Product selectivity of solar-driven CO 2 reduction and H 2 O oxidation reactions has been successfully controlled by tuning the spatial distance between Pt/Au bimetallic active sites on different crystal facets of CeO...
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Product selectivity of solar-driven CO 2 reduction and H 2 O oxidation reactions has been successfully controlled by tuning the spatial distance between Pt/Au bimetallic active sites on different crystal facets of CeO 2 catalysts. The replacement depth of Ce atoms by monatomic Pt determines the distance between bimetallic sites, while Au clusters are deposited on the surface. This space configuration creates a favourable microenvironment for the migration of active hydrogen species (*H). The *H is generated via the activation of H 2 O on monatomic Pt sites and migrate towards Au clusters with a strong capacity for CO 2 adsorption. Under concentrated solar irradiation, selectivity of the (100) facet towards CO is 100 %, and the selectivity of the (110) and (111) facets towards CH 4 is 33.5 % and 97.6 %, respectively. Notably, the CH 4 yield on the (111) facet is as high as 369.4 μmol/g/h, and the solar-to-chemical energy efficiency of 0.23 % is 33.8 times higher than that under non-concentrated solar irradiation. The impacts of high-density flux photon and thermal effects on carriers and *H migration at the microscale are comprehensively discussed. This study provides a new avenue for tuning the spatial distance between active sites to achieve optimal product selectivity.
The previous neglect of shale oil multi-component characteristics and the nanpore wall properties of real shale result in an insufficient understanding of shale oil flow mechanisms in nanopores . Meanwhile, research o...
The previous neglect of shale oil multi-component characteristics and the nanpore wall properties of real shale result in an insufficient understanding of shale oil flow mechanisms in nanopores . Meanwhile, research on the flow regimes of shale oil remains lacking. In this study, molecular dynamics simulations are employed to investigate the flow of shale oil in hydroxylated quartz nanopores and rough kerogen nanopores. Simulation results show that the flow regime changed as the pressure gradient (∇ p ) increased to a critical value (∇ p c ). The velocity profile was parabolic when ∇ p < ∇ p c , but gradually became piston-like when ∇ p ≥ ∇ p c . Because increasing ∇ p leads the adsorbed molecules desorbing, aggregating in the pore center, and forming clusters that are not easy to shear. Increasing vertical force from pore wall causes fluid aggregation in the pore center as ∇ p increases. The ∇ p c in kerogen nanopores is larger than that in quartz nanopores due to the rough kerogen surface and sticky layers. Multi-component fluids have higher ∇ p c than single-component fluids in quartz nanopores. However, they have the same ∇ p c in kerogen nanopores due to the rough kerogen surface. This investigation can provide theoretical basis for high-efficient production of shale oil.
CFD modelling and experiments are carried out to study the influences of flow field on the measurement accuracy of ultrasonic water meters. The swirl generator and flow disturber are selected to change the flow field ...
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CFD modelling and experiments are carried out to study the influences of flow field on the measurement accuracy of ultrasonic water meters. The swirl generator and flow disturber are selected to change the flow field distributions inside the pipe. The calculation results show that the installation of left-handed swirl generator induces a specific flow pattern of the fluid inside the pipe, while the installation of flow disturber leads to the distortion of the axial velocity distributions. The critical distance of the fluid reaching the steady flow is 10D for left-handed swirl generator and flow disturber. In the experiment part, six different ultrasonic water meters are selected for the intrinsic errors tests. The results show that the installations of swirl generator and flow disturber induce the intrinsic errors shift to negative values. Compared with the flow disturber, the swirl generator has greater impact on the measurement accuracy.
Photocatalytic water splitting technology can directly convert solar energy into H 2 via a zero-carbon route, offering a sustainable solution for solar utilization and H 2 supply. Among various developed photocatalyst...
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Photocatalytic water splitting technology can directly convert solar energy into H 2 via a zero-carbon route, offering a sustainable solution for solar utilization and H 2 supply. Among various developed photocatalysts, Z-scheme heterojunction mimicking natural photosynthesis by combining two dissimilar semiconductors for redox reactions in series has unequivocally demonstrated its superiority in enhanced charge transfer, robust redox driving force, and wide optical absorption range. A comprehensive understanding on the fundamental principles of interface engineering between semiconductor components is the key to construct an efficient Z-scheme heterojunction. By focusing on different types of semiconductors, this article thoroughly expounds the coupling principles of components in binary mediator-free and ternary solid-mediator Z-scheme heterojunctions for photocatalytic water splitting, from the viewpoint of band structure alignment and interfacial electric field design. In addition to the well summarized research progresses in recent years, perspectives on the challenges and opportunities for developing advanced Z-scheme heterojunctions are provided.
