Abstract
The development of efficient and robust earth-abundant electrocatalysts for the oxygen evolution reaction (OER) is an ongoing challenge. Here, a novel and stable trimetallic NiFeCr layered double hydroxide (LDH) electrocatalyst for improving OER kinetics is rationally designed and synthesized. Electrochemical testing of a series of trimetallic NiFeCr LDH materials at similar catalyst loading and electrochemical surface area shows that the molar ratio Ni:Fe:Cr = 6:2:1 exhibits the best intrinsic OER catalytic activity compared to other NiFeCr LDH compositions. Furthermore, these nanostructures are directly grown on conductive carbon paper for a high surface area 3D electrode that can achieve a catalytic current density of 25 mA cm(-2) at an overpotential as low as 225 mV and a small Tafel slope of 69 mV dec(-1) in alkaline electrolyte. The optimized NiFeCr catalyst is stable under OER conditions and X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, and elemental analysis confirm the stability of trimetallic NiFeCr LDH after electrochemical testing. Due to the synergistic interactions among the metal centers, trimetallic NiFeCr LDH is significantly more active than NiFe LDH and among the most active OER catalysts to date. This work also presents general strategies to design more efficient metal oxide/hydroxide OER electrocatalysts.