Self-Assembly-Assisted Facile Synthesis of MoS2-Based Hybrid Tubular Nanostructures for Efficient Bifunctional Electrocatalysis

Flower-like 1T-MoS2/NiCo2S4 on a carbon cloth substrate as an efficient electrocatalyst for the hydrogen evolution reaction

The 1T-MoS₂/NiCo₂S₄ composite in situ grown on carbon cloth (CC) was successfully prepared by a two-step hydrothermal method as an efficient electrode for the hydrogen evolution reaction. The morphology and composition characterization show that the composite has a flower-like structure with a large number of edges and surfaces exposed, and the content of the 1T phase in MoS₂ is 63%. 1T-MoS₂/NiCo₂S₄/CC exhibits an overpotential of 107 mV at 10 mA cm^-2, and a Tafel slope of 66.4 mV dec^-1 in an alkaline electrolyte. After continuous electrolysis for 24 h at an overpotential of 170 mV, 86% of the original current density was retained in an chronoamperometry measurement. The outstanding catalytic performance of the composite is ascribed to its unique structure, high 1T-MoS₂ content and the synergistic catalysis between 1T-MoS₂ and NiCo₂S₄. This work provides a facile and effective strategy for fabricating the 1T-MoS₂/NiCo₂S₄/CC composite and demonstrates that the composite is expected to be a competitive non-noble HER catalyst.

Two-Dimensional MoS2: Structural Properties, Synthesis Methods, and Regulation Strategies toward Oxygen Reduction

Compared with three-dimensional (3D) and other materials, two-dimensional (2D) materials with unique properties such as high specific surface area, structurally adjustable band structure, and electromagnetic properties have attracted wide attention. In recent years, great progress has been made for 2D MoS₂ in the field of electrocatalysis, and its exposed unsaturated edges are considered to be active sites of electrocatalytic reactions. In this review, we focus on the latest progress of 2D MoS₂ in the oxygen reduction reaction (ORR) that has not received much attention. First, the basic properties of 2D MoS₂ and its advantages in the ORR are introduced. Then, the synthesis methods of 2D MoS₂ are summarized, and specific strategies for optimizing the performance of 2D MoS₂ in ORRs, and the challenges and opportunities faced are discussed. Finally, the future of the 2D MoS₂-based ORR catalysts is explored.

Rational design of nanomedicine for photothermal-chemodynamic bimodal cancer therapy

Given the diversity, complexity, and heterogeneity of persistent tumors, traditional nanoscale monotherapeutic systems suffer from dissatisfactory curative efficiency with incidence of metastasis or relapse. In parallel, the trend of clinical research on the basis of nanomedicines has increasingly shifted from monotherapy toward combinatorial therapy for admirable synergetic performances. In this regard, cutting-edge nanomedicines harnessing photothermal-chemodynamic bimodal therapy (PTT/CDT) have opened up a highly-efficient and relatively-safe cancer theranostic paradigm. Still, the integration of PTT/CDT functional units into one nanomedicine remains a herculean but meaningful task to achieve notable super-additive effects. This review aims to elucidate underlying synergistic interactions of PTT/CDT and highlight intriguing designs of nanomedicines for PTT/CDT including nanomaterial selection, performance optimization, multimodal therapy, visualization strategies, and targeting strategies. Furthermore, an outlook on further improvements of PTT/CDT is provided, emphasizing significant scientific issues that require remediation for clinical translation. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Construction of hierarchical yolk-shell nanospheres organized by ultrafine Janus subunits for efficient overall water splitting

Although the bimetal sulfide is intensively pursued in catalytic systems, synthesis of ultrafine sized bimetal sulfide Janus subunits is still a great challenge. In this work, ultrafine NiS₂/MoS₂ Janus subunits organized on yolk-shell nanospheres (NSs) are synthesized by a novel and facile approach. The greatly reduced particle size of both two-dimensional MoS₂ and one-dimensional NiS₂ on the ultrafine NiS₂/MoS₂ Janus subunits endows the yolk-shell NSs with numerous intimate interfaces of bimetal sulfide hybrids greatly promoting the intimate electronic interaction and dissociation of water molecules. Benefiting from the ultrafine NiS₂/MoS₂ Janus subunits, abundant edge sites and the high density of interfaces, the as-prepared NiS₂/MoS₂ yolk-shell NSs exhibit high electrocatalytic activity with a low η₁₀ value of 135 and 293 mV for the HER and OER, respectively. In addition, a low cell voltage (1.58 V) is achieved by using NiS₂/MoS₂ yolk-shell NSs as both anode and cathode. This study has significant indications in exploring the ultrafine nanoparticles for the water splitting reaction, fuel cells and organic synthesis.

Two-dimensional MoS2/Fe-phthalocyanine hybrid nanostructures as excellent electrocatalysts for hydrogen evolution and oxygen reduction reactions

Two-dimensional (2D) MoS2 nanostructures have been extensively investigated in recent years because of their fascinating electrocatalytic properties. Herein, we report 2D hybrid nanostructures consisting of 1T' phase MoS2 and Fe-phthalocyanine (FePc) molecules that exhibit excellent catalytic activity toward both the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). X-ray absorption spectra revealed an increased Fe-N distance (2.04 Å) in the hybrid complex relative to the isolated FePc. Spin-polarized density functional theory calculations predicted that the Fe center moves toward the MoS2 layer and induces a non-planar structure with an increased Fe-N distance of 2.05 Å, which supports the experimental results. The experiments and calculations consistently show a significant charge transfer from FePc to stabilize the hybrid complex. The excellent HER catalytic performance of FePc-MoS2 is characterized by a low Tafel slope of 32 mV dec-1 at a current density of 10 mA cm-2 and an overpotential of 0.123 V. The ORR catalytic activity is superior to that of the commercial Pt/C catalyst in pH 13 electrolyte, with a more positive half-wave potential (0.89 vs. 0.84 V), a smaller Tafel slope (35 vs. 87 mV·dec-1), and a much better durability (9.3% vs. 40% degradation after 20 h). Such remarkable catalytic activity is ascribed to the HER-active 1T' phase MoS2 and the ORR-active nonplanar Fe-N4 site of FePc.

Hydrothermal synthesis of MoS2 nanosheet loaded TiO2 nanoarrays for enhanced visible light photocatalytic applications

A molybdenum disulfide (MoS₂) nanosheet-decorated titanium dioxide (TiO₂) NRA heterojunction composite was fabricated successfully through a two-step hydrothermal approach. Microstructures and optical properties of specimens were characterized by field-emission scanning electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy. The gaps of the TiO₂ nanorods have been filled with tiny MoS₂ nanosheets, which can increase the surface area of MoS₂/TiO₂ NRA composite thin films. In addition, the photocatalytic activity of the thin films were measured and discussed in greater detail. The appropriate hydrothermal reaction temperature of MoS₂ is important for the growth of perfect MoS₂/TiO₂ NRA composites with significantly enhanced photocatalytic performance. The photodegradation rate and k value of MoS₂-220/TiO₂ are 86% and 0.0105 min⁻¹, respectively, which are much larger than those of blank TiO₂. The enhanced photocatalytic performance could be attributed to the higher visible light absorption and the reduced recombination rate of photogenerated electron–hole pairs.

A molybdenum disulfide (MoS₂) nanosheet-decorated titanium dioxide (TiO₂) NRA heterojunction composite was fabricated successfully through a two-step hydrothermal approach.