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Exploring high efficiency S‐scheme heterojunction photocatalysts with strong redox ability for removing volatile organic compounds from the air is of great interest and importance. However, how to predict and regulate the transport of photogenerated carriers in heterojunctions is a great challenge. Here, density functional theory calculations were first used to successfully predict the formation of a CdS quantum dots/InVO4 atomic‐layer (110)/(110) facet S‐scheme heterojunction. Subsequently, a CdS quantum dots/InVO4 atomic‐layer was synthesized by in‐situ loading of CdS quantum dots with (110) facets onto the (110) facets of InVO4 atomic‐layer. As a result of the deliberately constructed built‐in electric field between the adjoining facets, we obtain a remarkably enhanced photocatalytic degradation rate for ethylene. This rate is 13.8 times that of pure CdS and 13.2 times that of pure InVO4. In‐situ irradiated X‐ray photoelectron spectroscopy, photoluminescence and time‐resolved photoluminescence measurements were carried out. These experiments validate that the built‐in electric field enhanced the dissociation of photoexcited excitons and the separation of free charge carriers, and results in the formation of S‐scheme charge transfer pathways. The reaction mechanism of the photocatalytic C2H4 oxidation is investigated by in‐situ electron paramagnetic resonance. This work provides a mechanistic insight into the construction and optimization of semiconductor heterojunction photocatalysts for application to environmental remediation. [ABSTRACT FROM AUTHOR]

Transition metal oxides, especially bimetal oxides, are considered as one of the most promising anode materials for high‐performance lithium‐ion batteries (LIBs) due to their ultra‐high theoretical capacity. However, it is difficult to achieve fast charging at high rates due to the issues of poor electrical conductivity, large volume expansion, and poor reaction kinetics. The design of advanced nanostructured anode materials is very important to boost lithium storage performance. Herein, the multi‐hierarchical heterostructure material NiCo2O4/ZnCo2O4/Carbon Cloth (NCO/ZCO/CC) including carbon cloth substrate, ZnCo2O4 nanosheets, and NiCo2O4 nanowires is prepared as a binder‐free anode for LIBs. Benefiting from the special hierarchical nanostructure and the synergistic interaction of the component, the as‐prepared NCO/ZCO/CC anode material exhibits good electrical conductivity, structural stability, and electrochemical kinetics, which can provide a high reversible areal capacity of 2.55 mAh cm−2 at 2 mA cm−2 after 200 cycles. At a high current density of 5 mA cm−2, the NCO/ZCO/CC electrode only takes about 20 min to fully charge and it can still reach a capacity of 1.50 mAh cm−2 with a capacity retention of 86.2% after 400 cycles, revealing the potential for fast charging at high rates. [ABSTRACT FROM AUTHOR]

Metal oxide semiconductor hetero- and homojunctions are commonly constructed to improve the performance of hydrogen sensors at room temperature. In this study, a simple two-step hydrothermal method was employed to prepare TiO2 films with homojunctions of rutile and anatase phases (denoted as TiO2-R/A). Then, the microstructure of anatase-phase TiO2 was altered by controlling the amount of hydrochloric acid to realize a more favorable porous structure for charge transport and a larger surface area for contact with H2. The sensor used a Pt interdigital electrode. At an optimal HCl dosage (25 mL), anatase-phase TiO2 uniformly covered rutile-phase TiO2 nanorods, resulting in a greater response to H2 at 2500 ppm compared with that of a rutile TiO2 nanorod sensor by a factor of 1153. The response time was 21 s, mainly because the homojunction formed by the TiO2 rutile and anatase phases increased the synergistic effect of the charge transfer and potential barrier between the two phases, resulting in the formation of more superoxide (O2−) free radicals on the surface. Furthermore, the porous structure increased the surface area for H2 adsorption. The TiO2-R/A-based sensor exhibited high selectivity, long-term stability, and a fast response. This study provides new insights into the design of commercially competitive hydrogen sensors. [ABSTRACT FROM AUTHOR]

Low electronic conductivity and large volume changes during the (de)lithiation process are the two main challenges for ZnO anode materials used for lithium‐ion batteries (LIB). Here, a free‐standing, flexible, and binder‐free LIB electrode composed of ZnO nanorods and carbon cloth (CC) is fabricated. This is then decorated with Ag nanoparticles and finally coated by an amorphous carbon layer to form the hybrid electrode: (C@(Ag&ZnO)). The voids among the nanorods are sufficient to accommodate the volume expansion of the ZnO while the flexible CC, which acts as the current collector, relieves the volume change‐induced stress. The Ag nanoparticles are effective in improving the conductivity. This composite electrode shows excellent LIB performance with a stable long cycling life over 500 cycles with a reversible capacity of 1093 mAh g−1 at a current density of 200 mA g−1. It also shows good rate performance with reversible capacity of 517 mAh g−1 under a high‐current density of 5000 mA g−1. In situ Raman spectroscopy is conducted to investigate the contributions of the amorphous carbon layer to the capacity of the whole electrode and the synergy between the CC and ZnO nanorods. [ABSTRACT FROM AUTHOR]

It is of particular significance to unveil the authentic coloration mechanism of the multivalent praseodymium colored ZrSiO4 yellow pigments for advanced decoration applications. We herein adopted a facile strategy to modulate the fluorine‐assisted zircon crystallization and thereby obtained ultrafine Pr‐ZrSiO4 yellow pigments, which have a remarkably narrow size distribution and average diameters within 250–400 nm. By virtue of some cogent combinative spectra of reflection, absorption, excitation, and emission from three types of elaborately‐designed H2‐, air‐, and O2‐based pigments, the coloration mechanism for the Pr‐colored zircon was systematically unveiled: both Pr4+ and Pr3+ coexist invariably in the pigments, while the former contributes primarily to the ligand‐to‐metal charge transfer from O2p to Pr(IV)4f for the blue–violet absorption to generate the yellow hue, and the latter is inclined to discolor the pigments. Therefore, an oxidizing atmosphere is preferable to produce brilliant Pr‐ZrSiO4 pigments with enhanced chromatic properties. The stark spectroscopic distinctions between the wide‐band absorption from the nonluminescent tetravalency and the narrow‐band absorption from the luminescent trivalency can expand our understanding to the rare‐earth‐based inorganic pigments. [ABSTRACT FROM AUTHOR]

The use of heterojunctions is a promising solution to the problem of cross‐sensitivity in gas sensors. In this work, a carbon monoxide sensor based on the CuO/TiO2 heterojunction was designed and fabricated. Due to the good adsorption properties of CuO materials to CO, and the heterojunction interface charge transfer, the CuO/TiO2 thin film sensor exhibits high sensitivity to CO at room temperature. The response is as high as 10.8–200 ppm CO, about 10 times its response to H2. Interference from H2 is greatly reduced by optimizing the structure of the CuO/TiO2 heterojunction. This reliable detection of carbon monoxide with excellent discrimination against H2 is of great significance for the development of CO gas sensors. [ABSTRACT FROM AUTHOR]