An enhanced oxygen evolution reaction on 2D CoOOH via strain engineering: an insightful view from spin state transition

Spin state of Co 3+ ion transfers from low spin (LS: t62ge0g) to high spin (HS: t42ge2g) under strain engineering. HS CoOOH is much active for OER, because of small O 2 release energy (0.03 eV) and effective directly O–O bond coupling (1.21 eV).