Fast and selective reduction of nitroarenes under visible light with an earth-abundant plasmonic photocatalyst

Modulating Iron Crystals with Lattice Chalcophile-Siderophile Elements for Selective Dechlorinations Over Hydrogen Evolution

Selective dechlorination of organic chlorides over hydrogen evolution reaction (HER) remains a challenge because of their coincidence. Nanoscale zerovalent iron (nFe0) draws a promising picture of in situ groundwater dechlorination, but its indiscriminate reactivity limits the application. Here, nFe0 crystals are designed with electron shuttles and improved hydrophobic nature based on elemental chalcophile-siderophile characteristics, where chalcophile-siderophile S served as a bridge to allow impregnating nFe0 crystals with weakly siderophile and strongly chalcophile Cu. Even impregnations of lattice chalcophile-siderophile elements into the nFe0 crystals are evidenced at both intraparticle and individual-particle levels. The modulated Fe microenvironment and physicochemical properties broke the reactivity-selectivity-longevity-stability trade-off. Compared to nFe0, superhydrophobic Cu─S─nFe0 with lattice expansion promoted dechlorination by 20-fold but inhibited HER by 150-fold, utilizing ≈80-100% electrons from the Fe0 reservoir. This work demonstrates the concept of engineering nFe0 lattice with tunable structure-property relationships, mimicking reductive dehalogenases by selectively interacting with halocarbon functional groups for efficient dehalogenation and sustainable groundwater remediation.

Colloidal quantum dots: surface and interface engineering for light-driven hydrogen production

Solar energy is the most abundant and clean energy resource for the production of hydrogen, which is inexpensive but requires robust semiconductors. Colloidal quantum dots (CQDs) are considered an ideal semiconductor for hydrogen production. Although light-driven hydrogen production systems have been explored for multifarious CQD-based materials and devices, a comprehensive summary on surface and interface engineering has been rarely reported. In this review, we discuss the surface and interface modification strategies for CQD-based light-driven hydrogen production and emphasize on direct light-driven hydrogen generation systems categorized into photoelectrochemical cells and photocatalysis systems. Furthermore, we describe the recent research advances in this growing field by highlighting various strategies developed for the optimization of surface and interface characteristics, such as core-shell structural design, passivation layer modification, surface ligand optimization, heterostructure construction, co-catalyst loading, and defect engineering. Finally, a future outlook on and the challenges in surface and interface regulation of CQD-based light-driven hydrogen production systems are highlighted. It is expected that this review will stimulate continued interest in harnessing the significant potential of CQDs for solar-to-hydrogen conversion.

Ionic-Fence Effect in Au Nanoparticle-Loaded UiO-66 Metal-Organic Frameworks for Highly Chemoselective Hydrogenation

The chemoselective reaction are vital for fine chemicals, which requires economical and environmentally friendly catalysts. In order to improve the selectivity of multi-reaction competition, herein, we propose a novel ionic-fence strategy to synthesize heterogeneous catalyst for efficient hydrogenation. Practically, UIO-66 metal-organic frameworks (MOF) modified with pyridinium-linker has been constructed through post-synthetic chains with paired anion via quaternization and ion exchange to form ionic-fence MOF (IFMOF-Cl), which can manage the adsorption mode of nitro substrate, further confine the formation of metal nanoparticles with high dispersity. The optimal Au@IFMOF-Cl catalyst demonstrates satisfactory selectivity for hydrogenation of nitro group compared to acetylene group in 4-nitrophenylacetylene. Specifically, it owns a high yield of 4-aminophenylacetylene (~97 %) with ultra-high catalytic efficiency (3880 h-1 TOF) and long stability, far superior to other catalysts without ionic fence effect. Adsorption experiments and density functional theory studies reveal that the incorporation of ionic fence could modulate the adsorption energy of nitro group, which is responsible for the high selectivity enhancement. Notably, this ionic-fence strategy exhibits comprehensive universality towards a wide range of substrates (23 kinds in total), providing a promising avenue for precisely engineering the internal microenvironments of catalysts to achieve highly selective synthesis of fine chemicals.

Precisely Tailoring the Second Coordination Sphere of a Cobalt Single-Atom Catalyst for Selective Hydrogenation of Halogenated Nitroarenes

The development of highly efficient and cost-effective nonprecious metal catalysts for the selective hydrogenation of halogenated nitroarenes is very appealing yet challenging. Here, we demonstrate that the hydrogenation activity and selectivity of Co single-atom catalyst (SAC) can be tuned by tailoring the structure of second coordination sphere via P doping. As revealed by synchrotron radiation-based X-ray absorption spectroscopy characterizations, such a P doping on N-coordinated Co SAC results in the unsymmetric Co-N4P1 coordination structure. With a combination of experimental characterizations and theoretical simulations, we find that tailoring the second coordination sphere can greatly improve H2 dissociation and product desorption. As a result, the Co-N4P1 SAC exhibits superior activity, selectivity and stability for the hydrogenation of halogenated nitroarenes to corresponding amines (20 examples, >99 % yields) at 80 °C under 0.5 MPa H2 pressure, significantly outperforming most heterogeneous catalysts reported in the literature. We expect that this work opens a new avenue for the design of highly efficient nonprecious metal SACs for important hydrogenation reactions.

