Assembling metallic 1T-MoS2 nanosheets with inorganic-ligand stabilized quantum dots for exceptional solar hydrogen evolution

Structural-Phase Catalytic Redox Reactions in Energy and Environmental Applications

The structure-property engineering of phase-based materials for redox-reactive energy conversion and environmental decontamination nanosystems, which are crucial for achieving feasible and sustainable energy and environment treatment technology, is discussed. An exhaustive overview of redox reaction processes, including electrocatalysis, photocatalysis, and photoelectrocatalysis, is given. Through examples of applications of these redox reactions, how structural phase engineering (SPE) strategies can influence the catalytic activity, selectivity, and stability is constructively reviewed and discussed. As observed, to date, much progress has been made in SPE to improve catalytic redox reactions. However, a number of highly intriguing, unresolved issues remain to be discussed, including solar photon-to-exciton conversion efficiency, exciton dissociation into active reductive/oxidative electrons/holes, dual- and multiphase junctions, selective adsorption/desorption, performance stability, sustainability, etc. To conclude, key challenges and prospects with SPE-assisted redox reaction systems are highlighted, where further development for the advanced engineering of phase-based materials will accelerate the sustainable (active, reliable, and scalable) production of valuable chemicals and energy, as well as facilitate environmental treatment.

Photocatalytic H2 Evolution on TiO2 Assembled with Ti3C2 MXene and Metallic 1T-WS2 as Co-catalysts

The biggest challenging issue in photocatalysis is efficient separation of the photoinduced carriers and the aggregation of photoexcited electrons on photocatalyst's surface. In this paper, we report that double metallic co-catalysts Ti3C2 MXene and metallic octahedral (1T) phase tungsten disulfide (WS2) act pathways transferring photoexcited electrons in assisting the photocatalytic H2 evolution. TiO2 nanosheets were in situ grown on highly conductive Ti3C2 MXenes and 1T-WS2 nanoparticles were then uniformly distributed on TiO2@Ti3C2 composite. Thus, a distinctive 1T-WS2@TiO2@Ti3C2 composite with double metallic co-catalysts was achieved, and the content of 1T phase reaches 73%. The photocatalytic H2 evolution performance of 1T-WS2@TiO2@Ti3C2 composite with an optimized 15 wt% WS2 ratio is nearly 50 times higher than that of TiO2 nanosheets because of conductive Ti3C2 MXene and 1T-WS2 resulting in the increase of electron transfer efficiency. Besides, the 1T-WS2 on the surface of TiO2@Ti3C2 composite enhances the Brunauer-Emmett-Teller surface area and boosts the density of active site.

Insight into the factors influencing the photocatalytic H2 evolution performance of molybdenum sulfide

The specific surface area and composition are found to be the key factors influencing the photocatalytic performance of MoS_2+x.

Differentiating Polymorphs in Molybdenum Disulfide via Electron Microscopy

The presence of rich polymorphs and stacking polytypes in molybdenum disulfide (MoS₂ ) endows it with a diverse range of electrical, catalytic, optical, and magnetic properties. This has stimulated a lot of interest in the unique properties associated with each polymorph. Most techniques used for polymorph identification in MoS₂ are macroscopic techniques that sample averaged properties due to their limited spatial resolution. A reliable way of differentiating the atomic structure of different polymorphs is needed in order to understand their growth dynamics and establish the correlation between structure and properties. Herein, the use of electron microscopy for identifying the atomic structures of several important polymorphs in MoS₂ , some of which are the subjects of mistaken assignment in the literature, is discussed. In particular, scanning transmission electron microscopy-annular dark field imaging has emerged as the most effective and reliable approach for identifying the different phases in MoS₂ and other 2D materials because its images can be directly correlated to the atomic structures. Examples of the identification of polymorphs grown under different conditions in molecular beam epitaxy or chemical vapor deposition, for example, 3R, 1T, 1T'-phases, and 1T'-edges, are presented, including their atomic structures, fascinating properties, growth methods, and corresponding thermodynamic stabilities.

Metallic MoS2 for High Performance Energy Storage and Energy Conversion

Metallic phase 2D molybdenum disulfide (MoS₂ ) is an emerging class of materials with remarkably higher electrical conductivity and catalytic activities. The goal of this study is to review the atomic structures and electrochemistry of metallic MoS₂ , which is essential for a wide range of existing and new enabling technologies. The scope of this paper ranges from the atomic structure, band structure, electrical and optical properties to fabrication methods, and major emerging applications in electrochemical energy storage and energy conversion. This paper also thoroughly covers the atomic structure-properties-application relationships of metallic MoS₂ . Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of metallic MoS₂ is advancing actual applications of this material. This new level of understanding also enables a myriad of new and exciting applications, which motivated this review. There are excellent reviews already on the traditional semiconducting MoS₂ , and this review, for the first time, focuses on the uniqueness of conducting metallic MoS₂ for energy applications and offers brand new materials for clean energy application.

Self-assembled inorganic clusters of semiconducting quantum dots for effective solar hydrogen evolution

The catalytic activity of CdSe QDs could be enhanced more than 150-fold by forming self-assembled clusters with ZnSe QDs madeex situ.

CoAl-layered double hydroxide nanosheets as an active matrix to anchor an amorphous MoSx catalyst for efficient visible light hydrogen evolution

CoAl LDH nanosheet supported MoS_x efficiently catalyzes H₂ evolution from an erythrosin B–triethanolamine molecular system under visible light (≥420 nm).

Highly active dye-sensitized photocatalytic H2 evolution catalyzed by a single-atom Pt cocatalyst anchored onto g-C3N4 nanosheets under long-wavelength visible light irradiation

A single-atom Pt cocatalyst anchored onto g-C₃N₄ nanosheets could efficiently catalyze H₂ evolution from an Eosin Y-sensitized system under 520 nm irradiation.

Thiomolybdate [Mo3S13]2−nanocluster: a molecular mimic of MoS2active sites for highly efficient photocatalytic hydrogen evolution

As a MoS₂edge site mimic, the [Mo₃S₁₃]²⁻nanocluster can efficiently catalyze H₂evolution from a Ru(bpy)₃²⁺–H₂A molecular system under visible light.