NiCu alloys anchored defect-rich NiFe layered double-hydroxides as efficient electrocatalysts for overall water splitting

Abstract

Designing bifunctional electrocatalytic materials with non-precious metals for efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a tremendous challenge. NiFe layered double-hydroxide (NiFe-LDH) materialss with modifiable nanostructures and tunable electronic properties have attracted considerable attention. At present, its modification strategies mainly include single structural defect, simple material composite and so on, while there are few studies involving multiple structure defect synergy. In this work, environmental-friendly hydrothermal-electrodeposition method was employed to build oxygen defects on the surface of NiFe layered double hydroxides and anchor NiCu nanoclusters with abundant, cheap nickel foam (NF) as the conductive substrate. The synergistic effect of oxygen defects and NiCu alloys resulted in a significant increase in the exposure of active sites and an enjoyable enhancement in intrinsic electrocatalytic activity. The obtained NiFe-LDH-Vo@NiCu sample exhibits outstanding OER (244 mV@50 mA cm−2)/HER (85 mV@10 mA cm−2) performance in 1 M KOH solution. Furthermore, NiFe-LDH-Vo@NiCu presents ultra-low battery voltage of 1.54 V as well as remarkable stability as a bifunctional electrode. Finally, DFT calculations were applied to reveal the effects of the introduction of O vacancies and the anchoring of NiCu nanoclusters on the internal electronic structure of NiFe-LDH materials. In general, this research can provide new insights into designing of high performance NiFe-LDH electrocatalysts.