Highly Active Methanol Oxidation Electrocatalyst Based On 2d Nio Porous Nanosheets:A Combined Computational And Experimental Study

Two-dimensional (2D) nanostructures are attractive candidates for electrocatalytic applications owing to their excellent mechanical flexibility and large exposed surfaces. In this work, we present ultra-thin 2D NiO porous nanosheets prepared by a simple, economical and green experimental method (hydrothermal, freeze-drying, and sintering) as efficient electrocatalysts for direct methanol fuel cell (DMFC) application. Benefiting from the ultra-thin 2D framework and porous nanostructure, the 550-NiO catalyst (annealed at 550 degrees C) exhibit higher current density (12.54mA cm(-2)) and faster charge transfer in the catalytic process, due to its abundant solid state redox couples (Ni2+/Ni3+ = 0.991), suitable oxygen defects and surface coverage of redox species (2.90 x 10(-7) mol cm(-2)). First-principles density functional theory calculations were employed to provide mechanistic insights into the methanol oxidation reaction over the NiO catalyst via methanol dehydrogenation to CO involving O-H and C-H bond scissions, and subsequently, CHO oxidation with OH. The most plausible reaction pathway of methanol oxidation on NiO (100) is predicted to be CH3OH -> CH3O -> CH2O -> CHO -> CHOOH -> COOH -> CO2. The reported facile, simple, low-cost and method provides an avenue for the rational design and synthesis of 2D NiO porous nanostructured electrode materials for DMFC and beyond. (C) 2021 Elsevier Ltd. All rights reserved.