Nickel Boride/Boron Carbide Particles Embedded in Boron‐Doped Phenolic Resin‐Derived Carbon Coating on Nickel Foam for Oxygen Evolution Catalysis in Water and Seawater Splitting

Abstract Electrolysis of seawater can be a promising technology, but chloride ions in seawater can lead to adverse side reactions and the corrosion of electrodes. A new transition metal boride‐based self‐supported electrocatalyst was prepared for efficient seawater electrolysis by directly soaking nickel foam (NF) in a mixture of phenolic resin (PR) and boron carbide (B 4 C), followed by an 800 °C annealing. During PR carbonization process, the reaction of B 4 C and NF generated nickel boride (Ni x B) with high catalytic activity, while PR‐derived carbon coating was doped with boron atoms from B 4 C (B−C PR ). The B−C PR coating fixed Ni x B/B 4 C particles in the frames and holes to improve the space utilization of NF. Meanwhile, the B−C PR coating effectively protected the catalyst from the corrosion by seawater and facilitates the transport of electrons. The optimal Ni x B/B 4 C/B−C PR /NF required 1.50 and 1.58 V to deliver 100 and 500 mA cm −2 , respectively, in alkaline natural seawater for the oxygen evolution reaction.