A system and method for synthesizing a nanoparticle material includes dissolving a metal nitrate in deionized water, adding a hydrogel precursor in the deionized water containing the dissolved metal nitrate to create an aqueous solution, heating the aqueous solution, cooling the aqueous solution to create a solid gel, and calcinating the solid gel to create a metal oxide nanoparticle material. The metal oxide nanoparticle material may include a zinc oxide-based nanoparticle material. The hydrogel precursor may include an agarose gel. The solid gel may be calcinated at approximately 600 C. The solid gel may be calcinated for approximately five hours in the presence of air. The aqueous solution may be heated to a boil. The aqueous solution may be heated at a temperature of 100 C.

In one aspect, metal oxide compositions having electronic structure of multiple band gaps are described. In some embodiments, a metal oxide composition comprises a (Co,Ni)O alloy having electronic structure including multiple band gaps. The (Co,Ni)O alloy can include a first band gap and a second band gap, the first band gap separating valence and conduction bands of the electronic structure.

The invention relates to electrodes comprising doped nickelate-containing compositions comprising a first component-type comprising one or more components with an 03 structure of the general formula: A.sub.aM.sup.1vM.sup.2wM.sup.3xM.sup.4yM.sup.5zO.sub.2 wherein A comprises one or more alkali metal selected from sodium, lithium and potassium M.sup.1 is nickel in oxidation state 2+, M.sup.2 comprises one or more metals in oxidation state 4+, M.sup.3 comprises one or more metals in oxidation state 2+, M.sup.4 comprises one or more metals in oxidation state 4+, and M.sup.5 comprises one or more metals in oxidation state 3+ wherein 0.855a1; 0<v<0.5; at least one of w and y is >0; x0; z0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality; together with one or more component-types selected from a second component-type comprising one or more components with a P2 structure of the general formula: A.sub.a<M.sup.1vM.sup.2wM.sup.3x<M.sup.4y<M.sup.5zO.sub.2 wherein A comprises one or more alkali metal selected from sodium, lithium and potassium; M.sup.1 is nickel in oxidation state 2+, M.sup.2 comprises one or more metals in oxidation state 4+, M.sup.3 comprises one or more metals in oxidation state 2+, M.sup.4 comprises one or more metals in oxidation state 4, and M.sup.5 comprises one or more metals in oxidation state 3+ wherein 0.4a<1; 0<v<0.5; at least one of w and y is >0; x0, preferably x>0; z>0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality; and a third component-type comprising one or more components with a P3 structure of the general formula: A.sub.aM1.sub.vM2.sub.wM.sup.3.sub.xM.sup.4.sub.yM.sup.5.sub.zO.sub.2 wherein A comprises one or more alkali metals selected from sodium, lithium and potassium; M.sup.1 is nickel in oxidation state 2+, M.sup.2 comprises one or more metals in oxidation state 4+, M.sup.3 comprises one or more metals in oxidation state 2, M.sup.4 comprises one or more metals in oxidation state 4+, and M.sup.5 comprises one or more metals in oxidation state 3+ wherein 0.4a<1, 0<v<0.5, At least one of w and y is >0; x0; z0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality.

A simple one pot sol-gel method for the synthesis of bi-metal nanostructures is based on non-noble metals (Fe, Co and Sn) and titanium. The method involves the synthesis of mixed metal nanoscale composites using low cost precursors which allow for the synthesis of desired nanocomposite materials with self-scarifying titanium or silica supports. The procedure does not require any surfactant or any need for pH controlled step. Applicants' method involves the in-situ generation of precursors and their simultaneous entrapment in a gel. This simple one pot synthesis allows for the synthesis of homogenous size, shape and distribution of targeted nanostructures. Further, this method can be applied for the preparation of various nanocomposite materials using different choices of metals and self-scarifying supports. Applicants also show that Pd, the noble metal based nanocomposite is feasible.

