Formaldehyde (HCHO) is a major indoor pollutant and long-term exposure to HCHO may cause health problems such as nasal tumors and skin irritation. Photocatalytic oxidation is considered as the most promising strategy for the decomposition of HCHO. Herein, for the first time, a direct g-C3N4-TiO2 Z-scheme photocatalyst without an electron mediator was prepared by a facile calcination route utilizing affordable P25 and urea as the feedstocks. Photocatalytic activities of the as-prepared samples were evaluated by the photocatalytic oxidation decomposition of HCHO in air. It was shown that the photocatalytic activity of the prepared Z-scheme photocatalysts was highly dependent on the g-C3N4 content. At the optimal g-C3N4 content (sample U100 in this study), the apparent reaction rate constant was 7.36 × 10(-2) min(-1) for HCHO decomposition, which exceeded that of pure P25 (3.53 × 10(-2) min(-1)) by a factor of 2.1. The enhanced photocatalytic activity could be ascribed to the formation of a g-C3N4-TiO2 Z-scheme photocatalyst, which results in the efficient space separation of photo-induced charge carriers. Considering the ease of the preparation method, this work will provide new insights into the design of high-performance Z-scheme photocatalysts for indoor air purification.

In this work, three types of MnO 2 nanostructures, viz., microsphere/nanosheet core-corona hierarchical architectures, one-dimensional (1D) nanorods, and nanotubes, have been synthesized employing a simple hydrothermal process. The formation mechanisms have been rationalized. The materials have been thoroughly characterized by X-ray diffraction, Brunauer-Emmett-Teller spectrometry, field-emission scanning electron miscroscopy, energy dispersive spectroscopy, and transmission electron microscopy. The microsphere/nanosheet core-corona hierarchical structures are found to be the layered birnessite-type MnO 2 , while 1D nanorods and nanotubes are of the R-MnO 2 phase. These MnO 2 nanostructures are used as a model system for studying the shape/phase-dependent electrocatalytic properties for the oxygen reduction reaction, which have be investigated by cyclic and linear sweep voltammetry. It is found that R-MnO 2 nanorods/tubes possess largely enhanced electrocatalytic activity compared to birnessite-type MnO 2 core-corona spheres despite the latter having a much higher specific surface area. The vast difference in electrocatalytic activity is discussed in terms of crystal structure, oxygen adsorption mode, and exposed crystal facets.

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Photocatalytic reduction of CO2 into renewable hydrocarbon fuels is an alternative way to develop reproducible energy, which is also a promising way to solve the problem of the greenhouse effect. In this work, graphitic carbon nitride (g-C3N4) was synthesized by directly heating thiourea at 550 °C and then a certain amount of Pt was deposited on it to form g-C3N4-Pt nanocomposites used as catalysts for photocatalytic reduction of CO2 under simulated solar irradiation. The main products of photocatalysis were CH4, CH3OH and HCHO. The deposited Pt acted as an effective cocatalyst, which not only influenced the selectivity of the product generation, but also affected the activity of the reaction. The yield of CH4 first increased upon increasing the amount of Pt deposited on the g-C3N4 from 0 to 1 wt%, then decreased at 2 wt% Pt loading. The production rates of CH3OH and HCHO also increased with the content of Pt increasing from 0 to 0.75 wt% and the maximum yield was observed at 0.75 wt%. The Pt nanoparticles (NPs) could facilitate the transfer and enrichment of photogenerated electrons from g-C3N4 to its surface for photocatalytic reduction of CO2. At the same time, Pt was also used a catalyst to promote the oxidation of products. The transient photocurrent response further confirmed the proposed photocatalytic reduction mechanism of CO2. This work indicates that the deposition of Pt is a good strategy to improve the photoactivity and selectivity of g-C3N4 for CO2 reduction.

Amorphous CoSnO 3 @C nanoboxes have been synthesized by thermal annealing of CoSn(OH) 6 nanoboxes, followed by carbon nanocoating. Benifiting from the unique structure, they exhibit exceptional long-term cycling stability over 400 cycles for highly reversible lithium storage.Next-generation lithium-ion batteries (LIBs) with higher energy/power density are vitally important for electric vehicles and mobile electronics with a market value of billions of dollars. The development of highperformance electrode materials, especially those with long service life, is the key to implement them for practical use. In this contribution, we have rationally designed a multifeatured nanostructure, amorphous CoS-nO 3 @C nanoboxes, for highly reversible lithium storage. This unique structure incorporates several desirable design rationales for long-life anode materials based on hollow nanostructures, carbon nanopainting, mixed conductive matrix and crystalline texture engineering. In favor of the synergy and interplay of the matrix effect and intrinsic structural advantages, the CoSnO 3 @C nanoboxes exhibit an exceptional cycle life of over 400 cycles and improved high-rate capability when evaluated as an anode material for lithium-ion batteries.

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Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution-electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

Au–TiO2–graphene photocatalysts display high visible-light hydrogen production activity due to the load of Au nanoparticles and introduction of graphene.