Gas sensor properties of nanopore-bearing Co₃O₄particles containing Pt or Pd particles

Abstract

Nanopores were successfully formed in cobalt oxide particles by carrying out sintering to remove the shell of core-shell type cobalt oxide particles comprised of a cobalt oxide core and a polyvinylpyrrolidone (PVP) shell. During synthesis of the cobalt oxide partices, PVP-covered Pt or Pd particles were added to achieve metal loading on the nanopores and surfaces of the cobalt oxide particles. The crystallite size of the cobalt oxide particles was~15 nm, the particle diameter was~50 nm, and the nanopores measured 2-6 nm in diameter. The positions of the Pt or Pd particles in the cobalt oxide particles were verified by stereo-transmission electron microscopy observations. In terms of the particle gas sensor properties, the loading of Pt or Pd particles into the cobalt oxide particle nanopores increased the responsiveness to acetone gas, and as a result, the acetone gas selectivity was improved over hydrogen gas. Upon comparison between cobalt oxide particles bearing Pt or Pd particles only on the surface and those containing Pt or Pd particles within the pores, the later was found to exhibit an approximately 4-fold acetone/hydrogen gas selectivity.

Ultra-Sensitive Photo-Induced Hydrogen Gas Sensor Based on Two-Dimensional CeO2-Pd-PDA/rGO Heterojunction Nanocomposite

“…A bias voltage of 1 V was applied throughout the experiments, and the resistivity change in the sensor was measured upon exposure to the target gas. The response of the sensor (R) was calculated towards the target gas as follows [ 52 , 53 , 54 ]: where R a is the sensor’s resistivity in air and R g is the sensor’s resistivity in contact with the target gas. The response and recovery times were calculated when the sensor reached 90% of its response and recovery (back to its initial baseline).…”

Highly Sensitive, Flexible H2 Gas Sensors Based on Less Platinum Bimetallic Ni–Pt Nanocatalyst-Functionalized Carbon Nanofibers

“…Flexible and wearable technologies have made significant advances in recent years in terms of constructing bendable or foldable device architectures without altering their functionality by adopting economically viable fabrication methods. , Sensors are predicted as essential elements in portable and foldable devices used for consumer electronics, robotics, homeland security, health care, and environmental monitoring applications. Many types of flexible strain, pressure, temperature, gas, humidity, magnetic, chemical, electrochemical, light, and electropotential sensors have been developed for various wearable and flexible electronic applications. − In the gas sensing sector, classical MOS-based sensors, , which require high operating temperatures, are currently being replaced by low-power sensors based on graphene, carbon nanotubes, and 2D organic/inorganic materials , for the detection of various gases that can be easily integrated with flexible/wearable devices. , Alternate approaches to MOS-based gas sensors are metal doping or functionalization on MOS, e.g., Pd, Pt, Ag, Au, Ni, Ru, etc., , to selectively detect analyte gases. However, such approaches also require moderate temperatures for their operation, which impedes their applications in flexible electronics.…”

“…3−6 In the gas sensing sector, classical MOS-based sensors, 7,8 which require high operating temperatures, are currently being replaced by low-power sensors based on graphene, carbon nanotubes, and 2D organic/inorganic materials 9,10 for the detection of various gases that can be easily integrated with flexible/wearable devices. 11,12 Alternate approaches to MOS-based gas sensors are metal doping or functionalization on MOS, e.g., Pd, Pt, Ag, Au, Ni, Ru, etc., 13,14 to selectively detect analyte gases. However, such approaches also require moderate temperatures for their operation, which impedes their applications in flexible electronics.…”

Effect of Crystal Defect on Gas Sensing Properties of Co3O4 Nanoparticles

“…Many attempts have been made to improve the sensor signal response as well as response and recovery speed for the real-time detection of chemical substances. − Among many types of sensors, since a metal oxide gas sensor is considered as one of the basic technologies for the identification and measurement of chemical substances, , tin oxide, cobalt oxide, tungsten oxide, zinc oxide, etc., have been adopted as sensor materials. In addition, many types of compounds based on the metal oxides have been developed for selective gas sensing. ,− …”

“…Recently, various unique Co 3 O 4 nanostructures have been developed to improve the sensing activity, − and Co 3 O 4 with various nanostructures exhibited the sensing properties of different gases including hydrogen, acetone, isoprene, and nitrogen dioxide. − ,, Although several efficient studies have been conducted to reveal the effective factors for high activity, − the sensing properties of Co 3 O 4 gas sensors vary in different reports; thus, it is difficult to reveal the relationship between the structure and the sensing properties.…”