A method of making a layered MXene material comprises a) introducing dried MAX phase powder into a vessel under anhydrous, inert conditions, the MAX phase powder comprising a general formula of M.sub.n+1AX.sub.n (n=1, 2, 3, or 4), wherein M is a transition metal or p-block metalloid selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Cu, Ni, Ag, Zn, Cd, In, Sn, and Pb; interlayer A is a Group III, IV, or V metalloid selected from the group consisting of Al, Si, Ga, Ge, In, Sn, Pb, As, Bi, Sb, and X is one of C (carbon) and N (nitrogen); b) introducing a halogen and solvent to the dried MAX phase to create a halogen solution having a predetermined concentration; c) allowing a reaction to proceed for about 24 hours between 30-90 C. to create a reaction slurry comprising a MXene material.

A quantum dot including a nanoparticle template including a first semiconductor nanocrystal including a Group II-VI compound, a quantum well including a second semiconductor nanocrystal disposed on the nanoparticle template, the second semiconductor nanocrystal including a Group IIIA metal excluding aluminum and a Group V element; and a shell comprising a third semiconductor nanocrystal disposed on the quantum well, the third semiconductor nanocrystal including a Group II-VI compound, wherein the quantum dot does not include cadmium, a band gap energy of the second semiconductor nanocrystal is less than a band gap energy of the first semiconductor nanocrystal, the band gap energy of the second semiconductor nanocrystal is less than a band gap energy of the third semiconductor nanocrystal, and the quantum dot includes an additional metal including an alkali metal, an alkaline earth metal, aluminum, iron, cobalt, nickel, copper, zinc, or a combination thereof.

A layered niobate which is used as a photocatalyst. The layered niobate has the formula [H.sub.aA.sub.b].sup.+[Sr.sub.2Nb.sub.3O.sub.10].sup.. [Sr.sub.2Nb.sub.3O.sub.10].sup. forms main layers. [H.sub.aA.sub.b].sup.+ forms interlayers, wherein H includes H.sup.+ and H.sub.3O.sup.+, A is K.sup.+, Cs.sup.+ and Rb.sup.+, 0.6a1, 0b0.4, and a+b=1. The layered niobate has different spacings between the main layers.

A lithium metal composite oxide powder including: secondary particles that are aggregates of primary particles, and single particles that are present independently of the secondary particles, wherein the lithium metal composite oxide is represented by composition formula (I), and the single particles have an average crushing strength exceeding 80 MPa:

Li[Li.sub.x(Ni.sub.(1-y-z-w)Co.sub.yMn.sub.zM.sub.w).sub.1-x]O.sub.2(I)

wherein M is one or more metal elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga, La and V, 0.1x0.2, 0y0.4, 0z0.4, and 0w0.1.

A method of preparing a boron allotrope-organic lateral heterostructural article includes providing an article comprising a substrate comprising a portion thereof coupled to a boron allotrope comprising an elemental boron layer; generating an organic compound vapor from a solid organic compound source, said organic compound vapor having a higher enthalpy of adsorption on said substrate compared to enthalpy of adsorption on said boron allotrope; and contacting said organic compound vapor with said article to selectively deposit said organic compound on a substrate portion not coupled to said boron allotrope to provide a heterostructural article comprising said organic compound and said boron allotrope laterally adjacent one to the other and providing a lateral interface one with the other.

A positive active material, including: a lithium transition metal composite oxide represented by Formula 1:
Li.sub.aNi.sub.bM1.sub.cM2.sub.dM3.sub.eO.sub.2Formula 1 wherein, in Formula 1, M1 comprises Co, Mn, or a combination thereof, M2 comprises Mg and Ti, M3 comprises Al, B, Ca, Na, K, Cr, V, Fe, Cu, Zr, Zn, Sr, Sb, Y, Nb, Ga, Si, Sn, Mo, W, Ba, a rare earth element, or a combination thereof, 0.9a1.1, 0.7b<1.0, 0<c0.3, 0<d0.03, 0e0.05, and 0.95(b+c+d+e)1.05, and a molar ratio of Ti:Mg in M2 is about 1:1 to about 3:1.

Embodiments of the present disclosure relate to forming a two-dimensional crystalline dichalcogenide by positioning a substrate in an annealing apparatus. The substrate includes an amorphous film of a transition metal and a chalcogenide. The film is annealed at a temperature from 500 C. to 1200 C. In response to the annealing, a two-dimensional crystalline structure is formed from the film. The two-dimensional crystalline structure is according to a formula MX.sub.2, M includes one or more of molybdenum (Mo) or tungsten (W) and X includes one or more of sulfur (S), selenium (Se), or tellurium (Te).

Provided are electrochemical cells that include as a cathode active material within the cathode of the cell secondary particles that provide excellent capacity and improved cycle life. The particles are characterized by grain boundaries between adjacent crystallites of the plurality of crystallites and comprising a second composition having a layered -NaFeO.sub.2-type structure, a cubic structure, a spinel structure, or a combination thereof, wherein the electrochemically active cathode active material has an initial discharge capacity of 180 mAh/g or greater; and wherein the electrochemical cell has an impedance growth at 4.2V less than 50% for greater than 100 cycles at 45 C.

A positive electrode for a rechargeable battery, comprising a lithium metal oxide powder having a layered crystal structure and having the formula Li.sub.xTm.sub.yHm.sub.zO.sub.6, with 3x4.8, 0.60y2.0, 0.60z2.0, and x+y+z=6, wherein Tm is one or more transition metals of the group consisting of Mn, Fe, Co, Ni, and Cr; wherein Hm is one or more metals of the group consisting of Zr, Nb, Mo and W. The lithium metal oxide powder may comprise dopants and have the formula Li.sub.xTm.sub.yHm.sub.zM.sub.mO.sub.6 A, wherein A is either one or more elements of the group consisting of F, S or N; and M is either one or more metal of the group consisting of Ca, Sr, Y, La, Ce and Zr, with either >0 or m>0, 0.05, m0.05 and x+y+z+m=6.

A zeolite crystal has an AFX structure and a hexagonal plate shape. Ratio of a maximum Feret diameter (L1) in a plan view with respect to a plate thickness in a side view is greater than or equal to 2.