NiFe Layered Double Hydroxide on Nitrogen Doped TiO₂ Nanotube Arrays toward Efficient Oxygen Evolution

Enormous efforts have been devoted to the development of new catalysts or unique nanostructures with high activity and stability at low cost for oxygen evolution reaction (OER). Herein, we designed the fabrication of NiFe layered double hydroxide (LDH) nanoplates supported on nitrogen doped TiO₂ nanotube arrays as a superior OER electrocatalyst and investigated the impacts of NiFe-LDH loading and nitrogen doping concentration on electrocatalytic performance. When the load and nitrogen content are 0.6 mg cm^-2 and 20.9%, respectively, the NiFe/N-TiO₂ exhibits outstanding OER properties and requires a lower overpotential of only 235 mV to achieve the current density of 10 mA cm^-2 with a smaller Tafel slope of 48.9 mV dec^-1 and admirable durability. The enhanced OER performance of the composite is attributed to the intimate coupling of LDH-based catalysts with intrinsically high activity and N-TiO₂ substrate with the large surface area and vertical nanotube structure. Moreover, nitrogen doping not only increases the electrical conductivity but also weakens the NiFe LDHs' surface-oxygen interaction, resulting in suitable bond strength of oxygen-related intermediate species. Our findings expand the development of designing novel composite nanostructures for promising OER catalysts.