Recent Progress on Layered Sn and Pb-Based Mono Chalcogenides: Synthesis, Structure, Optical, and Thermoelectric Properties and Related Applications

The research on two-dimensional materials has gained significant traction due to their potential for thermoelectric, optical, and other properties. The development of two-dimensional (2D) nanostructured-based TE generators and photodetectors has shown promising results. Over the years, researchers have played a crucial role in advancing this field, enhancing the properties of 2D materials through techniques such as doping, alloying, and various growth methods. Among these materials, black phosphorus, transition metal dichalcogenides, graphene, and IVA-VIA compounds stand out for their remarkable electronic, mechanical, and optical properties. This study presents a comprehensive review of the progress in the field, focusing on IVA-VIA compounds and their applications in TE and photodetector technologies. We summarize recent advancements in enhancing these materials' TE and optical properties and provide an overview of various synthesis techniques for their fabrication. Additionally, we highlight their potential applications as photodetectors in the infrared spectrum. This comprehensive review aims to equip researchers with a deep understanding of the TE and optical properties of 2DMs and their potential applications and to inspire further advancements in this field of research.

Single source precursor route to nanometric tin chalcogenides

Low-temperature solution phase synthesis of nanomaterials using designed molecular precursors enjoys tremendous advantages over traditional high-temperature solid-state synthesis. These include atomic-level control over stoichiometry, homogeneous elemental dispersion and uniformly distributed nanoparticles. For exploiting these advantages, however, rationally designed molecular complexes having certain properties are usually required. We report here the synthesis and complete characterization of new molecular precursors containing direct Sn-E bonds (E = S or Se), which undergo facile decomposition under different conditions (solid/solution phase, thermal/microwave heating, single/mixed solvents, varying temperatures, etc.) to afford phase-pure or mixed-phase tin chalcogenide nanoflakes with defined ratios.

Dimethyltin(IV)-4,6-dimethyl-2-pyridylselenolate: an efficient single source precursor for the preparation of SnSe nanosheets as anode material for lithium ion batteries

The air stable tin(IV) complex [Me₂Sn{2-SeC₅H₂(Me-4,6)₂N}₂] has been synthesized, characterized by NMR, elemental analysis, and single crystal XRD, and employed as a single source molecular precursor (SSP) for the facile synthesis of orthorhombic SnSe nanosheets. The crystal structure, phase purity, morphology and band gap of the nanosheets were investigated by pXRD, EDS, electron microscopy and diffuse reflectance spectroscopy techniques, respectively. It was found that the preferential orientation of planes and the morphology of the nanosheets rely upon the reaction conditions. The band gaps of the nanosheets were blue shifted with respect to the bulk band gap of the material. The synthesized SnSe nanosheets have been employed as an anode material in lithium ion batteries (LIBs). The material exhibits an initial specific capacity of 1134 mA h g^-1 at a current density of 50 mA g^-1 and was found to retain a capacity of 380 mA h g^-1 even after 70 cycles with 100% efficiency.

Di-tert-butyltin(IV) 2-pyridyl and 4,6-dimethyl-2-pyrimidyl thiolates: versatile single source precursors for the preparation of SnS nanoplatelets as anode material for lithium ion batteries

New air and moisture stable di-tert-butyltin complexes derived from 2-mercaptopyridine (HSpy), [^tBu₂Sn(Spy)₂], [^tBu₂Sn(Cl)(Spy)] and 4,6-dimethyl-2-mercaptopyrimidine (HSpymMe₂) [^tBu₂Sn(Cl)(SpymMe₂)], have been prepared and utilized as single-source molecular precursors for the preparation of orthorhombic SnS nanoplatelets by a hot injection method and thin films by aerosol assisted chemical vapour deposition (AACVD). The complexes were characterized by NMR (¹H, ¹³C, ¹¹⁹Sn) and elemental analysis and their structures were unambiguously established by the single crystal X-ray diffraction technique. Thermolysis of these complexes in oleylamine (OAm) produced SnS nanoplatelets. The morphologies, elemental compositions, phase purity and crystal structures of the resulting Oam-capped nanoplatelets were determined by electron microscopy (SEM, TEM), energy dispersive X-ray spectroscopy (EDS) and pXRD, while the band gaps of the nanoplatelets were evaluated by diffuse reflectance spectroscopy (DRS) and were blue shifted relative to the bulk material. The morphology and preferential growth of the nanoplatelets were found to be significantly altered by the nature of the molecular precursor employed. The synthesized SnS nanoplatelets were evaluated for their performance as anode material for lithium ion batteries (LIBs). A cell comprised of an SnS electrode could be cycled for 50 cycles. The rate capability of SnS was investigated at different current densities in the range 0.1 to 0.7 A g^-1 which revealed that the initial capacity could be regained.

