To the synthesis and characterization of layered metal phosphorus triselenides proposed for electrochemical sensing and energy applications

First-principles study of Ga2Ge2S3Se3 monolayer: a promising photocatalyst for water splitting

Recently, the quaternary Janus monolayers with the formula A2B2X3Y3 have been shown to be promising candidates for optoelectronic applications, especially in the photocatalytic water splitting reaction. Therefore, first-principles calculations were employed to investigate the photocatalytic properties of Ga2Ge2X3Y3 (X and Y represent S, Se or Te atoms) monolayers. The Ga2Ge2S3Se3 and Ga2Ge2Se3Te3 monolayers exhibit dynamic and thermal stability, supported by high cohesive energies (3.78-4.20 eV) and positive phonon dispersion. With a moderate Young's modulus (50.02-65.31 N m-1) and high Poisson's ratio (0.39-0.41), these monolayers offer a balance of stiffness and flexibility, making them suitable for flexible electronic applications. Especially, the difference in work function of 0.27 eV induces an intrinsic electric field in the Ga2Ge2S3Se3 monolayer, making the electronic structure of this material be suitable for the photocatalytic water splitting process. With light irradiation, the oxygen evolution reaction (OER) happened simultaneously, producing electrons and H+ protons for the hydrogen evolution reaction (HER) to happen at a low potential barrier. Moreover, the Ga2Ge2S3Se3 monolayer has a high absorption rate α(ω) of 105-106 cm-1 and a high electron mobility of 430.82-461.50 cm2 V-1 s-1. These characteristics result in a good solar-to-hydrogen of the Ga2Ge2S3Se3 monolayer (14.80%) which is promising for use in photon-driven water splitting.

XPS Analysis of FexNiyPS3 vdW Materials Used in the Hydrogen Evolution Processes

In response to the global demand for sustainable energy solutions, the quest for stable and cost-effective hydrogen production has garnered significant attention in recent decades. Here, the emergence of layered metal phosphorus trichalcogenides (MPX3, M: transition metal, X: chalcogen) materials and their two-dimensional counterparts with customizable composition and electronic structure holds great promise for such purposes. In the present study, we successfully synthesized large-scale and high-quality FePS3, NiPS3, and an alloyed counterpart, Fe0.5Ni0.5PS3. Subsequent systematic investigations were conducted to probe their respective electronic structures and assess their hydrogen evolution reaction (HER) properties. Remarkably, our results unveiled the successful modulation of the bandgap for FexNiyPS3, ultimately bestowing it with the most favorable HER performance for Fe0.5Ni0.5PS3 when compared to the other two samples. Furthermore, our exploration into the evolution of the X-ray photoelectron spectroscopy (XPS) spectra demonstrated that the charge conversions of metal cations play a pivotal role in the HER reactions. This critical insight further enriches our understanding of the fundamental mechanisms governing the performance of the prepared layered MPX3-based electrocatalysts, thus facilitating a comprehensive and detailed analysis of the pre- and post-HER reactions. This work not only sheds light on the intricate interplay between composition, electronic structure, and catalytic performance in the realm of novel electrocatalysts, but also contributes to the broader scientific community's pursuit of sustainable and efficient hydrogen production.

Probing Active Sites on Pristine and Defective MnPX3 (X: S and Se) Monolayers for Electrocatalytic Water Splitting

The state-of-the-art density functional theory approach was used to study the structural and electronic properties of pristine and defective MnPX3 monolayers as well as their activity toward water and hydrogen evolution reaction (HER) catalytic performance. The adsorption behavior of H2O on a pristine MnPX3 structure is of physisorption nature, whereas the adsorption energy is significantly increased for the defective structures. At the same time, the water dissociation process is more energetically favorable, and the reactivity of MnPX3 is determined by the vacancy configuration. Following Nørskov's approach, the HER catalytic performance is evaluated by calculating the hydrogen adsorption free energy on the respective MnPX3 surface. Our calculation results demonstrate that defective 2D MnPX3 with low coordinated P shows significantly higher HER performance compared to the pristine counterpart.

A novel exfoliated manganese phosphoselenide as a high-performance anode material for lithium ions storage

Layered manganese phosphoselenide (MnPSe3) is expected to be a potential anode for Li ions storage due to it combines the merits of phosphorus with metal selenide. It promotes charge transfer and ensures a high theoretical capacity of up to 746 mA h g−1. In this work, a comprehensive study clearly demonstrated that bulk MnPSe3 electrode is the inability to maintain the integrity of the structure with severe detectable fracture or pulverization after full lithiation/delithiation, resulting in poor rate capability and cycling stability. Additionally, exfoliated few-layered MnPSe3 nanoflakes by the ultrasonic method show enhanced electrical conductivity and resistance to volume expansion. It has a high initial discharge/charge capacity reaching to 524/796 mA h g−1 and outstanding cycling stability with charge capacities of 709 mA h g−1 after 100 cycles at 0.2 A g−1 within the potential window of 0.005–3 V vs. Li+/Li. While further improving the cycles, the retention rate was still held at ∼72% after 350 cycles. This work provides new insights into exploiting new novel layered materials, such as MnPSe3 as anodes for lithium-ion batteries.