Oxygen reduction reaction (ORR) plays a pivotal role in advanced electrochemical energy conversion devices. However, the ORR conversion efficiency is extremely limited. The major obstacles originate from the adsorption and activation of O 2 on the electrode surface. A novel nanocomposite catalyst, photosensitizers (PS) meso-tetraphenylporphyrin iron(III) chloride (FePcCl)/NiCoFe-layered double hydroxides (NiCoFe-LDHs) is designed in this study. Herein, owing to excellent oxygen molecules activation ability and remarkable illumination absorption feature, FePcCl/NiCoFe-LDHs is employed to uncover the relationship between the intrinsic ORR activity and PS behaviour. Interestingly, the reaction mechanism of singlet 1 O 2 is proposed owing to the combination of electrochemical ORR catalysed via LDHs and PS. The boosted cathodic ORR properties exhibit singlet 1 O 2 dependent response arising from the synergistic effect to selectively produce active intermediates in alkaline medium. This work imparts the promising new mechanism about the high 4-electron ORR selectivity via material design, which will guide the development of photo-assisted energy conversion devices.

Solar energy has the potential to be the next-generation power source if the intermittent nature can be overcome via rational energy storage engineering. The competitiveness of solar rechargeable batteries can be further enhanced if the demand for multiple energy storage scenarios can be met within one device. Moreover, active electrochemical materials with different energy storage types are the critical component of this energy storage system. In this work, dual-duty electrochemical functional materials were introduced to guide multi-scene solar energy storage device design and fabrication. Furthermore, dual-duty NiCo2S4 nanosheets were prepared and applied to solar rechargeable batteries. A photo-assisted aqueous polysulfide/iodide flow battery was designed and fabricated with a charging voltage as low as 0.05 V, showing the good electrocatalytic performance of NiCo2S4 nanosheets for aqueous redox couples. Moreover, the low charging voltage leads to 93.5% of input electric energy saving under one sun illumination (AM 1.5, 100 mW cm(-2)). On the other hand is the photo-assisted sodium-ion battery with a NiCo2S4 anode, showing a remarkably low charging voltage of 0.67 V and a high discharge medium voltage of 1.05 V. The battery can save about 67.6% of input electric energy under 1 sun illumination.

High-entropy oxides receive significant attention owing to their “four effects”. However, they still suffer from harsh construction conditions such as high temperature and high pressure and present a block-like structure. Herein, in this work, Ni-Mn-Cu-Co-Fe-Al high-entropy layered oxides (HELOs) with a layered nanosheet structure were constructed by a simple pathway of topological transformation under relatively low temperature (300 °C) with six-membered Ni-Mn-Cu-Co-Fe-Al layered double hydroxides (LDHs) precursors, which exhibited an outstanding activity and excellent selectivity for CO 2 photoelectroreduction (obtaining the highest carbon monoxide yield of 909.55 µmol·g −1 ·h −1 under −0.8 V vs. reversible hydrogen electrode (RHE), which is almost twice that of pure electrocatalysis). In addition, the charging voltage of a photo-assisted Zn-CO 2 battery with HELOs as electrode was reduced from 2.62 to 2.40 V; the discharging voltage of the battery was increased from 0.51 to 0.59 V with the assistance of illumination. The improvement of round-trip efficiency of the battery indicates that light played a positive role in both the charging and discharging processes. This study not only lays an important foundation for the development of high-entropy oxides but also expands their application in the field of photoelectrochemistry.

Magnetic materials are being increasingly used in anti-counterfeiting coatings, but the dark colors of magnetic materials greatly limit their applications. This necessitates the development of light-colored magnetic materials. In this study, the heterogeneous precipitation method was used to deposit a layer of titanium dioxide (TiO2) on the surface of magnetic spherical metal particles, followed by the deposition of a layer of Ag by the reduction method, in order to achieve a light color. In the experiment, the particles were initially coated with a few tens of nanometers of TiO2 with a strong shading effect, followed by a further coating of Ag of the same thickness with a similar shading performance. Not only did this achieve a lighter color, but there was no reduction in the magnetic properties of the material after the application of the coating. Scanning electron microscopy (SEM), scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS), X-ray diffractometry (XRD), and other methods were used to study the changes in morphology and composition before and after the magnetic material was coated. A magnetic tester was used to study the changes in magnetic strength before and after the magnetic material was coated.

ZnO and TiO2 are semiconductor nanomaterials that are widely used in photocatalysis. However, the relatively high recombination rate and low quantum yield of photogenerated electron–hole pairs limit their practical applications. In this study, a series of TiO2/ZnO/diatomite composites with various compositions were successfully prepared via a two-step precipitation method. They exhibited stronger UV–visible absorption properties and substantially lower fluorescence intensities than those of ZnO and ZnO/diatomite, which was mainly due to the low recombination rate of the photogenerated electron–hole pairs in the composite system. The reaction intermediates of methylene blue were detected by liquid chromatography–mass spectrometry, and the degradation process was determined. The best composite catalyst was used for the degradation of gaseous methylbenzene and gaseous acetone. The gaseous acetone degradation product was determined to be acetaldehyde via gas chromatography–mass spectrometry. The results show that the composite catalyst exhibited a good photocatalytic degradation of both liquid pollutants and harmful volatile gases. When applied to the hydrogen and oxygen evolution reactions, the composite catalyst retained a good photoresponsivity and electrolytic efficiency.

