The Marvel Cinematic Universe has become one of the most successful and popular franchises worldwide due to its continuous development. Therefore, this essay employs content analysis to investigate ...the worldbuilding and character develop issues in the Marvel Cinematic Universe productions. The findings reveal that the dense interconnections within the productions of the franchise makes it challenging for new audiences to enter. The repetition and declined quality of the plot of the Marvel Cinematic Universe’s productions after Avengers: Endgame (2019) has also made old fans begin to lose interest. The imbalance between old and new characters leads the franchise to an awkward situation. To address these problems, Marvel can slow down the pace of new releases, so that the new audiences will be given more time to know the fictional world by catching up previous productions. Besides, Marvel Studios can have more time to improve the quality of their works to maintain the attraction to old audiences. Furthermore, they should focus on balancing the development of both old and new characters to better serve different audiences.
Solar-driven CO2 conversion to chemical fuels in an aqueous solution is restricted not only by photocatalysts but also by mass transfer. Here, a regulatable three-phase interface on a porous ...fixed-bed is constructed for efficient C–C coupling in photocatalytic CO2 reduction. The photocatalytic results show that ∼90% selectivity towards C2+ products is obtained by a Cu/Cd0.5Zn0.5S photocatalyst, with a yield of 6.54 μmol/h (an irradiation area of 0.785 cm2), while only 0.94 μmol/h (an irradiation area of 19.625 cm2) is achieved with a commonly used suspension photocatalytic reactor. We find that under the same CO2 feed rate, the local CO2 concentration in this porous fixed-bed photoreactor is obviously higher than in the suspension photoreactor. The larger local CO2 coverage derived from a higher CO2 supply and aggregation enhances the C–C coupling, thereby generating more C2+. Even an observable three-phase interface on the porous fixed-bed can be regulated by adjusting the CO2 supply, for which the optimal gas inlet rate is 5–10 sccm.
Display omitted
•A homemade porous fixed-bed photoreactor for overcoming the mass transfer bottleneck was designed and constructed.•A three-phase interface was formed and regulated by adjusting CO2 feed, while a K+ tracer experiment was used to observe it.•Local CO2 concentration from the three-phase interface enhanced ∗CO–COH coupling, with ∼90% selectivity to C2+ products.
Abstract Controlling the concentrations of H 2 O and CO 2 at the reaction interface is crucial for achieving efficient electrochemical CO 2 reduction. However, precise control of these variables ...during catalysis remains challenging, and the underlying mechanisms are not fully understood. Herein, guided by a multi-physics model, we demonstrate that tuning the local H 2 O/CO 2 concentrations is achievable by thin polymer coatings on the catalyst surface. Beyond the often-explored hydrophobicity, polymer properties of gas permeability and water-uptake ability are even more critical for this purpose. With these insights, we achieve CO 2 reduction on copper with Faradaic efficiency exceeding 87% towards multi-carbon products at a high current density of −2 A cm −2 . Encouraging cathodic energy efficiency (>50%) is also observed at this high current density due to the substantially reduced cathodic potential. Additionally, we demonstrate stable CO 2 reduction for over 150 h at practically relevant current densities owning to the robust reaction interface. Moreover, this strategy has been extended to membrane electrode assemblies and other catalysts for CO 2 reduction. Our findings underscore the significance of fine-tuning the local H 2 O/CO 2 balance for future CO 2 reduction applications.
Indium-based oxides are promising electrocatalysts for producing formate via CO2 reduction reaction, in which ∗OCHO is considered the key intermediate. Here, we identified that the ∗COOH pathway ...could be preferential to produce formate on In2O3 of In/In2O3 heterojunction due to the synergistic effect of oxygen species and vacancy. Specifically, ∗CO2 and ∗COOH were observed on In2O3 and related to formate production by in situ Raman spectroscopy. The theoretical calculations further demonstrated that the energy barrier of the ∗COOH formation on In2O3 was decreased in the presence of oxygen vacancy, similar to or lower than that of the ∗OCHO formation on the In surface. As a result, a formate selectivity of over 90% was obtained on prepared In/In2O3 heterojunction with 343 ± 7 mA cm−2 partial current density. Furthermore, when using a Si-based photovoltaic as an energy supplier, 10.11% solar–to–fuel energy efficiency was achieved.
Display omitted
•Different amounts of oxygen species and vacancies were constructed on In2O3.•The ∗COOH pathway for CO2 reduction to formate production on In2O3 was confirmed.•8.33% solar-to-formate and 10.11% solar-to-fuel were achieved when driven by photovoltaics.
