Hydrophilic Modification of Polylactic Acid Fiber and the Usage of Natural Dye for Multi-Levered Improvement of the Fabric Staining Depth and the Stability Effect

Polylactic acid (PLA) fiber is a degradable material with good environmental friendliness for textile applications. However, the main problems of difficult dyeing of PLA fibers were: high crystallinity to the adsorption of dyes, more ester and methyl groups producing non-hydrophilic problems, long chains making dyes difficult to penetrate, and producing a low dyeing rate. Here, we attempted to change the crystallinity of the PLA fiber to a lower degree from hydrophobic to hydrophilicity property variation, destroy the long chain structure to grant more staining sites, and improve the PLA fiber staining depth and the resilience dyeing effect with deep eutectic solvent (DES) treatment and natural dyes. We discovered that a controlled DES treatment process could make PLA fibers less crystallized, help amorphous areas form, and break up long chains, which lead to more dye sites. After DES treatment, the crystallinity decreased from 56.12 to 29.86%, and the instantaneous water contact angle decreased from 108.79 to 64.39°. The DES-treated PLA fabric exhibited a higher K/S value of 15.14 for natural dyes under specific conditions. The fabric, which had remarkable fastness characteristics and wash resistance, could endure frequent laundering and fulfill the demands of everyday use. Moreover, the fabric had good antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans and possessed a certain level of biocompatibility with fibroblasts. This DES treatment and natural dye combination method offered a new strategy for improving PLA fabric staining depth and color fastness, making it a promising option for low-carbon environmental protection in the textile industry

Effect of Bulk Hydrogen on the Photocatalytic Activity of Semiconducting Ta₃N₅: A Hybrid-DFT Viewpoint

Ta3N5 is a promising candidate for photocatalytic water splitting. Hydrogen impurities are always introduced into the Ta3N5 lattice during ammonolysis of TaOx precursors. Limited attention has been paid to the effect of hydrogen impurities in Ta3N5 on photocatalytic water splitting. In this study, the feasible configurations of hydrogen impurities in Ta3N5 and their effect on Ta3N5-based photocatalytic water splitting are theoretically investigated. Hybrid-DFT (density functional theory) calculations for hydrogen-doped Ta3N5 show that hydrogen impurities are probably introduced into Ta3N5 as interstitial defects due to low formation energy of interstitial hydrogen-doped Ta3N5. Hydrogen in Ta3N5 leads to a significant positive shift (vs RHE) in the band edge positions of Ta3N5, which can undermine the energetics for water reduction and increase the onset potential for water oxidation. Hydrogen impurities also act as shallow level donors, which can compensate for acceptors and aggravate the band edge engineering to realize beneficial energetics for Ta3N5

Study on the Ambient Temperature as an Important but Easily Neglected Factor in the Process of Preparing Photovoltaic All-Inorganic CsPbIBr₂ Perovskite Film by the Elegant Solvent-Controlled Growth Strategy

All-inorganic CsPbIBr2 perovskite has received extensive attention in the field of solar cells due to its good wet and thermal stability as well as a moderate band gap. In the preparation of CsPbIBr2 film by one-step spin-coating method, the amount of dimethyl sulfoxide solvent remaining in the precursor film has a great influence on the process of film growth. Therefore, it is necessary to ensure that an appropriate amount of solvent exists in the precursor film before annealing. Herein, we adopted the solvent-controlled growth (SCG) strategy, that is, standing by the precursor films in the nitrogen glovebox for a period of time before annealing, to make sure that excess solvent can be evaporated from the precursor film. In this work, we found that the ambient temperature is an important but easily neglected factor in the process of preparing CsPbIBr2 film by the SCG strategy. When the ambient temperature is 20 °C, SCG treatment is required to obtain a flat and dense CsPbIBr2 film. However, SCG treatment is not essential at 30 °C. The ambient temperature has an impact on the evaporation rate of the solvent in the precursor film, and thus affects the effect of the SCG strategy. This work highlights that, when preparing CsPbIBr2 film by a one-step spin-coating method, in order to obtain a high-quality CsPbIBr2 film, the influence of ambient temperature on solvent-controlled growth strategy should be considered