While modern industry has contributed to the prosperity of an increasingly urbanized society, it has also led to serious pollution problems, with discharged wastewater and exhaust gases causing significant environmental harm. Titanium dioxide (TiO2), which is an excellent photocatalyst, has received extensive attention because it is inexpensive and able to photocatalytically degrade pollutants in an environmentally friendly manner. TiO2 has many advantages, including high chemical stability, low toxicity, low operating costs, and environmental friendliness. TiO2 is an N-order semiconductor material with a bandgap of 3.2 eV. Only when the wavelength of ultraviolet light is less than or equal to 387.5 nm, the valence band electrons can obtain the energy of the photon and pass through the conduction band to form photoelectrons, meanwhile the valence band forms a photogenerated hole. And light in other wavelength regions does not excite this photogenerated electrons. The most common methods used to improve the photocatalytic efficiency of TiO2 involve increasing its photoresponse range and reducing photogenerated-carrier coupling. The morphology, size, and structure of a heterojunction can be altered through element doping, leading to improved photocatalytic efficiency. Mainstream methods for preparing TiO2 are reviewed in this paper, with several excellent preparation schemes for improving the photocatalytic efficiency of TiO2 introduced. TiO2 is mainly prepared using sol-gel, solvothermal, hydrothermal, anodic oxidation, microwave-assisted, CVD and PVD methods, and TiO2 nanoparticles with excellent photocatalytic properties can also be prepared. Ti-containing materials are widely used to purify harmful gases, as well as contaminants from building materials, coatings, and daily necessities. Therefore, the preparation and applications of titanium materials have become globally popular research topics.

In the past decade, the power conversion efficiency of metal halide perovskite solar cells (PSCs) are advancing by leaps and bounds. Among them, hole-transport-layer-free carbon-based perovskite solar cells are superior to those devices with hole-transform-layer and gold electrodes in terms of cost and stability. But its relatively low power conversion efficiency (PCE) limits its commercialization. As for perovskite solar cells, the light-harvesting layer holding properties of higher crystallinity and wider absorbing range means a better photoelectric performance. In this work, PbS quantum dots (photovoltaic semiconductor with an absorption edge at near-infrared) were introduced into the perovskite layer as an additive to form a hybrid structure photo-active layer. The I- capped PbS quantum dots which are derived from ligand exchange processing work as nucleation centers and facilitate the nucleation and aging steps in the formation of polycrystal perovskite film. Benefiting from wider absorbing range and higher crystallinity. When adding a 5% molar ratio of PbS QDs, the conversion efficiency of devices based on PbS QDs@MAPbI3 hybrid film is 24% higher than that based on pure MAPbI3, which is specifically reflected in higher short-circuit current (JSC) and fill factor (FF). Finally, the PSCs based on the hybridized light-harvesting-layer and carbon electrode achieved an efficiency of 12.16% and an FF of 0.55 or higher, and the humidity stability is also superior to the Au electrode system.

The key to the commercialization of sustainable energy conversion technologies is the development of high-performance catalysts. The discovery of a stable, efficient, and low-cost multi-function catalysts is the key. We used a simple green precipitation method to load nanozinc oxide particles onto a diatomite substrate. The ZnO is nano-sized. This precipitation method produces ZnO nanoparticles in situ on diatomite. The catalysts degraded 90% of Methylene blue solution and also degraded gaseous benzene and gaseous acetone. Not only can the catalysts be used for the organic degradation of wastewater, but it also has the potential to degrade volatile organic compounds. Photocatalytic efficiency is closely related to the generation and separation of photogenerated electrons and holes. The effective suppression of the recombination rate of photoliving carriers and thus improvement of the photocatalytic activity, has become a key research area. At present, photocatalysis is an effective technology to inhibit photogenerated carrier recombination, which is often studied in sewage treatment. Photoelectrochemical decomposition of water reduces the recombination of photogenerated electrons and holes by applying an external bias, thus improving the quantum efficiency for the complete mineralization of organic pollutants. The composite catalysts were used for oxygen and hydrogen extraction reactions, and a comparison of the catalysts with various loading ratios showed that the photoelectrochemical decomposition of water activity of the composite catalysts are due to pure ZnO, and the efficiency is highest when the loading ratio is 10%. This work provides new methods for the design and further optimization of the preparation of photoelectrochemical decomposition of water catalysts.

