Electronic modulation and reaction-pathway optimization on three-dimensional seaweed-like NiSe@NiMn LDH heterostructure to trigger effective oxygen evolution reaction.

ABSTRACT

The development of low-cost and high-efficiency electrocatalysts for the oxygen evolution reaction (OER) is essential to produce high-purity hydrogen in large scale. Herein, a three-dimensional (3D) seaweed-like hierarchical structure was fabricated using two-dimensional (2D) NiMn LDH nanosheets wrapped on one-dimensional (1D) NiSe nanowires with nickel foam (NF) as a substrate (NiSe@NiMn LDH/NF) via hydrothermal and electrodeposition processes. Owing to the strong interfacial synergy, 3D seaweed-like hierarchical structure, higher conductivity, and strong structural stability, the NiSe@NiMn LDH/NF exhibited superior OER performance with an overpotential of 287 mV at 100 mA cm-2, and stably operated for 160 h at large current. Moreover, the overall water splitting system with NiSe@NiMn LDH/NF as the anode and Pt/C/NF as the cathode exhibited a low cell voltage of 1.59/1.64 V to reach 50/100 mA cm-2, and excellent stability for 110 h at 300 mA cm-2. The density function theory (DFT) calculations unveiled that NiSe@NiMn LDH enabled the interfacial synergy, reallocating the electron density at the interface, and further weakening the energy barrier of OH* by strengthening chemical bonds with OH* intermediates to improve the intrinsic OER activity.