Achieving High OER\nPerformance by Tuning the Co/Mn\nContent in Prussian Blue Analogues

The need for efficient, economical, and clean energy\nsystems is\nincreasing, and as a result, interest in water-splitting techniques\nto produce green hydrogen is also increasing. However, the sluggish\nkinetics of the oxygen evolution reaction (OER) hinders the practical\napplication and widespread use of water-splitting technologies; therefore,\nto address this challenge, it is essential to develop cost-effective\nand efficient OER catalysts. In this work, we have synthesized an\ninexpensive and tunable FeCoMn Prussian blue analogue (PBAs) as an\nefficient OER catalyst via a straightforward process. The ratio of\nthe Co and Mn to optimize the electrochemical performance, and as\na result, the FeCo<sub>0.41</sub>Mn<sub>0.42</sub> PBA catalyst demonstrated\nthe best electrochemical performance (260/304 mV overpotential at\n10/50 mA cm<sup>–2</sup>, a low Tafel slope of 48 mV dec<sup>–1</sup> and a good stability of 72 h at 10 mA cm<sup>–2</sup>). Additionally, X-ray absorption spectroscopy (XAS) measurements\nand density functional theory (DFT) calculations suggest that the\nFeCo<sub>0.41</sub>Mn<sub>0.42</sub> PBA possesses the optimized electronic\ndensity distribution at the active site (Co), and the doping of Mn\nand Fe can not only increase the electricity conductivity but also\nactivate the critical H<sub>2</sub>O deprotonation step.