Heteroatom-doping is an effective way to regulate the electronic structure of carbon so as to improve their Na-ion storage capability. In all kinds of heteroatoms, selenium (Se)-doping has rarely been investigated even though Se has unique physicochemical properties. Herein, we report a facile fabrication of Se/N-codoped carbon nanosheets (N/Se-CNs) with 10 at% N and 2 at% Se by an oxidation-selenization process. The synchrotron X-ray photoelectron spectroscopy (XPS) measurements indicate that Se doping can significantly change the electronic structures of carbon nanosheets, because Se can act as stronger electron-withdrawing units for Na storage compared with C and N. Therefore, Se can better play the role of improving the conductivity and wettability of the carbon materials. And Se atoms effectively enlarge the interlayer distance of carbon nanosheets to enhance the Na-ion diffusion kinetics and also generate extra active sites for Na-ion storage. Served as anode materials for SIBs, the N/Se-CNs delivers higher specific capacity and better rate capability compared with only N-doped carbon nanosheets. Therefore, Se-doping is an effective way for improvement of Na-storage capability of carbon materials. Moreover, this work should provide a new pathway for design of carbons doped by heteroatoms with large atomic size towards excellent Na-ion storage.

Volatile organic compounds (VOCs) are the most harmful contaminants that have been identified, most of which are gaseous organic pollutants. In this study, TiO2@diatomite catalysts with various loading amounts of TiO2 were fabricated using a facile solvothermal method with anhydrous ethanol as a solvent for the removal of VOCs. X-ray diffraction analysis revealed that TiO2 has an anatase phase and the introduction of diatomite has no negative effect. The catalysts were characterized using scanning electron microscopy and transmittance electron microscopy techniques. The results indicate that after introducing diatomite, TiO2 nanoparticles are mostly square-like and intact, and are uniformly immobilized in the diatomite. Finally, their photocatalytic performance was investigated using liquid ultraviolet spectrometry and gas chromatography-mass spectrometry. Among the catalysts tested, 0.35TiO2@diatomite (with a mass ratio of TiO2 to diatomite of 0.35) exhibited higher photocatalytic activity than the other samples, i.e., pure TiO2 and diatomite, and could effectively remove acetone and benzene, demonstrating its potential market application and practical significance.

The design of carbon anode materials with both high gravimetric and volumetric performances is one of the main limitations in the real applications of sodium-ion batteries (SIBs). Herein, we develop novel micro/nanostructure carbon microspheres (CMSs) assembled of onion-like carbons via an in situ pyrolysis approach. When used as anode materials for SIBs, the CMSs electrode possesses a high pressing density of 1.36 g cm(-3) . The CMSs exhibit a high reversible gravimetric capacity of 275 mAh g(-1) and a reversible volumetric capacity of 374 mAh cm(-3) at 100 mA g(-1), which can be comparable to the volumetric capacity of graphite for lithium-ion batteries. At high current densities of 1, 2 and 5 A g(-1), the reversible gravimetric capacities can still be maintained at 195, 165 and 115 mAh g(-1) and the volumetric capacities can reach up to 265, 224 and 156 mAh cm(-3). Such excellent electrochemical performances should be attributed to the special spherical micro/nanostructure of CMSs, which can not only guarantee a high density, but also provide void spaces to alleviate the volume variation and enhance Na ions diffusion kinetics. Accordingly, this study proposes a new strategy for the design of carbon materials with both high gravimetric and volumetric performances. (C) 2019 Elsevier Ltd. All rights reserved.

Nitrogen-rich carbon-onion-constructed nanosheets prepared from Co–hexamine coordination frameworks exhibit high-rate and ultrastable Na- and K-ion storage capability.

Na-ion storage in graphitic carbons is a kinetically unfavorable process. It is envisioned that decreasing the size of graphitic layers can efficiently enhance Na-ion storage by shortening the diffusion pathway. However, because of the lack of model graphitic carbons, investigation on the effect of decreasing the graphitic layer size on Na-ion storage has not yet been carried out. In this work, quadrangular carbon nanotubes (q-CNTs) with herringbone-like graphitic walls are employed as model materials to exhibit the idea above. The q-CNTs show reduced dependence on the electrolytes. They deliver high capacity, excellent rate performance, and ultralong cyclic stability in both ether-based and ester-based electrolytes. Typically, the q-CNTs-600 exhibits high reversible capacities of 212 and 200 mA h g(-1) at 0.1 A g(-1) in ether-based and ester-based electrolytes, respectively. Even at 5 A g(-1), the reversible capacity of 132 mA h g(-1) can still be maintained in the ether-based electrolyte. The excellent Na-ion storage features of q-CNTs should be due to the herringbone-like graphitic walls and small graphitic layer size, which can weaken the control of electrolyte on the Na-ion diffusion kinetics by shortening the diffusion distance and providing more diffusion channels. Accordingly, these graphitic q-CNTs are expected to be promising anodes for sodium ion batteries.