Tailoring Ca<sub>2</sub>Mn<sub>2</sub>O<sub>5</sub> Based Perovskites for Improved Oxygen Evolution Reaction

2018-10-29T00:00:00Z (GMT) by Neha Bothra Sandhya Rai Swapan K. Pati
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 Ca<sub>2</sub>Mn<sub>2</sub>O<sub>5</sub>, 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 <i>e</i><sub><i>g</i></sub> filling of the metal center is observed which affects the catalytic activity. 30% Ce doped Ca<sub>2</sub>Mn<sub>2</sub>O<sub>5</sub> 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<sub>0.7</sub>Ca<sub>1.3</sub>­Mn<sub>2</sub>O<sub>5</sub> as an efficient, cost-effective catalyst for OER.