Boron-modified cobalt iron layered double hydroxides for high efficiency seawater oxidation

Developing efficient and stable oxygen evolution reaction (OER) catalysts that can work well at high current densities for seawater electrolysis is desirable but remains a significant challenge. Here a novel and scalable strategy is developed to synthesize partially amorphous boron-modified cobalt iron layered double hydroxides (B-Co2Fe LDH). Benefiting from enhanced electronic kinetics and abundant active sites, this hierarchical nanosheet-nanoflake-structured B-Co2Fe LDH catalyst shows superb OER catalytic activity, requiring overpotentials of 205 and 246 mV to drive current densities of 10 and 100 mA cm−2, respectively, in 1 M KOH, along with a small Tafel slope of 39.2 mV dec−1. Its partial amorphousness feature leads to enhanced stability and corrosion resistance, which help the B-Co2Fe LDH catalyst to work well in the critical seawater condition. It requires overpotentials of 310 and 376 mV to drive current densities of 100 and 500 mA cm−2, respectively, in 1 M KOH seawater and can work continuously for 100 h without producing any hypochlorite. This work can enable the development of LDH catalysts for highly selective seawater oxidation using a general approach. [Display omitted] •A novel strategy is developed to synthesize partially amorphous boron-modified cobalt iron layered double hydroxides.•The B-Co2Fe LDH catalyst has a hierarchical nanosheet-nanoflake structure to expose active sites with strong corrosion resistance.•It requires low overpotential and shows excellent stability for OER in alkaline seawater.•In situ Raman and post-OER analysis are applied to analyze the transformation of B-Co2Fe LDH during OER.