Two-Dimensional Hierarchical CoTe/NiFe Layered Double Hydroxide Heterostructure for High-Performance Electrocatalytic Water Oxidation

The development of high-performance electrocatalysts with low cost is essential for electrocatalytic water oxidation. Here, we report a strategy for boosting oxygen evolution reaction (OER) catalytic activity of the NiFe layered double hydroxide (LDH) by implementing metal-metalloid compounds of CoTe nanosheets (NSs). The hybridized material (CoTe NS/NiFe LDH) shows an intriguing hierarchical 2D-2D heterostructure, where the intact interface between the CoTe NS and NiFe LDH is formed. Self-supported growth of the CoTe NS on the NiFe LDH improves charge transfer and reaction kinetics during the OER due to the enhanced metal-oxygen covalency caused by shifting metal d-orbitals and oxygen p-orbitals from the Fermi level. Moreover, the hierarchical heterostructure of the nanometer-scale CoTe NS on the micrometer-scale NiFe LDH could maximize the number of active sites for the OER. Therefore, CoTe NS/NiFe LDH exhibits low overpotentials of 235 and 252 mV at 30 and 80 mA cm-2 in an alkaline condition (1 M aqueous KOH solution), respectively, with excellent stability over 120 h, outperforming the benchmark RuO2 catalyst.