The subject invention pertains to the synthesis and characterization of V.sub.2O.sub.5/CdE NW/QD heterostructures. The V.sub.2O.sub.5/CdE heterostructures are versatile new materials constructs for light harvesting, charge separation, and the photocatalytic production of solar fuels; polymorphism of V.sub.2O.sub.5 and compositional alloying of both components provides for a substantial design space for tuning of interfacial energy offsets. Also provided are a new class of type-II heterostructures composed of cadmium chalcogenide QDs (CdE where E=S, Se, or Te) and ?-V.sub.2O.sub.5 nanowires (NWs). The synthesis and characterization of V.sub.2O.sub.5/CdE NW/QD heterostructures, prepared via successive ionic layer adsorption and reaction (SILAR) and linker-assisted assembly (LAA), the characterization of their photoinduced charge-transfer reactivity using transient absorption spectroscopy, and their performance in the photocatalytic reduction of protons to hydrogen are also disclosed.

The present invention provides a positive electrode active material precursor having a uniform particle size distribution and a method of preparing the same, and, specifically, provides a positive electrode active material precursor represented by Formula 1, wherein a percentage of fine powder with an average particle diameter (D.sub.50) of 1 ?m or less generated when the positive electrode active material precursor is rolled at 2.5 kgf/cm.sup.2 is less than 1%, and an aspect ratio is 0.93 or more, and a method of preparing the positive electrode active material precursor.

[Ni.sub.xCO.sub.yM.sup.1.sub.zM.sup.2.sub.w](OH).sub.2[Formula 1]

In Formula 1, 0.55?x<1, 0<y?0.5, 0<z?0.5, and 0?w?0.1, M.sup.1 includes at least one selected from the group consisting of Mn and Al, and M.sup.2 includes at least one selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y.

A metal hydroxide includes Ni element. An axial lattice constant c ? of the metal hydroxide satisfies: 0.363x+4.2?c?0.363x+4.4, where, based on a total molar mass of a metal element in the metal hydroxide, a molar percentage of the Ni element in the metal hydroxide is x. The lattice constant c of the metal hydroxide falls within a specified value range. The positive electrode material prepared from the metal hydroxide serving as a precursor is of excellent structural stability in a charging and discharging environment, and improves the cycle performance, high-temperature performance, and safety performance of lithium-ion batteries.

Disclosed herein is a process for making a particulate (oxy)hydroxide, carbonate, or oxide of TM which includes nickel and at least one metal selected from the group consisting of cobalt, manganese, and aluminum. The process includes providing an aqueous solution (?1) containing a water-soluble salt of Ni, one of an aqueous solution (?2) containing a water-soluble salt of Co, an aqueous solution (?3) containing a water-soluble salt of Mn, or an aqueous solution (?4) containing a water-soluble compound of Al, an aqueous solution (?) containing an alkali metal hydroxide or carbonate and, optionally, an aqueous solution (?) containing ammonia or an organic acid or its alkali metal salt, combining solution (?1) and solution (?) and at least one of solutions (?2), (?3), (?4), and, if applicable, solution (?), in different locations of a continuous reactor, and removing the particles from the liquid by a solid-liquid separation method.

The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including an overlithiated lithium manganese-based oxide, and capable of preventing the degradation in electrochemical properties of a lithium secondary battery, including rate characteristics, caused by an excess of lithium and manganese in the lithium manganese-based oxide, and particularly reducing side reactions between the lithium manganese-based oxide and a liquid electrolyte during high-voltage operation, and a lithium secondary battery including the same.

Electrocatalytic materials and methods of making the electrocatalytic materials are provided. Such a method may comprise forming precursor nanosheets comprising a precursor metal on a surface of a substrate; exposing the precursor nanosheets to a modifier solution comprising a polar, aprotic solvent and a metal salt at a temperature and for a period of time, the metal salt comprising a metal cation and an anion, thereby forming modified precursor nanosheets; and calcining the modified precursor nanosheets for a period of time to form an electrocatalytic material comprising structurally modified nanosheets and the substrate, each nanosheet extending from the surface of the substrate and having a solid matrix. The solid matrix defines pores distributed throughout the solid matrix and comprises a precursor metal oxide and domains of another metal oxide distributed throughout the precursor metal oxide; or the solid matrix comprises the precursor metal oxide and nanoparticles of the another metal oxide distributed on a surface of the solid matrix.