Fabrication of hierarchically flower-like trimetallic coordination polymers via ion-exchange strategy for efficient electrocatalytic oxygen evolution

Designing a highly efficient electrocatalyst with more active sites and faster charge transfer is crucial to improve oxygen evolution reaction (OER) performance. Herein, hierarchically trimetallic Co0.7Fe0.24Ni0.06-BDC (1,4-benzenedicarboxylate, denoted as BDC) coordination polymers have been prepared via ion-exchange by immersing Co-BDC micro-flowers into bimetallic solution under mild conditions. This strategy introduces the other transition metal ions into Co-BDC micro-flower structure without destroying Co-BDC superior flower-like morphology. As electrocatalyst in OER, Co0.7Fe0.24Ni0.06-BDC exhibits an outstanding performance with a small overpotential of 291 mV at 50 mA·cm−2 and a Tafel slope of 60.8 mV·dec−1. Durability of Co0.7Fe0.24Ni0.06-BDC is demonstrated by long-term electrochemical stability for 12 h at current density of 10 mA·cm−2. This enhanced OER activity of Co0.7Fe0.24Ni0.06-BDC micro-flowers attribute to the superior morphology of micro-flowers and the synergistic effect of tri-metal, inducing the presence of abundant active sites and fast charge transfer. This work suggests that Co0.7Fe0.24Ni0.06-BDC micro-flowers have great practical potential in the field of OER.