Growth of MSe semiconductor nanowires on metal substrates through an Ag2Se-catalyzed solution–solid–solid mechanism (M = Zn, Cd and Mn)

Abstract

The growth of metal chalcogenide nanowires (NWs) on metal substrates is challenging work since the direct reactions taking place between the chalcogen (S, Se or Te) and zero-valent metal (M⁰) are frequently unable to regulate the crystallization of nanocrystals in an anisotropic one-dimensional (1D) manner. We here report the use of Ag₂Se seeds as catalyst particles to realize the growth of metal selenide (MSe) NWs on their respective metal foil or flakes, including ZnSe/Zn, CdSe/Cd, and MnSe/Mn material systems. Metal foil or flakes (M = Zn, Cd and Mn) serve as a support substrate as well as a metal cation source during the NW synthesis. The preformed Ag₂Se seeds play the roles of not only catalytic particles that initiate a so-called solution–solid–solid process to produce crystalline MSe NWs on metal substrates, but also inert impurities that promote an electrochemical anodic reaction of the metal to supply metal cations (M⁰ − 2e → M²⁺) for the NW formation. The microstructural studies by HRTEM reveal the polytypism and particularly the diameter-dependence of crystal phases and growth directions in the resulting MSe NWs, which can be rationalized from the viewpoints of the energetics and the catalyst/NW interfacial structures. These semiconductor NWs grown on metal foil or flakes may find wide use in photoelectric catalysis and devices without a transfer process of free-standing NWs onto a conductive support substrate.