As above mentioned, the high-valence transition metal species are recognized as active sites for OER. The promoted formation of high-valence metal species in an electrocatalyst and thus decreased energy barriers can improve its OER catalytic activity. This was previously achieved with current synthetic strategies, such as doping heteroatoms , incorporating electron-deficient elements as electron sinks , designing strong interface coupling effect , etc., and then promoting the oxidation of M 2+ to M 3+ in the OER catalysts. A combination of the Raman and XPS results verified the critical role of high-valence metal in forming the active phase, which promises improved activity of CoNiCuFe-PBA in the electrocatalytic OER compared with the CoNiCuFe-oxide counterpart. To be more specific, a large amount of high valence state species with low coordination number, i.e. Co 3+ and Ni 3+ of the CoNiCuFe-PBA catalyst can optimize the *OH adsorption energy and promote the formation of MOOH active phases to produce oxygen efficiently. In this context, CoNiCuFe-PBA with a better crystallinity could be transformed more easily into the active oxyhydroxide phase and maintain for a long time, leading to both more advantageous OER activity and stability (Figure ). In contrast, there exists an indispensable step of M 2+ to M 3+ in the OER process of CoNiCuFe-Oxide, instead of adsorbing the second OH -and forming MOOH. Therefore, the design of OER catalysts should seek methods for more active phase (namely MOOH) transformation rather than simply for amorphous structures.