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Solar-powered volatile organic compound oxidation attracts interest, but its efficiency suffers from poor utilization of photogenerated electrons. Oxygen can capture the electrons and convert them into superoxide radicals upon being activated. As a unique oxygen-deficiency oxide, WO2 chemisorbs and activates oxygen and functions as a potential cocatalyst for improving the utilization of charge carriers. Here, we report a WO2/SnS2 composite photocatalyst with SnS2 nanosheets vertically growing out of WO2 nanofibers. In situ X-ray photoelectron spectroscopy and density functional theory calculations suggest the electron transfer from WO2 to SnS2, creating an internal electric field (IEF) at the interfaces with a direction pointing from WO2 to SnS2. The IEF promotes spatial charge separation by driving photogenerated electrons in SnS2 to move to WO2, while photogenerated holes remain immobile. WO2 shows a strong affinity for oxygen-containing species and chemisorbs O2 and H2O molecules in a dissociative way, significantly reducing the kinetic barriers for the production of reactive oxygen species (•OH and •O2–). Under visible light irradiation, the WS30 nanofibers exhibit enhanced photocatalytic degradation of HCHO and CH3COCH3, 4.8 and 7.2 times greater than that of pristine SnS2, respectively. The enhanced performance is attributed to the one-dimensional fibrous nanostructures, robust chemisorption of reactants, and IEF-driven charge separation. This work may inspire efforts to develop higher oxygen-affinity photocatalysts for photodegradation. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation technology can mineralize hazardous volatile organic compounds (VOCs), but the poor photocatalytic oxidation activity limits its practical application. Here we develop Cu‐doped WO3 electrospun nanofibers through a non‐equivalent doping strategy. The Cu dopant prefers substituting five‐coordinated W atoms atop the WO3 matrix, inducing strong dopant/matrix interaction (SDMI) effect and prominent charge rearrangement. A localized electric field (LEF) forms pointing from positively charged WO3 matrix to negatively charged Cu dopant, which triggers efficient photoexcited charge separation. Further, the Cu dopant promoted the production of ⋅OH radicals and thereby enhanced VOCs photodegradation. The 0.7 % Cu‐doped WO3 nanofibers show optimal photocatalytic oxidation performance towards formaldehyde and acetone, 5.5 and 4.8 times higher than pristine WO3 nanofibers, respectively. This work highlights the role of dopant‐induced LEF on the charge carriers separation and might shed light on developing more efficient photocatalysts with non‐equivalent dopants. [ABSTRACT FROM AUTHOR]

Chitosan-based carbon materials have attracted great attention in electrochemical energy storage. Introducing iron metal or iron compounds into carbon materials favors to boost their electrochemical performance. Herein, chitosan-based graphitic carbon@Fe3C composites (CSGC@Fe3C) have been prepared as anode materials for lithium ion battery by a simple pyrolysis method. By manipulating the temperature higher than 700 °C, pure Fe3C encapsulated in chitosan-based graphitic carbon with different mass ratio from 30 to 53.8 wt% can be achieved. The resulting CSGC@Fe3C composites retain porous carbon sheet structure embedded with a large amount of Fe3C nanoparticles in size from 20 to 300 nm. The electrochemical measurements demonstrate CSGC@Fe3C with 53.8 wt% Fe3C as anode material for lithium ion battery can provide a highest reversible capacity of 423 mAh g−1 at 0.1 A g−1 over 100 charge/discharge cycles and stable cycling capacity of 195 mAh g−1 at a high current density of 2 A g−1 during 200 cycles. The catalysis of Fe3C on the reversible formation and decomposition of solid electrolyte interphase (SEI) has been corroborated and results in the improvement of surface capacitive contribution. This work provides a basic insight into metal carbides constructing biomass-based carbon anode materials to realize high-performance electrochemical energy storage device. [ABSTRACT FROM AUTHOR]

