Tailoring Ni-Fe-B Electronic Effects in Layered Double Hydroxides for Enhanced Oxygen Evolution Activity.

NiFe layered double hydroxides (LDHs) are state-of-the-art catalysts for the oxygen evolution reaction (OER) in alkaline media, yet they still face significant overpotentials. Here, quantitative boron (B) doping is introduced in NiFe LDHs (ranging from 0% to 20.3%) to effectively tailor the Ni-Fe-B electronic interactions for enhanced OER performance. The co-hydrolysis synthesis approach synchronizes the hydrolysis rates of Ni and Fe precursors with the formation rate of B─O─M (M: Ni, Fe) bonds, ensuring precise B doping into the NiFe LDHs. It is demonstrated that B, as an electron-deficient element, acts as an "electron sink" at doping levels from 0% to 13.5%, facilitating the transition of Ni to the active Ni, thereby accelerating OER kinetics. However, excessive B doping (13.5-20.3%) effectively generates oxygen vacancies in the LDHs, which increases electron density at Ni sites and hinders their transition to Ni, thereby reducing OER activity. Optimal OER performance is achieved at a B doping level of 13.5%, with an overpotential of only 208 mV to reach a current density of 500 mA cm, placing it among the most effective OER catalysts to date. This Ni-Fe-B electronic engineering opens new avenues for developing highly efficient anode catalysts for water-splitting hydrogen production.