Nanostructured transition metal oxides useful for water oxidation catalysis

1. A composition comprising a nanocluster consisting of a nanostructured transition metal oxide consisting of at least one of cobalt, iron, manganese, niobium, tungsten, or a mixture of two or more of said metals wherein said transition metal oxide is capable of oxidizing two H20 molecules to obtain four protons, and a porous matrix wherein the nanostructured transition metal oxide is embedded on and/or in the porous matrix.

2. The composition of claim 1 , wherein the nanostructure is a nanorod.

3. The composition of claim 2 , wherein the nanostructure is a nanorod and the nanocluster comprises a bundle of parallel nanorods.

4. The composition of claim 3 , wherein two or more nanorods of the bundle of parallel nanorods are interconnected to each other by one or more short bridges.

5. The composition of claim 2 or 3 , wherein each nanorod has a diameter of from about 6 nm to about 10 nm.

6. The composition of claim 2 or 3 , wherein the length of each nanorods is from about 40 nm to about 60 nm.

7. The composition of claim 3 , wherein the nanocluster has a crystalline nature.

8. The composition of claim 1 , wherein the transition metal oxide is Co 3 O 4 , MnO 2 , Mn 2 O 3 , or Mn 3 O 4 .

9. The composition of claim 1 , wherein the porous matrix is a mesoporous scaffold.

10. The composition of claim 9 , wherein the mesoporous scaffold is a mesoporous silica scaffold.

11. The composition of claim 9 , wherein the porous matrix comprises a KIT-6 nanopore or SBA-15.

12. The composition of claim 1 , wherein the composition catalyzes the reaction:

CO 2 +H 2 O→CH 3 OHO 2

visible light,

with a turnover frequency (TOF) equal to or more than 1,000 s −1 per nanocluster.

13. The composition of claim 12 , wherein the TOF is equal to or more than 1,140 s −1 per nanocluster.