Molybdenum disulfide nanosheets vertically grown on self-supported titanium dioxide/nitrogen-doped carbon nanofiber film for effective hydrogen peroxide decomposition and "memory catalysis"

A self-supporting catalyst consisting of 1D/2D vertical molybdenum disulfide@titanium dioxide/nitrogen-doped carbon nanofiber (MoS₂@TiO₂/NCNFs) was prepared and tested. It showed efficient hydrogen peroxide (H₂O₂) decomposition to generate hydroxyl radical (OH) and degradation of various pollutants under solar irradiation. The contribution of the increase in MoS₂ edges for decomposing H₂O₂ was 0.0698 min^-1. That is 9.83 times the rate of the original MoS₂ edges resulting from the vertical structure. Specially, the catalyst degraded various aromatic pollutants even in the dark by releasing electrons stored in its graphite component to realize "memory catalysis". Also, it exhibited high degradation efficiency under outdoor solar irradiation. The catalyst was easily separated from the treated water, avoiding complex separation processes. All these features suggest this catalyst has great potential in practical water and sewage treatment applications.

Tungsten-inert gas welding electrodes as low-cost, green and pH-universal electrocatalysts for the hydrogen evolution reaction

Lanthanated tungsten electrodes were shown to be green, durable, low-cost, pH-universal and efficient electrocatalysts for the hydrogen evolution reaction.

Embedding Carbon Nitride into a Covalent Organic Framework with Enhanced Photocatalysis Performance

We report a new strategy to construct porous carbon nitride (PCN) by embedding a heptazine unit-the primary building block of carbon nitride-into the backbone of a covalent organic framework (COF). The strategy results in a new type of PCN which bears a fibrous morphology, high surface area and wide visible absorption. The photocatalytic performance was evaluated by photodegradation of an organic dye. We found that the introduction of the heptazine unit has a prominent effect on the catalytic activity, which demonstrates an effective strategy to prepare carbon nitride materials. This work opens up a new way for the preparation of carbon nitride for photocatalysis applications.

Crystalline (Ni1-xCox)5TiO7 nanostructures grown in situ on a flexible metal substrate used towards efficient CO oxidation

Severe environmental contamination and the urgent demand for a clean atmosphere require an efficient and low-cost solution to address problems such as CO emission. In this study, we report the in situ integration of non-noble (Ni_1-xCo_x)₅TiO₇ nanostructures with different Co concentrations and tunable size on a flexible metal network support using a conventional PEO method; we further report their utilization for efficient CO oxidation. It was found that the Co/Ni ratios in the original electrolyte precursors directly result in the different size and morphology evolution. The (Ni_1-xCo_x)₅TiO₇ nanowire arrays with x = 0.16 exhibit the best performance towards CO catalytic oxidation along with a good catalytic stability. Further analysis using XPS indicates that the CO catalytic oxidation was mainly determined by the amount of defective oxygen, lattice oxygen and surface area. The single crystal nature, large surface area, excellent CO catalytic capability and strong substrate adhesion of the (Ni_1-xCo_x)₅TiO₇ nanostructures on a flexible metal substrate will open up more applications in CO oxidation ranging from processing autovehicle exhaust to chemical gas emissions in the industry.

WO3-x Nanoplates Grown on Carbon Nanofibers for an Efficient Electrocatalytic Hydrogen Evolution Reaction

The search for non-noble metal catalysts with high activity for the hydrogen evolution reaction (HER) is crucial for efficient hydrogen production at low cost and on a large scale. Herein, we report a novel WO3-x catalyst synthesized on carbon nanofiber mats (CFMs) by electrospinning and followed by a carbonization process in a tubal furnace. The morphology and composition of the catalysts were tailored via a simple method, and the hybrid catalyst mats were used directly as cathodes to investigate their HER performance. Notably, the as-prepared catalysts exhibit substantially enhanced activity for the HER, demonstrating a small overpotential, a high exchange current density, and a large cathodic current density. The remarkable electrocatalytic performances result from the poor crystallinity of WO3-x, the high electrical conductivity of WO3-x, and the use of electrospun CNFs. The present work outlines a straightforward approach for the synthesis of transition metal oxide (TMO)-based carbon nanofiber mats with promising applications for the HER.

Heterogeneous WSx/WO₃ Thorn-Bush Nanofiber Electrodes for Sodium-Ion Batteries

Heterogeneous electrode materials with hierarchical architectures promise to enable considerable improvement in future energy storage devices. In this study, we report on a tailored synthetic strategy used to create heterogeneous tungsten sulfide/oxide core-shell nanofiber materials with vertically and randomly aligned thorn-bush features, and we evaluate them as potential anode materials for high-performance Na-ion batteries. The WSx (2 ≤ x ≤ 3, amorphous WS3 and crystalline WS2) nanofiber is successfully prepared by electrospinning and subsequent calcination in a reducing atmosphere. To prevent capacity degradation of the WSx anodes originating from sulfur dissolution, a facile post-thermal treatment in air is applied to form an oxide passivation surface. Interestingly, WO3 thorn bundles are randomly grown on the nanofiber stem, resulting from the surface conversion. We elucidate the evolving morphological and structural features of the nanofibers during post-thermal treatment. The heterogeneous thorn-bush nanofiber electrodes deliver a high second discharge capacity of 791 mAh g(-1) and improved cycle performance for 100 cycles compared to the pristine WSx nanofiber. We show that this hierarchical design is effective in reducing sulfur dissolution, as shown by cycling analysis with counter Na electrodes.

Tuning of the crystal engineering and photoelectrochemical properties of crystalline tungsten oxide for optoelectronic device applications

WO₃crystals with {002} or {111} facets primarily exposed, WO₃films with dominant orientations, doping and heterostructuring are highlighted.

CdS-decorated triptycene-based polymer: durable photocatalysts for hydrogen production under visible-light irradiation

Nanocomposites formed by CdS with porous triptycene-based polymers are effective catalysts for photocatalytic hydrogen production.