End Group Modification for Black Phosphorus: Simultaneous Improvement of Chemical Stability and Gas Sensing Performance

Abstract

Black phosphorus (BP) nanosheets have been receiving attention for gas sensing showing superior sensitivity and selectivity among various two-dimensional materials. However, the instability of BP nanosheets due to chemical degradation, especially in humid environments, has severely limited their potential applications. Here, we propose to control the chemical stability of BP nanosheets through modifying their end groups via silanization treatment. Compared with other chemical passivation methods, the end group modification strategy proposed here can be well-controlled and results in little variation in the electronic structure of the puckered phosphorus plane. The results show that modification with fluoroalkylsilane leads the hydrophilic BP to become hydrophobic and exhibits extended chemical stability in oxidizing, humid environments. The sensitivity of fluoroalkylsilane-modified BP (F-BP) to NO2 improved by 3.9-fold in comparison with that of pristine BP nanosheets. More importantly, the NO2 sensing response could remain stable under changing relative humidity ranging from 5% to 95%. Such excellent sensing performance is ascribed to the strong interaction between NO2 and BP decorated with fluoroalkylsilane, as confirmed by density functional theory calculations. This work offers an effective means for preventing degradation of BP in ambient environments and provides a promising solution to solve the issue regarding humidity dependence in gas sensors.

NASICON-type Na3Fe2(PO4)3 material for an excellent room temperature CO sensor

“…The Langmuir curve is the representation of the quantitative relationship between gas sensitivity and concentration explicitly. 46,47 As shown in Fig. 9(d), most of the data fall well on the Langmuir adsorption isotherm curve, implying that the gas responsivity of the NFP sensor is dominated by the concentration of CO gas adsorption at the surface of NFP.…”

Dual Improvement in Sensitivity and Humidity Tolerance of a NO2 Sensor Based on 3-Aminopropyltriethoxysilane Self-Assembled Monolayer-Functionalized SnSe2 for Explosive Photolysis Gas Detection

“…The results above are consistent with the Raman spectra. As the functionalization time increases, the deficit of water can result in incomplete hydrolysis, which can impede the formation of monolayers and diminish the efficiency of APTES molecules in electron donation to the SnSe 2 surface. , Moreover, extended silanization time will lead to the formation of nonconductive multilayer polysiloxane, which will hamper electron transport and increase sensor resistance Figure S5a,b displays the I – V curves for AS0 and AS3 sensors; each curve is a straight line, confirming Ohmic contact between the sensitive materials and electrodes.…”

“…Based on functionalized poly(3,4-ethylene-dioxythiophene)-poly(styrene sulfonate) with various SAMs, Jiang and co-authors developed an electronic nose system that successfully executed the categorization of ketones, alcohols, alkanes, aromatics, and amines . In contrast to pure black phosphorus nanosheets, the sensor created by Xu et al that was fluoroalkylsilane-modified displayed superior responsiveness to NO 2 and extended chemical stability in humid conditions . As shown, SAM technology is a simple and efficient way to improve the gas selectivity and humidity tolerance of gas sensors by tailoring the terminal groups.…”

Flexible/wearable resistive gas sensors based on 2D materials

“…From this view, Xu et al 133 improved the chemical stability of the BP by modifying its end oxygen functional groups by salinization and fabricated a flexible NO 2 gas sensor. In this work, they first synthesized BP nanosheet by simple liquid exfoliation and then surface of BP nanosheet was modified with hydrophobic fluoroalkylsilane through salinization.…”