Removal of iron and manganese from acidic aqueous solution by pyrite and pyrite-calcium sulfite

Pyrite and calcium sulfite were used to remove iron and manganese from an acidic aqueous solution. The concentration of Fe was decreased to be smaller than 0.05 g/L in 60 min when pyrite and air were added into the acidic aqueous solution, but the concentration of Mn in the solution remained unchanged. After the process of iron removal, calcium sulfite and air were used to remove manganese ions from the solution, and the efficiency of manganese ion removal was larger than 75% in 240 min (with less than 0.05 g/L Fe and 0.5 g/L Mn in the solution). Meanwhile, experiments were conducted to simultaneously remove iron and manganese from artificially simulated acidic leaching solution of laterite nickel ore. When the proposed method was used to purify the leaching solution of laterite nickel ore, Fe3+ and Mn2+ ions were effectively removed from the acidic solution, and the recovery efficiency of nickel and cobalt was greater than 98%.

Regulating Charge Separation Via Periodic Array Nanostructures for Plasmon-Enhanced Water Oxidation

Plasmonic resonance intensity in metallic nanostructures plays a crucial role in charge generation and separation, directly affecting plasmon-induced photocatalytic activity. Engineering strategies to enhance plasmonic effects involve designing specific nanostructures, such as triangular nanoplates with sharp corners or dimer nanostructures with hot spots. However, these approaches often lead to a trade-off between enhanced plasmonic intensity and resonance energy, which ultimately determines local charge density and photocatalytic performance. Here, inspired by theoretical predications, it is shown that a flexibly controlled plasmonic photocatalyst, consisting of an ordered array of Au nanoparticles on a SrTiO3 surface, exhibits an enhanced surface plasmon resonance (SPR) intensity while maintaining a constant SPR resonant energy, due to the presence of surface lattice resonance. This trade-off results in improved charge separation efficiency and an increase in local charge density at catalytically active sites, as verified by theoretical simulations, surface photovoltage microscopy, and ultrafast transient absorption spectroscopy. Moreover, the optimized periodic photocatalyst shows a 7-fold increase in water oxidation activity over disordered nanostructures. This work provides a novel approach for balancing the intensity and energy of SPR, which will contribute to optimizing photocatalytic activity on plasmonic platforms.

Unlocking the catalytic potential of heterogeneous nonprecious metals for selective hydrogenation reactions

Selective hydrogenation has been employed extensively to produce value-added chemicals and fuels, greatly alleviating the problems of fossil resources and green synthesis. However, the design and synthesis of highly efficient catalysts, especially those that are inexpensive and abundant in the earth's crust, is still required for basic research and subsequent industrial applications. In recent years, many studies have revealed that the rational design and synthesis of heterogeneous catalysts can efficaciously improve the catalytic performance of hydrogenation reactions. However, the relationship between nonprecious metal catalysts and hydrogenation performance from the perspective of different catalytic systems still remains to be understood. In this review, we provide a comprehensive and systematic overview of the recent advances in the synthesis of nonprecious metal catalysts for heterogeneous selective hydrogenation reactions including thermocatalytic hydrogenation/transfer hydrogenation, photocatalytic hydrogenation and electrocatalytic reduction. In addition, we also aim to provide a clear picture of the recent design strategies and proposals for the nonprecious metal catalysed hydrogenation reactions. Finally, we discuss the current challenges and future research opportunities for the precise design and synthesis of nonprecious metal catalysts for selective hydrogenation reactions.

Swiss roll nanoarrays for chiral plasmonic photocatalysis

Manipulating the chirality at nanoscale has drawn great attention among scientists, considering its pivotal role in various applications of current interest, including nano-optics, biomedicine, and photocatalysis. In this work, we delve into this arena by fabricating chiral Swiss roll nanoarray (SRNA) continuous films employing colloidal lithography. The technique permits the dimension of Swiss roll metamaterials to reduce to nanoscale, thus achieving chiroptical response (circular dichroism (CD)) in the visible region. The interplay between the CD signals and plasmon resonance modes is revealed through theoretical simulations, enabling a deep understanding of chiral plasmonic metamaterials. The polarization-sensitive photocatalytic activity of chiral SRNAs is investigated, noting a marked increase in the reaction rate when the chirality of SRNAs matches with the handedness of circularly polarized light (CPL). Notably, the SRNA continuous films based on substrate possess integration and reusability without complex recycling process, enhancing their practicality in applications like sensing and plasmonic nanochemistry, particularly toward polarization-dependent photocatalysis.

