A High‐Performance Nitro‐Explosives Schottky Sensor Boosted by Interface Modulation

Abstract

4039wileyonlinelibrary.com mole cules and depends highly on the analyte concentrations. [8][9][10][11][12] As a result, the traditional Ohm-contacted nanosensor has diffi culty in realizing the ultrasensitive detection in real circumstances where open environment must be considered. Recently, it was demonstrated that Schottky contact could largely improve the sensitivity of nanosensors due to that Schottky barrier serves as a "gate" controlling the current passing through the barrier, [ 13,14 ] and the value of this current highly depends on the Schottky barrier height (SBH). A small change in SBH will lead to a huge change in current, which is the basis of the Schottky barrier enhanced sensing. [ 13 ] The selection of the components of the Schottky junction is of vital importance to improve the sensor performance, which highly depends on the energy band structure and adsorption characteristics. It is reported that a higher SBH favors a better sensitivity in a Schottky-gated sensor toward electron acceptor analytes detection, while for electron donor analytes detection, the result is opposite. [ 15 ] Thus, the insertion of another semiconductor that could both modulate the SBH and increase the adsorption energy will greatly increase the sensitivity and selectivity in a Schottky junction sensor. Graphene or reduced graphene oxide (rGO) with high charge carrier mobility, atomically thin nature and abundant adsorption sites, [16][17][18][19][20] makes the semiconductor/graphene Schottky heterojunction (Barristor) ultrasensitive for gas sensing. [ 21,22 ] Vertical silicon nanowires (SiNWs) array offers distinct merits in terms of the capability for surface functionalization and the suffi cient gaps for molecules diffusion, and SiNWs array-based sensor has been considered an ideal platform for gas sensing due to the higher signal-to-noise ratios and faster response. [ 23,24 ] The electron affi nity of TiO 2 (4.0 eV) is only a bit smaller than that of silicon (4.05 eV); [ 25 ] thus the insertion of TiO 2 into Si/rGO should be an ideal choice to support the above assertion. As a result, the SiNWs array/TiO 2 /rGO ternary junction will provide a new approach for designing ultrasensitive and selective sensors.Nitro-explosives is one of the most important categories in common explosives, and the detection of them has been a research focus due to plenty of adverse events, increasing threat of terrorism attack, and the need for homeland security. [ 1,9,26,27 ] The sensitive, selective, and rapid detection of nitro-explosives vapors is still a challenge due to the low vapor pressure of

Transition‐Metal‐Doped p‐Type ZnO Nanoparticle‐Based Sensory Array for Instant Discrimination of Explosive Vapors

“…The responses for PA and RDX are 36.1% and 45.5%, which are much higher than those of the best Schottky sensor based on SiNWs array/TiO 2 /rGO junction (4% for PA and 9% for RDX) . What is more, all the response time and recovery time for TNT, DNT, PA, PNT, and RDX are less than 8 s, which is remarkably superior than all of the other sensors . This comparison further confirms that the present transition‐metal‐doping method could be a very promising strategy to put the nanomaterials‐based explosive sensors into practical application.…”

“…The comparison of the performance (including the sensor response, response time, and recovery time) of the present transition‐metal‐doped ZnO nanoparticle‐based sensors and other recently reported chemiresistor or Schottky sensors toward explosive vapors detection can be found in Table 1 . It is clearly shown that the present transition‐metal‐doped ZnO nanoparticle‐based sensors belong to the best TNT and DNT sensors since the responses toward them are 45.5% and 38.9%, respectively, and are comparable to the best titania (B) nanowires‐based chemiresistor gas sensor (47% for TNT and 38% for DNT). The responses for PA and RDX are 36.1% and 45.5%, which are much higher than those of the best Schottky sensor based on SiNWs array/TiO 2 /rGO junction (4% for PA and 9% for RDX) .…”

“…It is clearly shown that the present transition‐metal‐doped ZnO nanoparticle‐based sensors belong to the best TNT and DNT sensors since the responses toward them are 45.5% and 38.9%, respectively, and are comparable to the best titania (B) nanowires‐based chemiresistor gas sensor (47% for TNT and 38% for DNT). The responses for PA and RDX are 36.1% and 45.5%, which are much higher than those of the best Schottky sensor based on SiNWs array/TiO 2 /rGO junction (4% for PA and 9% for RDX) . What is more, all the response time and recovery time for TNT, DNT, PA, PNT, and RDX are less than 8 s, which is remarkably superior than all of the other sensors .…”

Surface defect engineering: gigantic enhancement in the optical and gas detection ability of metal oxide sensor

“…For metal-oxide nanomaterials, because the high surface-to-volume ratio and surface defect of nanostructures, which made the metal-oxide nanomaterials are quite sensitive for the environment variation [19][20][21][22][23][24][25][26] . Many articles reported that Schottky contact mechanism can enhance the performance of metal-oxide nanomaterials, such as piezotronic devices 27,28 , nanogenerators [29][30][31][32] and nanosensors 20,[33][34][35][36][37][38][39] .…”

Artificial Olfactory System for Trace Identification of Explosive Vapors Realized by Optoelectronic Schottky Sensing

“…Explosives detection‐related terrorist attack has become a major threat to the homeland security and social stability, and thus the exploration of reliable detection methods toward trace explosives is of great urgency . Up to now, much efforts have been made in the field of trace explosives detection, such as ion mobility spectrometry method, fluorescent method, and gas sensing method . Among them, the detection of vapor‐phase explosives has the merits of noncontacting and simple sampling.…”