Controllable synthesis of P-doped MoS2 nanopetals decorated N-doped hollow carbon spheres towards enhanced hydrogen evolution

Garnering sensitivity: A horseradish peroxidase and MoS2@black phosphorene based electrochemical biosensor for glyphosate detection

Glyphosate (GLY) is one of the most widely used herbicides, and the presence of its residues in food samples poses a threat to human health. Developing a monitoring system could help address food safety concerns. This study presents an innovative electrochemical sensing platform to detect GLY, which employs molybdenum disulfide (MoS2) and black phosphorene (BP) nanocomposites (MoS2@BP) with horseradish peroxidase (HRP) for the working electrode modification. The MoS2@BP nanocomposite is synthesized using a hydrothermal method, and its characteristics are investigated through different methods including scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction methods. The presence of BP enhances electrical conductivity and increases specific surface area, while MoS2 improves the electrochemical properties of the composites and provides a protective effect on BP. The modification of MoS₂@BP on the electrode surface helps to accelerate the direct electron transfer of HRP with enhanced electrochemical responses. Furthermore, the incorporation of amino acid residues from HRP significantly enhances the recognition of GLY, thereby improving the selectivity and sensitivity of this electrochemical sensor. The sensor operates effectively within a linear concentration range from 0.118 nmol/L to 20.65 nmol/L, with a low detection limit of 0.0393 nmol/L (3σ). Furthermore, the sensor is successfully applied to detect GLY in real cornmeal samples with satisfactory results, demonstrating its potential applications in food safety monitoring.

Aerophobic P-MoS2 on MOF-Derived Co,N-Codoped Carbon Nanosheets with Accelerated H2 Bubble Release Dynamics for Efficient Alkaline Water Splitting at 1000 mA cm-2

Rapid bubble release at high current densities results in the detachment of catalysts and performance degradation, posing a persistent challenge in actual alkaline water electrolysis (AWE). Here, hierarchical nanosheet structures (CoNC@P-MoS2) are constructed, with P-doped MoS2 on the surface of Co,N-codoped carbon. It exhibits low hydrogen evolution reaction overpotentials of 30 and 354 mV at 10 and 1000 mA cm-2 in 1 M KOH, respectively, with a small Tafel slope of 36 mV dec-1. The constructed CoNC@P-MoS2||NiFe-DLH cell requires only 1.44 and 1.92 V to achieve overall water splitting at 10 and 1000 mA cm-2, which outperforms the traditional catalysts like Pt/C||IrO2. The introduction of P stabilizes surface hydroxyl (OH*) and increases the proton penetration depth, thereby greatly enhancing its intrinsic activity. It also makes the surface aerophobic by introducing more microfeatures, which greatly improves the geometric activity by increasing the bubble release rate (∼5.8 times). Low energy consumption of 3.92 kW h Nm-3 was achieved with an energy efficiency close to 80%. Bubble growth kinetics analysis reveals that the time and growth factors for CoNC@P-MoS2 are increased to 0.54 and 11.79 from 0.45 and 6.09 for CoNC, respectively, which highlights its fast bubble reaction dynamics. The results suggest the feasibility of CoNC@P-MoS2 as a potential high-performance catalyst in commercial AWE.

Enhanced Electrochemical Catalysis: Hydrogen Evolution Using Bimetallic Sulfides on Nickel Foam

Hydrogen is considered clean energy with broad application prospects for the 21st century, and water electrolysis plays a crucial role in hydrogen production. However, economic limitations and large overpotential values hinder its development. In this study, we deposited nickel (Ni), iron (Fe), and sulfur (S) onto nickel foam (NF) using the constant potential method to form the Ni-S-Fe/NF catalyst, which exhibited an exceptionally low overpotential (31 mV) at a current density of -10 mA cm-2, and a Tafel slope of 75.1 mV dec-1 in 1 M sodium hydroxide. It showed a minor charge resistance (1.256 Ω). The amorphous phase structure and optimized catalyst composition promoted outstanding hydrogen evolution activity. This work offers valuable perspectives on the industrial application of hydrogen production.

