Tailoring Ca₂Mn₂O₅ Based Perovskites for Improved Oxygen Evolution Reaction

The commercialization of numerous electrochemical energy systems is inhibited by the sluggish kinetics of oxygen evolution reactions (OERs) and oxygen reduction reactions (ORRs). OER catalysts should be stable, active, and cheap for their application in electrochemical reactions. Recently, Mn based double perovskites have emerged as suitable catalysts for the OER. We present a density functional theory based comprehensive study on the pristine and doped Ca₂Mn₂O₅, where Ca is replaced with inexpensive alkaline earths, main group elements, and lanthanides to elucidate how the electronic structure can aptly be tuned by doping, for the best catalytic performance. The catalytic performance has been assessed on the basis of the theoretical overpotential calculated for each case. Doping assisted modification of the e_g filling of the metal center is observed which affects the catalytic activity. 30% Ce doped Ca₂Mn₂O₅ shows the best activity in terms of the lowest overpotential value of 0.14 V. We have developed a simple predictive model using 4 electronic structure based descriptors. This study suggests Ce_0.7Ca_1.3­Mn₂O₅ as an efficient, cost-effective catalyst for OER.