Recurrent Neural Networks: A Comprehensive Review of Architectures, Variants, and Applications

Simplified synthesis of direct Z-scheme Bi2WO6/PhC2Cu heterojunction that shows enhanced photocatalytic degradation of 2,4,6-TCP: Kinetic study and mechanistic insights.

MXenes, the largest and most diverse group of emerging two-dimensional materials, have potentials across multiple applications. The increasing attention is driven by the fascinating tunable surface properties, and synergetic chemistry facilitated by the presence of multiple chemical bonds dominated by covalent and metallic bonds between transition metals (M) and non-metals, X (such as carbon, nitrogen, or both). Although the various available synthesis approaches offer opportunities for tuning MXenes for specific applications, their inherent environmental and toxicity risks as well as poor scale-up potential are currently hampering research and commercialization progress. Therefore, ongoing efforts are focused on developing less hazardous, scalable methodologies to limit the barriers. This review comprehensively surveys the literature from the seminal MXene paper to the present, offering insights into the factors, latest advancements, limitations, trends, and existing gaps in MXene synthesis, properties, and applications in the areas of environment and energy storage. Special emphasis is placed on the need to address environmental concerns associated with fluoride-based synthesis while an overview of safer, non-fluoride alternatives is provided. Furthermore, the most recent breakthroughs in scalable top-down dry selective etching (DSE), bottom-up solid-state direct synthesis, and structural editing protocol using chemical scissors are presented. In particular, this review critically examines the current state of knowledge and identifies key research progresses and areas that deserve intensive attention to facilitate safe and industrial-scale synthesis and application of MXenes for catalysis, environmental remediation, and energy storage. Addressing the identified gaps will accelerate the transformation of MXenes and their composites into the components of our everyday appliances. 

MXenes: Synthesis, properties, and applications for sustainable energy and environment

Bioconversion of a heterogeneous mixture of lignin-related aromatic compounds (LRCs) to a single product via microbial biocatalysts is a promising approach to valorize lignin. Here, Pseudomonas putida KT2440 was engineered to convert mixed p-coumaroyl- and coniferyl-type LRCs to β-ketoadipic acid, a precursor for performance-advantaged polymers. Expression of enzymes mediating aromatic O-demethylation, hydroxylation, and ring-opening steps was tuned, and a global regulator was deleted. β-ketoadipate titers of 44.5 and 25 grams per liter and productivities of 1.15 and 0.66 grams per liter per hour were achieved from model LRCs and corn stover-derived LRCs, respectively, the latter representing an overall yield of 0.10 grams per gram corn stover-derived lignin. Technoeconomic analysis of the bioprocess and downstream processing predicted a β-ketoadipate minimum selling price of $2.01 per kilogram, which is cost competitive with fossil carbon-derived adipic acid ($1.10 to 1.80 per kilogram). Overall, this work achieved bioproduction metrics with economic relevance for conversion of lignin-derived streams into a performance-advantaged bioproduct.

Lignin conversion to β-ketoadipic acid by Pseudomonas putida via metabolic engineering and bioprocess development.

The direct pyrolysis of metal-zeolite imidazolate frameworks (M-ZIFs) has been widely recognized as the predominant approach for synthesizing atomically dispersed metal-nitrogen-carbon single-atom catalysts (M/NC-SACs), which have exhibited exceptional activity and selectivity in the semihydrogenation of acetylene. However, due to weak adsorption of reactants on the single site and restricted molecular diffusion, the semihydrogenation of large organic molecules (e.g., phenylacetylene) was greatly limited for M/NC-SACs. In this work, a dual single-atom catalyst (h-Pd-Mn/NC) with hollow mesopores was designed and prepared using a general host-guest strategy. Taking the semihydrogenation of phenylacetylene as an example, this catalyst exhibited ultrahigh activity and selectivity, which achieved a turnover frequency of 218 molC═CmolPd-1 min-1, 16-fold higher than that of the commercial Lindlar catalyst. The catalyst maintained high activity and selectivity even after 5 cycles of usage. The superior activity of h-Pd-Mn/NC was attributed to the 4.0 nm mesopore interface of the catalyst, which enhanced the diffusion of macromolecular reactants and products. Particularly, the introduction of atomically dispersed Mn with weak electronegativity in h-Pd-Mn/NC could drive the electron transfer from Mn to adjacent Pd sites and regulate the electronic structure of Pd sites. Meanwhile, the strong electronic coupling in Pd-Mn pairs enhanced the d-electron domination near the Fermi level and promoted the adsorption of phenylacetylene and H2 on Pd active sites, thereby reducing the energy barrier for the semihydrogenation of phenylacetylene.

Pd-Mn/NC Dual Single-Atomic Sites with Hollow Mesopores for the Highly Efficient Semihydrogenation of Phenylacetylene.

2D metallene nanomaterials have spurred considerable attention in heterogeneous catalysis by virtue of sufficient unsaturated metal atoms, high specific surface area and surface strain. Nevertheless, the strong metallic bonding in nanoparticles aggravates the difficulty in the controllable regulation of the geometry of metallenes. Here we propose an efficient galvanic replacement strategy to construct Pd metallenes loaded on Nb2C MXenes at room temperature, which is triggered by strong metal-support interaction based on MD simulations. The Pd metallenes feature a chair structure of six-membered ring with the coordination number of Pd as low as 3. Coverage-dependent kinetic analysis based on first-principles calculations reveals that the tripodal Pd metallenes promote the diffusion of alkene and inhibit its overhydrogenation. As a consequence, Pd/Nb2C delivers an outstanding turnover frequency of 10372 h-1 and a high selectivity of 96% at 25 oC in the semihydrogenation of alkynes without compromising the stability. This strategy is general and scalable considering the plentiful members of the MXene family, which can set a foundation for the design of novel supported-metallene catalysts for demanding transformations. 

/pdf/tripodal-pd-metallenes-mediated-by-nb2c-mxenes-for-boosting-kd60omkh.pdf

Tripodal Pd metallenes mediated by Nb2C MXenes for boosting alkynes semihydrogenation

Bilingual attention based neural machine translation

Organics abatement and recovery from wastewater by a polymerization-based electrochemically assisted persulfate process: Promotion effect of chloride ion and its mechanism.

Funneling lignin-derived compounds into polyhydroxyalkanoate by Halomonas sp. Y3.

Highly efficient polyhydroxyalkanoate production from lignin using genetically engineered Halomonas sp. Y3.

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