Ultrathin 2D Violet Phosphorus Nanosheets: Facile Liquid‐Phase Exfoliation, Characterization, and Photoelectrochemical Application

Abstract

Violet phosphorus (VP) is a stable layered van der Waals phosphorus allotrope with unique electronic and optoelectronic properties. In this study, 2D VP nanosheets (NSs) are prepared by liquid phase exfoliation (LPE) method under ambient conditions. The prepared VP NSs are characterized and utilized for photoelectrochemical (PEC)-type photodetector (PD). The systematic PEC measurements reveal that the as-prepared VP-based PD shows tunable photo-response activities from ultraviolet to visible region. A current density of 0.52 µA cm −2 , a photo-responsivity of 31.70 µA W −1 , and a detectivity of 7.92 × 10 10 Jones can be obtained in 1.0 m KOH under 350 nm irradiation at 0 V, revealing the good self-powered capability of VP-based PD. Furthermore, the cycle and time stability tests exhibit the good chemical and environmental stability of the as-prepared PD via processing 10 000 s on/off switching and placing after one month. It is expected that this work can offer an understanding of a PEC-type VP NSs-based PD, and highlight the further promising applications of 2D VP NSs for other optoelectronic devices.

Discriminative Analysis of NOx Gases by Two-Dimensional Violet Phosphorus Field-Effect Transistors

“…The drain-source current ( I ds ) decreases when the gate voltage sweeps from −40 to 40 V. This result confirms that the VP channel has the p-type semiconductor property, and holes play a leading role for the conduction. This is in agreement with the finding of the p-type conduction of VP in air reported in the literature. , Our VP FET device holds an I on / I off ratio (current on–off ratio) of ∼1.61, in which the larger the on/off ratio of the FET, the higher the carrier mobility, hence the higher sensitivity of gas detection in theory …”

“…As shown in Figure S2c, there are six characteristic bands at 204, 353, 362, 373, 446, and 466 cm –1 in the Raman spectra. Specifically, the bands between 100 and 300 cm –1 are medium vibrational signals from the P–P bond, corresponding to the squeezing vibrational mode at 204 cm –1 ; while no significant signal is detected between 300 and 340 cm –1 or after 500 cm –1 . , The strong bands at 353, 362, 373, and 466 cm –1 are from the breathing and stretching modes of phosphorus cages along the backbone, , which is consistent with the reported Raman spectra of VP. , …”

“…Figure a shows the preparation process of the VP nanosheet FET sensor via mechanical and liquid-phase exfoliation methods. Similar to other 2D nanocrystals, the few-layer and monolayer VP flakes can be produced via mechanical , and liquid-phase exfoliation methods. , VP is a wan der Waals-layered structure composed of tubular strands . The weak van der Waals forces can be torn by mechanical and liquid-phase exfoliation processes to form thin flakes of VP .…”

“…This is in agreement with the finding of the p-type conduction of VP in air reported in the literature. 39,48 Our VP FET device holds an I on /I off ratio (current on−off ratio) of ∼1.61, in which the larger the on/off ratio of the FET, the higher the carrier mobility, hence the higher sensitivity of gas detection in theory. 24 Gas Analysis Performance of the VP FET.…”

“…38,55 The strong bands at 353, 362, 373, and 466 cm −1 are from the breathing and stretching modes of phosphorus cages along the backbone, 39,42 which is consistent with the reported Raman spectra of VP. 38,48 The electrical properties of VP nanosheets are critical to the sensing performance of the FET sensor. First, we tested the output and transfer characteristics of the VP FET device in an ambient environment.…”