This study aims to compare the anti-wetting and anti-fouling surface behavior in membrane distillation (MD) by two surface modification routes on porous polyvinylidene fluoride (PVDF) membranes. A ...superhydrophobic membrane (SiO2-PFTS/PVDF) was obtained by dynamically forming 1H,1H,2H,2H-perfluorooctyl trichlorosilane containing SiO2 nanoparticles on the membrane surface as in our previous study; whereas a superhydrophilic membrane (PVA/PVDF) was developed by attaching a thin layer of poly(vinylalcohol) hydrogel onto the membrane's surface. The effects of surface modification on their anti-wetting or anti-fouling properties were examined in MD using an aqueous NaCl solution with various organic foulants (e.g., kerosene, humic acid (HA), and sodium dodecyl benzene sulfonate (SDBS)). The results showed that the superhydrophobic SiO2-PFTS/PVDF membrane displayed excellent self-cleaning characteristics and wetting resistance against all three studied foulants. In contrast, the hydrophilic surface layer of the PVA/PVDF membrane only slowed down wetting and fouling when in contact with kerosene and HA. Nonetheless, when dealing with SDBS, its anti-wettability performance was comparable to that of the SiO2-PFTS/PVDF membrane. The superhydrophobic SiO2-PFTS/PVDF membrane exhibited anti-fouling and anti-wetting behaviors even though the extended Derjaguin–Landau–Verwey–Overbeek theory indicated the attraction force between the membrane surface and all three foulants.
•Two routes were used for superhydrophobic and superhydrophilic surface modification.•Three organic foulants examined in membrane distillation.•The anti-wetting and anti-fouling behaviors of three membranes were compared.•Superhydrophobic modification displayed much better self-cleaning property.•Superhydrophilic modification only slowed down wetting and fouling.
The “Z-scheme” TiO2-Au-BiOI photocatalyst showed the highest photocatalytic performance for N2 photofixation with 543.53 μmol L−1h−1 g−1 in the pure water system, which is 1.68, 1.85 and 6.69 times ...higher than that of TiO2-BiOI-Au, TiO2-BiOI and TiO2-Au, revealing most effective charge separation and transfer in such Z-scheme junction and the strongest redox capability for photocatalytic N2 fixation among these heterostructured photocatalysts.
Display omitted
•Various heterostructured photocatalysts, i.e., TiO2-BiOI-Au, TiO2-BiOI, TiO2-Au and TiO2-Au-BiOI are constructed.•The Z-scheme TiO2-Au-BiOI showed the highest N2 photofixation activity with 543.53 μmol L−1h−1 g−1 in pure water system.•The TiO2-Au-BiOI exhibited considerable performance in the real natural environment.
Aiming at comparing the charge separation efficiencies of various heterojunctions, such as p-n junction, metal–semiconductor junction, Z-scheme junction, TiO2-Au, TiO2-BiOI, TiO2-BiOI-Au and TiO2-Au-BiOI were synthesized by using n-type TiO2, p-type BiOI and plasmon metal Au as components for photocatalytic nitrogen fixation. The as-prepared “Z-scheme” TiO2-Au-BiOI photocatalyst showed the highest photocatalytic performance for N2 photofixation with 543.53 μmol L−1h−1 g−1 in the pure water system, which is 1.68 times higher than that of TiO2-BiOI-Au nanocomposite, 1.85 times higher than that of TiO2-BiOI and 6.69 times higher than that of TiO2-Au, revealing superiority of the heterojunctions of TiO2-Au-BiOI in kinetics among these different heterostructured photocatalysts during the photocatalytic N2 reduction process. Moreover, the as-prepared TiO2-Au-BiOI exhibited considerable performance under real natural environment, showing a promising potential in future application.
If combined with renewably generated electricity, electrochemical CO2 reduction (E-CO2R) could be used as a sustainable source of chemicals and fuels. Tandem catalysis approaches are attractive for ...providing the product selectivity, which would be required for commercial applications. Here, we demonstrate a two-step tandem electrocatalytic E-CO2R with efficient conversion of the intermediate species. The catalyst scaffold is Si(100), which is etched to form a textured surface consisting of micron-sized pyramid structures with the {111} facets. Two metals are used in the electrocatalytic cascade: Ag is employed to perform a two-electron reduction of CO2 to the intermediate CO, and Cu performs conversion to more reduced products. Using high-angle physical vapor deposition, we form separated, micron-scale areas of the two electrocatalysts on opposite sides of the pyramids, with their relative surface coverages being tunable with the deposition angle. Compared to the textured scaffolds with blanket Ag and Cu used as controls, bimetallic pyramid tandem catalysts have higher current densities and much lower faradic efficiencies (FE) for CO. These effects are due to efficient conversion of the CO formed on Ag to more reduced products on Cu. Methane is the main product to be enhanced by the cascade pathway: a bimetallic catalyst with approximately equal coverages of Ag and Cu produces methane with a FE of 62% at −1.1 V RHE, corresponding to a partial current density of 12.7 mA cm–2. We estimate an intermediate conversion yield for the CO intermediate of 80–90%, which is close to the mass-transport limited value predicted by reaction-diffusion simulations.
