Amine-free preparation of SnSe nanosheets with high crystallinity and their lithium storage properties

Core-shell (nano-SnX/nano-Li4Ti5O12)@C spheres (X = Se,Te) with high volumetric capacity and excellent cycle stability for lithium-ion batteries

Among binary tin chalcogenides as anode materials for lithium-ion batteries, SnSe and SnTe have attracted attention due to their high theoretical volumetric capacity. However, they suffer from sluggish dynamics and serious agglomeration during lithiation/delithiation processes, which leads to inferior cycling performance. This study reports core-shell structure (nano-SnSe/nano-Li₄Ti₅O₁₂)@C and (nano-SnTe/nano-Li₄Ti₅O₁₂)@C [denoted as (n-SnX/n-LTO)@C] with extraordinary lithium storage stability. Benefiting from the well-designed structural merits, the core-shell structure of (n-SnX/n-LTO)@C is well preserved over 500 cycles, suggesting its high structural integrity. The (n-SnSe/n-LTO)@C and (n-SnTe/n-LTO)@C anodes deliver high initial volumetric capacities of 3470.1 and 3885.4 mA h cm^-3 at 0.2 A g^-1 and maintain capacities of 2066.0 and 1975.3 mA h cm^-3 even after 500 cycles, respectively. This work provides a new avenue for designing novel binary tin chalcogenide lithium-ion battery anodes with high volumetric capacity and superior long-term cycling performance.

Tin Selenide (SnSe): Growth, Properties, and Applications

The indirect bandgap semiconductor tin selenide (SnSe) has been a research hotspot in the thermoelectric fields since a ZT (figure of merit) value of 2.6 at 923 K in SnSe single crystals along the b-axis is reported. SnSe has also been extensively studied in the photovoltaic (PV) application for its extraordinary advantages including excellent optoelectronic properties, absence of toxicity, cheap raw materials, and relative abundance. Moreover, the thermoelectric and optoelectronic properties of SnSe can be regulated by the structural transformation and appropriate doping. Here, the studies in SnSe research, from its evolution to till now, are reviewed. The growth, characterization, and recent developments in SnSe research are discussed. The most popular growth techniques that have been used to prepare SnSe materials are discussed in detail with their recent progress. Important phenomena in the growth of SnSe as well as the problems remaining for future study are discussed. The applications of SnSe in the PV fields, Li-ion batteries, and other emerging fields are also discussed.

Eco-friendly synthesis of SnSe nanoparticles: effect of reducing agents on the reactivity of a Se-precursor and phase formation of SnSe NPs

Tin monoselenide (SnSe) nanoparticles (NPs) have great potential to replace the conventional absorbers used in the fabrication of thin film solar cells.

Two dimensional layered Co0.85Se nanosheets as a high-capacity anode for lithium-ion batteries

In recent years, two-dimensional (2D) layered transitional metal chalcogenides (TMCs) have received much attention as promising electrode materials in energy storage. Although recent reports on 2D TMC nanostructures have demonstrated promising electrochemical performances, the major scientific challenge is to develop a viable synthesis process to produce layered structures of chalcogenides (Co, Ni or Fe based TMCs) as anode materials. In this work, we propose the synthesis of layered Co0.85Se nanosheets in a solution based method by using a 2D oriented attachment strategy. The as-prepared Co0.85Se nanosheets exhibit specific capacities as high as 675 mA h g(-1) at 100 mA g(-1). When the current densities were further increased to 200, 500 and 1000 mA g(-1), the reversible capacities can still reach up to 645, 574 and 493 mA h g(-1) with excellent cycling life of 95, 85 and 73%, respectively. Li-ion storage performance of layered Co0.85Se nanosheets is higher than that of Co0.85Se microspheres as well as cobalt sulfide. The superior electrochemical performance of Co0.85Se nanosheets is attributed to their 2D layered structure which enhances electrical conductivity and improves diffusion pathways of the Li-ion within the host material. The synthesis method described in this work serves as a general route for the design and preparation of other 2D layered TMCs.

