Seeding Layer Effect on the Microstructure of Hydrothermally Grown α‐Manganese Dioxide Nanowires on Three‐Dimensional Graphene Foam

Abstract

AbstractHydrothermal synthesis is a straightforward approach for producing high‐yield manganese dioxide (MnO2) nanostructures with efficient morphological control at low temperatures. This study investigates the microstructural dependency of hydrothermally grown α‐MnO2 nanowires (NWs) on pre‐treatment conditions on the substrate surface. Within this scope, α‐MnO2 NWs were synthesized on chemical vapor deposition (CVD)‐based graphene foam (GF) substrates pre‐treated via potassium permanganate (KMnO4) solution as a seeding layer with different concentrations (0.025, 0.050, 0.075, 0.1 M). A direct α‐MnO2 NWs growth (without pre‐treatment) was also performed on GF by hydrothermal method. The seeding layer effect on the NWs growth was elaborated to comprehend the process‐structure correlations by characterizing the resultant graphene foam/α‐MnO2 nanowires (GF/α‐MnO2 NWs) nanocomposites through Scanning Electron Microscopy (SEM), Raman Spectroscopy, X‐Ray Diffraction (XRD), and X‐Ray Photoelectron Spectroscopy (XPS). SEM, XRD, and Raman Spectroscopy revealed the successful acquisition of highly crystalline α‐MnO2 in one‐dimensional nanowire morphology on the high‐quality GF. Moreover, XPS results confirmed that all nanocomposites comprise α‐MnO2 and graphene without chemical degradation. Consequently, slight changes in solution concentration of seeding layers caused a noticeable alteration in the nanowire's structure, which could ensure effective control of nanocomposite properties without sacrificing the high purity of each component.