In-situ cathodic electrochemical activation enhances oxygen evolution performance of g-C3N4@S/NiFe-LDH heterojunctions

Abstract

The sluggish reaction kinetics of the oxygen evolution reaction (OER) markedly hinder water splitting, posing a critical challenge in the design of efficient catalysts. In this study, sulfur-doped NiFe layered double hydroxides (NiFe-LDH) supported on graphitic carbon nitride (g-C₃N₄) were synthesized via a hydrothermal method, resulting in the formation of n-n heterojunctions (g-C₃N₄@S/NiFe-LDH). This novel structure creates built-in electric fields that enhance electron transfer and modulate the valence electron states of the electrocatalyst for OER. During in-situ Electrochemical Activation (EA), particularly under the in-situ Cathodic Electrochemical Activation (CEA) method, a marked enhancement in high-valence nickel species (NiOOH) and metal sulfides was observed. This promotes electrocatalyst reconfiguration and facilitates the formation of high-valence metal species. Leveraging these synergistic effects, g-C₃N₄@S/NiFe-LDH demonstrates exceptional OER performance and durability under alkaline conditions, achieving an overpotential of 257 mV at 50 mA cm⁻² and a Tafel slope of 80 mV cm⁻². This work offers a innovative approach to the synthesis of highly efficient OER catalysts for alkaline media.