Introducing phosphorus atoms into MoS2 nanosheets through a vapor-phase hydrothermal process for the hydrogen evolution reaction

Molybdenum disulfide (MoS2)-based electrocatalysts have been considered as promising alternatives to platinum for use in the hydrogen evolution reaction (HER). Developing MoS2 electrocatalysts with more active sites has been recognized as an efficient way to enhance the HER activity. Moreover, phase transition and heteroatom doping show great influence on the HER performance. In this work, we develop a vapor-phase hydrothermal (VPH) approach to introduce phosphorus (P) atoms into a MoS2 nanosheet array on carbon fiber cloth, which presents enhanced HER activity compared with MoS2 without P-doping. The improved performance is due to the synergistic effects of the new active sites formed by the P dopants and the sulfur (S) vacancies in the MoS2 nanosheets generated by the doping of P atoms, which increases the number of active sites. In general, the obtained P-doped MoS2/CFC exhibits a lower onset potential of 80 mV and an overpotential of 162 mV at 10 mA cm-2 than MoS2 without P-doping in 0.5 M H2SO4, accompanied by extremely large cathodic current density and excellent stability. This strategy may open up opportunities for heteroatom doping of electrocatalysts for various applications and provide a new method for material synthesis.

2D nanocomposite materials for HER electrocatalysts - a review

Hydrogen energy has the potential to be a cost-effective and strong technology for brighter development. Hydrogen fuel production by water electrolyzers has attracted attention. 2D nanocomposites with distinctive properties have been extensively explored for various applications from hydrogen evolution reactions to improving the efficiency of water electrolyzer, which is the most eco-friendly, and high-performance for hydrogen production. Recently, typical 2D nanocomposites such as Metal-Free 2D, TMDs, Mxene, LDH, organic composites, and Heterostructure have recently been thoroughly researched for use in the HER. We discuss effective ways for increasing the HER efficiency of 2D catalysts in this paper, And the unique advantages and mechanisms for specific applications are highlighted. Several essential regulating strategies for developing 2D nanocomposite-based HER electrocatalysts are included such as interface engineering, defect engineering, heteroatom doping, strain & phase engineering, and hybridizing which improve HER kinetics, the electrical conductivity, accessibility to catalytic active sites, and reaction energy barrier can be optimized. Finally, the future prospects for 2D nanocomposites in HER are discussed, as well as a thorough overview of a variety of methodologies for designing 2D nanocomposites as HER electrocatalysts with excellent catalytic performance. We expect that this review will provide a thorough overview of 2D nanocatalysts for hydrogen production.

Engineering P-Fe2O3-CoP nanosheets for overall freshwater and seawater splitting

Tailoring surface composition and coordinative environment of catalysts in a nano-meter region often influence their chemical performance. It is reported that CoP exhibits a low dissociation ability of H-OH, originating from the poor desorption of intermediate species. Herein, we provide a feasible method to construct P-Fe2O3-CoP nanosheets through a gas-phase phosphorization process. P doping induces the formation of interfacial structure between Fe2O3 and CoP and the generation of defective structures. The resulting P-Fe2O3-CoP nanosheets afford high freshwater/seawater oxidation activity (250/270 mV@10 mA/cm2) in 1 mol/L (M) KOH, which is even lower than commercial RuO2. Compared with CoP||CoP, P-Fe2O3||P-Fe2O3, and Co3O4||Co3O4, the assembled P-Fe2O3-CoP||P-Fe2O3-CoP exhibits the superior water/seawater electrolysis performance with 1.61/1.65 V@10 mA/cm2. The synergistic effect of P doping, defective structure, and heterojunction leads to high water oxidation efficiency and water splitting efficiency.

