AgPd Nanoparticles Deposited on WO2.72 Nanorods as an Efficient Catalyst for One-Pot Conversion of Nitrophenol/Nitroacetophenone into Benzoxazole/Quinazoline

One-pot Construction of Metal Nanoparticles Loaded COF Catalysts for Aqueous Hydrogenation Reactions

The catalysis performance of metal nanoparticles (NPs) will be significantly deteriorated because of their spontaneous agglomeration during practical applications. Covalent-organic frameworks (COFs) materials with functional groups and well-defined channels benefit for the dispersion and anchor of metal ions and the confined growth of metal NPs, working as an ideal platform to compose catalytic systems. In this article, we report a one-pot strategy for the preparation of metal NPs loaded COFs without the need of post-modification. During the polymerization process, the pre-added metal ions were stabilized by the rapidly formed COF oligomers and hardly disturb the construction of COFs. After reduction, metal NPs are uniformly anchored on the COF matrix. Eventually, a wide spectrum of metal NPs, including Au, Pd, Pt, AuPd, CuPd, CuPt and CuPdPt, loaded COFs are successfully prepared. The versatility and metal ions anchoring mechanism are verified with four different COF matrixes. Taking AuPd NPs as example, the resultant AuPd NPs loaded COF materials can selectively decompose ammonium formate and produce hydrogen in-situ, exhibiting over 99 % conversion of hydrodechlorination for chlorobenzenes and nitro-reduction reaction for nitroaromatic compounds under ambient temperature in aqueous solution.

Electro-, thermo-, and photocatalysis of versatile nanocomposites toward tandem process

Tandem reactions involve multi-step processes conducted in one pot, offering a cost-effective, environmentally friendly, and efficient approach to chemical transformations with high atom economy. The catalytic systems employed in tandem reactions are crucial for achieving desirable activity, selectivity, and stability. Researchers worldwide have extensively explored catalytic processes driven by various energy fields, such as electrocatalysis, thermocatalysis, and photocatalysis, aiming to facilitate multiple reactions and bond transformations. Continuous advancements have been made in reaction conditions, catalyst design, and preparation methods. This review provides a comprehensive overview of recent progress in tandem reactions, specifically focusing on electro-, thermo-, and photocatalysis, and categorizes them into catalysts, reactors, and fields based on their applications. Furthermore, the review highlights the significance of rational design in nanomaterial catalysts and the integration of multiple energy sources, emphasizing their potential to enhance selectivity, performance, and the development of combined catalysis.

Transition-metal-catalyzed synthesis of quinazolines: A review

Quinazolines are a class of nitrogen-containing heterocyclic compounds with broad-spectrum of pharmacological activities. Transition-metal-catalyzed reactions have emerged as reliable and indispensable tools for the synthesis of pharmaceuticals. These reactions provide new entries into pharmaceutical ingredients of continuously increasing complexity, and catalysis with these metals has streamlined the synthesis of several marketed drugs. The last few decades have witnessed a tremendous outburst of transition-metal-catalyzed reactions for the construction of quinazoline scaffolds. In this review, the progress achieved in the synthesis of quinazolines under transition metal-catalyzed conditions are summarized and reports from 2010 to date are covered. This is presented along with the mechanistic insights of each representative methodology. The advantages, limitations, and future perspectives of synthesis of quinazolines through such reactions are also discussed.

Cu2O nanoparticle-catalyzed tandem reactions for the synthesis of robust polybenzoxazole

We report the synthesis of Cu₂O nanoparticles (NPs) by controlled oxidation of Cu NPs and the study of these NPs as a robust catalyst for ammonia borane dehydrogenation, nitroarene hydrogenation, and amine/aldehyde condensation into Schiff-base compounds. Upon investigation of the size-dependent catalysis for ammonia borane dehydrogenation and nitroarene hydrogenation using 8-18 nm Cu₂O NPs, we found 13 nm Cu₂O NPs to be especially active with quantitative conversion of nitro groups to amines. The 13 nm Cu₂O NPs also efficiently catalyze tandem reactions of ammonia borane, diisopropoxy-dinitrobenzene, and terephthalaldehyde, leading to a controlled polymerization and the facile synthesis of polybenzoxazole (PBO). The highly pure PBO (M_w = 19 kDa) shows much enhanced chemical stability than the commercial PBO against hydrolysis in boiling water or simulated seawater, demonstrating a great potential of using noble metal-free catalysts for green chemistry synthesis of PBO as a robust lightweight structural material for thermally and mechanically demanding applications.