Polytypic metal chalcogenide nanocrystals

By engineering chemically identical but structurally distinct materials into intricate and sophisticated polytypic nanostructures, which often surpass their pure phase objects and even produce novel physical and chemical properties, exciting applications in the fields of photovoltaics, electronics and photocatalysis can be achieved. In recent decades, various methods have been developed for synthesizing a library of polytypic nanocrystals encompassing IV, III-V and II-VI polytypic semiconductors. The exceptional performances of polytypic metal chalcogenide nanocrystals have been observed, making them highly promising candidates for applications in photonics and electronics. However, achieving high-precision control over the morphology, composition, crystal structure, size, homojunctions, and periodicity of polytypic metal chalcogenide nanostructures remains a significant synthetic challenge. This review article offers a comprehensive overview of recent progress in the synthesis and control of polytypic metal chalcogenide nanocrystals using colloidal synthetic strategies. Starting from a concise introduction on the crystal structures of metal chalcogenides, the subsequent discussion delves into the colloidal synthesis of polytypic metal chalcogenide nanocrystals, followed by an in-depth exploration of the key factors governing polytypic structure construction. Subsequently, we provide comprehensive insights into the physical properties of polytypic metal chalcogenide nanocrystals, which exhibit strong correlations with their applications. Thereafter, we emphasize the significance of polytypic nanostructures in various applications, such as photovoltaics, photocatalysis, transistors, thermoelectrics, stress sensors, and the electrocatalytic hydrogen evolution. Finally, we present a summary of the recent advancements in this research field and provide insightful perspectives on the forthcoming challenges, opportunities, and future research directions.

Selective hydrogenation of nitro compounds to amines by coupled redox reactions over a heterogeneous biocatalyst

Cleaner synthesis of amines remains a key challenge in organic chemistry because of their prevalence in pharmaceuticals, agrochemicals and synthetic building blocks. Here, we report a different paradigm for chemoselective hydrogenation of nitro compounds to amines, under mild, aqueous conditions. The hydrogenase enzyme releases electrons from H2 to a carbon black support which facilitates nitro-group reduction. For 30 nitroarenes we demonstrate full conversion (isolated yields 78 - 96%), with products including pharmaceuticals benzocaine, procainamide and mesalazine, and 4-aminophenol - precursor to paracetamol (acetaminophen). We also showcase gram-scale synthesis of procainamide with 90% isolated yield. We demonstrate potential for extension to aliphatic substrates. The catalyst is highly selective for reduction of the nitro group over other unsaturated bonds, tolerant to a wide range of functional groups, and exhibits excellent stability in reactions lasting up to 72 hours and full reusability over 5 cycles with a total turnover number over 1 million, indicating scope for direct translation to fine chemical manufacturing.

Shining light on the nitro group: distinct reactivity and selectivity

The nitro moiety is an indispensable functional group in organic synthesis due to its facile introduction and reduction to the corresponding amines for a plethora of organic transformations. Owing to its distinct electronegative and conventional properties, it has been used for activated aromatic nucleophilic substitution (SNAr) reactions, Smiles reactions, Henry reactions, acyl anion equivalents, etc. Recently, the excellent photochemical properties of nitroarenes have been rediscovered by several groups, and their untapped potential in organic synthesis under UV or visible light irradiation has been exploited. Photoexcited nitroarenes can undergo facile reduction to amines, azo-coupling, metal-free reductive C-N coupling with boronic acids via a 1,2-boronate shift, hydrogen atom transfer (HAT), oxygen atom transfer for anaerobic oxidation of organic molecules, molecular editing via nitrene intermediates, denitrative coupling of β-nitrostyrene, radical α-alkylation of nitroalkanes, etc. They have also been used as a photolabile protecting group in medicinal chemistry and chemical biology applications. Here, we summarise the recent findings on visible-light-mediated transformations involving nitro-containing organic molecules.

Synthesis of Photoresponsive Fast Self-healing Polyolefin Composites by Nickel-Catalyzed Copolymerization of Ethylene and Lignin Cluster Monomers

Polymers may suffer from sudden mechanical damages during long-term use under various harsh operating environments. Rapid and real-time self-healing will extend their service life, which is particularly attractive in the context of circular economy. In this work, a lignin cluster polymerization strategy (LCPS) was designed to prepare a series of lignin functionalized polyolefin composites with excellent mechanical properties through nickel catalyzed copolymerization of ethylene and lignin cluster monomers. These composites can achieve rapid self-healing within 30 seconds under a variety of extreme usage environments (underwater, seawater, extremely low temperatures as low as -60 °C, organic solvents, acid/alkali solvents, etc.), which is of great significance for real-time self-healing of sudden mechanical damage. More importantly, the dynamic cross-linking network within these composites enable great re-processability and amazing sealing performances.