Mo2C promoted electrocatalysis of the Pt/Mo2C (C) heterostructure for a superior hydrogen evolution reaction

Constructing a unique electrochemical interface to enhance the catalytic capacity of Pt-based catalysts is indispensable for wider application of the hydrogen evolution reaction (HER). Herein, platinum-analogous molybdenum carbide (Mo₂C) was combined with a lower content of Pt to construct the Pt/Mo₂C (C) heterostructure via a solid-phase method, using ammonium molybdate as the precursor. Vulcan-C served as a support to promote the distribution of the Pt and Mo₂C heterostructure, and cooperative effects between Pt and the Mo₂C heterostructure contributed to the significantly improved catalytic capacity of Pt. The obtained Pt/Mo₂C (C) exhibits superior HER activity and enhanced long-term durability in the acidic medium, with a low overpotential of 38 mV at 10 mA cm^-2 and a low Tafel slope of 24 mV dec^-1. In particular, a drastically enhanced amount of H₂ production can be achieved (6837.28 mmol h^-1 g^-1). This facile approach not only provides a new pathway for constructing novel heterostructures but also gives an insight into the design of cost-effective Pt-based materials for an efficient HER.

N, P co-doping triggered phase transition of MoS2 with enlarged interlayer spacing for efficient hydrogen evolution

Molybdenum disulfide (MoS2)-based transition-metal chalcogenides are considered to be cost-efficient, environmentally-friendly, and stable materials in the application of electrocatalytic hydrogen production.

MoS2-2xSe2x Nanosheets Grown on Hollow Carbon Spheres for Enhanced Electrochemical Activity

Electrochemical catalysts with high conductivity and low reaction potential are respected. In this paper, hollow carbon spheres (HCSs) were homogeneously coated with Se-doped MoS₂ (MoS_2-2xSe_2x) nanosheets by hydrothermal synthesis. The HCSs reduced the agglomeration of MoS_2-2xSe_2x nanosheets and improved their conductivity. Compared with the MoS₂-modified samples, Se doping increased the interlayer spacing which provided more active catalytic sites and improved the charge transfer. Thus, MoS_2-2xSe_2x-decorated samples revealed enhanced electrocatalytic activity. The composition of MoS_2-2xSe_2x nanosheets was adjusted by changing the ratios of sulfur and selenium precursors. In the case of a Se/S molar ratio of 0.1, the composite of HCS decorated with MoS_2-2xSe_2x nanosheets (C@MoS_2-2xSe_2x) revealed the lowest overpotential and the smallest Tafel slope.

Pt nanoparticles embedded spine-like g-C3N4 nanostructures with superior photocatalytic activity for H2 generation and CO2 reduction

Conventional two-dimensional (2D) graphitic carbon nitride, 2D g-C₃N₄ with its layered structures and flat and smooth 2D surface possesses certain disadvantages that is affecting their photocatalytic performances. In this paper, new nanostructured spine-like three-dimensional (3D) g-C₃N₄ nanostructures are created for the first time via a new three-step synthesis method. In this method, self-assembly of layered precursors and H⁺ intercalation introduced by acid treatment play an important role for the unique nanostructure formation of 3D g-C₃N₄ nanostructures. The spine-like 3D g-C₃N₄ nanostructures show a superior photocatalytic performance for H₂ generation, achieving 4500 μmol·g^-1·h^-1, 8.2 times higher than that on conventional 2D g-C₃N₄. Remarkably spine-like 3D g-C₃N₄ nanostructures demonstrate a clear photocatalytic activity toward CO₂ reduction to CH₄ (0.71 μmol·g^-1·h^-1) in contrast to the negligible photocatalytic performance of conventional 2D g-C₃N₄ for the reaction. Adding Pt clusters as co-catalysts substantially enhance the CH₄ generation rate of the 3D g-C₃N₄ nanostructures by 4 times (2.7 μmol·g^-1·h^-1). Spine-like 3D g-C₃N₄ caged nanostructure leads to the significantly increased active sites and negatively shifted conduction band position in comparison with conventional 2D g-C₃N₄, favorable for the photocatalytic reduction reaction. This study demonstrates a new platform for the development of efficient photocatalysts based on nanostructured 3D g-C₃N₄ for H₂ generation and conversion of CO₂ to useful fuels such as CH₄.

Improvement of HER activity for MoS2: insight into the effect and mechanism of phosphorus post-doping

The phosphorus-doped MoS₂ nanosheets were prepared by a post-doping method and exhibited good catalytic activity for hydrogen evolution reaction.

Vertically aligned MoS2 nanosheets on N-doped carbon nanotubes with NiFe alloy for overall water splitting

Schematic illustration of the formation process and performance of overall water splitting for NiFe-NCNT@MoS₂ samples.