Controllable synthesis 3D hierarchical structured MnO2@NiCo2O4 and its morphology-dependent activity

Abstract

The hierarchical structures with controlled size, shape, and interface are extremely attractive for their collective properties and synergetic effect. Herein, we report the α-MnO₂@NiCo₂O₄ heterostructures with the nanowire and nanosheet morphology prepared via hydrothermal reaction and a post-calcination treatment. The ultralong α-MnO₂ was used as a seed for the Ni–Co precipitant growth and self-assembly. The morphology of the Ni–Co precipitant was tailored using a solvent (water/methanol). After calcination, the shape of the precursor was maintained by α-MnO₂@NiCo₂O₄. α-MnO₂@NiCo₂O₄ demonstrates a morphology-dependent performance towards the catalytic combustion of dimethyl ether and the nanosheet-like α-MnO₂@NiCo₂O₄ exhibits a better performance than that of the nanowire-like counterpart. The catalytic activity is related to the reducibility, surface oxygen species, and the apparent activation energy.