Recent Progress Toward Electrocatalytic Conversion of Nitrobenzene

Despite that extensive efforts have been dedicated to the search for advanced catalysts to boost the electrocatalytic nitrobenzene reduction reaction (eNBRR), its progress is severely hampered by the limited understanding of the relationship between catalyst structure and its catalytic performance. Herein, this review aims to bridge such a gap by first analyzing the eNBRR pathway to present the main influential factors, such as electrolyte feature, applied potential, and catalyst structure. Then, the recent advancements in catalyst design for eNBRR are comprehensively summarized, particularly about the impacts of chemical composition, morphology, and crystal facets on regulating the local microenvironment, electron and mass transport for boosting catalytic performance. Finally, the future research of eNBRR is also proposed from the perspectives of performance enhancement, expansion of product scope, in-depth understanding of the reaction mechanism, and acceleration of the industrialization process through the integration of upstream and downstream technologies.

Efficient reduction-oxidation coupling degradation of nitroaromatic compounds in continuous flow processes

Nitroaromatic compounds (NACs) with electron-withdrawing nitro (-NO2) groups are typical refractory pollutants. Despite advanced oxidation processes (AOPs) being appealing degradation technologies, inefficient ring-opening oxidation of NACs and practical large-scale applications remain challenges. Here we tackle these challenges by designing a reduction-oxidation coupling (ROC) degradation process in LaFe0.95Cu0.05O3@carbon fiber cloth (LFCO@CFC)/PMS/Vis continuous flow system. Cu doping enhances the photoelectron transfer, thus triggering the -NO2 photoreduction and breaking the barriers in the ring opening. Also, it modulates surface electronic configuration to generate radicals and non-radicals for subsequent oxidation of reduction products. Based on this, the ROC process can effectively remove and mineralize NACs under the environmental background. More importantly, the LFCO catalyst outperformed most of the recently reported catalysts with lower cost (13.72 CNY/ton) and higher processing capacity (3600 t/month). Furthermore, the high scalability, material durability, and catalytic activity of LFCO@CFC under various realistic environmental conditions prove the potential ability for large-scale applications.

Electron transfer and energy exchange between a covalent organic framework and CuFeS2 nanoparticles

CuFeS2 is a prominent chalcogenide that possesses similar optical properties and a significantly lower cost, compared to gold. Additionally, covalent organic frameworks are a class of materials at the forefront of current research, mainly used as photoactive components and porous absorbers. Hence, in this work, hydrophilic CuFeS2 particles are coupled with multi-functional covalent organic frameworks through ionic bonding to produce a hybrid material with unique and optimized properties. To render the CuFeS2 particles negatively charged and dispersible in water, we coated them with sodium dodecyl sulfonate, shifting the surface plasmon resonance of the nanoparticles from 472 to 492 nm. When they are electrostatically assembled with the positively charged COFs, an S-scheme is formed and the fluorescence of the hybrid materials is highly quenched, with the electron transfer happening from the networks to the nanoparticles and a simultaneous energy exchange which is dependent on the emission wavelength. Through detailed fluorescence spectroscopy, time-resolved measurements and Stern-Volmer analysis, we identified an efficient emission quenching that differs from the bulk to the exfoliated hybrid system, while detailed electron microscopy studies demonstrated the strong interaction between the two components. The quenching mechanisms and the on or off surface resonance dependent lifetime could be applied to photocatalytic and photovoltaic applications.

Constructing Functional Radiation-Resistant Thorium Clusters for Catalytic Redox Reactions

When catalytic reactions are interfered with by radiation sources, thorium clusters are promising as potential catalysts due to their superior radiation resistance. However, there is currently very little research on the design synthesis and catalytic application of radiation-stable thorium clusters. In this work, we have elaborately engineered and fabricated three high-nuclear thorium cluster catalysts denoted as Th12L3-MA12, Th12L3-MA6-BF6, and Th12L3-Fcc12, which did not undergo any significant alterations in their molecular structures and compositions after irradiation with 690 kGy γ-rays. We systematically investigated the photocatalytic/thermocatalytic properties of these radiation-resistant thorium clusters for the first time and found that γ-rays could not alter their catalytic activities. In addition, it was found that ligand engineering could modulate the catalytic activity of thorium clusters, thus expanding the range of catalytic applications of thorium clusters, including reduction reactions (nitroarene reduction) and some oxidation reactions (N-heterocyclic oxidative dehydrogenation and diphenylmethane oxidation). Meanwhile, all of these organic transformation reactions achieved a >80% conversion and nearly 100% product selectivity. Radiation experiments combined with DFT calculations showed that the synergistic catalysis of thorium-oxo core and ligands led to the generation of specific active species (H+, O2•-, or tBuO/tBuOO•) and activation of substrate molecules, thus achieving superior catalytic performance. This work is not only the first to develop radiation-resistant thorium cluster catalysts to perform efficient redox reactions but also provides design ideas for the construction of high-nuclearity thorium clusters under mild conditions.

