TiO 2 : Si nanotube/1T-MoSe 2 nanosheet hybrids with highly efficient hydrogen evolution catalytic activity

Iron molybdenum selenide supported on reduced graphene oxide as an efficient hydrogen electrocatalyst in acidic and alkaline media

It is of great significance to develop inexpensive and high-efficiency electrocatalysts for the hydrogen evolution reaction (HER). In this work, we synthesized iron molybdenum selenide (FeSe₂-MoSe₂) loaded on reduced graphene oxide (FeSe₂-MoSe₂/rGO) by a one-step hydrothermal method. We further optimized the Fe/Mo ratio and determined the best ratio to be 1-1. In acidic (or alkaline) solution, the optimized FeSe₂-MoSe₂(1-1)/rGO has a small Tafel slope of 55 (or 80) mV dec^-1 and needs an overpotential of 101 (or 178) mV to achieve 10 mA cm^-2. These good properties are mainly due to the structure of bimetallic selenides combining rGO. Moreover, rGO enhances the electrical conductivity. Furthermore, the synergistic effect between FeSe₂-MoSe₂(1-1) and rGO results in better HER performance. Density functional theory (DFT) calculation proves that FeSe₂-MoSe₂(1-1)/rGO has a small work function. Based on our reasonable design and analysis, FeSe₂-MoSe₂(1-1)/rGO is expected to be an efficient and robust catalyst for large-scale applications.

Phase Transitions and Water Splitting Applications of 2D Transition Metal Dichalcogenides and Metal Phosphorous Trichalcogenides

2D layered materials turn out to be the most attractive hotspot in materials for their unique physical and chemical properties. A special class of 2D layered material refers to materials exhibiting phase transition based on environment variables. Among these materials, transition metal dichalcogenides (TMDs) act as a promising alternative for their unique combination of atomic-scale thickness, direct bandgap, significant spin-orbit coupling and prominent electronic and mechanical properties, enabling them to be applied for fundamental studies as catalyst materials. Metal phosphorous trichalcogenides (MPTs), as another potential catalytic 2D phase transition material, have been employed for their unusual intercalation behavior and electrochemical properties, which act as a secondary electrode in lithium batteries. The preparation of 2D TMD and MPT materials has been extensively conducted by engineering their intrinsic structures at the atomic scale. In this study, advanced synthesis methods of preparing 2D TMD and MPT materials are tested, and their properties are investigated, with stress placed on their phase transition. The surge of this type of report is associated with water-splitting catalysis and other catalytic purposes. This study aims to be a guideline to explore the mentioned 2D TMD and MPT materials for their catalytic applications.

Effect of Ag loading position on the photocatalytic performance of TiO2 nanocolumn arrays

Plasmonic metal/semiconductor composites have attracted great attention for efficient solar energy harvesting in photovoltaic and photocatalytic applications owing to their extremely high visible-light absorption and tuned effective band gap. In this work, Ag-loaded TiO₂ nanocolumn (Ag-TNC) arrays were fabricated based on anodic aluminum oxide (AAO) template by combining atomic layer deposition (ALD) and vacuum evaporation. The effects of the Ag loading position and deposition thickness, and the morphology, structure and composition of Ag-deposited TNC arrays on its optical and photocatalytic properties were studied. The Ag-filled TiO₂ (AFT) nanocolumn arrays exhibited higher removal efficiency of methylene blue (MB) compared with Ag-coated TiO₂ (ACT) nanocolumn arrays and pure TiO₂ nanocolumns arrays. Both experimental and theoretical simulation results demonstrated that the enhanced photocatalytic performance of AFT nanocolumn arrays was attributed to the surface plasmon resonance (SPR) of Ag and the absorption of light by TiO₂. These results represent a promising step forward to the development of high-performance photocatalysts for energy conversion and storage.

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.

Synthesis and applications of nano-TiO2: a review

TiO₂-based nanomaterials have attracted prodigious attention as a photocatalysts in numerous fields of applications. In this thematic issue, the mechanism behind the photocatalytic activity of nano-TiO₂ as well as the critical properties have been reviewed in details. The synthesis routes and the variables that affect the size and crystallinity of nano-TiO₂ have also been discussed in detail. Moreover, a newly emerged class of color TiO₂, TiO₂ in aerogel form, nanotubes form, doped and undoped form, and other forms of TiO₂ have been discussed in details. Photocatalytic and photovoltaic applications and the type of nano-TiO₂ that is more suitable for these applications have been discussed in this review.

Luminescent, stabilized and environmentally friendly [EuW10O36]9--Chitosan films for sensitive detection of hydrogen peroxide

Fabrications and applications of luminescent films have been an interesting and important challenge within the realm of academia and industry. Herein, a novel fluorescence-based strategy for the H₂O₂ detection has been developed by fabrication of stabilized, thin, transparent, and luminescent films composed of europium-containing polyoxometalates (Eu-POM) and environmentally friendly chitosan (CS) via a facile solution casting approach. In comparison with pure Eu-POM, enhanced fluorescent properties are obtained from the as-prepared Eu-POM/CS films in terms of prolonged fluorescence lifetime and a remarkable fluorescent quenching effect in the presence of hydrogen peroxide (H₂O₂). The fluorescence intensity of Eu-POM/CS films exhibits a linear correlation in response to the H₂O₂ concentration over a wide range of 1.1-66 μM, with a detection limit of 0.11 μM. Furthermore, the fluorescent films display a high detection selectivity which are capable of differentiating hydrogen peroxide (H₂O₂) from the interfering species, such as sugars, l-amino acids, and other metabolites. All these advances towards the development of Eu-POM/CS films open up new applications for luminescent films, but most importantly, they can help in the far-reaching technological implementations of a simple, cost-effective method for the detection of H₂O₂ in many fields.