Probing the Performance Limitations in Thin-Film FeVO₄ Photoanodes for Solar Water Splitting

FeVO₄ is a potentially promising n-type multimetal oxide semiconductor for photoelectrochemical water splitting based on its favorable optical band gap of ca. 2.06 eV that allows for the absorption of visible light up to around 600 nm. However, the presently demonstrated photocurrent values on FeVO₄ photoanodes are yet considerably low when comparing with α-Fe₂O₃, although FeVO₄ can absorb comparable wavelengths of sunlight as α-Fe₂O₃. Donor-type doping and constructing nanoporous film morphology have afforded desirable (but far from satisfactory) improvements in FeVO₄ photoanodes, whereas the fundamental properties, such as absorption coefficients and the nature of optical transition, and a quantitative analysis of the efficiency losses for FeVO₄ photoanodes remain elusive. In the present study, we conduct a thorough experimental analysis of structural, optical, charge transport, and surface catalysis properties of FeVO₄ thin films to investigate and clarify how and where the efficiency losses occur. Based on the results, the charge recombination pathways and light-harvesting loss in FeVO₄ thin-film photoanodes are identified and quantitatively determined. Our study will deepen the understanding on the photoelectrochemical behaviors of FeVO₄ photoanodes and will also shed light on the optimization routes to engineer this material to approach its theoretical maximum

Hollow Mesoporous Co(PO₃)₂@Carbon Polyhedra as High Performance Anode Materials for Lithium Ion Batteries

The hollow mesoporous Co­(PO3)2@carbon nanocomposite (H–Co­(PO3)2@C) was synthesized using ZIF-67 as the template by a facile one-step thermal decomposition reaction. As an anode for lithium ion batteries, its reversible capacity remains up to 601 mAh g–1 at 1 C after 500 cycles. Such a high reversible capacity along with the excellent rate capability and long-term cycling stability benefits from the hollow mesoporous structure and uniform carbon framework encapsulated active nanocrystals. These results render the as-prepared H–Co­(PO3)2@C to be a promising anode material for high performance lithium ion batteries

Band Structure Engineering of Carbon Nitride: In Search of a Polymer Photocatalyst with High Photooxidation Property

The electronic band structure of a semiconductor photocatalyst intrinsically controls its level of conduction band (CB) and valence band (VB) and, thus, influences its activity for different photocatalytic reactions. Here, we report a simple bottom-up strategy to rationally tune the band structure of graphitic carbon nitride (g-C₃N₄). By incorporating electron-deficient pyromellitic dianhydride (PMDA) monomer into the network of g-C₃N₄, the VB position can be largely decreased and, thus, gives a strong photooxidation capability. Consequently, the modified photocatalyst shows preferential activity for water oxidation over water reduction in comparison with g-C₃N₄. More strikingly, the active species involved in the photodegradation of methyl orange switches from photogenerated electrons to holes after band structure engineering. This work may provide guidance on designing efficient polymer photocatalysts with the desirable electronic structure for specific photoreactions

Ultrathin and Conformal TiO_<i>x</i> Overlayers on WO₃ Photoelectrodes for Simultaneous Surface Trap Passivation and Heterojunction Formation

Nanoporous structures facilitate the exposure of active sites and allow a high ratio of the space charge region to the bulk in water-splitting photoelectrodes. However, unfavorable surface defects may develop on nanoporous photoelectrodes, which deteriorate the band bending (built-in electric field) and trigger serious charge carrier recombination. To maximize the advantages of nanoporous structures in photoelectrodes, one common strategy is the introduction of ultrathin overlayers to passivate undesirable surface defects and traps, which usually require advanced deposition technologies such as atomic layer deposition. In this study, a process of drop-casting followed by O2 plasma treatment is employed to realize ultrathin and conformal TiOx overlayers on WO3 photoelectrodes. Notably, the ultrathin TiOx overlayer demonstrates dual effects of surface trap passivation and heterojunction formation on WO3 photoelectrodes, which result in suppressed surface charge recombination and enhanced band bending. The as-derived TiOx-modified WO3 photoanode shows an increase in water-splitting photocurrent (increased by 81% at 1.6 V vs the reversible hydrogen electrode), along with a 160 mV cathodic shift in photocurrent onset potential. The proposed approach here provides valuable insights into the room-temperature fabrication of uniform and ultrathin overlayers for nanostructure modification