Condensed Matter Systems Exposed to Radiation: Multiscale Theory, Simulations, and Experiment

This roadmap reviews the new, highly interdisciplinary research field studying the behavior of condensed matter systems exposed to radiation. The Review highlights several recent advances in the field and provides a roadmap for the development of the field over the next decade. Condensed matter systems exposed to radiation can be inorganic, organic, or biological, finite or infinite, composed of different molecular species or materials, exist in different phases, and operate under different thermodynamic conditions. Many of the key phenomena related to the behavior of irradiated systems are very similar and can be understood based on the same fundamental theoretical principles and computational approaches. The multiscale nature of such phenomena requires the quantitative description of the radiation-induced effects occurring at different spatial and temporal scales, ranging from the atomic to the macroscopic, and the interlinks between such descriptions. The multiscale nature of the effects and the similarity of their manifestation in systems of different origins necessarily bring together different disciplines, such as physics, chemistry, biology, materials science, nanoscience, and biomedical research, demonstrating the numerous interlinks and commonalities between them. This research field is highly relevant to many novel and emerging technologies and medical applications.

Constructing High-Active Surface of Plasmonic Tungsten Oxide for Photocatalytic Alcohol Dehydration

Plasmonic semiconductors with broad spectral response hold significant promise for sustainable solar energy utilization. However, the surface inertness limits the photocatalytic activity. Herein, a novel approach is proposed to improve the body crystallinity and increase the surface oxygen vacancies of plasmonic tungsten oxide by the combination of hydrochloric acid (HCl) regulation and light irradiation, which can promote the adsorption of tert-butyl alcohol (TBA) on plasmonic tungsten oxide and overcome the hindrance of the surface depletion layer in photocatalytic alcohol dehydration. Additionally, this process can concentrate electrons for strong plasmonic electron oscillation on the near surface, facilitating rapid electron transfer within the adsorbed TBA molecules for C-O bond cleavage. As a result, the activation barrier for TBA dehydration is significantly reduced by 93% to 6.0 kJ mol-1, much lower than that of thermocatalysis (91 kJ mol-1). Therefore, an optimal isobutylene generation rate of 1.8 mol g-1 h-1 (selectivity of 99.9%) is achieved. A small flow reaction system is further constructed, which shows an isobutylene generation rate of 12 mmol h-1 under natural sunlight irradiation. This work highlights the potential of plasmonic semiconductors for efficient photocatalytic alcohol dehydration, thereby promoting the sustainable utilization of solar energy.

Hollow g-C3N4@Ag3PO4 Core-Shell Nanoreactor Loaded with Au Nanoparticles: Boosting Photothermal Catalysis in Confined Space

Low solar energy utilization efficiency and serious charge recombination remain major challenges for photocatalytic systems. Herein, a hollow core-shell Au/g-C3N4@Ag3PO4 photothermal nanoreactor is successfully prepared by a two-step deposition method. Benefit from efficient spectral utilization and fast charge separation induced by the unique hollow core-shell heterostructure, the H2 evolution rate of Au/g-C3N4@Ag3PO4 is 16.9 times that of the pristine g-C3N4, and the degradation efficiency of tetracycline is increased by 88.1%. The enhanced catalytic performance can be attributed to the ordered charge movement on the hollow core-shell structure and a local high-temperature environment, which effectively accelerates the carrier separation and chemical reaction kinetics. This work highlights the important role of the space confinement effect in photothermal catalysis and provides a promising strategy for the development of the next generation of highly efficient photothermal catalysts.

Iron-Based Catalysts with Oxygen Vacancies Obtained by Facile Pyrolysis for Selective Hydrogenation of Nitrobenzene

The development of preparation strategies for iron-based catalysts with prominent catalytic activity, stability, and cost effectiveness is greatly significant for the field of catalytic hydrogenation but still remains challenging. Herein, a method for the preparation of iron-based catalysts by the simple pyrolysis of organometallic coordination polymers is described. The catalyst Fe@C-2 with sufficient oxygen vacancies obtained in specific coordination environment exhibited superior nitro hydrogenation performance, acid resistance, and reaction stability. Through solvent effect experiments, toxicity experiments, TPSR, and DFT calculations, it was determined that the superior activity of the catalyst was derived from the contribution of sufficient oxygen vacancies to hydrogen activation and the good adsorption ability of FeO on substrate molecules.

Zr-Based MOF-Stabilized CO2-Responsive Pickering Emulsions for Efficient Reduction of Nitroarenes

A Pickering emulsion is a natural microreactor for interfacial catalysis in which an emulsifier is critical. Recently, a metal-organic framework (MOF) has attracted attention to emulsify water-organic mixtures for constructing a Pickering emulsion. However, a few stimuli-responsive Pickering emulsions based on MOFs have been reported, and the MOF emulsifiers cannot be regenerated at room temperature. Herein, the Zr-MOF with a rodlike morphology is synthesized using ionic liquid as a modulator and then modified with n-(trimethoxysilylpropyl)imidazole (C3im) to prepare a series of functionalized Zr-MOFs (MOF-C3im). It is found that MOF-C3im is an excellent emulsifier to construct stable and CO2-responsive Pickering emulsions even at low content (>0.20 wt %). Notably, the emulsification and demulsification of the emulsions can be easily and reversibly switched by bubbling of CO2 and N2 alternatively at room temperature because CO2 and imidazole molecules anchored on the Zr-MOF underwent a reversible acid-base reaction, resulting in an obvious change in the wettability of the emulsifier. As a proof of concept, the reduction reactions of nitrobenzene have been successfully carried out in these Pickering emulsions, demonstrating the efficient integration as a microreactor for chemical reaction, product separation, and emulsifier recycling under ambient conditions. This strategy provides an innovative option to develop stimulus-responsive Pickering emulsions for sustainable chemical processes.

