Highly active, robust and versatile multifunctional, fully non-noble metals based electro-catalyst compositions and methods of making for energy conversion and storage
The invention provides noble metal-free electro-catalyst compositions for use in acidic media, e.g., acidic electrolyte. The noble metal-free electro-catalyst compositions include non-noble metal absent of noble metal. The non-noble metal is non-noble metal oxide, and typically in the form of any configuration of a solid or hollow nano-material, e.g., nano-particles, a nanocrystalline thin film, nanorods, nanoshells, nanoflakes, nanotubes, nanoplates, nanospheres and nanowhiskers or combinations of myriad nanoscale architecture embodiments. Optionally, the noble metal-free electro-catalyst compositions include dopant, such as, but not limited to halogen. Acidic media includes oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, and direct methanol fuel cells and oxygen evolution reaction (OER) in PEM-based water electrolysis and metal air batteries, and hydrogen generation from solar energy and electricity-driven water splitting.
1. A nanostructured, noble metal-free, electro-catalyst composition in an acidic electrolyte in a proton exchange membrane-based system, comprising:
a non-noble metal oxide in a form selected from the group consisting of nano-particle, nanocrystalline thin film, nanorod, nanoshell, nanoflake, nanotube, nanoplate, nanosphere, nanowhisker and combinations thereof, of a general formula 1:
(a x b y )O z :wc (I)
wherein, a is Cu, Zn, Sc, Fe, Co, Ti, V, Ni, Cr, Ta, Sn, Nb, W, Mo, Y, La, Ce, Nd, Er, Gd, Yb or mixtures thereof; b is Mn; O is oxygen; c represents dopant that is an element in Groups III, V, VI and VII of the Periodic Table or mixtures thereof; x and y are each a number greater than 0 and less than or equal to 2, x and y being the same or different; z is a number that is greater than 0 and less than or equal to 4, and w is from greater than 0% by weight to about 20% by weight, based on total weight of the composition;
wherein, the noble metal-free electro-catalyst is absent of any noble metal, and
wherein the proton exchange membrane-based system is an oxygen evolution reaction in an acid mediated proton exchange membrane-based water electrolyzer, or an oxygen reduction reaction in an acid mediated proton exchange membrane-based fuel cell.
2. The composition of claim 1 , wherein the dopant is selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, antimony, bismuth, aluminum, boron and mixtures thereof.
3. The composition of claim 1 , wherein the dopant is present is an amount from about 10 to about 15 weight percent based on total weight of the composition.
4. The composition of claim 1 , wherein the non-noble metal is a binary metal oxide comprising copper oxide and manganese oxide, and the dopant is fluorine.
5. The composition of claim 1 , wherein x is 1.5, y is 1.5, z is 4 and w is 5, 10 or 15 percent by weight.
6. The composition of claim 1 , wherein x is 1.5, y is 1.5, z is 2.75 and w is 1.25 by formula unit.