High-Temperature Hydrogen Sensing Performance of Ni-Doped TiO2 Prepared by Co-Precipitation Method

Abstract

This work deals with the substantially high-temperature hydrogen sensors required by combustion and processing technologies. It reports the synthesis of undoped and Ni-doped TiO2 (with 0, 0.5, 1 and 2 mol.% of Ni) nanoparticles by a co-precipitation method and the obtained characteristics applicable for this purpose. The effect of nickel doping on the morphological variation, as well as on the phase transition from anatase to rutile, of TiO2 was investigated by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The resistive sensors prepared with these powders were tested toward H2 at 600 °C. The results indicate that 0.5% Ni-doped TiO2 with almost equal amounts of anatase and rutile shows the best H2 sensor response (ΔR/R0 = 72%), response rate and selectivity. The significant improvement of the sensing performance of 0.5% Ni-doped TiO2 is mainly attributed to the formation of the highest number of n-n junctions present between anatase and rutile, which influence the quantity of adsorbed oxygen (i.e., the active reaction site) on the surface and the conductivity of the material.

Review: Influences of Semiconductor Metal Oxide Properties on Gas Sensing Characteristics

“…Substitution of Ti by Ni by different synthesis methods such as anodization (Li et al, 2013) and wet chemical synthesis of particles (Lontio Fomekong et al, 2020) resulted in change in the conductivity type, inducing effective reduction in the band gap of anatase phase, and thus playing a great role in sensing properties. The presence of Ni as an impurity in the TiO 2 lattice is also known to create more oxygen vacancies due to the introduction of higher impurity levels that directly affect the gas sensing performance (Sun et al, 2012;Postica et al, 2018;Degler et al, 2019).…”

“…Lontio Fomekong et al (2020) have recently synthesized Nidoped TiO 2 NPs by the oxalate-assisted coprecipitation method and conducted research to analyze the effect of Ni dopant on gas sensing properties. Their results indicate that the Ni doping modifies the ratio between the anatase and rutile phases that has proven to have an impact on the hydrogen sensing properties.…”

Synthesis Methods of Obtaining Materials for Hydrogen Sensors

“…In the domain of sensors, especially for hydrogen sensors, several methods of synthesis and deposition have been used most often: sol-gel [ 60 , 61 ], hydrothermal [ 62 ], thermal evaporation [ 63 , 64 ], PLD [ 65 , 66 ], magnetron sputtering [ 67 , 68 ], co-precipitation [ 69 , 70 ] and spin coating [ 71 , 72 ].…”

“…Fomekong et al [ 68 ] studied the influence of TiO 2 doping with different concentrations of Ni, by the method of co-precipitation. The 0.5% Ni doped sensor indicated the best response in terms of sensitivity for hydrogen, as well as for selectivity.…”

Early-Stage Gas Identification Using Convolutional Long Short-Term Neural Network with Sensor Array Time Series Data

“…Besides the conventional high-temperature oxygen sensors, high-temperature carbon monoxide (CO) and hydrocarbons (HCs) sensors are considered necessary to directly determine the fuel combustion efficiency and catalytic efficiency for direct on-board diagnosis (OBD) purposes. Due to the highly aggressive operating environment, only limited sensors have been reported to be able to detect gases above 600 °C [ 3 , 4 , 5 ]. Ceramic oxides-based gas sensors have been widely explored for high-temperature applications due to their high thermal stability, simple structures, ease of fabrication and low cost.…”