To improve the performance of an array-based sensing system, a novel one-pot method was designed to prepare multi-optical signal channel gold nanoclusters (MS-AuNCs), including chemiluminescence (CL) and fluorescence (FL). And multi parameters were extracted from the CL and FL spectra of MS-AuNCs to realize the excellent performance of sensing arrays for heavy metal ion differentiation. In this synthetic strategy, 11-mercaptoundecanoic acid (MUA) was used as the capping agent to form Au(I)–thiol complexes first. Then luminol was introduced as a reductant to reduce the Au(I)–thiol complexes and as a chemiluminescent reagent to form MS-AuNCs. Compared with previous methods for preparing luminescent functionalized nanoparticles, the proposed method could obtain functionalized nanoparticles with multi-optical signal channels in one step and is much simple. The obtained MS-AuNCs exhibited excellent CL performance when reacting with hydrogen dioxide. The peak position of the MS-AuNCs FL emission spectra does not shift as increasing excitation wavelengths. The bright orange FL of MS-AuNCs was strong enough to be seen with naked eye. Based on five parameters extracted from the CL and FL spectra of MS-AuNCs, one sensing array was developed for distinguishing heavy metal ions. The sensing strategy could differentiate seven heavy metal ions with different concentrations, including Al3+, Co2+, Cr3+, Cu2+, Hg2+, Pb2+ and Zn2+. Moreover, novel multi-optical signal channel gold nanoclusters were obtained for the first time in this work, which may find more promising applications in fields such as bioassays and bioimaging. [ABSTRACT FROM AUTHOR]

Conversion of biomass waste into nitrogen‐doped porous carbon has been considered as a promising approach to achieve energy storage materials. Nitrogen‐doped activated carbon materials have been successfully prepared by molten salt pyrolysis (MSP) using melamine modified‐denim fabric waste as precursor. The molten salt medium provides liquid condition to carbonize and activate the denim fabric waste. Melamine produces a large amount of nitrogen element for doping the carbon materials. The obtained nitrogen‐doped denim fabric‐based carbon materials (NDFC‐MSP) are composed of small fibrous fragment and thin sheet, and exhibit a high specific surface area (1975.2 m2⋅g−1) and high pore volume (1.087 cm3⋅g−1). Moreover, NDFC‐MSP sample with a high nitrogen content of 6.93 wt.% possesses a maximum specific capacitance of 345.8 F⋅g−1 at 0.25 A⋅g−1 in 6 M KOH electrolyte. It also displays a high specific capacitance of 230 F⋅g−1 at 10 A⋅g−1. The cycle stability shows 95.5% retention after 5000 charge‐discharge cycles at 1 A⋅g−1. In addition, the fabricated symmetric NDFC‐MSP supercapacitor with a wide voltage range of 1.8 V generates a maximum energy density of 17.0 Wh⋅kg−1 at power density of 225 W kg−1 in 1 M Na2SO4 aqueous electrolyte. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti 3 C 2 /Pd was designed for efficient catalytic transfer hydrogenation of nitrobenzene. • Experimental and DFT theoretical studies unravel unique catalytic mechanism. • Electron transfer at Ti 3 C 2 /Pd interfaces changes Pd electron configure (4 d 10 → 4 d 10-x). • Electron-deficient Pd boosts formic acid dissociation for atomic H* production. • Ti 3 C 2 /Pd chemisorbs active H* and inhibits undesirable H 2 evolution. Catalytic transfer hydrogenation (CTH) with formic acid attracts much interest in catalysis, but the sluggish H* production and undesirable H 2 evolution reaction (HER) limit its practical applications. Herein we anchored Pd nanoparticles (NPs) on layered Ti 3 C 2 MXene for efficient and selective CTH of nitrobenzene in the presence of formic acid. Some electrons in Pd NPs transferred to Ti 3 C 2 MXene upon formation of Ti 3 C 2 /Pd nanohybrids, as confirmed by XPS and DFT simulations. The electron transfer changed Pd valance electron configuration from 4 d 10 to 4 d 10-x. Such electron-deficient Pd NPs tuned reaction pathway and promoted formic acid dissociation, both of which favored the production of active H* atoms, i.e., the exact reductant for CTH. Compared with Pd NPs, Ti 3 C 2 /Pd showed stronger adsorption of H* and therefore inhibited the occurrence of HER (2H*→H 2). Owing to favorable H* production and HER inhibition, Ti 3 C 2 /Pd (15 wt% Pd) showed enhanced nitrobenzene CTH performance with turnover frequency of 351.7 h−1 and 99% aniline selectivity, outperforming most of current catalysts. Our work might inspire designing more advanced CTH catalysts by tuning their valance electron configurations with 2D MXene materials. [ABSTRACT FROM AUTHOR]