Synthesis of quinazolinone and quinazoline derivatives using green chemistry approach

Green chemistry has been most compelling area of research. Green chemistry is vital to long-term sustainability, not only because of its fundamental notion of reducing the use and manufacture of hazardous materials, but also because of its broad applicability as one of the most efficient and problem-solving pathways for the synthesis of new materials. Various chemists have studied a plethora of strategies to lessen the release of hazardous chemical waste, waste material recyclization and reuse. New techniques have been created based on a green chemistry strategy that includes the utilization of catalysts, nanosized materials and composites, such as metal and non-metal nanoparticles, their oxides and salts, and different heterocyclic rings. Quinazolines and quinazolinones are biologically significant heterocyclic rings with a wide range of characteristics. In a summary, this chapter focuses on recent novel synthesis methods for quinazoline and quinazolinone derivatives, which are vital to humanity.

Rhodium-catalyzed coupling-cyclization reaction of isocyanides and 2-azidophenyloxyacrylates: synthesis of N-(3-substituted benzo[d]oxazol-2(3H)-ylidene)amines and dihydrobenzo[d]oxazoles

A rhodium-catalyzed coupling cyclization of isocyanides with 2-azidophenyloxyacrylates has been developed. The reaction provides a new method for the synthesis of N-(3-substituted benzo[d]oxazol-2(3H)-ylidene)amines and dihydrobenzo[d]oxazoles.

Iodine-catalyzed synthesis of benzoxazoles using catechols, ammonium acetate, and alkenes/alkynes/ketones via C–C and C–O bond cleavage

An efficient metal-free synthesis strategy of benzoxazoles was developed via coupling catechols, ammonium acetate, and alkenes/alkynes/ketones. The developed methodology represents an operationally simple, one-pot and large-scale procedure for the preparation of benzoxazole derivatives using molecular iodine as the catalyst.

A metal-free one-pot multi-component method for the efficient synthesis of 2-aryl benzoxazoles via coupling of catechols, ammonium acetate and alkenes/alkynes/ketones using an I₂–DMSO catalyst system is illustrated.

Nanoparticle-Catalyzed Green Chemistry Synthesis of Polybenzoxazole

Enabling catalysts to promote multistep chemical reactions in a tandem fashion is an exciting new direction for the green chemistry synthesis of materials. Nanoparticle (NP) catalysts are particularly well suited for tandem reactions due to the diverse surface-active sites they offer. Here, we report that AuPd alloy NPs, especially 3.7 nm Au₄₂Pd₅₈ NPs, catalyze one-pot reactions of formic acid, diisopropoxy-dinitrobenzene, and terephthalaldehyde, yielding a very pure thermoplastic rigid-rod polymer, polybenzoxazole (PBO), with a molecular weight that is tunable from 5.8 to 19.1 kDa. The PBO films are more resistant to hydrolysis and possess thermal and mechanical properties that are superior to those of commercial PBO, Zylon. Cu NPs are also active in catalyzing tandem reactions to form PBO when formic acid is replaced with ammonia borane. Our work demonstrates a general approach to the green chemistry synthesis of rigid-rod polymers as lightweight structural materials for broad thermomechanical applications.

Recent developments of nanocatalyzed liquid-phase hydrogen generation

Hydrogen is the most effective and sustainable carrier of clean energy, and liquid-phase hydrogen storage materials with high hydrogen content, reversibility and good dehydrogenation kinetics are promising in view of "hydrogen economy". Efficient, low-cost, safe and selective hydrogen generation from chemical storage materials remains challenging, however. In this Review article, an overview of the recent achievements is provided, addressing the topic of nanocatalysis of hydrogen production from liquid-phase hydrogen storage materials including metal-boron hydrides, borane-nitrogen compounds, and liquid organic hydrides. The state-of-the-art catalysts range from high-performance nanocatalysts based on noble and non-noble metal nanoparticles (NPs) to emerging single-atom catalysts. Key aspects that are discussed include insights into the dehydrogenation mechanisms, regenerations from the spent liquid chemical hydrides, and tandem reactions using the in situ generated hydrogen. Finally, challenges, perspectives, and research directions for this area are envisaged.

