Electrochemical methods and systems using catalytic materials

1. A method of generating oxygen, comprising:

providing a voltage source electrically connected to a first electrode and a second electrode; and an alkaline electrolyte in contact with the first electrode and the second electrode;

determining an occupancy of a σ-bonding orbital of e g symmetry parentage as a guide for selecting a catalyst for the second electrode;

preparing a catalyst for the second electrode, the catalyst to have an occupancy of the σ-bonding orbital of e g symmetry parentage of B, B′, or each of B and B′, is in a range of 0.5 to 1.6 and a mass evolution reaction activity that is higher than that of IrO 2 , the catalyst being selected from a group of compounds of formula (I): A x A′ 1−x B y B′ 1−y O 3+−δ (I)

wherein each of A and A′, independently, is a rare earth or alkaline earth metal, x is in a range of 0 to 1, each of B and B′, independently, is a transition metal, y is in a range of 0 to 1, and 6 is in a range of 0 to 1;

measuring the catalyst's specific and mass oxygen evolution reaction activity, and

catalyzing the oxygen evolution reaction when an oxygen-generating voltage is applied across the first electrode and the second electrode; and

applying the oxygen-generating voltage across the first electrode and the second electrode.

2. The method of claim 1 , wherein the catalyst includes a perovskite.

3. The method of claim 1 , wherein A is Ba and A′ is Sr.

4. The method of claim 3 , wherein B is Co.

5. The method of claim 4 , wherein B′ is Fe.

6. The method of claim 5 , wherein the catalyst has the formula Ba 0.5 Sr 0.5 CO 0.8 Fe 0.2 O 3−δ .

7. The method of claim 1 , wherein the occupancy of the σ-bonding orbital of e g symmetry parentage of B, B′, or each of B and B′, is in a range of 0.8 to 1.5.

8. The method of claim 1 , wherein the occupancy of the σ-bonding orbital of e g symmetry parentage of B, B′, or each of B and B′, is approximately 1.2.