Three‐dimensional (3D) printing, also known as additive manufacturing, is a fabrication method that has recently received worldwide attention. It provides a convenient and economical way to prepare ...3D structures in designable ways. As the technology has developed and the operational costs have decreased, the applications of 3D printing have greatly expanded. Catalyst fabrication is a promising area for 3D printing. Printing processes result in better control of catalyst structures and catalyst distribution. In this perspective, a general overview of the commonly available 3D printing methods that are feasible for the preparation of heterogeneous catalysts is given. Additionally, recent works on printing strategies and new materials for catalysts are discussed. Future development is also addressed.
Three‐dimensional (3D) printing is a fabrication method that has received worldwide attention. Recently, 3D printing has been applied to catalyst fabrication. In this perspective, a general overview of the commonly available 3D printing methods that are feasible for the preparation of heterogeneous catalysts is given. Recent works on printing strategies and new materials for catalysts are discussed. Future development is also addressed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Defects are now recognized to be a useful tool in tailoring the properties of metal-organic frameworks (MOFs). The introduction of missing linker and cluster defects into MOFs provides additional ...active sites, optimizes the acidity/basicity, improves the conductivity, tailors mechanical responses and creates more pore space to enhance diffusion and mass transfer in MOFs. Structural defects in MOFs have been demonstrated to be beneficial in areas such as catalysis, decontamination, bio-applications, adsorption, separation, energy storage, energy conversion, electronics, magnetics, optical functional materials and others. Defective MOFs are also excellent model materials for the fundamental study of defect chemistry. In this review, we provide a general overview of the commonly available methods that are feasible for the creation and characterization of structural defects in MOF materials. Additionally, recent studies on various applications of defective MOFs are highlighted, aiming to provide new insights into the design and introduction of structural defects to synthesize MOF materials with high performance and to promote the wide application of defective MOFs in various fields. Challenges and future perspectives on defect engineering of MOFs are also addressed.
An overview of important recent advances on synthesis, characterization and application of defective metal-organic frameworks is provided.
Solar vapor generation is a facile and an efficient way for solar energy harvesting, which is applied to address the issue of fresh water extraction from sewage or brine. Several solar vapor ...generation devices have been developed in the past few years, but the low evaporation rate still remains as a challenge. In this work, a novel double‐layer solar vapor generation device, named as Ag‐PSS‐AG/AG device, is reported. This device is based on the hierarchical composition of silver nanoparticles (Ag NPs) and poly (sodium‐p‐styrenesulfonate) (PSS) decorated agarose gel (AG). The device reveals a synergetic effect of the two layers with high light‐harvesting and water‐transfer performance, respectively, leading to an ultrahigh vapor generation rate of 2.10 kg m−2 h−1 with a solar thermal efficiency of 92.8% under 1 sun illumination. This high evaporation rate is mainly owing to the powerful light‐thermal conversion of Ag NPs as well as the outstanding water transfer capability of agarose hydrogel. Consequently, this device can be directly used for the purification of sewage and muddy water. It is also promising for applications in separation, humidity management, and others.
A novel double‐layer solar vapor generation device based on the hierarchical composition of silver nanoparticles and agarose gel is designed. With the synergetic effect of the two functional layers, the device exhibits an ultrahigh vapor generation rate of 2.10 kg m−2 h−1 with a solar thermal efficiency of 92.8% under 1 Sun illumination.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The hydroisomerization of n -alkanes over bifunctional catalysts has played an increasingly important role in the modern petroleum industry due to its evident effects on the enhancement of the ...quality of fossil fuels. However, the preparation of bifunctional catalysts with excellent catalytic performance remains a significant challenge because of the complicated synergistic effects between the metal sites and Brønsted acid sites and the limited diffusion of alkene intermediates in the acid support. To overcome this challenge, the improvement of the metal–acid balance and the synthesis of hierarchical acid supports have become two commonly employed strategies. On the one hand, the favourable metal–acid balance is beneficial for the ideal consecutive hydroisomerization mechanism, which can be achieved by choosing the appropriate ratio of metal sites to Brønsted acid sites, controlling the nanoscale distance between two active sites, reducing the acidity and function of Brønsted acid sites, enhancing the function of metal sites and lowering the cost of preparation. On the other hand, via the “top down” (like desiliconization post-treatment) or “bottom up” (like templating methods) methods, the prepared hierarchical acid supports have more pore mouths or evidently reduced diffusion length. As a result, the alkene intermediates can either undergo isomerization at pore mouth instead of diffusing in the microporous channels or diffuse out fast from the short microporous channels, so that the diffusion limitation of alkene intermediates can be overcome and their cracking is inhibited. In this review, we summarize the recent advances in the developments of bifunctional catalysts for n -alkane hydroisomerization. The novel synthesis methods of the bifunctional catalysts are introduced, as well as the catalytic behaviours and the reaction mechanisms over catalysts. The effects of the metal–acid balance and the textural property on the catalytic performances are also discussed. The summarized studies reveal excellent potential for the design and preparation of novel bifunctional catalysts with excellent catalytic performances for n -alkane hydroisomerization.
Phenylpropanoid biosynthesis in plants engenders a vast variety of aromatic metabolites critically important for their growth, development, and environmental adaptation. Some of these aromatic ...compounds have high economic value. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the pathway; it diverts the central flux of carbon from the primary metabolism to the synthesis of myriad phenolics. Over the decades, many studies have shown that exquisite regulatory mechanisms at multiple levels control the transcription and the enzymatic activity of PALs. In this review, a current overview of our understanding of the complicated regulatory mechanisms governing the activity of PAL is presented; recent progress in unraveling its post-translational modifications, its metabolite feedback regulation, and its enzyme organization is highlighted.
Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in phenylpropanoid biosynthesis pathway. It is controlled under a multitude of regulatory mechanisms. In this review, a current overview on our understanding of the complicated regulatory mechanisms governing the activity of PAL is presented.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
• Plants produce several hundreds of thousands of secondary metabolites that are important for adaptation to various environmental conditions. Although different groups of secondary metabolites are ...synthesized through unique biosynthetic pathways, plants must orchestrate their production simultaneously. Phenylpropanoids and glucosinolates are two classes of secondary metabolites that are synthesized through apparently independent biosynthetic pathways. Genetic evidence has revealed that the accumulation of glucosinolate intermediates limits phenylpropanoid production in a Mediator Subunit 5 (MED5)-dependent manner.
• To elucidate the molecular mechanism underlying this process, we analyzed the transcriptomes of a suite of Arabidopsis thaliana glucosinolate-deficient mutants using RNAseq and identified misregulated genes that are rescued by the disruption of MED5.
• The expression of a group of Kelch Domain F-Box genes (KFBs) that function in PAL degradation is affected in glucosinolate biosynthesis mutants and the disruption of these KFBs restores phenylpropanoid deficiency in the mutants.
• Our study suggests that glucosinolate/phenylpropanoid metabolic crosstalk involves the transcriptional regulation of KFB genes that initiate the degradation of the enzyme phenylalanine ammonia-lyase, which catalyzes the first step of the phenylpropanoid biosynthesis pathway. Nevertheless, KFB mutant plants remain partially sensitive to glucosinolate pathway mutations, suggesting that other mechanisms that link the two pathways also exist.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Nanoparticle/metal-organic frameworks (MOF) based composites have recently attracted significant attention as a new class of catalysts. Such composites possess the unique features of MOFs (including ...clearly defined crystal structure, high surface area, single site catalyst, special confined nanopore, tunable, and uniform pore structure), but avoid some intrinsic weaknesses (like limited electrical conductivity and lack in the "conventional" catalytically active sites). This review summarizes the developed strategies for the fabrication of nanoparticle/MOF composites for catalyst uses, including the strategy using MOFs as host materials to hold and stabilize the guest nanoparticles, the strategy with subsequent MOF growth/assembly around pre-synthesized nanoparticles and the strategy mixing the precursors of NPs and MOFs together, followed by self-assembly process or post-treatment or post-modification. The applications of nanoparticle/MOF composites for CO oxidation, CO₂ conversion, hydrogen production, organic transformations, and degradation of pollutants have been discussed. Superior catalytic performances in these reactions have been demonstrated. Challenges and future developments are finally addressed.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The sluggish rate of the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells has been a major challenge. Significantly increasing efforts have been made worldwide towards a ...highly active ORR catalyst with high durability. Among all the catalysts exploited, Pt electrocatalysts are still the best in terms of a comprehensive evaluation. The investigation of Pt-based ORR catalysts is necessary for a practical ORR catalyst with low Pt content. This paper reviews recent progress in the studies of the mechanism, nanostructure, size effect and carbon supports of Pt electrocatalysts for the ORR. The importance of the size and structure control of Pt ORR catalysts, related with carbon support materials, is indicated. The potential methods for such control are discussed. The progress in theoretical studies and
in situ
catalyst characterization are also discussed. Finally, challenges and future developments are addressed.
This paper reviews progress in studies of the mechanism, nanostructure, size effect and carbon supports of Pt electrocatalysts for the ORR.
Flavonoids represent a large family of specialized metabolites involved in plant growth, development, and adaptation. Chalcone synthase (CHS) catalyzes the first step of flavonoid biosynthesis by ...directing carbon flux from general phenylpropanoid metabolism to flavonoid pathway. Despite extensive characterization of its function and transcriptional regulation, the molecular basis governing its posttranslational modification is enigmatic. Here, we report the discovery of a proteolytic regulator of CHS, namely, KFBCHS, a Kelch domain-containing F-box protein in Arabidopsis thaliana. KFBCHS physically interacts with CHS and specifically mediates its ubiquitination and degradation. KFBCHS
exhibits developmental expression patterns in Arabidopsis leaves, stems, and siliques and strongly responds to the dark-to-light (or the light-to-dark) switch, the blue, red, and far-red light signals, and UV-B irradiation. Alteration of KFBCHS
expression negatively correlates to the cellular concentration of CHS and the production of flavonoids. Our study suggests that KFBCHS serves as a crucial negative regulator, via mediating CHS degradation, coordinately controlling flavonoid biosynthesis in response to the developmental cues and environmental stimuli.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Supported Ni catalysts are promising for CO2 hydrogenation because of their relatively cheap price with comparable activity to noble metal catalysts. The product of CO2 hydrogenation over a supported ...Ni catalyst can theoretically be methane, CO, methanol and formic acid. The electronic and geometric structures of a supported Ni catalyst have a significant effect on the activity and selectivity of CO2 hydrogenation. Supported single nickel atom catalysts are found to tend to form carbon monoxide, methanol and, theoretically, formic acid. The selectivity depends on the support. The supported nickel cluster on indium oxide and In2O3–ZrO2 is highly selective for methanol synthesis. Supported nickel nanoparticles are normally good catalysts for methane formation at reasonably low temperatures. However, the structural effect of the supported Ni catalyst on CO2 hydrogenation has not been well investigated. The mechanism is still in debate. To further improve the activity and stability with tunable selectivity, the structure control of the Ni catalyst is very necessary for CO2 hydrogenation, which is highly structure sensitive. In this review, recent advances in the understanding of the structural effects of supported Ni catalysts on CO2 hydrogenation are summarized, including theoretical studies, operando or in situ catalyst characterization and experimental studies. Future development is therefore finally addressed.
PDF
