The introduction of Cu and P centers in the NiFe-based nanoalloy not only increases the stability of the resulting transition metal-based hierarchical nanostructure (NiFeCuP) but also enhances its catalytic activity (faster OER kinetics with an overpotential of 213 mV at 10 mA/cm²). Various X-ray-based techniques along with detailed electron imaging and electrochemical measurements of NiFeCuP before and after OER allowed us to understand the relationship between the local geometry of catalytically active sites and their extent of participation in the OER activity based on crystal field theory.