Scalable Production of Boron Quantum Dots for Broadband Ultrafast Nonlinear Optical Performance

Abstract

A simple and effective approach based on the liquid phase exfoliation (LPE) method has been put forward for synthesizing boron quantum dots (BQDs). By adjusting the interactions between bulk boron and various solvents, the average diameter of produced BQDs is about 7 nm. The nonlinear absorption (NLA) responses of as-prepared BQDs have been systematically studied at 515 nm and 1030 nm. Experimental results prove that BQDs possess broadband saturable absorption (SA) and good third-order nonlinear optical susceptibility, which are comparable to graphene. The fast relaxation time and slow relaxation time of BQDs at 515 nm and 1030 nm are about 0.394–5.34 ps and 4.45–115 ps, respectively. The significant ultrafast nonlinear optical properties can be used in optical devices. Here, we successfully demonstrate all-optical diode application based on BQDs/ReS2 tandem structure. The findings are essential for understanding the nonlinear optical properties in BQDs and open a new pathway for their applications in optical devices.

Experimental synthesis, functionalized modifications and potential applications of monoelemental zero-dimensional boron nanomaterials

“…With regard to the top-down synthesis approach, mechanical milling is extensively employed to prepare 0D boron nanomaterials. 68,69,[71][72][73][74][75][77][78][79][80]82,85,89 Mechanical milling is divided into different types, including dry ball milling, neat ionic-liquid (IL) milling, solvent milling, sonication-assisted milling, articial and machine grinding. The operation of mechanical milling is oen continuously conducted for a few, several and even dozens of hours at low temperature or room temperature (RT).…”

“…81 Sonication (700 W) in advance or aerwards at a low (5 C) temperature or RT is necessary for ball milling, which ensures a high dispersion of boron resource precursors or the produced 0D boron in the solvent. 74,75,79 Meng et al prepared BQDs via ultrasonication and ball millingassisted exfoliation. 74 Bulk boron powder was added in ethylene glycol to produce a suspension, which then underwent bath sonication to achieve boron sheets.…”

“…74,75,79 Meng et al prepared BQDs via ultrasonication and ball millingassisted exfoliation. 74 Bulk boron powder was added in ethylene glycol to produce a suspension, which then underwent bath sonication to achieve boron sheets. The concentrated dispersion of boron sheets underwent ball milling, together with a rotation rate of 500 rpm for 24 h by a high-energy ball milling machine.…”

“…In previous reports, the sonochemistry method is utilized to conduct LPE of bulk boron, including ice-bath sonication, highenergy (400/700 W) sonication, low-temperature (5 C) ultrasonication, and probe (10 mm) ultrasonication. 70,[74][75][76]79,81,83 Sometimes, the LPE process of bulk boron involves high-energy sonication or low-temperature ultrasonication followed by ball milling or cascade fractionation steps, 74,75,83 and mechanical milling followed by sonication steps. 79 The ultrasonic-assisted LPE approach has been widely employed to prepare 0D boron nanomaterials.…”

“…70 Meng et al reported scalable production of $7 nm BQDs from ultrasonication and ball millingassisted exfoliation. 74 Bulk boron powder was dispersed in ethylene glycol to form the suspension that was treated by bath sonication with a high power of 700 W for 3 h at 5 C to produce boron sheets, followed by centrifugation to remove unexfoliated boron particles and high-energy ball milling to obtain BQDs. Probe ultrasonication and high-energy ball milling (jar) were combined to exfoliate bulk boron powder ($10 mm, average lateral particle size) in dimethylformamide liquid media to obtain $7.1 nm BQDs through mechanochemical reactions.…”