Direct Z-scheme 1D/2D WO2.72/ZnIn2S4 hybrid photocatalysts with highly-efficient visible-light-driven photodegradation towards tetracycline hydrochloride removal

There are increasing environmental concerns of serious pollution from emission of antibiotic wastewater. Herein, a series of direct Z-scheme WO_2.72/ZnIn₂S₄ (WOZIS) hybrid photocatalysts composed of one-dimensional (1D) WO_2.72 (WO) nanorods and two-dimensional (2D) ZnIn₂S₄ (ZIS) nanosheets have been designed and constructed for tetracycline hydrochloride (TCH) degradation without presence of solid-state electron mediators. The crystalline phase, chemical composition, morphology, optical properties and photocatalytic activity of the as-prepared samples were characterized by the XRD, XPS, SEM, HRTEM, BET, UV-vis DRS, and PL. Obviously, all the WOZIS hybrid photocatalysts exhibited significantly enhanced photocatalytic activity towards TCH degradation. Meanwhile, WOZIS-1 sample with WO/ZIS molar ratio of 1:1 showed the highest photocatalytic activity. The significantly enhanced photoactivity of WOZIS hybrid photocatalyst was due to Z-scheme charge separation mechanism based on the build of tight interfacial contacts between WO nanorods and ZIS nanosheets, thereby driving efficient charge separation. Moreover, the high photocatalytic stability of as-prepared WOZIS-1 hybrid sample was revealed through seven successive cycling reactions.

Hetero-structured Iron Molybdate Nanoparticles: Synthesis, Characterization and Photocatalytic Application

This study focuses on the synthesis of iron molybdate [Fe2(MoO4)3] nanoparticles (NPs) using simple co-precipitation process. The catalyst synthesized was characterized by advanced instrumental techniques such as XRD, SEM, EDX, TGA and FTIR, which confirmed the successful synthesis of NPs. Organic compound Rhodamine B (Rh. B) dye was selected for photo-degradation due to its complex structure and carcinogenic nature. Results exhibited that at neutral pH, the synthesized catalyst is highly effective for the degradation of Rh. B. For 20 mg/L initial concentration with an initial pH of 6.7, the degradation efficiency of Rh. B reaches 98  % within 180 min. Furthermore, the solution pH (1 to 11) affects the catalytic activity. This indicates that at neutral and/or alkaline pH, the usage of iron molybdate overwhelms the efficiency of Fenton-like reaction. It has been observed that Fe2(MoO4)3 showed excellent stability as after recycling it for 9 times its performance remained effective. Based on these data, the synthesized catalyst could be conveniently employed for degradation of toxic pollutants.

A mesoporous non-precious metal boride system: synthesis of mesoporous cobalt boride by strictly controlled chemical reduction

Generating high surface area mesoporous transition metal boride is interesting because the incorporation of boron atoms generates lattice distortions that lead to the formation of amorphous metal boride with unique properties in catalysis. Here we report the first synthesis of mesoporous cobalt boron amorphous alloy colloidal particles using a soft template-directed assembly approach. Dual reducing agents are used to precisely control the chemical reduction process of mesoporous cobalt boron nanospheres. The Earth-abundance of cobalt boride combined with the high surface area and mesoporous nanoarchitecture enables solar-energy efficient photothermal conversion of CO₂ into CO compared to non-porous cobalt boron alloys and commercial cobalt catalysts.

Monodisperse nanoparticles for catalysis and nanomedicine

The growth and breadth of nanoparticle (NP) research now encompasses many scientific and technologic fields, which has driven the want to control NP dimensions, structures and properties. Recent advances in NP synthesis, especially in solution phase synthesis, and characterization have made it possible to tune NP sizes and shapes to optimize NP properties for various applications. In this review, we summarize the general concepts of using solution phase chemistry to control NP nucleation and growth for the formation of monodisperse NPs with polyhedral, cubic, octahedral, rod, or wire shapes and complex multicomponent heterostructures. Using some representative examples, we demonstrate how to use these monodisperse NPs to tune and optimize NP catalysis of some important energy conversion reactions, such as the oxygen reduction reaction, electrochemical carbon dioxide reduction, and cascade dehydrogenation/hydrogenation for the formation of functional organic compounds under greener chemical reaction conditions. Monodisperse NPs with controlled surface chemistry, morphologies and magnetic properties also show great potential for use in biomedicine. We highlight how monodisperse iron oxide NPs are made biocompatible and target-specific for biomedical imaging, sensing and therapeutic applications. We intend to provide readers some concrete evidence that monodisperse NPs have been established to serve as successful model systems for understanding structure-property relationships at the nanoscale and further to show great potential for advanced nanotechnological applications.

