the active materials for solution-processed thin film gas/humidity sensors for use in environmental, medical, food packaging, laboratory, and industrial applications.

Comparison of ZnO Nanoparticles Prepared by Precipitation and Combustion for UV and Sunlight-Driven Photocatalytic Degradation of Methylene Blue

“…Figure 7 a depicts the Raman shift for vibrational analysis of ZnO NPs. The ZnO NPs revealed dominant peaks at 100 and 440 cm −1 , which assigned the E 2 (low) and E 2 (high) modes, respectively [ 29 , 30 ]. The E 2 (low) vibration represented the zinc crystal lattice in ZnO, while the E 2 (high) vibration represented the oxygen vibration.…”

“…The peak at 223 could be assigned to 2TA or 2E 2 (low) modes. [ 30 , 32 ]. These peaks indicate the disordered structures for both ZnO NPs prepared by precipitation and combustion.…”

Preparation of ZnO Thick Films Activated with UV-LED for Efficient H2S Gas Sensing

“…ZnO films can be prepared on different substrates by means of various facile and low-cost deposition techniques such as drop casting, spin coating, ink jet printing and screen printing [18]. The screen-printing technique is versatile and allows for the costeffective deposition of thick films on various types of substrates [19].…”

Control over the Surface Properties of Zinc Oxide Powders via Combining Mechanical, Electron Beam, and Thermal Processing

“…For example, dispersion of commercial or synthesized powders is a method for optimizing the structure of the used metal oxide, carried out by particle size reduction, changing the porosity, and improving the morphology of the formed active layer. In particular, the influence of milling conditions (speed, time, medium) on the sensory properties of ZnO powders has been investigated, and the optimal dispersion parameters with maximum response in various gas environments have been identified in [ 5 ]. Similar studies have been carried out for other ZnO applications [ 6 , 7 ].…”