Unraveling the Kinetic Role of Doping in the Oxygen Evolution Reaction on Ce–Mn ₃ O ₄ Electrocatalysts

Heteroatom doping is a widely adopted strategy for designing efficient oxygen evolution reaction (OER) electrocatalysts; however, the kinetic role of heteroatoms in the OER remains poorly understood. Herein, using Ce–Mn 3 O 4 electrocatalysts, we reveal how dopants modulate the OER kinetics and enhance the intrinsic OER activity of Mn 3 O 4 . Without altering the OER mechanism, the 1.25% Ce–Mn 3 O 4 exhibits approximately twice the intrinsic activity of Mn 3 O 4 . With operando electrochemical transient absorption spectroscopy, Ce doping accelerates the formation rate of the first OER intermediate (*OH species) ∼4-fold and the rate of rate-determining step ( k RDS ) about 3–4 times. The strong correlation between enhanced intrinsic OER activity and accelerated reaction kinetics indicates the decisive role of k RDS in boosting OER intrinsic activity. Notably, the acceleration of reaction kinetics is more prominent at low potentials. This should be the kinetic reason for the negative shift of onset potential and greater activity of OER by Ce doping in Mn 3 O 4 .