Colloidal synthesis of metal chalcogenide nanomaterials from metal-organic precursors and capping ligand effect on electrocatalytic performance: progress, challenges and future perspectives

Renewable and sustainable functional nanomaterials, which can be employed in alternative green energy sources, are highly desirable. Transition metal chalcogenides are potential catalysts for processes resulting in energy generation and storage. In order to optimize their catalytic performance, high phase purity and precise control over shape and size are indispensable. Metal-organic precursors with pre-formed bonds between the metal and the chalcogenide atoms are advantageous in synthesizing phase pure transition metal chalcogenides with controlled shape and sizes. This can be achieved by the decomposition of metal-organic precursors in the presence of suitable surfactants/capping agents. However, the recent studies on electrocatalysis at the nanoscale level reveal that the capping agents attached to their surface have a detrimental effect on their efficiency. The removal of surfactants from active sites to obtain bare surface nanoparticles is necessary to enhance catalytic activity. Herein, we have discussed the properties of different metal-organic precursors and the role of surfactants in the colloidal synthesis of metal chalcogenide nanomaterials. Moreover, the effect of surfactants on their electrocatalytic performance, the commonly used strategies for removing surfactants from the surface of nanomaterials and the future perspectives are reviewed.

Defect Engineering in Ultrathin SnSe Nanosheets for High-Performance Optoelectronic Applications

Ultrathin lamellar SnSe is highly attractive for applications in areas such as photonics, photodetectors, photovoltaic devices, and photocatalysis, owing to its suitable band gap, exceptional light absorption capabilities, and considerable carrier mobility. On the other hand, SnSe nanosheets (NSs) still face challenges of being difficult to prepare and their devices having low photoelectric conversion efficiencies. Herein, ultrathin SnSe NSs with controlled Se defects were synthesized with high yield by a facial Li intercalation-assisted liquid exfoliation method. The loss of Se, a narrowing of the band gap, and an increase in lattice disorders involving vacancies, distortions, and phase transition were observed in SnSe NSs prepared with a long lithiation process. Comparing between the 24 and 72 h lithiation samples, the ones processed for a longer time displayed a faster recombination time due to more defect-induced mid-states. Inspiringly, enhancements of 4-10 times were observed for photodetector device parameters such as photocurrent, photoresponsivity, photoresponse speed, and specific detectivity of the 72 h lithiation SnSe NSs. Additionally, these devices show good stability and a broad detection range, from ultraviolet to the near infrared region. Our results provide a promising avenue for the mass production of SnSe NSs with high photoelectric performance and open up opportunities for applications in photonics, optoelectronics, and photocatalysis.

Organoselenium ligands for heterogeneous and nanocatalytic systems: development and applications

Organoselenium ligands have attracted great attention among researchers during the past two decades. Various homogeneous, heterogeneous and nanocatalytic systems have been designed using such ligands. Although reports on selenium ligated homogeneous catalysts are quite high in number, significant work has also been done on the development of heterogeneous and nanocatalytic systems using organoselenium ligands. A review article, focusing on the utility of organoselenium compounds in the development of catalytic systems, was published in 2012 (A. Kumar, G. K. Rao, F. Saleem and A. K. Singh, Dalton Trans., 2012, 41, 11949). Moreover, it mainly covered the homogeneous catalysts. There are no review articles in the literature on heterogeneous and nanocatalytic systems designed using organoselenium compounds and their applications. Hence, this perspective aims to cover the developments pertaining to the synthetic aspects of such catalytic systems (using organoselenium compounds) and their applications in catalysis of a variety of chemical transformations. Salient features and advantages of organoselenium compounds have also been highlighted to justify the rationale behind their use in catalyst development. Their performance in various chemical transformations [viz. Suzuki-Miyaura coupling, Heck coupling, Sonogashira coupling, O-arylation of phenol, transfer hydrogenation of aldehydes and ketones, aldehyde-alkyne-amine (A3) coupling, hydration of nitriles, conversion of aldehydes to amides, cross-dehydrogenative coupling (CDC), photodegradation of substrates (formic acid, methylene blue), reduction of nitrophenols, electrolysis (hydrogen evolution reaction and oxygen reduction reactions), organocatalysis and dye sensitized solar cells] and relevant aspects of catalytic processes (such as recyclability, substrate scope and green aspects) have been critically analyzed. Future perspectives have also been discussed.

