Penglei Wang

Realizing room-temperature self-powered ethanol sensing of ZnO nanowire arrays by combining their piezoelectric, photoelectric and gas sensing characteristics

Room-temperature self-powered ethanol sensing has been realized from ZnO nanowire (NW) arrays by combining their piezoelectric, photoelectric and gas sensing characteristics. Under the assistance of UV illumination, the piezoelectric output of ZnO NWs acts not only as a power source, but also as a response signal to ethanol gas at room temperature. Upon exposure to 700 ppm ethanol at room temperature under 67.5 mW cm−2 UV illumination, the piezoelectric output voltage of ZnO NWs (under 34 N compressive forces) decreases from 0.80 V (in air) to 0.12 V and the response is up to 85. The room-temperature reaction between the UV-induced chemisorbed oxygen ions and ethanol molecules increases the carrier density in ZnO NWs, resulting in a strong piezoelectric screening effect and very low piezoelectric output. Our study can stimulate a research trend on designing new gas sensors and investigating new gas sensing mechanisms.

Biomolecule-adsorption-dependent piezoelectric output of ZnO nanowire nanogenerator and its application as self-powered active biosensor.

Self-powered active biosensor has been realized from ZnO nanowire (NW) nanogenerator (NG). The piezoelectric output generated by ZnO NW NG can act not only as a power source for driving the device, but also as a biosensing signal. After immersing in 10(-3) g ml(-1) human immunoglobulin G (IgG), the piezoelectric output voltage of the device under compressive deformation decreases from 0.203±0.0176 V (without IgG) to 0.038±0.0035 V. Such a self-powered biosensor has higher response than transistor-type biosensor (I-V behavior). The response of self-powered biosensor is in a linear relationship with IgG concentration (logarithm, 10(-7)-10(-3) g ml(-1)) and the limit of detection (LOD) on IgG of the device is about 6.9 ng ml(-1). The adsorption of biomolecules on the surface of ZnO NWs can modify the free-carrier density, which vary the screening effect of free-carriers on the piezoelectric output. The present results demonstrate a feasible approach for actively detecting biomolecules by coupling the piezotronic and biosensing characteristics of ZnO NWs.

The conversion of PN-junction influencing the piezoelectric output of a CuO/ZnO nanoarray nanogenerator and its application as a room-temperature self-powered active H2S sensor

Room-temperature, high H2S sensing has been realized from a CuO/ZnO nanoarray self-powered, active gas sensor. The piezoelectric output of CuO/ZnO nanoarrays can act not only as the power source of the device, but also as the H2S sensing signal at room temperature. Upon exposure to 800 ppm H2S at room temperature, the piezoelectric output of the device greatly decreased from 0.738 V (in air) to 0.101 V. The sensitivity increased to 629.8, much higher than bare ZnO nanoarrays. As the device was exposed to H2S, a CuO/ZnO PN-junction was converted into a CuS/ZnO Ohmic contact, which greatly increased the electron density in the nanowire and enhanced the screen effect on the piezoelectric output. Our results can stimulate a research trend on designing new composite piezoelectric material for high-performance self-powered active gas sensors.

Detecting Liquefied Petroleum Gas (LPG) at Room Temperature Using ZnSnO3/ZnO Nanowire Piezo-Nanogenerator as Self-Powered Gas Sensor.

High sensitivity, selectivity, and reliability have been achieved from ZnSnO3/ZnO nanowire (NW) piezo-nanogenerator (NG) as self-powered gas sensor (SPGS) for detecting liquefied petroleum gas (LPG) at room temperature (RT). After being exposed to 8000 ppm LPG, the output piezo-voltage of ZnSnO3/ZnO NW SPGS under compressive deformation is 0.089 V, much smaller than that in air ambience (0.533 V). The sensitivity of the SPGS against 8000 ppm LPG is up to 83.23, and the low limit of detection is 600 ppm. The SPGS has lower sensitivity against H2S, H2, ethanol, methanol and saturated water vapor than LPG, indicating good selectivity for detecting LPG. After two months, the decline of the sensing performance is less than 6%. Such piezo-LPG sensing at RT can be ascribed to the new piezo-surface coupling effect of ZnSnO3/ZnO nanocomposites. The practical application of the device driven by human motion has also been simply demonstrated. This work provides a novel approach to fabricate RT-LPG sensors and promotes the development of self-powered sensing system.

Realizing room-temperature self-powered ethanol sensing of Au/ZnO nanowire arrays by coupling the piezotronics effect of ZnO and the catalysis of noble metal

By coupling the piezotronics effect of ZnO and the catalysis of noble metal, room-temperature self-powered active ethanol sensing was obtained from Au/ZnO nanowire arrays. The piezoelectric output generated by Au/ZnO nanowire arrays acts not only as power source, but also as response signal to ethanol at room temperature. Upon exposure to 1200 ppm ethanol, the piezoelectric output of Au/ZnO nanowire arrays decreased from 1.54 V (in air) to 0.43 V. Our research can stimulate a research trend on the development of the next generation of room-temperature gas sensors and will further expand the scope for self-powered nanosystems.

Synthesis of CdS nanorod arrays and their applications in flexible piezo-driven active H2S sensors

A flexible piezo-driven active H2S sensor has been fabricated from CdS nanorod arrays. By coupling the piezoelectric and gas sensing properties of CdS nanorods, the piezoelectric output generated by CdS nanorod arrays acts not only as a power source, but also as a response signal to H2S. Under externally applied compressive force, the piezoelectric output of CdS nanorod arrays is very sensitive to H2S. Upon exposure to 600 ppm H2S, the piezoelectric output of the device decreased from 0.32 V (in air) to 0.12 V. Such a flexible device can be driven by the tiny mechanical energy in our living environment, such as human finger pinching. Our research can stimulate a research trend on designing new material systems and device structures for high-performance piezo-driven active gas sensors.