Visible-Light-Driven Selective Hydrogenation of Nitrostyrene over Layered Ternary Sulfide Nanostructures

Selective hydrogenation of nitrostyrenes is a great challenge due to the competitive activation of the nitro groups (─NO2 ) and carbon-carbon (C═C) double bonds. Photocatalysis has emerged as an alternative to thermocatalysis for the selective hydrogenation reaction, bypassing the precious metal costs and harsh conditions. Herein, two crystalline phases of layered ternary sulfide Cu2 WS4 , that is, body-centered tetragonal I-Cu2 WS4 nanosheets and primitive tetragonal P-Cu2 WS4 nanoflowers, are controlled synthesized by adjusting the capping agents. Remarkably, these nanostructures show visible-light-driven photocatalytic performance for selective hydrogenation of 3-nitrostyrene under mild conditions. In detail, the I-Cu2 WS4 nanosheets show excellent conversion of 3-nitrostyrene (99.9%) and high selectivity for 3-vinylaniline (98.7%) with the assistance of Na2 S as a hole scavenger. They also can achieve good hydrogenation selectivity to 3-ethylnitrobenzene (88.5%) with conversion as high as 96.3% by using N2 H4 as a proton source. Mechanism studies reveal that the photogenerated electrons and in situ generated protons from water participate in the former hydrogenation pathway, while the latter requires the photogenerated holes and in situ generated reactive oxygen species to activate the N2 H4 to form cis-N2 H2 for further reduction. The present work expands the rational synthesis of ternary sulfide nanostructures and their potential application for solar-energy-driven organic transformations.

Highly Efficient Iron-Based Catalyst for Light-Driven Selective Hydrogenation of Nitroarenes

Light-driven hydrogenation of nitro compounds to functionalized amines is of great importance yet a challenge for practical applications, which calls for the development of high-performance, nonprecious photocatalysts and efficient catalytic systems. Herein, we report a high-efficiency Fe3O4@TiO2 photocatalyst via a sol-gel and subsequent pyrolysis strategy, which exhibits desirable photothermal hydrogenation performance of nitro compounds to functionalized amines with the excellent selectivity of >90% exceeding those of the state-of-the-art heterogeneous photocatalysts. Our experimental results and theoretical calculations for the first time reveal that Fe3O4 is the major active phase, and the strong metal-support interaction between Fe3O4 and reducible TiO2 further leads to performance improvement, taking advantage of the enhanced photothermal effect and the improved adsorption for the reactant and hydrazine hydrate. Notably, a variety of halonitrobenzenes and pharmaceutical intermediates can be completely converted to functionalized amines with high selectivities, even in gram-scale reactions. This work provides a new insight into the rational design of nonprecious photo/thermo-catalysts for other catalytic reactions.

Visible-light-induced iron-catalyzed reduction of nitroarenes to anilines

An efficient visible-light-induced iron-catalyzed reduction of nitroarenes to anilines by using N-ethylmorpholine (NEM) as a reductant under mild conditions has been developed. The reaction proceeds with photosensitizer-free conditions and features good to excellent yields and broad functional group tolerance. Preliminary mechanistic investigations showed that this reaction was conducted via ligand-to-metal (NEM to Fe3+) charge transfer and nitro triplet biradical-induced hydrogen atom transfer processes.

Reinforcing the Efficiency of Photothermal Catalytic CO2 Methanation through Integration of Ru Nanoparticles with Photothermal MnCo2O4 Nanosheets

Carbon dioxide (CO2) hydrogenation to methane (CH4) is regarded as a promising approach for CO2 utilization, whereas achieving desirable conversion efficiency under mild conditions remains a significant challenge. Herein, we have identified ultrasmall Ru nanoparticles (∼2.5 nm) anchored on MnCo2O4 nanosheets as prospective photothermal catalysts for CO2 methanation at ambient pressure with light irradiation. Our findings revealed that MnCo2O4 nanosheets exhibit dual functionality as photothermal substrates for localized temperature enhancement and photocatalysts for electron donation. As such, the optimized Ru/MnCo2O4-2 gave a high CH4 production rate of 66.3 mmol gcat-1 h-1 (corresponding to 5.1 mol gRu-1 h-1) with 96% CH4 selectivity at 230 °C under ambient pressure and light irradiation (420-780 nm, 1.25 W cm-2), outperforming most reported plasmonic metal-based catalysts. The mechanisms behind the intriguing photothermal catalytic performance improvement were substantiated through a comprehensive investigation involving experimental characterizations, numerical simulations and density functional theory (DFT) calculations, which unveiled the synergistic effects of enhanced charge separation efficiency, improved reaction kinetics, facilitated reactant adsorption/activation and accelerated intermediate conversion under light irradiation over Ru/MnCo2O4. A comparison study showed that, with identical external input energy during the reaction, Ru/MnCo2O4-2 had a much higher catalytic efficiency compared to Ru/TiO2 and Ru/Al2O3. This study underscores the pivotal role played by photothermal supports and is believed to engender a heightened interest in plasmonic metal nanoparticles anchored on photothermal substrates for CO2 methanation under mild conditions.

