3D fibrous root system-like Co(PO3)2/NiCoP heterojunction of Fe-Cr bimetallic co-doping as a bifunctional electrocatalyst for overall water splitting

To tackle the conversion and storage of extra renewable electricity and satisfy the ceaselessly expanding worldwide energy need, the craft of affordable and steady bifunctional electrocatalysts stands as vital. In this work, a FeCr co-doped Co(PO 3 ) 2 /NiCoP (FC-CPO/NCP) heterojunction electrocatalyst with self-supported 3D fibrous root system-like structure is successfully fabricated on nickel foam via a classic two-step hydrothermal-phosphatization approach. This fibrous root system-like nanostructure offers abundant porous channels and exposed active sites, which efficiently accelerate the electrolyte transport and enable the smooth proceeding of electrocatalytic reactions. Meanwhile, benefiting from its intrinsic interfacial composition and synergistic effect of dual metal doping, the FC-CPO/NCP catalyst facilitates the rapid electron transfer, optimizes the electronic structure and elevates the catalytic activity. Electrochemical characterizations verify that the as-prepared catalyst delivers appropriate bifunctional activities, showing the overpotentials of 225 mV for OER and 55 mV for HER at 10 mA cm −2 in alkaline electrolyte. When assembled as both electrodes into an electrolyzer for overall water splitting, the system achieves a current density of 10mA cm −2 at the cell voltage of 1.50 V and maintains robust stability over 72 h of continuous operation. This work provides an efficient and economical strategy for the rational design of high-performance electrocatalysts, thereby advancing the progress of sustainable energy conversion devices.