Fe-Ion-Catalyzed Synthesis of CdSe/Cu Core/Shell Nanowires

Abstract

CdSe/Cu core/shell nanowires (NWs) are successfully synthesized by a wet chemical method for the first time. By utilizing the solution–liquid–solid (SLS) mechanism, CdSe NWs are fabricated by Bi seeds, which act as catalysts. In the subsequent radial overcoating of the Cu shell on the CdSe NWs, Fe ions have been proven to be an indispensable and efficient catalyzer. The thickness of the Cu shell could be well controlled in the range of 3 to 6 nm by varying the growth temperature (from 300 to 360 °C). Our synthetic strategy pioneers a new possibility for the controlled synthesis of semiconductor–metal heterostructure NWs (especially for II–VI semiconductors), such as CdS/Cu, ZnS/Au, and ZnO/Ag, which had broad application prospects in photoconductors, thin-film transistors, and light-emitting diodes. Theoretically, electrons flow from a higher Fermi-level material to the bottom Fermi-level at the metal–semiconductor heterojunction interface, which aligns the Fermi level and establishes the Schottky barrier. It leads to excess negative charges in metals and excess positive charges in semiconductors. Therefore, those effective electron traps reduce the probability of photogenerated electron–hole pair recombination efficiently, which has been widely applied in solar cells, sensors, photocatalysis, and energy storage. The breakthrough and innovation of this synthesis method have opened up a new synthetic route with a mild reaction environment, low energy consumption, and convenience.

Research progress of out-of-plane GeSn nanowires

“…In contrast to VLS, SLS growth is carried out in solution (usually using organic solvents), so the boiling point of organic solvents also limits the choice of candidate metals or metal alloys [78]. For the typical reaction conditions of the SLS mechanism (200 °C-350 °C), low melting point metals such as Sn (231.9 °C) [104], In (156.6 °C) [105,106], Bi (271.4 °C) [107,108], Ga (29.8 °C) [109,110] are commonly chosen, while for high melting point metals such as Au [111], Au nanoparticles need to be confined to small sizes to keep their melting points within the boiling points of organic solvents when grown by the SLS mechanism [112].…”

Synthesis of CdSe Nanowires and CuInSe2 Nanosheets for Hydrogen Evolution

“…The SLS mechanism was first demonstrated by Buhro in 1995, who developed a generic approach to the fabrication of 1D colloidal nanomaterials. − Relied on advantages in low reaction temperature, controlled stoichiometry, uniform 1D morphology, environmental friendliness, and so forth, the SLS mechanism has been applied in the synthesis of binary (CdSe), ternary (CuInSe 2 ), axial heterojunctions (CdS/CuInSe 2 , ZnSe/ZnTe), core/shell nanowires (NWs) (CdSe/Cu), doped NWs (CdSe doped Cu NWs), and other 1D nanomaterials. , The material, size, and morphology of various seeds in the SLS mechanism play significant roles in the reaction, which determined the starting reaction temperature, diameter and stoichiometric ratio of products, crystal phase, yield, and other related properties . The low-melting metallic nanoparticles (NPs) In, Bi, and Sn catalyze the decomposition of metal–organic precursors at the solution–liquid interface and solubilize the semiconductor compositions .…”

Lattice-Matched CoP/CoS2 Heterostructure Cocatalyst to Boost Photocatalytic H2 Generation

“…The global shortage of fossil fuels and the environmental pollution have resulted in growing demand for clean and renewable energy. − As a clean fuel, hydrogen has a high energy density and causes zero pollution, so it is recognized as a key environmentally friendly energy source. − Among the sustainable strategies to produce H 2 via the conversion of solar energy, semiconductor-based photocatalytic water splitting techniques have attracted widespread attention. , Nevertheless, the solar-to-H 2 conversion efficiency is still low because of fast charge-carrier recombination. , Recently, it is reported that functionalized cocatalysts can be integrated with the semiconductor and act as active catalytic centers. In addition, the cocatalyst can form Schottky junctions with the semiconductor, thus achieving the directional transfer of photogenerated electrons, which is quite helpful for promoting the efficiency of the photocatalytic hydrogen evolution reaction (HER). − …”