Surface Coordination of Black Phosphorus for Robust Air and Water Stability

Abstract

At itanium sulfonate ligand is synthesized for surface coordination of black phosphorus (BP). In contrast to serious degradation observed from the bare BP,the BP after surface coordination exhibits excellent stability during dispersion in water and exposure to air for al ong period of time, therebys ignificantly extending the lifetime and spurring broader application of BP.Atomically thin black phosphorus (BP), an ew member of two-dimensional (2D) materials,h as attracted increasing interest because of its unique electronic and optical properties and promising applications. [1][2][3][4][5][6][7][8][9][10][11][12][13] BP crystals have strong inplane bonds and the weak van der Waals interlayer interaction enables exfoliation into few-layer BP sheets or phosphorene (single-layer BP). [14][15][16][17][18] As am etal-free layered semiconductor,B Ph as thickness-dependent band gaps varying from 0.3 eV for bulk to 2.0 eV for phosphorene. [3] Moreover,B Pw ith high mobility and as izeable band gap is at the electronic intersection of graphene (a zero-gap highmobility 2D material) and semiconducting transition metal dichalcogenides (large-gap low-mobility 2D materials). [2,[19][20][21] These fascinating properties suggest that BP is not only promising in nanoscale electronic devices, [22][23][24][25][26] but also suitable for near-a nd mid-infrared region optoelectronic applications. [27][28][29][30][31] Moreover,BPnanosheets possess excellent photochemical and photothermal properties with potential catalytic and biomedical applications. [11,32] In spite of these promising properties,afundamental obstacle hindering the application of BP is its lack of air-and water-stability. [3] It has been demonstrated that BP is very reactive to oxygen and water under ambient conditions, resulting in compositional and physical changes and consequently considerable degradation in the electronic and optical properties. [10,26,[33][34][35][36] Long-term exposure of BP to humid air or water can even completely etch the materials away.[37] This poses as evere limitation to the adoption of BP in flexible electronics and photoelectronics,a nd its instability in water further limits potential electrochemical and biomedical applications.T herefore,m uch effort has been made to understand the degradation mechanism and to improve the stability of BP. [10,22,[38][39][40][41][42][43] Optical microscopy and atomic force microscopy (AFM) have revealed droplet-like structures on the surface of BP upon exposure to air. [10,37,38] Consequently, capping layers have been developed to encapsulate BP sheets and enhance the air-stability of BP,but oxygen and water may enter through the interfaces causing eventual breakdown. [38] Ther ole of oxygen and water in BP degradation has been studied recently, [42] and it has been shown that degradation of BP under ambient conditions is initiated by contact with oxygen but water does not play aprimary role in the reaction. However,water is capable of removing P x O y from the surface and exposing P 0 to con...

Black phosphorus: a two-dimensional reductant for in situ nanofabrication

“…S6), and further modification is required to enhance the stability. 29 Extinction spectra are acquired from the BP@Au composites. As shown in Fig.…”

“…18,19 BP has strong in-plane bonds in conjunction with weak van der Waals interlayer interactions thereby enabling exfoliation into few-layer BP sheets or phosphorene (single-layer BP). [20][21][22][23][24] Since 2014, BP has attracted tremendous research interest [25][26][27][28][29][30][31][32][33][34][35][36][37][38] because of its unique properties such as layerdependent direct bandgap, 28,39 anisotropy, 25,26,31,32,34,40 hingelike structure, 41 and quasi-one-dimensional excitonicnature, 42 all of which contrast markedly with those of other types of 2D materials. Nevertheless, BP degrades under ambient conditions as a result of the reaction with oxygen (P→P x O y ) and subsequent transformation to PO 4 3-in the presence of water.…”

Zonisamide-loaded triblock copolymer nanomicelles as a novel drug delivery system for the treatment of acute spinal cord injury

“…Compared to free ZNS, this prolonged effective drug duration of released ZNS may provide better neuroprotective effects in vivo. 25,47,48 Neuron and axon density are critical indicators of anatomical recovery from SCI. 43,49 In histopathologic examination, a statistically significant increase of NF was observed in the ZNS-M group (Figure 9).…”

2D Black Phosphorus for Energy Storage and Thermoelectric Applications

“…Although BP bulk stands out as the most thermodynamically stable allotrope of phosphorus, the atomically thin phosphorene gradually degrades in the presence of air . It is found that unprotected phosphorene possesses strong affinity for oxygen or water molecules upon exposure to ambient conditions, which presents a fundamental obstacle hindering the potential adoption of phosphorene in (photo) electronics and electrochemical devices.…”