Substrate-free 2d tellurene

Abstract

The present disclosure generally relates to compositions comprising substrate-free 2D tellurene crystals, and the method of making and using the substrate-free 2D tellurene crystals. The 2D tellurene crystals of the present disclosure are characterized by an X-ray diffraction pattern (CuKα radiation, λ=1.54056 A) comprising a peak at 23.79 (2θ±0.1°) and optionally one or more peaks selected from the group consisting of 41.26, 47.79, 50.41, and 64.43 (2θ±0.1°).

1 . A composition comprising substrate-free 2D tellurene crystals. 
     
     
         2 . The composition of  claim 1 , wherein the 2D tellurene crystals have a lateral length from 0.1-500 μm. 
     
     
         3 . The composition of  claim 2 , wherein the 2D tellurene crystals have a lateral length from 0.1-100 μm. 
     
     
         4 . The composition of  claim 1 , wherein the 2D tellurene crystals have a thickness from 0.5-250 nm. 
     
     
         5 . The composition of  claim 4 , wherein the 2D tellurene crystals have a thickness from 0.5-100 nm. 
     
     
         6 . The composition of  claim 1 , wherein the 2D tellurene crystals comprises 2D tellurene single crystals. 
     
     
         7 . The composition of  claim 1 , wherein the 2D tellurene crystals comprises mono layer 2D tellurene crystals. 
     
     
         8 . The composition of  claim 1 , wherein the 2D tellurene crystals comprises two or more layers of 2D tellurene crystals. 
     
     
         9 . The composition of  claim 1 , wherein the 2D tellurene crystals are characterized by an X-ray diffraction pattern (CuKα radiation, λ=1.54056 A) comprising a peak at 23.79 (2θ±0.1°) and optionally one or more peaks selected from the group consisting of 41.26, 47.79, 50.41, and 64.43 (2θ±0.1°). 
     
     
         10 . A method of preparing substrate-free 2D tellurene crystals, wherein the method comprises reacting sodium tellurite (Na 2 TeO 3 ) and hydrazine (N 2 H 4 ) in an alkaline condition (pH >7) with the presence of polyvinylpyrrolidone (PVP). 
     
     
         11 . The method of  claim 10 , wherein the mole ratio of Na 2 TeO 3 /PVP is 10-100:1. 
     
     
         12 . The method of  claim 10 , wherein the reaction temperature is 120-250° C. 
     
     
         13 . The method of  claim 10 , wherein the reaction time is at least 1 hours. 
     
     
         14 . The method of  claim 11 , wherein acetone is added to the as-synthesized 2D tellurene crystals to provide 2D tellurene crystals with a thickness of 0.5-10 nm. 
     
     
         15 . The method of  claim 11 , wherein NaOH is added to the as-synthesized 2D tellurene crystals to provide 2D tellurene crystals with a thickness of 0.5-10 nm.