Densities ( ρ ) and speed of sound ( u ) have been reported for the binary mixtures containing 1, 3- dichlorobenzene (1, 3-DCB) with methyl acetate, ethyl acetate, propyl acetate, butyl acetate and pentyl acetate at ...
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Densities ( ρ ) and speed of sound ( u ) have been reported for the binary mixtures containing 1, 3- dichlorobenzene (1, 3-DCB) with methyl acetate, ethyl acetate, propyl acetate, butyl acetate and pentyl acetate at four different temperatures ( T = 303.15, 308.15, 313.15 and 318.15 K) and at atmospheric pressure. The experimental data of densities and speeds of sound has been further utilized to calculate excess molar volume ( V m E ) and excess isentropic compressibility ( κ S E ) the excess properties have been fitted to Redlich-Kister equation. Further, V m E results have also been discussed by using Prigogine–Flory–Patterson (PFP). The experimental speeds of sound data in the present investigated mixtures were compared with various theoretical models like collision factor theory (CFT) and free length theory (FLT) to check their relative merits of pure component properties. Moreover, the experimental excess functions were correlated in terms of FTIR spectral analysis.
The ever decreasing amount of fossil fuels and increasing environmental pollution are alarming threats for green and sustainable future. Designing a new catalyst is, therefore, of paramount significance in the quest t...
The ever decreasing amount of fossil fuels and increasing environmental pollution are alarming threats for green and sustainable future. Designing a new catalyst is, therefore, of paramount significance in the quest to discover sustainable, robust, and environmentally benign materials for clean and sustainable energy generation. Herein, we developed a hierarchically oriented catalyst of calcined poly(ferrocenedimethano)-cyclotriphosphazene-microspheres (CPFC-MS) supported with nickel-aluminum layered double hydroxide and decorated with nanoparticles (NPs) of rhodium-nickel, [email protected] x Ni 1 - x ( x = 2.06–6.75), for H 2 generation from ammonia borane (AB) hydrolysis . The highly active catalyst was characterized by scanning electron microscopy (SEM), Raman spectroscopy , high-resolution transmission electron microscopy (HRTEM) and TEM, energy dispersive X-ray spectroscopy (EDX), fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). The as-fabricated [email protected] @Rh x Ni 1- x ( x = 2.06–6.75) catalysts were tested for AB hydrolysis and the results showed remarkable performance and higher stability for H 2 generation. The [email protected] @Rh 2.06 Ni 7.32 catalyst, having the lowest Rh-contents, exhibited maximum H 2 generation with a turn over frequency (TOF) of 780 mol H 2 hr −1 mol Rh −1 and an activation energy (E a ) of 40.3 kJ/mol with excellent sustainability . The superior activity is ascribed to the synergetic effect between RhNi NPs and their well-dispersion over hierarchically oriented [email protected] support, while higher stability due to LDH-AlNi/RhNi attractions. This work will provide new opportunities for polyphosphazenes and LDH derived hierarchically oriented sustainable catalysts for green energy production for sustainable future.
Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas‐phase heterogeneous (photo)catalytic hydrogenation of CO 2 to CO and CH 3 OH by In 2 O 3− x (OH) y . A key step in the reaction pathway is envisi...
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Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas‐phase heterogeneous (photo)catalytic hydrogenation of CO 2 to CO and CH 3 OH by In 2 O 3− x (OH) y . A key step in the reaction pathway is envisioned to be the heterolysis of H 2 on a proximal Lewis acid–Lewis base pair, the SFLP, the chemistry of which is described as In⋅⋅⋅In‐OH + H 2 → In‐OH 2 + ⋅⋅⋅In‐H − . The product of the heterolysis, thought to be a protonated hydroxide Lewis base In‐OH 2 + and a hydride coordinated Lewis acid In‐H − , can react with CO 2 to form either CO or CH 3 OH. While the experimental and theoretical evidence is compelling for heterolysis of H 2 on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In 2 O 3− x (OH) y can enable dissociation of H 2 at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.
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