Enhancing charge transfer in NiFe-LDH anodes via Ti4O7 integration for high-performance alkaline water electrolysis

Abstract

Exploring efficient oxygen evolution reaction (OER) electrocatalysts is critical for improving the performance of alkaline water electrolyzers (AWEs). Nickel–iron layered double hydroxide (NiFe-LDH) is regarded as a promising candidate but suffers from intrinsically low electrical conductivity that restricts charge transfer during OER catalysis. Herein, we present a facile and scalable strategy to fabricate a NiFe-LDH/Ti₄O₇ composite OER catalyst by integrating highly conductive Magnéli-phase Ti₄O₇ with NiFe-LDH, serving as the anode of AWE. The resulting composite preserves the flower-like morphology of pristine NiFe-LDH while achieving a high electrical conductivity of 0.81 S cm⁻¹. Electronic structure analysis shows that the work function difference between NiFe-LDH and Ti₄O₇ generates a built-in electric field at the heterointerface, driving electron transfer from NiFe-LDH to Ti₄O₇, which induces band gap narrowing for NiFe-LDH/Ti₄O₇, thereby accelerating charge transport and thus boosting OER kinetics. The optimal composite displays a high OER activity with an overpotential of 262 mV at 10 mA cm⁻², outperforming pure NiFe-LDH (290 mV). When directly spray-coated onto a Zirfon membrane to form the catalyst-coated membrane (CCM), the assembled AWE operates a cell voltage of 1.66 V at a current density of 0.5 A cm⁻², which is 40 mV lower than that of pure NiFe-LDH (1.70 V), and maintains stable performance for over 351 h. This work demonstrates that the integration with conductive Ti₄O₇ facilitates charge transfer in NiFe-LDH-based anodes, providing a strategy for the fabrication of high-performance electrodes for AWE application.