Electronic Tuning of Zinc Oxide by Direct Fabrication of Chromium (Cr) incorporated photoanodes for Visible-light driven Water Splitting Applications

Herein, we report the synthesis of Cr incorporated ZnO sheets arrays microstructures and construction of photoelectrode through a direct aerosol assisted chemical vapour deposition (AACVD) method. The as-prepared Cr incorporated ZnO microstructures were characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, powdered X-ray spectroscopy, X-ray photoelectron spectroscopy and UV-Vis diffused reflectance spectroscopy. The Cr incorporation in ZnO red shifted the optical band gap of as-prepared photoanodes. The 15% Cr incorporation in ZnO has shown enhanced PEC performance. The AACVD method provides an efficient in situ incorporation approach for the manipulation of morphological aspects, phase purity, and band structure of photoelectrodes for an enhanced PEC performance.

A Novel Tin-Doped Titanium Oxide Nanocomposite for Efficient Photo-Anodic Water Splitting

Herein, we report the expedient synthesis of new nanocomposite Sn_0.39Ti_0.61O₂·TiO₂ flakes using simple sol-gel and calcination methods. In order to prepare this material, first, we generated a polymeric gel using cost-effective and easily accessible precursors such as SnCl₄, titanium isopropoxide, and tetrahydrofuran (THF). A small amount of triflic acid was used to initiate THF polymerization. The calcination of the resulting gel at 500 °C produced a Sn-Ti bimetallic nanocomposite. This newly synthesized Sn_0.39Ti_0.61O₂·TiO₂ was characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible spectroscopy. The photoelectrochemical (PEC) studies were performed for the first time using Sn_0.39Ti_0.61O₂·TiO₂ coated over fluorine-doped tin oxide (FTO) under simulated 1 sun solar radiation. The chronoamperometric study of the Sn_0.39Ti_0.61O₂·TiO₂/FTO revealed the repeatable and substantially higher photocurrent for the oxygen evolution reaction (OER) when compared to only TiO₂. Moreover, the synthesized material exhibited high stability both in the presence and absence of light. The photocatalytic studies suggested that the sol-gel-synthesized Sn_0.39Ti_0.61O₂·TiO₂ can be efficiently used as a photoanode in the water-splitting reaction.

Green synthesis of ZnO–Co3O4 nanocomposite using facile foliar fuel and investigation of its electrochemical behaviour for supercapacitors

Currently, the sustainable fabrication of supercapacitors with enhanced properties is one of the significant research hotspots.

Sn-C and Se-C Co-Bonding SnSe/Few-Layered Graphene Micro-Nano Structure: Route to a Densely Compacted and Durable Anode for Lithium/Sodium-Ion Batteries

Developing anodes with a high and stable energy density for both gravimetric and volumetric storage is vital for high-performance lithium/sodium-ion batteries. Herein, an SnSe/few-layered graphene (FLG) composite with a high tap density (2.3 g cm^-3) is synthesized via the plasma-milling method, in which SnSe nanoparticles are strongly bound with the FLG matrix, owing to both Sn-C and Se-C bonds, to form nanosized primary particles and then assemble to microsized secondary granules. The FLG can effectively alleviate the large stress generated from the volume expansion of SnSe during cycling based on its superstrength. Furthermore, as demonstrated by the density-functional theory calculations, the Sn-C and Se-C co-bonding benefitting from the formation of substantial vacancy defects on the P-milling-synthesized FLG enables strong affinity between SnSe nanoparticles and the FLG matrix, preventing SnSe from aggregating and detaching even after long-term cycling. As an anode for lithium-ion batteries, it exhibits high gravimetric and volumetric capacities (864.8 mAh g^-1 and 1990 mAh cm^-3 at 0.2 A g^-1), a high rate (612.6 mAh g^-1 even at 5.0 A g^-1), and the longest life among the reported SnSe-based anodes (capacity retention of 92.8% after 2000 cycles at 1.0 A g^-1). Subsequently, an impressive cyclic life (capacity retention of 91.6% after 1000 cycles at 1.0 A g^-1) is also achieved for sodium-ion batteries. Therefore, the SnSe/FLG composite is a promising anode for high-performance lithium/sodium-ion batteries.

Effect of cationic disorder on the energy generation and energy storage applications of NixCo3−xS4 thiospinel

Thiospinels show interesting catalytic and energy storage applications, however, the cationic disorder can have major influence on the energy generation and/or energy storage applications.

Structural investigations of SnS1−xSexsolid solution synthesized from chalcogeno-carboxylate complexes of organo-tin by colloidal and solvent-less routes

Tin chalcogenides are important semiconducting materials due to their non-toxic nature, cost effectiveness and layered structure.

Facile synthesis of a PbS1−xSex (0 ≤ x ≤ 1) solid solution using bis(N,N-diethyl-N′-naphthoylchalcogenoureato)lead(ii) complexes

A precise composition and band gap tunable PbS_1−xSe_x solid solution was prepared by a single source route.

Synthesis of chalcopyrite-type and thiospinel minerals/materials by low temperature melts of xanthates

Xanthate complexes are used in the low temperature atom efficient synthesis of some geological and technologically important ternary compounds.