Spatial Decoupling of Redox Chemistry for Efficient and Highly Selective Amine Photoconversion to Imines

Light-driven primary amine oxidation to imines integrated with H2 production presents a promising means to simultaneous production of high-value-added fine chemicals and clean fuels. Yet, the effectiveness of this strategy is generally limited by the poor charge separation of photocatalysts and uncontrolled hydrogenation of imines to secondary amines. Herein, a spatial decoupling strategy is proposed to isolate redox chemistry at distinct sites of photocatalysts, and CoP core–ZnIn2S4 shell (CoP@ZnIn2S4) coaxial nanorods are assembled as the proof-of-concept photocatalyst. Directional and ultrafast carrier separation occurs between the CoP core and the ZnIn2S4 shell, as confirmed by in situ X-ray photoelectron spectroscopy, surface photovoltage spectroscopy, and transient absorption spectroscopy analyses. Toward the photoconversion of model substrate benzylamine to N-benzylbenzaldimine, CoP@ZnIn2S4 exhibits a 48-time higher production rate and >99% selectivity when compared to ZnIn2S4 (ca. 20% selectivity), and the detailed reaction mechanism has been verified by in situ diffuse reflectance infrared Fourier transform spectroscopy

Band-Edge Electronic Structure on Photo(electro)catalytic Performance of ABO₂ (A = Cu, Ag; B = Al, Ga, In): Elucidating the Role of Valence Electron States

A profound understanding of the band-edge electronic structure is crucial for advancing the development of highly efficient photocatalytic materials and unraveling the underlying mechanisms. This study employs a unified and consistent assessment protocol, offering a systematic exploration of the inherent connections between the band-edge electronic structure and the photo(electro)catalytic performance of a series of delafossite ABO2 compounds (A = Cu, Ag; B = Al, Ga, In). These compounds exhibit characteristics of indirect bandgap semiconductors, with fundamental and optical bandgaps spanning from 1.45 to 3.57 eV. Notably, the Cu-based ABO2 compounds display a significantly larger fundamental bandgap and excel as photocathode materials when the B-site element is held constant. Among these, CuInO2 emerges as the most promising candidate, showcasing superior photo(electro)catalytic performance. Extensive density functional theory calculations unravel intricate insights into the interplay between the band-edge electronic structure and valence orbital hybridization of the A- and B-site elements, providing invaluable perspectives for comprehending and enhancing the photo(electro)catalytic performance of such compounds. The findings in this study not only establish robust theoretical foundations for integrating ABO2 compounds into the field of photo(electro)catalysis but also lay the groundwork for future material design and optimization

Polar Bear Hair Inspired Supra-Photothermal Promoted Water Splitting

The photothermal effect has recently been applied to oxygen evolution reaction (OER) electrodes, which can effectively convert solar energy into heat to promote the reaction kinetics. However, optimized materials that can more efficiently collect and utilize solar energy are demanded. Here, inspired by the thermal insulation ability of polar bear hairs, we fabricated a villous carbon frameworks (VCF) embedded with FeNi3 alloys. Under illumination, the achieved local temperature surpassed the bare carbon frameworks (CF). This highly promoted the OER performance of the inner electrocatalysts. With light illumination intensity of 0.25 W cm–2, the VCF demonstrated an overpotential of 194 mV to deliver 100 mA cm–2 current density. The current density at 1.45 V could reach over 300 mA cm–2, about 8.5-fold of that without illumination, outperforming traditional photothermal electrocatalysts. Meanwhile, quasi-operando soft X-ray absorption spectroscopy (SXAS) manifested that the photothermal effect of the VCF would boost the electron rearrangement of iron–nickel species during OER and optimize the adsorption of oxygen intermediates. Our design principle was transferable to other catalysts whose performance could be accelerated by the photothermal effect