On the catalytic transfer hydrogenation of nitroarenes by a cubane-type Mo3S4 cluster hydride: disentangling the nature of the reaction mechanism

Cubane-type Mo₃S₄ cluster hydrides decorated with phosphine ligands are active catalysts for the transfer hydrogenation of nitroarenes to aniline derivatives in the presence of formic acid (HCOOH) and triethylamine (Et₃N). The process is highly selective and most of the cluster species involved in the catalytic cycle have been identified through reaction monitoring. Formation of a dihydrogen cluster intermediate has also been postulated based on previous kinetic and theoretical studies. However, the different steps involved in the transfer hydrogenation from the cluster to the nitroarene to finally produce aniline remain unclear. Herein, we report an in-depth computational investigation into this mechanism. Et₃N reduces the activation barrier associated with the formation of Mo-HHOOCH dihydrogen species. The global catalytic process is highly exergonic and occurs in three consecutive steps with nitrosobenzene and N-phenylhydroxylamine as reaction intermediates. Our computational findings explain how hydrogen is transferred from these Mo-HHOOCH dihydrogen adducts to nitrobenzene with the concomitant formation of nitrosobenzene and the formate substituted cluster. Then, a β-hydride elimination reaction accompanied by CO₂ release regenerates the cluster hydride. Two additional steps are needed for hydrogen transfer from the dihydrogen cluster to nitrosobenzene and N-phenylhydroxylamine to finally produce aniline. Our results show that the three metal centres in the Mo₃S₄ unit act independently, so the cluster can exist in up to ten different forms that are capable of opening a wide range of reaction paths. This behaviour reveals the outstanding catalytic possibilities of this kind of cluster complexes, which work as highly efficient catalytic machines.

Anchoring Pt Single Atoms on Te Nanowires for Plasmon-Enhanced Dehydrogenation of Formic Acid at Room Temperature

Formic acid (HCOOH), as a promising hydrogen carrier, is renewable, safe, and nontoxic. However, the catalytic dehydrogenation of HCOOH is typically conducted at elevated temperature. Here, HCOOH decomposition is successfully achieved for hydrogen production on the developed Pt single atoms modified Te nanowires with the Pt mass loading of 1.1% (1.1%Pt/Te) at room temperature via a plasmon-enhanced catalytic process. Impressively, 1.1%Pt/Te delivers 100% selectivity for hydrogen and the highest turnover frequency number of 3070 h-1 at 25 °C, which is significantly higher than that of Pt single atoms and Pt nanoclusters coloaded Te nanowires, Pt nanocrystals decorated Te nanowires, and commercial Pt/C. A plasmonic hot-electron driven mechanism rather than photothermal effect domains the enhancement of catalytic activity for 1.1%Pt/Te under light. The transformation of HCOO* to CO2 δ -* on Pt atoms is proved to be the rate-determining step by further mechanistic studies. 1.1%Pt/Te exhibits tremendous catalytic activity toward the decomposition of HCOOH owing to its plasmonic hot-electron driven mechanism, which efficiently stimulates the rate-determining step. In addition, hot electrons generated by the Te atoms nearby Pt single atoms are regarded to directly inject into the reactants adsorbed and activated on Pt single atoms.

Facile construction of reduced graphene oxide supported three-dimensional polyaniline/WO2.72 nanobelt-flower as a full solar spectrum light response catalyst for efficient photocatalytic conversion of bromate

As a carcinogenic byproduct in drinking water treatment, bromate has raised global concerns on environmental and health hazard, calling for effective treatments. In the current work, a novel reduced graphene oxide supported polyaniline/WO_2.72 nanobelt-flower (RGO/PANI/WO_2.72) ternary composite was prepared through a solvent volatilization method for photocatalytic reduction of bromate. The prepared sample was characterized, and the influence of aqueous pH, ions and dissolved oxygen on the bromate reduction was explored. As expected, the introduction of RGO and PANI on the WO_2.72 exhibited great synergistic effects on the separation of photogenerated carriers. The calculated reduction rate constant of RGO/PANI/WO_2.72 was about six times as high as that of pure WO_2.72. Specially, the prepared photocatalyst possessed strong optical absorption in a broad range of 250-2500 nm, and thus displaying excellent catalytic performance in utilization of all solar spectrum energy. Moreover, the RGO/PANI/WO_2.72 exhibited stable photocatalytic activity in cycling test. Considered holistically, the present study offered a valuable approach for rational construction of heterogeneous structure in the development of bromate-catalyzed reduction.

