Efficient Oxygen Evolution Reaction Performance Achieved by Tri-Doping Modification in Prussian Blue Analogs

The high cost of hydrogen production is the primary factor limiting the development of the hydrogen energy industry chain. Additionally, due to the inefficiency of hydrogen production by water electrolysis technology, the development of high-performance catalysts is an effective means of producing low-cost hydrogen. In water electrolysis technology, the electrocatalytic activity of the electrode affects the kinetics of the oxygen evolution reaction (OER) and the hydrogen evolution rate. This study utilizes the liquid phase co-precipitation method to synthesize three types of Prussian blue analog (PBA) electrocatalytic materials: Fe/PBA(Fe4Fe(CN)63), Fe-Mn/PBA((Fe, Mn)3Fe(CN)62·nH2O), and Fe-Mn-Co/PBA((Mn, Co, Fe)3IIFeIII(CN)62·nH2O). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses show that Fe-Mn-Co/PBA has a smaller particle size and higher crystallinity, and its grain boundary defects provide more active sites for electrochemical reactions. The electrochemical test shows that Fe-Mn-Co/PBA exhibits the best electrochemical performance. The overpotential of the oxygen evolution reaction (OER) under 1 M alkaline electrolyte at 10/50 mA·cm−2 is 270/350 mV, with a Tafel slope of 48 mV·dec−1, and stable electrocatalytic activity is maintained at 5 mA·cm−2. All of these are attributed to the synergistic effect of Fe, Mn, and Co metal ions, grain refinement, and the generation of grain boundary defects and internal stresses.