Boosting oxygen evolution activity via Cr-induced electronic and structural modulation in NiFe-LDH nanosheets

Abstract

In this study, a series of NiFeCr layered double hydroxide (NiFeCr-LDH) materials with sheet-like morphology and different electronic structure distributions were synthesized via a facile one-step hydrothermal method by adjusting the elemental ratios. As a reliable and stable electrocatalyst, this trimetallic material exhibits prominent advantages in enhancing the kinetics of the oxygen evolution reaction (OER). Under identical catalyst loading, the NiFeCr-3 sample with an Fe : Cr molar ratio of 5 : 3 demonstrated the optimal electrocatalytic performance. This improvement was primarily attributed to the formation of highly active NiOOH species during the catalytic process, while the abundant charge-transfer pathways and variable ionic valence states further contributed to its intrinsic OER activity. In alkaline electrolyte tests, the overpotentials required to achieve current densities of 50 mA cm⁻² and 100 mA cm⁻² were only 287 mV and 331 mV, respectively, with a Tafel slope of 86.5 mV dec⁻¹. Furthermore, the catalyst exhibited excellent long-term stability, maintaining its activity for over 100 hours at a current density of 20 mA cm⁻². Electrochemical measurements and X-ray photoelectron spectroscopy analysis collectively confirmed the synergistic effects among the metal centers in NiFeCr-LDHs. Its catalytic activity was significantly higher than that of NiFe-LDH, indicating the potential of this work for developing high-performance water–alkali electrocatalysts.