Electrochemistry of Layered Semiconducting A III B VI Chalcogenides: Indium Monochalcogenides (InS, InSe, InTe)

Recent Progress of Transition Metal Selenides for Electrochemical Oxygen Reduction to Hydrogen Peroxide: From Catalyst Design to Electrolyzers Application

Hydrogen peroxide (H2O2) is a highly value-added and environmental-friendly chemical with various applications. The production of H2O2 by electrocatalytic 2e- oxygen reduction reaction (ORR) has emerged as a promising alternative to the energy-intensive anthraquinone process. High selectivity Catalysts combining with superior activity are critical for the efficient electrosynthesis of H2O2. Earth-abundant transition metal selenides (TMSs) being discovered as a classic of stable, low-cost, highly active and selective catalysts for electrochemical 2e- ORR. These features come from the relatively large atomic radius of selenium element, the metal-like properties and the abundant reserves. Moreover, compared with the advanced noble metal or single-atom catalysts, the kinetic current density of TMSs for H2O2 generation is higher in acidic solution, which enable them to become suitable catalyst candidates. Herein, the recent progress of TMSs for ORR to H2O2 is systematically reviewed. The effects of TMSs electrocatalysts on the activity, selectivity and stability of ORR to H2O2 are summarized. It is intended to provide an insight from catalyst design and corresponding reaction mechanisms to the device setup, and to discuss the relationship between structure and activity.

Tunable electronic and optical properties of BAs/WTe2heterostructure for theoretical photoelectric device design

The geometric structure of the BAs/WTe2heterojunction was scrutinized by employingab initiocalculations grounded on density functional theory. Multiple configurations are constructed to determine the equilibrium state of the heterojunction with optimal stability. The results show that the H1-type heterojunction with interlayer distance of 3.92 Å exhibits exceptional stability and showcases a conventional Type-II band alignment, accompanied by a direct band gap measuring 0.33 eV. By applying external electric field and introducing strain, one can efficaciously modulate both the band gap and the quantity of charge transfer in the heterojunction, accompanied by the transition of band alignment from Type-II to Type-I, which makes it expected to achieve broader applications in light-emitting diodes, laser detectors and other fields. Ultimately, the heterojunction undergoes a transformation from a semiconducting to a metallic state. Furthermore, the outstanding optical characteristics inherent to each of the two monolayers are preserved, the BAs/WTe2heterojunction also serves to enhance the absorption coefficient and spectral range of the material, particularly within the ultraviolet spectrum. It merits emphasis that the optical properties of the BAs/WTe2heterojunction are capable of modification through the imposition of external electric fields and mechanical strains, which will expand its applicability and potential for future progression within the domains of nanodevices and optoelectronic apparatus.

Controlling the terminal layer atom of InTe for enhanced electrochemical oxygen evolution reaction and hydrogen evolution reaction performance

Herein, we report the method of molecular-beam-epitaxial growth (MBE) for precisely regulating the terminal surface with different exposed atoms on indium telluride (InTe) and studied the electrocatalytic performances toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The improved performances result from the exposed In or Te atoms cluster, which affects the conductivity and active sites. This work provides insights into the comprehensive electrochemical attributes of layered indium chalcogenides and exhibits a new route for catalyst synthesis.

Theoretical study on the photocatalytic properties of 2D InX(X = S, Se)/transition metal disulfide (MoS2 and WS2) van der Waals heterostructures

Harvesting solar energy for artificial photosynthesis is an emerging field in alternative energy research. In this work, the photocatalytic properties of InX(X = S, Se)/transition metal disulfide (MoS₂ and WS₂) van der Waals heterostructures have been investigated. The calculation results indicate that these heterostructures exhibit improved photocatalytic performance over that of isolated InX or transition metal disulfide monolayers. The studied heterostructures all have type-II band alignment with holes and electrons located at the TMD and InX side, respectively. This facilitates the spatial separation of photogenerated carriers and improves the photocatalytic efficiency. The carrier mobility of the designed heterostructures can be boosted compared with the isolated monolayers, thus enhancing the carrier transport properties. Moreover, the strain-tuned heterostructures can prominently manipulate the light-harvesting capability especially from the visible light to infrared light range. Among the studied heterostructures, InSe/MoS₂ with the suitable band edge positions, excellent transport properties and strain tolerance, and the lowest overpotential for oxygen evolution, stands out as the most promising candidate for photocatalytic applications. This work opens an avenue for the design of highly efficient heterostructure photocatalysts for solar-to-energy applications.

CVD growth of large-area InS atomic layers and device applications

Group-III monochalcogenides of two-dimensional (2D) layered materials have attracted widespread attention among scientists due to their unique electronic performance and interesting chemical and physical properties. Indium sulfide (InS) is attracting increasing interest from scientists because it has two distinct crystal structures. However, studies on the synthesis of highly crystalline, large-area, and atomically thin-film InS have not been reported thus far. Here, the chemical vapor deposition (CVD) synthesis method of atomic InS crystals has been reported in this paper. The direct chemical vapour phase reaction of metal oxides with chalcogen precursors produces a large-sized hexagonal crystal structure and atomic-thickness InS flakes or films. The InS atomic films are merged with a plurality of triangular InS crystals that are uniform and entire and have surface areas of 1 cm2 and controllable thicknesses in bilayers or trilayers. The properties of the as-grown highly crystalline samples were characterized by spectroscopic and microscopic measurements. The ion-gel gated InS field-effect transistors (FETs) reveal n-type transport behavior, and have an on-off current ratio of >103 and a room-temperature electron mobility of ∼2 cm2 V-1 s-1. Moreover, our CVD InS can be transferred from mica to any substrates, so various 2D materials can be reassembled into vertically stacked heterostructures, thus facilitating the development of heterojunctions and exploration of the properties and applications of their interactions.