Cobalt Entrapped in N,S-Codoped Porous Carbon: Catalysts for Transfer Hydrogenation with Formic Acid

Catalysts with Co nanoparticles (NPs) entrapped in N,S-codoped carbon shells were successfully fabricated by pyrolysis of porous organic polymers (POPs) with cobalt salts. The encapsulated structure consisting of Co NPs and N,S-codoped carbon layers was verified by TEM, XRD, and X-ray photoelectron spectroscopy. The catalysts displayed excellent activity and stability for the catalytic transfer hydrogenation (CTH) of nitrobenzene with formic acid under base-free conditions. Furthermore, the resultant catalysts allowed for highly efficient and selective transfer hydrogenation of various functionalized nitroarenes to the corresponding anilines. Through control experiments, the covered Co NPs were identified as active sites for CTH. The incorporation of S into the N-doped carbon lattice promoted the electron transfer from metallic cobalt NPs to their shells, which played a significant role in the acceleration of CTH. Moreover, the Co-NSPC-850 catalyst pyrolyzed at 850 °C showed excellent stability in the recycling experiments.

Superfine CoNi alloy embedded in Al2O3 nanosheets for efficient tandem catalytic reduction of nitroaromatic compounds by ammonia borane

Tunable Co_xNi_1−x/Al₂O₃ nanocatalysts have been prepared and used for the efficient tandem catalytic dehydrogenation of ammonia borane and hydrogenation of nitroaromatics.

Surface Modification on Pd-TiO2 Hybrid Nanostructures towards Highly Efficient H2 Production from Catalytic Formic Acid Decomposition

Metal-containing nanocrystals with well-designed surface structures represent a class of model systems for revealing the fundamental physical and chemical processes involved in heterogeneous catalysis. Herein it is shown how surface modification can be utilized as an efficient strategy for controlling the surface electronic state of catalysts and, thus, for tuning their catalytic activity. As model catalysts, the Pd-tetrahedron-TiO₂ nanostructures, modified on the surface with different foreign atoms, showed a varied activity in the catalytic decomposition of formic acid towards H₂ production. The catalytic activity increases with a reduction in the work function of modified atoms; this reduction can be well explained by a surface polarization mechanism. In this hybrid system, the difference in the work functions of Pd and modified atoms results in surface polarization on the Pd surface and, thus, in the tuning of its charge state. Together with the Schottky junction between TiO₂ and metals, the tuned charge state enables the promotion of catalytic efficiency in the catalytic decomposition of formic acid to H₂ and CO₂ .

Pd nanoparticles supported on a covalent triazine-based framework material: an efficient and highly chemoselective catalyst for the reduction of nitroarenes

Well-dispersed Pd nanoparticles supported on a triazine-based framework were prepared and the material displayed excellent catalytic activity for the transfer hydrogenation of nitroarenes.

Ultrathin Tungsten Oxide Nanowires/Reduced Graphene Oxide Composites for Toluene Sensing

Graphene-based composites have gained great attention in the field of gas sensor fabrication due to their higher surface area with additional functional groups. Decorating one-dimensional (1D) semiconductor nanomaterials on graphene also show potential benefits in gas sensing applications. Here we demonstrate the one-pot and low cost synthesis of W₁₈O₄₉ NWs/rGO composites with different amount of reduced graphene oxide (rGO) which show excellent gas-sensing properties towards toluene and strong dependence on their chemical composition. As compared to pure W₁₈O₄₉ NWs, an improved gas sensing response (2.8 times higher) was achieved in case of W₁₈O₄₉ NWs composite with 0.5 wt. % rGO. Promisingly, this strategy can be extended to prepare other nanowire based composites with excellent gas-sensing performance.