Though superliquid-repelling surfaces are universally important in the fields of fundamental research and industrial production, the understanding and development of these surfaces to impacting liquid droplets remain elusive, especially the changes of wettability states. Surface roughness is required to obtain superliquid-repelling surfaces. However, the effect of surface roughness on the transition of these surfaces' wettability states is uncertain. Herein, we unveiled the relationship of surface roughness on regulating the wettability states of superliquid-repelling surfaces with randomly distributed rough structures through experiment and calculations. The roughness was controlled via regulating the size of surface rough structures, which were formed by a facile coating method. The results indicated that the surface rough structures could impact the value of the polar component (γsp) and then impact the wettability states of superliquid-repelling surfaces. Quantitatively, when the increment of surface roughness was low, the decrement of γsp was low and the wettability state of the superliquid-repelling surface was superhydrophobicity. When the increment of surface roughness was high, the decrement of γsp was high and the wettability state of the superliquid-repelling surface converted to superamphiphobicity. The findings will shed light onto the development of superliquid-repelling surfaces in future studies.
Abstract Nanocellulose derived from plant cell wall, due to its unlimited sources, is regarded as a next-generation green material for the automotive industry because of its high tensile strength (≥3 GPa), high elasticity modulus (110–220 GPa), and low density (1.6 g/cm 3 ). This study first introduces the structural characteristics, preparation techniques, and mechanical properties of nanocellulose. Then, three types of nanocellulose composites, including nanocellulose directly reinforced polymers, hybrid fiber-cellulose composites, and all cellulose composites (ACCs), are reviewed. The corresponding preparation techniques, material properties, reinforcement mechanisms of nanocellulose, and application limitations are discussed in detail. To overcome the insufficient mechanical properties of nanocellulose directly reinforced polymers and ACCs toward the manufacture of automobile structural components, self-assembly techniques prove to be effective to prepare macroscopic fibers by first aligning nanocellulose and then assembling them into continuous micro-size fibers. We reviewed different self-assembly techniques and multiscale modeling techniques of cellulose nanofibers (CNFs) assembled microfibers. Furthermore, we proposed a finite element or finite volume technique-based micromechanics framework to predict the homogenized responses of CNFs assembled microfibers, which serve as a fundamental layer to construct a multiscale modeling strategy toward CNFs assembled microfiber-based composite structures. The proposed multiscale modeling strategy is expected to greatly facilitate the development of CNFs assembled microfiber-based composite structures and significantly advance the application of nanocellulose in automotive structural applications.
Graphitic carbon nitride (g-C3N4) has attracted extensive research attention because of its virtues of a metal-free nature, feasible synthesis, and excellent properties. However, the low specific surface area and mediocre charge separation dramatically limit the practical applications of g-C3N4. Herein, porous nitrogen defective g-C3N4 (PDCN) was successfully fabricated by the integration of urea-assisted supramolecular assembly with the polymerization process. Advanced characterization results suggested that PDCN exhibited a much larger specific surface area and dramatically improved charge separation compared to bulk g-C3N4, leading to the formation of more active sites and the improvement in mass transfer. The synthesized PDCN rendered a 16-fold increase in photocatalytic tetracycline degradation efficiency compared to g-C3N4. Additionally, the hydrogen evolution rate of PDCN was 10.2 times higher than that of g-C3N4. Meanwhile, the quenching experiments and electron spin resonance (ESR) spectra suggested that the superoxide radicals and holes are the predominant reactive species for the photocatalytic degradation process. This study may inspire the new construction design of efficient g-C3N4-based visible-light photocatalysts.
Abstract Currently, conventional dimethoxymethane synthesis methods are environmentally unfriendly. Here, we report a photo-redox catalysis system to generate dimethoxymethane using a silver and tungsten co-modified blue titanium dioxide catalyst (Ag.W-BTO) by coupling CO 2 reduction and CH 3 OH oxidation under mild conditions. The Ag.W-BTO structure and its electron and hole transfer are comprehensively investigated by combining advanced characterizations and theoretical studies. Strikingly, Ag.W-BTO achieve a record photocatalytic activity of 5702.49 µmol g −1 with 92.08% dimethoxymethane selectivity in 9 h of ultraviolet-visible irradiation without sacrificial agents. Systematic isotope labeling experiments, in-situ diffuse reflectance infrared Fourier-transform analysis, and theoretical calculations reveal that the Ag and W species respectively catalyze CO 2 conversion to *CH 2 O and CH 3 OH oxidation to *CH 3 O. Subsequently, an asymmetric carbon-oxygen coupling process between these two crucial intermediates produces dimethoxymethane. This work presents a CO 2 photocatalytic reduction system for multi-carbon production to meet the objectives of sustainable economic development and carbon neutrality.
Photocatalysis plays a vital role in sustainable energy conversion and environmental remediation because of its economic, eco-friendly, and effective characteristics. Nitrogen-rich graphitic carbon nitride (g-C3N5) has received worldwide interest owing to its facile accessibility, metal-free nature, and appealing electronic band structure. This review summarizes the latest progress for g-C3N5-based photocatalysts in energy and environmental applications. It begins with the synthesis of pristine g-C3N5 materials with various topologies, followed by several engineering strategies for g-C3N5, such as elemental doping, defect engineering, and heterojunction creation. In addition, the applications in energy conversion (H2 evolution, CO2 reduction, and N2 fixation) and environmental remediation (NO purification and aqueous pollutant degradation) are discussed. Finally, a summary and some inspiring perspectives on the challenges and possibilities of g-C3N5-based materials are presented. It is believed that this review will promote the development of emerging g-C3N5-based photocatalysts for more efficiency in energy conversion and environmental remediation.