Plasmon-Induced Radical-Radical Heterocoupling Boosts Photodriven Oxidative Esterification of Benzyl Alcohol over Nitrogen-Doped Carbon-Encapsulated Cobalt Nanoparticles

Selective oxidation of alcohols under mild conditions remains a long-standing challenge in the bulk and fine chemical industry, which usually requires environmentally unfriendly oxidants and bases that are difficult to separate. Here, a plasmonic catalyst of nitrogen-doped carbon-encapsulated metallic Co nanoparticles (Co@NC) with an excellent catalytic activity towards selective oxidation of alcohols is demonstrated. With light as only energy input, the plasmonic Co@NC catalyst effectively operates via combining action of the localized surface-plasmon resonance (LSPR) and the photothermal effects to achieve a factor of 7.8 times improvement compared with the activity of thermocatalysis. A high turnover frequency (TOF) of 15.6 h-1 is obtained under base-free conditions, which surpasses all the reported catalytic performances of thermocatalytic analogues in the literature. Detailed characterization reveals that the d states of metallic Co gain the absorbed light energy, so the excitation of interband d-to-s transitions generates energetic electrons. LSPR-mediated charge injection to the Co@NC surface activates molecular oxygen and alcohol molecules adsorbed on its surface to generate the corresponding radical species (e.g., ⋅O2 - , CH3 O⋅ and R-⋅CH-OH). The formation of multi-type radical species creates a direct and forward pathway of oxidative esterification of benzyl alcohol to speed up the production of esters.

Photothermal Conversion by Carbon Black Facilitates Aryl Migration by Photon-Promoted Temperature Gradients

The Newman Kwart Rearrangement (NKR) offers an efficient and high-yielding method for producing substituted thiophenols from phenols. While an industrially important protocol, it suffers from high activation energy barriers (35-43 kcal/mol), requiring the use of extreme temperatures (>200 °C) and specialty equipment. This report details a highly efficient and straightforward method for facilitating the NKR using photothermal conversion. This underused, unique reactivity pathway arises from the irradiation of nanomaterials that relax via a non-radiative decay pathway to generate intense thermal gradients. We show carbon black (CB) can be an inexpensive and abundant photothermal agent under visible light irradiation to achieve a facile NKR under mild conditions. The scope includes a wide array of stereo- and electronically diverse substrates with increasing difficulty of rearrangement, including BHT and BINOL as effective substrates. Furthermore, we demonstrate the unique application for temporal control in a thermal reaction and tunability of thermal gradients by modulating light intensity. Ultimately, photothermal conversion enables high-temperature reactions with simple, visible light irradiation.

Versatile synthesis of nano-icosapods via cation exchange for effective photocatalytic conversion of biomass-relevant alcohols

Branched metal chalcogenide nanostructures with well-defined composition and configuration are appealing photocatalysts for solar-driven organic transformations. However, precise design and controlled synthesis of such nanostructures still remain a great challenge. Herein, we report the construction of a variety of highly symmetrical metal sulfides and heterostructured icosapods based on them, in which twenty branches were radially grown in spatially ordered arrangement, with a high degree of structure homogeneity. Impressively, the as-obtained CdS-PdxS icosapods manifest a significantly improved photocatalytic activity for the selective oxidation of biomass-relevant alcohols into corresponding aldehydes coupled with H2 evolution under visible-light irradiation (>420 nm), and the apparent quantum yield of the benzyl alcohol reforming can be achieved as high as 31.4% at 420 nm. The photoreforming process over the CdS-PdxS icosapods is found to be directly triggered by the photogenerated electrons and holes without participation of radicals. The enhanced photocatalytic performance is attributed to the fast charge separation and abundant active sites originating from the well-defined configuration and spatial organization of the components in the branched heterostructures.

Broadband and Spectrally Selective Photothermal Conversion through Nanocluster Assembly of Disordered Plasmonic Metasurfaces

Plasmonic metasurfaces have been realized for efficient light absorption, thereby leading to photothermal conversion through nonradiative decay of plasmonic modes. However, current plasmonic metasurfaces suffer from inaccessible spectral ranges, costly and time-consuming nanolithographic top-down techniques for fabrication, and difficulty of scale-up. Here, we demonstrate a new type of disordered metasurface created by densely packing plasmonic nanoclusters of ultrasmall size on a planar optical cavity. The system either operates as a broadband absorber or offers a reconfigurable absorption band right across the visible region, resulting in continuous wavelength-tunable photothermal conversion. We further present a method to measure the temperature of plasmonic metasurfaces via surface-enhanced Raman spectroscopy (SERS), by incorporating single-walled carbon nanotubes (SWCNTs) as an SERS probe within the metasurfaces. Our disordered plasmonic system, generated by a bottom-up process, offers excellent performance and compatibility with efficient photothermal conversion. Moreover, it also provides a novel platform for various hot-electron and energy-harvesting functionalities.

