Nanoscale engineering and Mo-doping of 2D ultrathin ReS2 nanosheets for remarkable electrocatalytic hydrogen generation

Facile and Scalable Colloidal Synthesis of Transition Metal Dichalcogenide Nanoparticles with High-Performance Hydrogen Production

Transition metal dichalcogenides (TMDs) have garnered significant attention as efficient electrocatalysts for the hydrogen evolution reaction (HER) due to their high activity, stability, and cost-effectiveness. However, the development of a convenient and economical approach for large-scale HER applications remains a persistent challenge. In this study, we present the successful synthesis of TMD nanoparticles (including MoS2, RuS2, ReS2, MoSe2, RuSe2, and ReSe2) using a general colloidal method at room temperature. Notably, the ReSe2 nanoparticles synthesized in this study exhibit superior HER performance compared with previously reported nanostructured TMDs. Importantly, the synthesis of these TMD nanoparticles can readily be scaled up to gram quantities while preserving their exceptional HER performance. These findings highlight the potential of colloidal synthesis as a versatile and scalable approach for producing TMD nanomaterials with outstanding electrocatalytic properties for water splitting.

Single Transition-Metal Atom Anchored on a Rhenium Disulfide Monolayer: An Efficient Bifunctional Electrocatalyst for the Oxygen Evolution and Oxygen Reduction Reactions

Developing efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) bifunctional electrocatalysts is attractive for rechargeable metal-air batteries. Meanwhile, single metal atoms embedded in 2D layered transition metal chalcogenides (TMDs) have become a very promising catalyst. Recently, many attentions have been paid to the 2D ReS2 electrocatalyst due to its unique distorted octahedral 1T' crystal structure and thickness-independent electronic properties. Here, the catalytic activity of different transition metal (TM) atoms embedded in ReS2 using the density functional theory is investigated. The results indicate that TM@ReS2 exhibits outstanding thermal stability, good electrical conductivity, and electron transfer for electrochemical reactions. And the Ir@ReS2 and Pd@ReS2 can be used as OER/ORR bifunctional electrocatalysts with a lower overpotential for OER (ηOER) of 0.44 V and overpotentials for ORR (ηORR) of 0.26 V and 0.27 V, respectively. The excellent catalytic activity is attributed to the optimal adsorption strength for oxygen intermediates coming from the effective modulation of the electronic structure of ReS2 after Ir/Pd doping. The results can help to deeply understand the catalytic activity of TM@ReS2 and develop novel and highly efficient OER/ORR electrocatalysts.

Cobalt-doped tin disulfide catalysts for high-capacity lithium-air batteries with high lifetime

Dual electrolyte lithium-air batteries have received widespread attention for their ultra-high energy density. However, the low internal redox efficiency of these batteries results in a relatively short operating life. SnS2 is widely used in Li-S batteries, Li-ion batteries, photocatalysis, and other fields due to the high discharge capacity in batteries. However, SnS2 suffers from low electrical conductivity and slow redox kinetics. In this study, Co-doped SnS2 is prepared by hydrothermal method for application in dual-electrolyte lithium-air batteries to study its electrochemical performance and its catalytic reaction process by DFT theory. Conductivity tests show that the Co doping enhances the electrical conductivity of the material and high transmission electron microscopy (HRTEM) results demonstrate that the Co doping of SnS2 increases the grain plane spacing and the material indicates that defects are created on the surface of the material, which is more beneficial to the electrochemical performance of the cell. Co-doped SnS2 exhibits excellent good cycling stability and high discharge capacity in a dual electrolyte lithium-air battery, maintaining a 0.7 V overpotential for 120 h at a current density of 0.1 mA cm-2, with a cell life of over 500 h and an initial discharge capacity showing excellent results up to 16 065 mA h g-1. In addition, this study explores the catalytic activity of Co-doped SnS2 based on density flooding theory (DFT). The results show that Co atoms have a synergistic effect with Sn atoms to perturb the lattice parameters. The calculations show that the catalytic activity is enhanced with the increasing of Co doping content and 3Co-Sn exhibits minimal overpotential.

