查看更多>>摘要：Photo/electrochemical fixation of atmospheric nitrogen (N2) into valuable chemicals is a favorable strategy to utilize the abundant natural resources for efficient catalysis. It is extremely desirable to discover immensely active, durable, and selective catalysts for effective photoelectrochemical N2 fixation. Herein, low-cost, non-noble metal-based porous Mo-doped WO3@CdS hollow microspheres as hierarchical heterostructures were synthesized that can effectively catalyze and reduce the gaseous N2 into ammonia (NH3). High Faradaic efficiency (36.72%) and fast average ammonia yield rate (38.99 μg h~(-1) mg_(cat)~(-1)) were observed at -0.3 V vs. RHE in the neutral solution at ambient conditions. Mo-doping and interconnected porous he tero structures synergistically deliver sufficient catalytic sites for effective photoelectrocatalytic N2 reduction. Furthermore, density functional theory (DFT) calculations validate that the Mo-doping WO3 is advantageous to decrease the energy barrier for N2 activation and protonation. Therefore, this work demonstrates the rational construction of transition metals-based hierarchical hollow photoelectrocatalysts towards efficient artificial N2 fixation.
查看更多>>摘要：The separation of photocarriers (e~- and h~-+) is of critical importance in initiating efficient catalytic reactions over semiconductor-based photocatalysts. Although heterostructures have been frequently built to separate photocarriers, the lack of proper heterogeneous interfaces greatly limits their efficacies. Here, we show that excellent heterogeneous interfaces can be built for in situ fabricated Ta3N5 @CaTaO2N heterostructures. These interfaces are characterized by perfectly matching (020) crystal facets of Ta3N5 and CaTaO2N, offering ideal channels for charge transportation. As revealed by both experimental and theoretical analysis, these seamless interfaces enable rapid spatial photocarrier separation, which in turn, contribute to exceptional photocatalytic activity. Under optimal conditions, Ta3N5 @CaTaO2N heterostructures achieve apparent quantum efficiency as high as 14.52% at 420 ± 20 nm for O2-evolution, substantially surpassing Ta3N5, CaTaO2N, and their mixtures. These results not only justify the importance of heterogeneous interfaces for photocarrier separation but also invigorate more attention upon heterostructures towards efficient solar water splitting.
查看更多>>摘要：Nickel-iron layer double hydroxide (NiFe LDH) is deemed as an attractive pre-catalyst to lower the reaction barrier of oxygen evolution reaction (OER). However, the catalytic efficiency of NiFe LDH is always hampered by the slow and incomplete reconstruction during OER process. Herein, a strategy of borate ion (BO3~(3-)) regulation is developed to achieve a fast and adequate reconstruction of NiFe LDH. The BO3~(3-) is easv to fill the oxv gen vacancy in NiFe LDH, which can narrow the band gap of NiFe LDH to realize an efficient reconstruction under OER conditions. DFT calculations demonstrate the enhanced effect of BO3~(3-) on adsorption of hydroxyl ion (OH~-) to further improve the OER activity. Sequentially, the BO3~(3-) decorated NiFe LDH (NiFeB) shows a desirable catalytic activity for OER with an ultralow overpotential of 201 mV to reach a current density of 10 mA cm~(-2), which is 40 mV lower than the overpotential of pure NiFe LDH. Moreover, membrane electrode assembly cell using anodic NiFeB and cathodic Pt/C for water splitting affords a cell voltage of only 2.0 V to drive a current density of 540 mA cm~(-2). This work widens the horizon of ion effect on electrocatalvsis and offers an effective approach for developing high-active electrocatalysts.
查看更多>>摘要：The low-coordinated atoms such as edges, single atoms and vacancies have been widely determined as reactive sites for catalytic oxidative desulfurization. However, the grain boundaries (GB) as a favorable atomic configuration has been ignored. In this work, a universal strategy is proposed to engineer grain boundaries into oxides via facile two-step growth. Take the W_(18)O_(49) nanowires as an example, the engineered GB can work as reactive sites to build stronger interfacial molecular interactions with dibenzothiophene (DBT) due to the low-coordinated W atoms with local electron-rich state, promoting the surface adsorption and activation performance towards DBT. Moreover, the molecular oxygen activation capacity is improved by GB to yield more superoxide radical relative to W_(18)O_(49). Benefiting from these features, the GB-W_(18)O_(49) deliver a greatly improved catalytic oxidative desulfurization behavior relative to W_(18)O_(49) nanowires, in which 97.7% DBT can be removed by GB-W_(18)O_(49) in 5 h but only 40.4% of W_(18)O_(49) nanowires.
查看更多>>摘要：The performance of CO2 methanation has critical relationships with oxygen vacancies, thus the fundamental insights of oxygen vacancies activation are of great importance. Herein, a series of Ni-based CeO2 catalysts fabricated via impregnation and electrospinning methods were employed to study the variation of CO2 methanation performance in terms of the dynamic analysis of intermediates and correlations of oxygen vacancies. The NiNPs@CeO2NF catalyst prepared by the co-electrospinning method shows superior catalytic performance with CO2 conversion of 50.6 % and 82.3 % at the low temperature of 250 °C and 300 °C, respectively, as well as excellent stability of 60 h at a high temperature of 400 °C. The achieved catalytic properties could be attributed to the confined environment and synergistic effect between Ni nanoparticles and CeO2 nanofibers. Additionally, in-situ Raman verified that nanofibers can form more active oxygen vacancies and adsorb well with CO2. In-situ DRIFTS analysis reveals that the monodentate and bridging bidentate formate were the key intermediates for CO2 methanation.
