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US-12623208-B2 - Titanium dioxide particles and methods of making the same

US12623208B2US 12623208 B2US12623208 B2US 12623208B2US-12623208-B2

Abstract

Provided herein are TiO 2-x nanoparticles and materials that show unusual photophysical and optical properties. These TiO 2-x particles and materials can be used as efficient photocatalysts for the reduction of CO 2 with H 2 O to produce CH 4 . Also provided herein are methods of making TiO 2-x nanoparticles using a polymer-derived mesoporous carbon (PDMC) as a template.

Inventors

  • Tewodros Asefa
  • Tao Zhang
  • Eliška Materna Mikmeková
  • Alexei M. TYRYSHKIN

Assignees

  • RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
  • INSTITUTE OF SCIENTIFIC INSTRUMENTS OF THE CZECH ACADEMY OF SCIENCES, V.V.I.

Dates

Publication Date
20260512
Application Date
20210514

Claims (9)

  1. 1 . A material comprising TiO 2-x nanoparticles, wherein: the material has a light absorption onset of about 400 nm to about 510 nm; x is a number ranging from 0.001 to 0.100; the nanoparticles have a substantially uniform size; the nanoparticles have an average size of about 5 to about 12 nm; and the material has an average pore size of about 5 to about 12 nm.
  2. 2 . The material of claim 1 , wherein the TiO 2-x is in an anatase phase.
  3. 3 . The material of claim 1 , which does not substantially aggregate with a plurality of equivalent particles.
  4. 4 . The material of claim 1 , which has a BET surface area of about 70 to about 110 m 2 g −1 .
  5. 5 . The material of claim 1 , which has a pore volume of about 0.1 to about 0.3 cm 3 g −1 .
  6. 6 . The material of claim 1 , which comprises at least one of optically-active mid-gap states related to oxygen vacancies or interstitial Ti 3+ species.
  7. 7 . The material of claim 6 , wherein the interstitial Ti 3+ species comprises a plurality of under-coordinated O − groups.
  8. 8 . A method of reducing carbon dioxide, the method comprising: contacting a gas comprising CO 2 with the material of claim 1 in the presence of light; and reducing the CO 2 to provide CH 4 .
  9. 9 . The method of claim 8 , wherein at least one of the following applies: the CH 4 production rate is about 16 to 35 μmol h −1 g −1 ; the light comprises ultraviolet radiation.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a 35 U.S.C. § 371 national phase application from, and claims priority to, PCT International Patent Application No. PCT/US2021/032469, filed May 14, 2021, which claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 63/025,225, entitled “TITANIUM DIOXIDE PARTICLES AND METHODS OF MAKING THE SAME,” filed May 15, 2020, the disclosures of which i-s are incorporated herein by reference in their entireties. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with government support under Grant Nos. CBET-1508611 and DMR-1508611 awarded by the National Science Foundation. The government has certain rights in this invention. BACKGROUND Nanostructured materials have interesting electronic, optical and magnetic properties, often drastically different from their bulk counterparts. Many of their properties can be further tuned and optimized for specific applications by changing the nanoscale size, shape, and structural/chemical compositions of the materials. This can be achieved, for example, through doping the nanomaterials with other elements (metals and heteroatoms), by conjugating them with other materials and creating heterojunctions, and by introducing nanopores into their surfaces. With the global production of over 10 million metric tons, TiO2 is one of the most widely used materials for various applications. Examples of its applications include commercial sunscreens, self-cleaning, paints, cosmetic products, and varnishes. TiO2 is also used in the paper/pulp, plastic, fiber, rubber, food, glass and ceramic industries. In nanosized powder forms, TiO2 has been explored for various photocatalytic reactions including water splitting and CO2 reduction. TiO2 is attractive for all these applications because of its semiconducting properties, inexpensiveness, environmental friendliness, and stability under various conditions. However, TiO2 is not very efficient in driving photocatalytic reactions for the following two reasons: (a) TiO2 has a large band gap (3.2 eV) and is thus capable of absorbing light only in the UV region of solar spectrum (ca. 3% of total solar spectrum), and (b) photoexcited electrons and holes in pristine TiO2 have fast recombination times, resulting in poor performance in redox reactions. While photocatalysis research on TiO2 has a long history, TiO2-based photocatalysis aimed to green energy applications has recently received renewed interest. One prominent example is utilizing TiO2 photocatalysts in the hydrogen evolution reaction (HER) to produce hydrogen (H2), a clean energy carrier, from water. Another example is converting the greenhouse gas CO2, which is largely produced from the combustion of fossil fuels and which continues to pose a danger of global warming, into synthetic fuels and valuable chemical feedstocks (such as CH4, CH3OH, HCOOH, carbonates and carbamates). Although photochemical reduction of CO2, using water or H2, have long been demonstrated, the problem still remains on improving a quantum efficiency (i.e., the proportion of light quanta utilized in a catalytic reaction out of total number of quanta absorbed) in the reaction. Large scale applications are still awaiting for availability of large-surface-area and sustainable TiO2 catalysts, specifically engineered for efficient reduction of CO2. In particular, catalysts that can do so with sustainable energy sources such as sunlight are of paramount importance to scale-up the process for a broad range of applications. Demands for novel materials that can be used for photochemical transformations with improved quantum efficiency are still high. The present invention addresses and meets this need. BRIEF SUMMARY OF THE INVENTION In various aspects, a material titanium oxide material containing TiO2-x is provided. The material has a light absorption onset of about 400 nm to about 510 nm, and x is a number ranging from 0.001 to 0.100. In various aspects, a method of making a titanium oxide particle is provided. The method includes contacting a titanium-containing compound with at least one polymer-derived mesoporous carbon (PDMC) material; and heating the titanium-containing compound and the PDMC at a temperature of about 500 to 1200° C. in an inert atmosphere to form titanium oxide particles. Advantageously, in various aspects, the titanium oxide materials described herein can reduce carbon dioxide as provided in the method described herein. The method includes contacting a gas comprising CO2 with any of the titanium oxide materials described herein in the presence of light; and reducing the CO2 to provide CH4. BRIEF DESCRIPTION OF THE FIGURES The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments of the present application. FIG. 1 illustrates a schematic illustration of one embodiment of the procedure to synthesize TiO2-x/PDMC and TiO2-x. First, PANI (po