Graphene foam supported multilevel network-like NiCo2S4 nanoarchitectures for robust lithium storage and efficient ORR catalysis

Abstract

A well-designed NiCo₂S₄-based composite has been fabricated by growing a highly active NiCo₂S₄ nanoarchitecture on a three-dimensional graphene foam (3DGF) via a facile solvothermal method and performing a subsequent sulfurization reaction. The obtained NiCo₂S₄@3DGF composites show unique multilevel network-like structures, in which the 3DGF supports network-like building blocks of interconnected NiCo₂S₄ nanowalls, which are assembled with extensive interconnected ultrathin mesoporous nanosheets. Benefiting from this rational composition combining NiCo₂S₄ and 3DGF and the well-designed network-like morphology with a high surface area, the obtained composites exhibit excellent electrochemical activities. When used as a free-standing anode for lithium-ion batteries, the composite exhibits a high reversible capacity of 1295 mA h g⁻¹, even after 150 cycles (at 500 mA g⁻¹) and a remarkable rate capability. When used as a catalyst for the oxygen reduction reaction, the composite also exhibits enhanced catalytic activity (4-electron pathway), excellent tolerance to methanol, and high durability, holding great promise as an efficient non-noble-metal catalyst in practical application. In addition, a probable growth mechanism of the NiCo₂S₄ nanoarchitecture on the surface of 3DGF has been proposed.