Sikai Zhao

Graduate Student

Education

Ph.D Candidate, Mineral processing engineering, Northeastern University
M.S., Mineral processing engineering, Northeastern University, 2017
B.S., Mineral processing engineering, Northeastern University, 2015

Current Research

Title: Quantum dot-based high-performance gas sensors
Abstract: In recent years, the demands for high-performance gas sensors are rapidly increasing in many fields including environmental monitoring, public health and security, medical diagnostics, and industrial process monitoring. Among various types of gas sensors, the resistive metal-oxide-semiconductors (MOS) are very attractive and widely applied due to their high sensitivity, low cost, facile operation, and high compatibility with microfabrication processes. The working principle of such gas sensors is based on the reversible changes in the sensor’s resistance caused by the gas adsorption and reaction on the surface of the sensing materials. Thus, the primary consideration for the fabrication of MOS gas sensors is the design and optimization of the sensing materials toward different target gases. Furthermore, the development of nanoscience and nanotechnology provides additional opportunities for controllable syntheses of high-performance MOS gas sensing materials. As confirmed by many reports, reducing the physical size of the building units of the sensing materials is an effective strategy to enhance the gas sensing properties of resistive MOS sensors. Specifically, a dramatic increase in sensor response can be achieved when the grain size becomes comparable or smaller than the Debye Screening Length (LD). Quantum dots (QDs), being one of the zero-dimensional nanomaterials with sizes below 10 nm, have attracted significant interest due to their uniquely tunable size-dependent electronic, chemical, and optical properties, leading to entirely new avenues for many applications. In this project, we aim to synthesize MOS QDs with control over the physical size and chemical compositions and explore their applications in high-performance gas sensing.

Publications

1.S. Zhao, Y. Shen et al. “Highly selective NO2 sensor based on p-type nanocrystalline NiO thin films prepared by sol–gel dip coating.” Ceramics International 44.1 (2018): 753-759.
2. S. Zhao, Y. Shen, et al. “Design of Au@ WO3 core−shell structured nanospheres for ppb-level NO2 sensing.” Sensors and Actuators B: Chemical 282 (2019): 917-926.
3. S. Zhao, Y. Shen, et al. “Complex-surfactant-assisted hydrothermal synthesis of one-dimensional ZnO nanorods for high-performance ethanol gas sensor.” Sensors and Actuators B: Chemical 286 (2019): 501-511.
4. S. Zhao, Y. Shen, et al. “Influence of Synthesis Conditions on Microstructure and NO2 Sensing Properties of WO3 Porous Films Synthesized by Non-Hydrolytic Sol–Gel Method.” Nanomaterials 9.1 (2019): 8.
5.K. Wei, S. Zhao, et al. “Controllable Synthesis of Zn-Doped α-Fe2O3 Nanowires for H2S Sensing.” Nanomaterials 9.7 (2019): 994.
6.Y. Shen, S. Zhao, et al. “Highly sensitive and selective room temperature alcohol gas sensors based on TeO2 nanowires.” Journal of Alloys and Compounds 664 (2016): 229-234.

Contact

sikaizhao@berkeley.edu