Mass transfer enhancement and crystallinity engineering are two prevailing technologies for photocatalyst modification. However, their relative effectiveness in enhancing photocatalytic activity remains unclear due to the lack of rational probing catalysts. In this study, we synthesized two distinct carbon nitride (C3N4) catalysts: one with a high specific surface area (CN-HA) and the other with improved crystallinity (CN-HC). These catalysts served as probes to compare their respective impacts on photocatalytic activities. Comprehensive characterization techniques and density functional theory (DFT) calculation results unveiled that crystallinity played a dominant role in light absorption and charge dynamics, while surface area primarily influenced mass transfer in photocatalysis. Importantly, our findings revealed that crystallinity engineering of photocatalyst achieved a greater impact on photocatalytic hydrogen evolution than that from mass transfer enhancement. Consequently, CN-HC demonstrated a remarkable improvement in photocatalytic performance for hydrogen evolution (6465.4 μmol h-1 g-1), surpassing both C3N4 and CN-HA by 19.4- and 2.4-fold, respectively, accompanied by a high apparent quantum yield of 23.8 % at 420 nm. This study not only unveils the dominant factor influencing the activity of photocatalysts but also provides a modified approach for robust solar fuel production, shedding light on the path toward efficient and sustainable energy conversion.
Abstract Photocatalytic technology based on carbon nitride (C 3 N 4 ) offers a sustainable and clean approach for hydrogen peroxide (H 2 O 2 ) production, but the yield is severely limited by the sluggish hot carriers due to the weak internal electric field. In this study, a novel approach is devised by fragmenting bulk C 3 N 4 into smaller pieces (CN‐NH 4 ) and then subjecting it to a directed healing process to create multiple order‐disorder interfaces (CN‐NH 4 ‐NaK). The resulting junctions in CN‐NH 4 ‐NaK significantly boost charge dynamics and facilitate more spatially and orderly separated redox centers. As a result, CN‐NH 4 ‐NaK demonstrates outstanding photosynthesis of H 2 O 2 via both two‐step single‐electron and one‐step double‐electron oxygen reduction pathways, achieving a remarkable yield of 16675 µmol h –1 g –1 , excellent selectivity (> 91%), and a prominent solar‐to‐chemical conversion efficiency exceeding 2.3%. These remarkable results surpass pristine C 3 N 4 by 158 times and outperform previously reported C 3 N 4 ‐based photocatalysts. This work represents a significant advancement in catalyst design and modification technology, inspiring the development of more efficient metal‐free photocatalysts for the synthesis of highly valued fuels.
Solar energy‐induced catalysis has been attracting intensive interests and its quantum efficiencies in plasmon‐mediated photothermal catalysis (P‐photothermal catalysis) and external heat‐coupled photocatalysis (E‐photothermal catalysis) are ultimately determined by the catalyst structure for photo‐induced energetic hot carriers. Herein, different catalysts of supported (TiO 2 ‐P25 and Al 2 O 3 ) platinum quantum dots are employed in photo, thermal, and photothermal catalytic dry reforming of methane. Integrated experimental and computational results unveil different active sites (hot zones) on the two catalysts for photo, thermal, and photothermal catalysis. The hot zones of P‐photothermal catalysis are identified to be the metal–support interface on Pt/P25 and the Pt surface on Pt/Al 2 O 3 , respectively. However, a change of the active site to the Pt surface on Pt/P25 is for the first time observed in E‐photothermal catalysis (external heating temperature of 700 °C). The hot zones contribute to the significant enhancements in photothermal catalytic reactivity against thermocatalysis. This study helps to understand the reaction mechanism of photothermal catalysis to exploit efficient catalysts for solar energy utilization and fossil fuels upgrading.
Traditional approaches to synthesizing bismuth nanoparticle decorated carbon nitride (C3N4) materials suffer from the complex synthesis process and the addition of a surfactant, which is not conducive to environmental protection. To address these problems, we adopted a simple and green flux-assisted approach for the first time to fabricate metallic bismuth nanoparticle decorated C3N4 (BiCCN). Electron microscopy results suggested that bismuth vanadate was converted into small bismuth nanoparticles via the flux-assisted approach. Highly dispersed Bi nanoparticles dramatically intensify light absorption, facilitate spatial charge separation as electron acceptors, shorten the charge diffusion length, and reserve more active sites for generating reactive species via surface photo-redox reactions. Consequently, the derived optimized photocatalyst BiCCN-15 rendered around 26 times higher photocatalytic degradation efficiency toward an endocrine disrupting compound (bisphenol A) than C3N4. This work provides a novel approach for developing non-precious metal decorated photocatalytic materials for sustainable water decontamination.
Photoreforming of lignin has been explored as a fascinating technology to generate clean hydrogen energy and value-added aromatic monomers from biomass. However, its upscaling is impeded by unsatisfactory selectivity due to the lack of mechanistic investigations in the uncontrollable reaction pathways. Herein, we successfully controlled the concentration and position of sulfur vacancies within the ultrathin ZnIn2S4 nanosheets to optimize the photo-driven lignin model reforming process. The competition of proton transfer between the hydrogen evolution and dissociation of the β-O-4 linkage in the model compound of lignin was identified, and the modulation of the proton migration pathway was realized through S vacancy engineering in ZnIn2S4 nanosheets toward target products. As such, excellent selectivity for hydrogen and chemical monomers was achieved with a high concentration of S vacancies in the bulk and on the surface of ZnIn2S4, respectively. This study endows new mechanistic insights into the biomass photoreforming process and elucidates the structure/chemistry-catalysis correlation of ZnIn2S4 photocatalysts, which are beneficial for photocatalyst design and rational solar fuel production.
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