Effect of Zn Doping in CuO Octahedral Crystals towards Structural, Optical, and Gas Sensing Properties

Chandra Prakash Goyal,S Ponnusamy,Niranjan S Ramgir,Hiroya Ikeda,C Muthamizhchelvan,Deepak Goyal,Sinjumol K Rajan,Yasuhiro Hayakawa,Yosuke Shimura,Mani Navaneethan

doi:10.3390/cryst10030188

Abstract

Monodispersed CuO octahedral crystals were successfully synthesized using a low-temperature co-precipitation method. Zinc doping in CuO created surface defects that enhanced oxygen adsorption on the surface crucial for gas sensing applications. Pure and Zn-doped CuO sensor films were realized using the doctor blade method. The sensor films showed selective response towards a low concentration of NO2 at a lower operating temperature of 150 °C. Doping with Zn causes the resistance of the sensor film to decrease due to the enhancement of charge carriers with an analogous improvement in the sensor response. The observed decrease in sensor resistance agreed well with the findings of the work function studies. Zinc doping resulted in an increase in work function by 180 meV which, after NO2 exposure, was found to increase by a further 130 meV, attributed to the oxidizing behavior of the test gas.

Highlights

Cupric oxide (CuO) is the most widely studied oxide of all other copper oxides
The X-ray diffractometer (XRD) patterns for pure and Zn-doped CuO films indicated the pure phase formation of CuO without any impurity peaks related to Zn or its suboxides. This can be attributed to the good dispersion of Zn2+ ions on the sites of Cu2+ ions in the CuO matrix [20,28,29]
CuO films were observed which suggests the substitution of Zn ions in place of Cu ions (Figure 2a)

Summary

Introduction

Cupric oxide (CuO) is the most widely studied oxide of all other copper oxides. Other copper suboxides, such as Cu2 O and Cu2 O3 , are not stable materials [1]. Copper oxide is a p-type semiconductor and has many notable properties like antibacterial capability, high stability, and ease of use It has been utilized in numerous applications including photocatalysis, supercapacitors, lithium ion batteries, infrared photo detectors, biosensors, and gas sensors [2,3,4,5,6,7,8]. It is an ideal absorber material for solar cells, as its optical absorption edge lies in the range between 1.2 eV and 1.9 eV [9,10]. Wang et al [8]

Methods

Results

Conclusion