Engineering Active Sites Enriched <i>2D-on-1D</i> NiFe and NiCo Layered Double Hydroxide-Decorated Ni Nanowire Networks for Oxygen Evolution Reaction
Khaled M. Amin, Kuan-Hsun Lin, Michael Duerrschnabel, Leopoldo Molina‐Luna, Wolfgang Ensinger
Abstract
Green energy technologies, including water splitting and fuel cells, are being extensively pursued to meet the increased demand for renewable energy and tackle the pollution issues related to fossil fuel consumption. The performance of these technologies primarily relies on noble-metal-oxide electrocatalysts, which are typically supported by macroscopic and weighty materials. Therefore, it is urgently needed, although it is still challenging to engineer highly efficient and naturally abundant electrocatalysts in micro- and nanostructures. Herein, we applied a facile strategy to fabricate highly efficient electrocatalysts based on different layered double hydroxides (LDHs), namely, NiCo and NiFe, grown over a free-standing 1D Ni nanowire network (Ni-NWN) for oxygen evolution reaction (OER). Benefiting from the synergy of coupling the 2D LDH nanosheets with its high catalytic activity and the Ni-NWN with its interconnected highly conductive structure and high porosity, the as-prepared NiFe LDH/Ni-NWN exhibited excellent OER performance with a low overpotential of only 222 mV to deliver 10 mA cm –2 . Furthermore, it revealed favorable kinetics, in terms of a 42 mV dec –1 Tafel slope and a low charge transfer resistance. The 3D architecture with its “nanosheet on nanowire” structure improves the mechanical stability, besides retaining efficient electron paths through the Ni-NWN and high ionic diffusion rates through the porous network, which in turn promotes the generation of active phases during OER and provides outstanding durability over 50 h. Furthermore, the architectures’ proposed strategy and flexible engineering are highly promising and could be adopted to fabricate other electrocatalysts for widespread applications.