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 (B4C), followed by an 800 °C annealing. During PR carbonization process, the reaction of B4C and NF generated nickel boride (NixB) with high catalytic activity, while PR‐derived carbon coating was doped with boron atoms from B4C (B−CPR). The B−CPR coating fixed NixB/B4C particles in the frames and holes to improve the space utilization of NF. Meanwhile, the B−CPR coating effectively protected the catalyst from the corrosion by seawater and facilitates the transport of electrons. The optimal NixB/B4C/B−CPR/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.

Transition Metal‐Based Electrocatalysts for Seawater Oxidation

“…Li et al. [ 100 ] prepared a new transition metal boride‐based electrocatalyst by placing nickel foam (NF) in a mixed solution of phenolic resin (PR) and boron carbide (B 4 C) and then annealing at 800 °C (Figure 7e). In addition, this catalyst not only can maintain fine OER stability in alkaline seawater (100 mA cm −2 , 24 h) but also shows good corrosion resistance in natural seawater.…”

“…e) Schematic illustration of the preparation process for Ni x B/B 4 C/B-C PR /NF. Reproduced with permission [100]. Copyright 2021, Wiley.…”

Recent advances in transition metal‐based electrocatalysts for seawater electrolysis

“…In addition to the effective application for HER, TMCs have also served as effective OER electrocatalysts due to the high electrical conductivity and corrosion resistance in seawater. For instance, Li et al reported facile immersion and calcination method for the fabrication of Ni x B/B 4 C, which was transformed from the precursors of the phenolic resin and boron carbide, as shown in the Figure 8A 86 . The SEM and TEM image showed the morphology of such catalyst (Figure 8B‐D), which exhibited nano‐sized particles (Figure 8C).…”

“…For instance, Li et al reported facile immersion and calcination method for the fabrication of Ni x B/B 4 C, which was transformed from the precursors of the phenolic resin and boron carbide, as shown in the Figure 8A. 86 The SEM and TEM image showed the morphology of such catalyst (Figure 8B-D), which exhibited nano-sized particles (Figure 8C). Typically, the B-doped carbon layer not only fixed the Ni x B/B 4 C nano-sized particles, but also played important role of the transport for electrons.…”

“…(A) Synthesis scheme for the Ni x B/B 4 C. (B) SEM image, (C) TEM image, (D) HRTEM image, (E) XRD pattern, (F) XPS spectra, and (G) Raman spectra for the Ni x B/B 4 C. Reproduced with permission from reference [86]. Copyright 2021, Chemistry Europe Societies.…”