From Nanoplates to Microtubes and Microrods: A Surfactant‐Free Rolling Mechanism for Facile Fabrication and Morphology Evolution of Ag₂S Films

Abstract

By a simple and facile wet-chemistry technique without any surfactant, various shapes of Ag(2)S crystals--including leaflike pentagonal nanoplates, crinkly nanoscrolls, hexagonal prismlike microtubes, and microrods--were fabricated in situ on a large-area silver-foil surface separately. Detailed experiments revealed that the Ag(2)S nanoplates were formed just by immersing the silver foil in a sulfur/ethanol solution at room temperature and atmospheric pressure, and they subsequently rolled into nanoscrolls and further grew into microtubes and microrods under solvothermal conditions. Inspired by the natural curling of a piece of foliage, we proposed a surfactant-free rolling mechanism to interpret the observed morphological evolution from lamellar to tubular structures. Based on these simple, practical, and green chemical synthetic routes, we can easily synthesize lamellar, scrolled, tubular, and clubbed Ag(2)S crystals by simply adjusting the reaction temperature, pressure, and time. It is very interesting to note that the current rolling process is quite different from the previous reported rolling mechanism that highly depends on the surfactants; we revealed that the lamellar Ag(2)S could be rolled into tubular structures without using any surfactant or other chemical additives, just like the natural rolling process of a piece of foliage. Therefore, this morphology-controlled synthetic route of Ag(2)S crystals may provide new insight into the synthesis of metal sulfide semiconducting micro-/nanocrystals with desired morphologies for further industrial applications. The optical properties of the pentagonal Ag(2)S nanoplates/film were also investigated by UV/Vis and photoluminescence (PL) techniques, which showed large blue-shift of the corresponding UV/Vis and PL spectra.

Room-temperature preparation of trisilver-copper-sulfide/polymer based heterojunction thin film for solar cell application

“…Similar to our previous low temperature synthesis of Ag 2 S and CuS films [29,30], we used the in situ room-temperature element conversion process to prepare Ag 3 CuS 2 nanostructured films. The films were conveniently synthesized through a direct reaction of a Ag/Cu bilayer reacting with sulfur in ethanol at room temperature, with an equation shown as 3Ag þ Cu þ 2S / Ag 3 CuS 2 .…”

Growth and properties of ZnO films on polymeric substrate by spray pyrolysis method

“…It is known that tubular structures can be formed from layered materials by a surfactant or additive assisted rolling mechanism [30]. According to this approach, the formation of wolfram disulfide and vanadium oxide nanotubes has been explained [30].…”

“…According to this approach, the formation of wolfram disulfide and vanadium oxide nanotubes has been explained [30]. The thermal stress has been proposed as a driving force for surfactant-free rolling mechanism used to explain the transformation of Ag 2 S from lamellar to tubular structures [30].…”

In situ fabrication of Bi2S3 nanocrystal film for photovoltaic devices

“…In our previous work, our group has developed a new in situ solvothermal method to prepare semiconductor metal iodide [24], metal sulfides [25] and metal selenide thin films [26,27], and also In 2 S 3 [28], a new kind of nanostructures for solar cell materials. In the hybrid cells, semiconducting polymers like regioregular poly-3-hexyl-thiophene(P3HT) acted as hole-conducting component, and inorganic semiconductor or organic molecule as electronconducting component.…”