查看更多>>摘要：Herein, an electrochemical (EC) system was applied as "co-catalyst" to enhance the activation of peroxymonosulfate (EC/Fe(III)/PMS) for efficient Sulfamethoxazole (SMX) degradation. The cathodic reduction reaction can facilitate electron transfer to Fe(III) and trigger the sustainable Fe(III)/Fe(II) redox cycle. Unexpectedly, in addition to hydroxyl radical (·OH) and sulfate radical (SO4~(·-)), non-radicals mechanism including singlet oxygen ^O^ and Fe(IV) were also found involved in EC/Fe(III)/PMS system. The degradation of SMX in EC/Fe(III)/PMS system was accomplished by the collaboration of radicals and non-radicals oxidation. The generation routes and mechanisms of involved reactive oxygen species (ROS) were explored. The relative contributions of ·OH, SO4~(·-), and nonradical species for the degradation of SMX were calculated to 4.75 %, 25.31 %, and 69.94 %, respectively. Besides, multiple degradation pathways of SMX were proposed by identifying the formed byproducts. The EC/Fe(III)/PMS process could efficiently degrade SMX under the influence of co-existing ions and inactivate pathogens in the wastewater.
查看更多>>摘要：This study theoretically and experimentally investigates the piezocatalytic and adsorption effects of different phases of polymorphic 1T MoS2 NFs. Piezoresponse force microscopy indicates a considerably high piezoelectric potential (piezopotential) at the few-layer 2H MoS2 NFs (40 mV), which is eight times higher than that at the few-layer MoS2 NFs (4.9 mV). This finding is confirmed by calculations based on density functional theory (DFT) and the finite element method (FEM). To verify whether the polymorphic MoS2 NFs would exhibit adsorption or piezocatalytic effects, the electrostatic surface charge of these NFs and the RhB solution is varied using sodium hydroxide and nitric acid solutions. The cationic dye is adsorbed on the surfaces of the 1T MoS2 NFs; however, the few-layer 2H MoS2 NFs generate a considerable quantity of hydroxyl species for degrading RhB molecules through the mechanical-force-induces piezopotential. This study discovers that the polymorphic MoS2 NFs exhibit a piezocatalysis-adsorption duality.
查看更多>>摘要：Development of new technologies for conversion of biomass-based compounds into energy sources and basic chemicals is important for a circular economy. In this study, a unique solar driven catalysis system is developed to convert cellulose into lactic acid (LA) using Cu modified natural palygorskite (Pal) catalyst. Adequate Cu incorporation reframes Pal with a reduced band gap. As the mass ratio of Cu goes beyond 6 wt%, extra Cu2O quantum dots (QDs) assemble in situ on the Cu-Pal surface and form Cu2O/Cu-Pal heterostructure, which effectively promotes the charge transfer and exposes abundant Lewis acid sites for synergistic adsorption and conversion of intermediates. Notably, the colloidal character of the Cu-Pal substrate enables intimate adsorption of catenulate cellulose. The 10 wt% Cu2O QDs/Cu-Pal nanocomposite exhibits remarkable photocatalytic LA selectivity under visible light. Time-resolved in-situ attenuated total reflectance infrared (ATR-IR) spectroscopy and the density functional theory calculation (DFT) are employed to help elucidate the photocatalytic mechanism. Both theoretical and experimental studies demonstrate that such a Cu-modified mineral catalyzes a series of tandem reactions for LA formation, including the precise cleavage of β-1,4-glycosidic bonds of cellulose into glucose, selective cleavage of the C3 -C4 bond of glucose to C3 intermediates via photogenerated holes, and the selective conversion of C3 into LA. Our findings provide a new potential sustainable alternative for biomass valorization.
查看更多>>摘要：Sluggish charge kinetics and NO diffusion largely restrict the photocatalytic efficiency of low-dose NO removal by layered carbon nitride (CN). Herein, a novel poly(heptazine imide)-based CN (CN-NaLi) with enlarged interlayer spacing was fabricated by an easy, efficient and unique molten-salt approach. The charge flows induced by the poly(heptazine imide) structure can be delocalized/separated/transferred, resulting in a significantly boosted efficiency of charge kinetics. The enlarged interlayers distance of CN-NaLi reduced the charge-recombination probability and promoted NO diffusion/adsorption/activation. Accordingly, abundant separated light-induced electrons can be supplied to react and activate the O2 molecules. Meanwhile, large amounts of adsorbed NO were fixed and converted into the intermediate product during the same time compared with unmodified CN. The reduced energy barrier endowed CN-NaLi with superior visible-light-driven performance, high stability, and decreased generation of toxic products in NO purification. This research highlighted the vital concerns in affecting the interlayer NO diffusion/adsorption/activation and charge delocalization/separation/transportation.
查看更多>>摘要：In this work, we report the synthesis and catalytical property of a palladium catalyst loaded on a hydrogen storage support-Pd/LaNi5 in reversible hydrogen storage of N-ethylcarbazole (NEC). We prepare LaNi5 nanoparticles by the molten salt reduction method and use galvanic replacement to deposit a thin Pd layer on the surface. Catalyzed by 1 wt%Pd/LaNi5, NEC absorbs 5.5 wt% H2 in 0.7 h at 453 K and 7 MPa H2, and perhydro-NEC desorbs 5.5 wt% in 2.1 h at 473 K and 0.1 MPa H2, which significantly outperforms Pd/Al2O3 catalyst with the same Pd loading. The significantly promoted catalytic performance is attributed to the ample lattice hydrogen bonding sites and fast bulk hydrogen diffusion kinetics of LaNi5, which breaks the limitation of active hydrogen bonding sites due to the competitive adsorption of hydrogen and the organic molecule in surface catalysis. The active role of the lattice hydrogen bonding sites makes hydrogen storage materials highly attractive for hydrogen-related catalysis
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