Mesoporous nickel-iron-manganese-alloy based metal/metal oxide composite thick film catalysts
Selective alloy corrosion is used to synthesize a robust and ultrafine mesoporous NiFeMn-based metal/metal oxide oxygen evolving catalyst with ligament and pore sizes in the range of 10 nm and a BET surface area of 43 m 2 /g. As an oxygen evolving catalyst, the mesoporous catalyst exhibits high stability (>264 hours) at a high current density (500 mA/cm 2 ) with a low overpotential (360 mV) using a moderate electrolyte concentration (1 M KOH). The catalyst is made from non-precious metals and its fabrication is straight forward and directly applicable to large-scale synthesis.
1. A nanostructured catalytic electrode, comprising:
(a) a nanoporous alloy material represented by the formula (Ni a Fe b )E t at %;
(b) wherein a is in the range of 30<a<100;
(c) wherein b is in the range of 0<b<60;
(d) wherein t is in the range of 0<t<40;
(e) wherein E is an element selected from the group of elements consisting of Mg, Al, Ti, Mn, Zn, and Ta; and
(f) a layer of an NiFe oxide covering one or more surfaces of the nanoporous alloy material.
2. The nanostructured electrode of claim 1 , wherein said nanoporous alloy material comprises Ni 60 Fe 30 Mn 10 .
3. The nanostructured electrode of claim 1 , wherein said layer of oxide has a thickness in the range of 1 nm to 10 nm.
4. The nanostructured electrode of claim 1 , wherein said layer of oxide is a uniform thickness with a thickness in the range of 1 nm to 50 nm.
5. The nanostructured electrode of claim 1 , wherein said layer of NiFe oxide comprises a NiFeE oxide layer, wherein E is an element selected from the group of elements consisting of Mg, Al, Ti, Mn, Zn, and Ta.
6. The nanostructured electrode of claim 1 , wherein said alloy material has ligaments and pores on the order of 10 nm and has a Brunauer-Emmett-Teller (BET) surface area on the order of 43 m 2 /g.
7. The nanostructured electrode of claim 1 , wherein said alloy material has a catalytic area per cm 2 on the order of 3×10 4 cm 2 .
8. The nanostructured electrode of claim 1 , wherein said alloy material exhibits a catalytic activity towards water oxidation of 500 mA/cm 2 at 360 mV overpotential in 1 M KOH electrolyte.
9. An electrochemical cell comprising:
(a) a vessel containing an aqueous alkali electrolyte and an ion permeable membrane separating the electrolyte into a first volume and a second volume;
(b) a cathode coupled to a source of current disposed in the first volume of electrolyte; and
(c) a nanostructured catalytic anode, wherein said anode comprises:
(i) an alloy material represented by the formula (Ni a Fe b )E t at %;
(ii) wherein a is in the range of 30<a<100;
(iii) wherein b is in the range of 0<b<60;
(iv) wherein t is in the range of 0<t<40; and
(v) wherein E is an element selected from the group of elements consisting of Mg, Al, Ti, Mn, Zn, and Ta; and
(vi) a layer of oxide covering one or more surfaces of the alloy material.
10. The cell of claim 9 , wherein a ratio of index a to index b in the alloy material represented by the formula (Ni a Fe b )E t at % is 2:1.
11. The cell of claim 10 , wherein the alloy material comprises: Ni 60 Fe 30 Mn 10 .
12. The cell of claim 9 , wherein the layer of oxide is a NiFe oxide layer that has a thickness in the range of 1 nm to 50 nm.
13. The cell of claim 9 , wherein the layer of oxide is a NiFeE oxide layer that has a thickness in the range of 1 nm to 50 nm, wherein E is an element selected from the group of elements consisting of Mg, Al, Ti, Mn, Zn, and Ta.
14. The cell of claim 9 , wherein said anode has ligaments and pores on the order of 10 nm and has a Brunauer-Emmett-Teller (BET) surface area on the order of 43 m 2 /g.
15. The cell of claim 9 , wherein said anode has a catalytic area per cm 2 on the order of 3×10 4 cm 2 .
16. The cell of claim 9 , wherein said anode exhibits a catalytic activity towards water oxidation of 500 mA/cm 2 at 360 mV overpotential in 1 M KOH electrolyte.