Low Power Consumption Gas Sensor Created from Silicon Nanowires/TiO₂ Core–Shell Heterojunctions

Abstract

Silicon nanowires/TiO (SiNWs/TiO) array with core-shell nanostructure was created by sol-gel and drop-casting methods. The hybrid material displayed excellent sensing performance for CH detection at room temperature. The chemiresistor sensor has a linear response toward CH gas in the 30-120 ppm range with a detection limit of 20 ppm, which is well below most CH sensors reported before. The enhanced gas sensing performance at room temperature was attributed to the creation of heterojunctions that form a depletion layer at the interface of SiNWs and TiO layer. Adsorption of oxygen and corresponding gas analyte on TiO layer could induce the change of depletion layer thickness and consequently the width of the SiNWs conductive channel, leading to a sensitive conductive response toward gas analyte. Compared to conventional metal oxide gas sensors, the room temperature gas sensors constructed from SiNWs/TiO do not need an additional heating device and work at power at the μW level. The low power consumption feature is of great importance for sensing devices, if they are widely deployed and connected to the Internet of Things. The innovation of room temperature sensing materials may push forward the integration of gas sensing element with wireless device.

Compositional and structural engineering of inorganic nanowires toward advanced properties and applications

“…A, Sensing mechanism of a p‐SiNW/TiO 2 array for CH 4 detection (top) and real‐time conductive response to CH 4 concentrations from 30 to 200 ppm at room temperature (bottom). Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…Reproduced with permission. 173 Copyright 2017, American Chemical Society. B, SEM and TEM images of fresh silicon NW arrays.…”

“…Porous silicon nanowires, possessing significantly enhanced surface area and defect density, are promising materials for the development of integrated gas sensors operating at room temperature, benefiting from the mature chemical etching technology in terms of large‐scale fabrication, cost savings, and convenience for hybrid design . Liu et al recently reported a simple SiNW‐TiO 2 core‐shell heterojunction created by the sol‐gel and drop‐casting methods (Figure A). The fabricated chemiresistor sensor exhibited a linear response to CH 4 gas in the 30‐120 ppm range, with a detection limit of 20 ppm at room temperature, benefiting from a depletion layer at the interface of SiNWs and the TiO 2 layer.…”

Highly sensitive NO2 sensors based on core‐shell array of silicon nanowires/polypyrrole and new insight into gas sensing mechanism of organic/inorganic hetero‐contact

“…[13,14]) or oxides (TeO 2 , ZnO, etc. [15,16]) also shows effective improvement in response magnitude and selectivity. Nevertheless, little efforts on SiNWs with C-S heterostructure have been performed so far.…”

One‐Step Synthesis of Charge‐Transfer Salt Nanosensors on Microelectrode Patterns

“…Specifically, because of the unique physical and chemical properties of 1D nanostructures, such as nanowires, they are considered a promising building block for ultrahigh performance sensors. [ 2–10 ] Despite their initial promise, nanosensors captured only $536.6 million of the market share in 2019. [ 11 ] A major bottleneck for nanosensor commercialization is a lack of scalable manufacturing methods.…”