Porous nanostructures of SnSe: role of ionic liquid, tuning of nanomorphology and mechanistic studies

Porous SnSe nanoparticles have been synthesized in imidazolium based RTILviaelectron beam irradiation. RTIL provides a stabilizing environment as well as anin situsource of reducing radicals for the reduction of precursors.

Aqueous phase one-pot green synthesis of SnSe nanosheets in a protein matrix: negligible cytotoxicity and room temperature emission in the visible region

A rapid, facile, reproducible and green method for synthesizing SnSe nanosheets in aqueous media is reported. Cyclic voltammetry studies indicate better thermodynamic feasibility for reducing SnSe, while the nanomaterial is nontoxic up to a 100 μM concentration in CHO cells.

Shape-programmed nanofabrication: understanding the reactivity of dichalcogenide precursors

Dialkyl and diaryl dichalcogenides are highly versatile and modular precursors for the synthesis of colloidal chalcogenide nanocrystals. We have used a series of commercially available dichalcogenide precursors to unveil the molecular basis for the outcome of nanocrystal preparations, more specifically, how precursor molecular structure and reactivity affect the final shape and size of II-VI semiconductor nanocrystals. Dichalcogenide precursors used were diallyl, dibenzyl, di-tert-butyl, diisopropyl, diethyl, dimethyl, and diphenyl disulfides and diethyl, dimethyl, and diphenyl diselenides. We find that the presence of two distinctively reactive C-E and E-E bonds makes the chemistry of these precursors much richer and interesting than that of other conventional precursors such as the more common phosphine chalcogenides. Computational studies (DFT) reveal that the dissociation energy of carbon-chalcogen (C-E) bonds in dichalcogenide precursors (R-E-E-R, E=S or Se) increases in the order (R): diallyl<dibenzyl<di-tert-butyl<diisopropyl<diethyl<dimethyl<diphenyl. The dissociation energy of chalcogen-chalcogen (E-E) bonds remains relatively constant across the series. The only exceptions are diphenyl dichalcogenides, which have a much lower E-E bond dissociation energy. An increase in C-E bond dissociation energy results in a decrease in R-E-E-R precursor reactivity, leading to progressively slower nucleation and higher selectivity for anisotropic growth, all the way from dots to pods to tetrapods. Under identical experimental conditions, we obtain CdS and CdSe nanocrystals with spherical, elongated, or tetrapodal morphology by simply varying the identity and reactivity of the dichalcogenide precursor. Interestingly, we find that precursors with strong C-E and weak E-E bond dissociation energies such as Ph-S-S-Ph serve as a ready source of thiol radicals that appear to stabilize small CdE nuclei, facilitating anisotropic growth. These CdS and CdSe nanocrystals have been characterized using structural and spectroscopic methods. An intimate understanding of how molecular structure affects the chemical reactivity of molecular precursors enables highly predictable and reproducible synthesis of colloidal nanocrystals with specific sizes, shapes, and optoelectronic properties for customized applications.

Molecular Chemistry to the Fore: New Insights into the Fascinating World of Photoactive Colloidal Semiconductor Nanocrystals

Colloidal semiconductor nanocrystals possess unique properties that are unmatched by other chromophores such as organic dyes or transition-metal complexes. These versatile building blocks have generated much scientific interest and found applications in bioimaging, tracking, lighting, lasing, photovoltaics, photocatalysis, thermoelectrics, and spintronics. Despite these advances, important challenges remain, notably how to produce semiconductor nanostructures with predetermined architecture, how to produce metastable semiconductor nanostructures that are hard to isolate by conventional syntheses, and how to control the degree of surface loading or valence per nanocrystal. Molecular chemists are very familiar with these issues and can use their expertise to help solve these challenges. In this Perspective, we present our group's recent work on bottom-up molecular control of nanoscale composition and morphology, low-temperature photochemical routes to semiconductor heterostructures and metastable phases, solar-to-chemical energy conversion with semiconductor-based photocatalysts, and controlled surface modification of colloidal semiconductors that bypasses ligand exchange.