High-valent metal molybdenum-doped NiFe LDH nanosheet for efficient oxygen evolution reaction

Abstract

Due to its unique layered structure and excellent stability, NiFe layered double hydroxide (NiFe LDH) is considered to be a promising catalyst for oxygen evolution reaction (OER). However, its OER performance is still limited by slow kinetics and poor conductivity. Reasonable design of multiple types of active sites has been proved to be an effective means to optimize the OER performance of NiFe LDH. In this study, a defective high-valence metal molybdenum (Mo) doped NiFe LDH electrocatalyst was designed to adjust the electronic structure and generate multiple types of active sites. NiFe LDH was used as the precursor of OER catalyst, and the high-valent metal Mo was introduced by electrodeposition. The electrodeposition process was optimized by adjusting the amount of Mo introduced and the electrodeposition time. A dandelion-like nickel–iron-molybdenum layered double hydroxide nanosheet/nickel foam (NiFeMo LDH/NF) electrocatalyst was designed using nickel foam (NF) as a self-supporting electrode. When the deposition time is 2400 s, the prepared NiFeMo LDH/NF-2400 s has a large electrochemical active area and a dense pore structure, with overpotentials of 220 and 280 mV at 10 and 50 mA cm⁻², respectively, showing excellent OER activity. Its stability is good, and it remains stable under 1.0 M KOH for 100 h of continuous operation. The results indicate that Mo doping can not only regulate the electronic structure of transition metals, and promote the generation of active sites, but also contributes to the transfer of electrons between the interfaces, thereby improving OER performance.