An anti-wetting graphene oxide modified PVDF composite membrane was prepared by a facial dynamical forming process, displaying superior anti-fouling properties than the pristine PVDF.
Display omitted
...•Graphene oxide (GO) was applied to modify PVDF membrane for membrane distillation.•The GO modification displayed significant improvement in anti-fouling properties.•GO nanosheets healed pore defect without introducing extra diffusion resistance.
Membrane surface modification by forming a functional layer is an effective way to improve the anti-fouling properties of membranes; however, the additional layer and the potential blockage of bulk pores may increase the mass transfer resistance and reduce the permeability. In this study, we applied a novel method of preparing anti-fouling membranes for membrane distillation by dispersing graphene oxide (GO) on the channel surface of polyvinylidene fluoride membranes. The surface morphology and properties were characterized by scanning electron microscopy, atomic force microscope, and Fourier transform infrared spectrometry. Compared to the membrane surface modification by nanoparticles (e.g. SiO2), GO was mainly located on the pore surface of the membrane bulk, rather than being formed as an individual layer onto the membrane surface. The performance was evaluated via a direct-contact membrane distillation process with anionic and cationic surfactants as the foulants, separately. Compared to the pristine PVDF membrane, the anti-fouling behavior and distillate flux of the GO-modified membranes were improved, especially when using the anionic surfactant as the foulant. The enhanced anti-fouling performance can be attributed to the oxygen containing functional groups in GO and the healing of the membrane pore defects. This method may provide an effective route to manipulate membrane pore surface properties for anti-fouling separation without increasing mass transfer resistance.
Electrochemical reduction of carbon dioxide (CO
2
) is promising to alleviate carbon emissions and produce fuels and materials in a circular way, yet effective tuning strategies and fundamental ...understanding are lacking. In particular, cell design is actually done by simplistic one- or two-dimensional models, which incorporate numerous assumptions, leading to potential errors and discrepancies. Here, we establish new two-dimensional multiphysics models that incorporate cell-specific geometry, gas–liquid two-phase flow, and electrochemical kinetics. We calculate the temporary and spatial variations of the local CO
2
concentration, electrochemical parameters, and products selectivity on the cathode surface, under different cell configurations and operating parameters. Products include dihydrogen (H
2
), carbon monoxide (CO), formic acid (HCOOH), ethylene (C
2
H
4
), ethanol (C
2
H
5
OH), and propanol (C
3
H
7
OH). We further investigated the effect of local CO
2
concentration on CO
2
reduction performance. We find that high local CO
2
concentration, above 8.7 mM, enhances the selectivity for C
1
products and the cathode polarization, whereas extremely low local CO
2
concentration, of 0.75–5.5 mM, favors the selectivity for C
2+
products, especially alcohols. C
2+
selectivity ranges from 81.3 to 88.6% at 4.8–5.5 mM local CO
2
concentration, while alcohol products selectivity ranges between 54.9 and 65.4% at 0.75–1.9 mM CO
2
concentration. These findings are attributed to the reduced CO
2
diffusion layer thickness to less than 10 μm at the cathode. This enhances the CO
2
mass transfer efficiency to the cathode, and eliminates temporal and spatial variations of the local CO
2
distribution along the cathode surface.
Accelerating electrocatalytic water splitting via hydrogen spillover has received increasing attention. However, the underlying mechanism of hydrogen spillover on hydrogen evolution is still ...ambiguous. Herein, a simulation study was carried out to determine the role of hydrogen spillover in pH- and potential-dependent hydrogen evolution over the NiCu bimetal catalyst. It was found that the current density was most prominently improved by hydrogen spillover in the neutral condition at −0.35 to −0.2 V vs reversible hydrogen electrode. By the parameter study, it was indicated that the potential and pH could improve the effect of hydrogen spillover on the current density by altering the surface reaction rates which include the hydrogen adsorption and desorption rates on the Ni and Cu particles. The pH would also affect the current density enhancement from the hydrogen spillover by the mass transfer limitation. To effectively utilize the hydrogen spillover for improved electrocatalytic hydrogen production, managing the surface reaction rate was important. Typically, the key principle was increasing the hydrogen adsorption rate of hydrogen donors and hydrogen desorption rate of hydrogen acceptors in the presence of hydrogen spillover. This fundamental understanding of hydrogen spillover contributes to the development of advanced electrocatalytic systems for hydrogen production.
PDF