ReS2 Nanoflowers-Assisted Confined Growth of Gold Nanoparticles for Ultrasensitive and Reliable SERS Sensing

ReS₂, as a new member of transition metal dichalcogenides (TMDCs), has emerged as a promising substrate for semiconductor surface-enhanced Raman spectroscopy (SERS) due to its unique optoelectronic properties. Nevertheless, the sensitivity of the ReS₂ SERS substrate poses a significant challenge to its widespread application in trace detection. In this work, we present a reliable approach for constructing a novel ReS₂/AuNPs SERS composite substrate, enabling ultrasensitive detection of trace amounts of organic pesticides. We demonstrate that the porous structures of ReS₂ nanoflowers can effectively confine the growth of AuNPs. By precisely controlling the size and distribution of AuNPs, numerous efficient and densely packed "hot spots" were created on the surface of ReS₂ nanoflowers. As a result of the synergistic enhancement of the chemical and electromagnetic mechanisms, the ReS₂/AuNPs SERS substrate demonstrates high sensitivity, good reproducibility, and superior stability in detecting typical organic dyes such as rhodamine 6G and crystalline violet. The ReS₂/AuNPs SERS substrate shows an ultralow detection limit of 10^-10 M and a linear detection of organic pesticide molecules within 10^-6-10^-10 M, which is significantly lower than the EU Environmental Protection Agency regulation standards. The strategy of constructing ReS₂/AuNPs composites would contribute to the development of highly sensitive and reliable SERS sensing platforms for food safety monitoring.

Rhenium-Based Electrocatalysts for Water Splitting

Due to the contamination and global warming problems, it is necessary to search for alternative environmentally friendly energy sources. In this area, hydrogen is a promising alternative. Hydrogen is even more promising, when it is obtained through water electrolysis operated with renewable energy sources. Among the possible devices to perform electrolysis, proton exchange membrane (PEM) electrolyzers appear as the most promising commercial systems for hydrogen production in the coming years. However, their massification is affected by the noble metals used as electrocatalysts in their electrodes, with high commercial value: Pt at the cathode where the hydrogen evolution reaction occurs (HER) and Ru/Ir at the anode where the oxygen evolution reaction (OER) happens. Therefore, to take full advantage of the PEM technology for green H2 production and build up a mature PEM market, it is imperative to search for more abundant, cheaper, and stable catalysts, reaching the highest possible activities at the lowest overpotential with the longest stability under the harsh acidic conditions of a PEM. In the search for new electrocatalysts and considering the predictions of a Trasatti volcano plot, rhenium appears to be a promising candidate for HER in acidic media. At the same time, recent studies provide evidence of its potential as an OER catalyst. However, some of these reports have focused on chemical and photochemical water splitting and have not always considered acidic media. This review summarizes rhenium-based electrocatalysts for water splitting under acidic conditions: i.e., potential candidates as cathode materials. In the various sections, we review the mechanism concepts of electrocatalysis, evaluation methods, and the different rhenium-based materials applied for the HER in acidic media. As rhenium is less common for the OER, we included a section about its use in chemical and photochemical water oxidation and as an electrocatalyst under basic conditions. Finally, concluding remarks and perspectives are given about rhenium for water splitting.

A Low-Temperature Synthetic Route Toward a High-Entropy 2D Hexernary Transition Metal Dichalcogenide for Hydrogen Evolution Electrocatalysis

High-entropy (HE) metal chalcogenides are a class of materials that have great potential in applications such as thermoelectrics and electrocatalysis. Layered 2D transition-metal dichalcogenides (TMDCs) are a sub-class of high entropy metal chalcogenides that have received little attention to date as their preparation currently involves complicated, energy-intensive, or hazardous synthetic steps. To address this, a low-temperature (500 °C) and rapid (1 h) single source precursor approach is successfully adopted to synthesize the hexernary high-entropy metal disulfide (MoWReMnCr)S₂ . (MoWReMnCr)S₂ powders are characterized by powder X-ray diffraction (pXRD) and Raman spectroscopy, which confirmed that the material is comprised predominantly of a hexagonal phase. The surface oxidation states and elemental compositions are studied by X-ray photoelectron spectroscopy (XPS) whilst the bulk morphology and elemental stoichiometry with spatial distribution is determined by scanning electron microscopy (SEM) with elemental mapping information acquired from energy-dispersive X-ray (EDX) spectroscopy. The bulk, layered material is subsequently exfoliated to ultra-thin, several-layer 2D nanosheets by liquid-phase exfoliation (LPE). The resulting few-layer HE (MoWReMnCr)S₂ nanosheets are found to contain a homogeneous elemental distribution of metals at the nanoscale by high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) with EDX mapping. Finally, (MoWReMnCr)S₂ is demonstrated as a hydrogen evolution electrocatalyst and compared to 2H-MoS₂ synthesized using the molecular precursor approach. (MoWReMnCr)S₂ with 20% w/w of high-conductivity carbon black displays a low overpotential of 229 mV in 0.5 M  H₂ SO₄ to reach a current density of 10 mA cm^-2 , which is much lower than the overpotential of 362 mV for MoS₂ . From density functional theory calculations, it is hypothesised that the enhanced catalytic activity is due to activation of the basal plane upon incorporation of other elements into the 2H-MoS₂ structure, in particular, the first row TMs Cr and Mn.

