Extraordinary H2S gas sensing performance of ZnO/rGO external and internal heterojunctions

Dang, Tran Khoa; Sơn, Nguyen Tăng; Lanh, Nguyen Thi; Phuoc, Phan Hong; Việt, Nguyễn Ngọc; Thong, Le Viet; Hung, Chu Manh; Duy, Nguyễn Văn; Hòa, Nguyễn Đức; Hiếu, Nguyễn Văn

doi:10.1016/j.jallcom.2021.160457

Cited by 28 publications

(13 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zinc oxide (ZnO) is an industrially important, low-cost, environmentally friendly, and abundant n-type semiconductor material with a direct band gap of 3.44 eV and a large exciton binding energy of 60 meV . It has been extensively studied for the last decades because of its vast number of potential applications ranging from optoelectronic devices, for example, ultraviolet (UV) sensors and light-emitting diodes (LEDs), to the recently suggested growth of ZnO nanostructures on graphene for photovoltaics and chemical sensor applications . Synthesis of ZnO quantum dots (QDs) has been achieved by using different chemical methods, such as sol–gel, polyol, and hydrothermal methods .…”

Section: Introductionmentioning

confidence: 99%

Excitons in ZnO Quantum Dots: The Role of Dielectric Confinement

et al. 2022

View full text Add to dashboard Cite

Quantum dots (QDs) grown by chemical synthesis methods are relatively unstable and present difficulties in dispersion and preservation. The most common way of surpassing the stability issues is to embed (and passivate) the QDs in a matrix material. However, some fundamental questions concerning the influence of the dielectric confinement caused by the matrix environment on the exciton energy and exciton binding energy of the QDs have not yet been properly addressed. Here we explore the exciton fine structure of wurtzite ZnO QDs by means of plane-wave million-atom atomistic pseudopotential calculations and a configuration interaction approach taking into account the dielectric confinement from the surrounding material. Our results indicate that the exciton energy increases and the exciton binding energy decreases as the dielectric constant of the surrounding material increases. The behavior of the exciton binding energy is caused by the presence of self-polarization potential induced by the dielectric mismatch in the surface of the QD. This mainly alters the localization of the hole charge density and thus reduces the electron–hole overlap and inevitably the exciton binding energy.

show abstract

Section: Introductionmentioning

confidence: 99%

Excitons in ZnO Quantum Dots: The Role of Dielectric Confinement

et al. 2022

View full text Add to dashboard Cite

show abstract

“…The local heterojunctions formed between graphene and ZnO are responsible for the sensor's high sensitivity to the target gas. 25 As the work function of ZnO is relatively smaller than that of graphene (Figure 5a), the electrons and holes diffuse in opposite directions to equate Fermi levels, causing depletion layer formation and energy band bending (Figure 5b). In the air environment, oxygen molecules adsorbed on ZnO accept electrons from its conduction band to form oxygen Upon exposure to CH 4 , the adsorbed gas molecules react with oxygen ions at grain boundaries and p−n junctions and release the electrons back to the conduction band.…”

Section: Resultsmentioning

confidence: 99%

“…The detailed gas sensing mechanism of GZnO is outlined in Figure . The local heterojunctions formed between graphene and ZnO are responsible for the sensor’s high sensitivity to the target gas . As the work function of ZnO is relatively smaller than that of graphene (Figure a), the electrons and holes diffuse in opposite directions to equate Fermi levels, causing depletion layer formation and energy band bending (Figure b).…”

Section: Resultsmentioning

confidence: 99%

Reduction of the Measurement Time of a Chemiresistive Gas Sensor Using Transient Analysis and the Cantor Pairing Function

Kanaparthi

Singh

2021

ACS Meas. Sci. Au

View full text Add to dashboard Cite

It is vital to measure the concentration of gas quickly in many gas sensing applications. Predicting the steadystate response from the earlier transient response is the economical and viable solution in this regard. However, existing transient analysis approaches either need huge data and computationally intensive algorithms or are inefficient. Here, we described a method to reduce the measurement time of the concentration of CH 4 with a chemiresistive gas sensor at room temperature (27 °C). The presented method considers the sensor's response at two fixed time intervals after gas exposure and maps their pairing number to the gas concentration. The proposed method measures the gas concentration in just 30 s from the gas exposure time. As the proposed method can quickly measure gas concentrations, it can be employed in widespread applications where quick quantification of gas is necessary.

show abstract

“…As an example, Figure 11 shows TEM images of an electrospun nanofiber of SnO 2 loaded with rGO [139]. Double-shell hollow nanofibers are usually obtained, with the rGO nanosheets on top of the MOS nanograins [139][140][141][142][143]. Generally, it has been found that the rGO-loaded MOS nanofibers are more sensitive to specific gases and that the optimal operating temperature (i.e., the temperature at which the sensor response reaches a maximum) is lower than that of the pure MOS nanofibers.…”

Section: Functionalization Of 1d Metal Oxide Nanostructuresmentioning

confidence: 99%

One-Dimensional Metal Oxide Nanostructures for Chemical Sensors

Hontañón¹,

Vallejos²

2022

21st Century Nanostructured Materials - Physics, Chemistry, Classification, and Emerging Applications in Industry, Biomedicine,

View full text Add to dashboard Cite

The fabrication of chemical sensors based on one-dimensional (1D) metal oxide semiconductor (MOS) nanostructures with tailored geometries has rapidly advanced in the last two decades. Chemical sensitive 1D MOS nanostructures are usually configured as resistors whose conduction is altered by a charge-transfer process or as field-effect transistors (FET) whose properties are controlled by applying appropriate potentials to the gate. This chapter reviews the state-of-the-art research on chemical sensors based on 1D MOS nanostructures of the resistive and FET types. The chapter begins with a survey of the MOS and their 1D nanostructures with the greatest potential for use in the next generation of chemical sensors, which will be of very small size, low-power consumption, low-cost, and superior sensing performance compared to present chemical sensors on the market. There follows a description of the 1D MOS nanostructures, including composite and hybrid structures, and their synthesis techniques. And subsequently a presentation of the architectures of the current resistive and FET sensors, and the methods to integrate the 1D MOS nanostructures into them on a large scale and in a cost-effective manner. The chapter concludes with an outlook of the challenges facing the chemical sensors based on 1D MOS nanostructures if their massive use in sensor networks becomes a reality.

show abstract

Extraordinary H2S gas sensing performance of ZnO/rGO external and internal heterojunctions

Cited by 28 publications

References 40 publications

Excitons in ZnO Quantum Dots: The Role of Dielectric Confinement

Excitons in ZnO Quantum Dots: The Role of Dielectric Confinement

Reduction of the Measurement Time of a Chemiresistive Gas Sensor Using Transient Analysis and the Cantor Pairing Function

One-Dimensional Metal Oxide Nanostructures for Chemical Sensors

Contact Info

Product

Resources

About