Regulating the electronic and magnetic properties of 1T'-ReS2 by fabricating nanoribbons and transition-metal doping: a theoretical study

Monolayer 1T'-type rhenium disulphide (1T'-ReS₂) has promising applications in spintronic devices due to its unique electronic properties induced by inversion loss in the crystal structure. A prerequisite of such applications is introducing magnetism in 1T'-ReS₂. Here, we studied the electronic and magnetic properties of zigzag 1T'-ReS₂ nanoribbons (1T'-ReS₂-NRs) and further tuned their magnetic properties by transition-metal doping. Our results show that 1T'-ReS₂-NRs exhibit tunable electronic properties ranging from indirect bandgap to direct bandgap to metallic properties. Among the energy-favoured S-terminated 1T'-ReS₂-NRs, only one exhibits robust magnetic properties. The magnetic properties of the other two nanoribbons can be effectively tuned by doping with certain transition metals. Among the configurations of TM-doped 1T'-ReS₂-NRs, only those with TM atoms introduced at the edge sites are energy-favoured. The magnetic properties of TM-doped 1T'-ReS₂-NRs are mainly contributed by the TM atom, the Re and S atoms at the edges of the nanoribbons. Besides this, the bulk Re and S atoms close to the TM atom also contribute positively to the magnetism and such contributions become weaker as the atoms are farther from the TM atom. These results provide deep insights into the modulations of the electronic and magnetic properties of 1T'-ReS₂ at the atomic scale, and thus should pave an effective path for fabricating 2D materials for spintronic devices.

Atomic Layer Deposition-Made MoS2-ReS2 Nanotubes with Cylindrical Wall Heterojunctions for Ultrasensitive MiRNA-155 Detection

As a member of the two-dimensional transition metal dichalcogenide family, rhenium disulfide (ReS₂) is a highly competitive favorite in the field of photoelectric sensors. Nevertheless, the rapid recombination of electron-hole pairs and poor electronic transmission capacity of pure ReS₂ limit its wider applications. As a new attempt to optimize its inherent structure and challenge its competency boundary, in this work, a bimetallic co-chamber feeding atomic layer deposition with a precise dose regulation strategy has been used to fabricate ReS₂ nanotubes (ReS₂-NTs) and MoS₂-ReS₂ heterojunction nanotubes (MoS₂-ReS₂-HNTs) based on the anodic aluminum oxide template sacrifice method for the first time. These obtained NTs have at least two advantages: they have a controllable diameter (40-500 nm), definite wall thickness (1 layer to 10 layers), and desirable Mo-to-Re ratio (0 to 90%), and their electron-transfer capacity and photocurrent response can be effectively enhanced by the incorporated Mo atoms. Further experiments indicated that MoS₂-ReS₂-HNTs with a real Mo-to-Re ratio of 31.0% exhibits the best photocurrent response performance, by which the ultrasensitive detection of cancer-related miRNA-155 with a linear range of 10 aM to 1 nM and a detection limit of 1.8 aM is achieved.

Concerted effect of Ni-in and S-out on ReS2 nanostructures towards high-efficiency oxygen evolution reaction

Herein, a one-step hydrothermal reaction is developed to synthesize Ni-doped ReS2 nanostructure with the sulphur defect. The material exhibited excellent OER activity with a current density of 10 mAcm-2 at...

Increasing Oxygen Vacancy of CeO2 Nanocrystals by Ni Doping and reduced Graphene Oxides Decoration towards the Electrocatalytic Hydrogen Evolution

The oxygen vacancy (VO) engineering is proved to be an effective approach for improving the hydrogen evolution reaction (HER) performance of low-cost metal oxides electrocatalysts. Cerium dioxide (CeO2), one of...

The fabrication of a flexible electrode with trace Rh based on polypyrrole for the hydrogen evolution reaction

A multi-potential step method is proposed for constructing flexible PPy/Rh film electrodes. The obtained PPy/Rh films exhibit excellent hydrogen evolution reaction (HER) catalytic performance and can be used as flexible electrodes that maintain their initial catalytic performance after bending. Characterization shows that the active sites of the catalyst are due to electron transfer between Rh and PPy.