Transition Metal-free Selenium-mediated Aryl Amines via Reduction of Nitroarenes

A scalable and operationally simple on water seleno-mediated reduction of nitroarenes to the respective aryl amines with NaBH4 is described. The reaction proceeds under transition metal-free conditions and is promoted by the formation of Na2 Se, which is the effective reducing agent involved in the mechanism. This mechanistic information enabled the development of a mild NaBH4 -free protocol for the selective reduction of nitro derivatives bearing labile moieties, including nitrocarbonyl compounds. The selenium-containing aqueous phase can be successfully reused up to four reduction cycles, thus further improving the efficiency of the protocol disclosed.

Heterogeneous V2O5/TiO2-Mediated Photocatalytic Reduction of Nitro Compounds to the Corresponding Amines under Visible Light

The hydrogenation of nitro compounds to their corresponding amines is developed using a heterogeneous and recyclable catalyst (V₂O₅/TiO₂) under irradiation of blue LED (9 W) at ambient temperature. Hydrazine hydrate is used as a reductant and ethanol is used as a solvent, facilitating green, sustainable, low-cost production. The synthesis of 32 (hetero)arylamines and their pharmaceutically relevant molecules (five) are described. Significant features of the protocol include catalyst recyclability, green solvent, ambient temperature, and gram-scale reactions. Among the other aspects studied are ¹H-NMR-assisted reaction progress monitoring, control experiments for mechanistic studies, protocol applications, and recyclability studies. Furthermore, the developed protocol enabled wide functional group tolerance, chemo-selectivity, high yield, and low-cost, sustainable, and environmentally benign synthesis.

Observation of Charge Separation Enhancement in Plasmonic Photocatalysts under Coupling Conditions

Surface plasmon resonance-induced charge separation plays key roles in plasmon-related applications, especially in photocatalysis and photovoltaics. Plasmon coupling nanostructures exhibit extraordinary behaviors in hybrid states, phonon scattering, and ultrafast plasmon dephasing, but plasmon-induced charge separation in these materials remains unknown. Here, we design Schottky-free Au nanoparticle (NP)/NiO/Au nanoparticles-on-a-mirror plasmonic photocatalysts to support plasmon-induced interfacial hole transfer, evidenced by surface photovoltage microscopy at the single-particle level. In particular, we observe a nonlinear increase in charge density and photocatalytic performance with an increase in excitation intensity in plasmonic photocatalysts containing hot spots as a result of varying the geometry. Such charge separation increased the internal quantum efficiency by 14 times at 600 nm in catalytic reactions as compared to that of the Au NP/NiO without a coupling effect. These observations provide an improved understanding of charge transfer management and utilization by geometric engineering and interface electronic structure for plasmonic photocatalysis.

Oxidation of Pharmaceuticals by Ferrate(VI)-Amino Acid Systems: Enhancement by Proline

The occurrence of micropollutants in water threatens public health and ecology. Removal of micropollutants such as pharmaceuticals by a green oxidant, ferrate(VI) (FeVIO42-, Fe(VI)) can be accomplished. However, electron-deficient pharmaceuticals, such as carbamazepine (CBZ) showed a low removal rate by Fe(VI). This work investigates the activation of Fe(VI) by adding nine amino acids (AA) of different functionalities to accelerate the removal of CBZ in water under mild alkaline conditions. Among the studied amino acids, proline, a cyclic AA, had the highest removal of CBZ. The accelerated effect of proline was ascribed by demonstrating the involvement of highly reactive intermediate Fe(V) species, generated by one-electron transfer by the reaction of Fe(VI) with proline (i.e., Fe(VI) + proline → Fe(V) + proline•). The degradation kinetics of CBZ by a Fe(VI)-proline system was interpreted by kinetic modeling of the reactions involved that estimated the rate of the reaction of Fe(V) with CBZ as (1.03 ± 0.21) × 106 M-1 s-1, which was several orders of magnitude greater than that of Fe(VI) of 2.25 M-1 s-1. Overall, natural compounds such as amino acids may be applied to increase the removal efficiency of recalcitrant micropollutants by Fe(VI).

Edge-oriented phosphatizing engineering of 2D Ni-MOFs with a tailored d-band center for boosting catalytic activity

Metal-organic framework (MOF)-based heterostructures have aroused widespread interest owing to their extensive compositional tunability and interesting catalytic properties. However, the precise edge-oriented growth of transition metal compounds at the edges of 2D MOFs to construct edge mode heterostructures remains a great challenge due to their inherent thermodynamic instability. Here, edge-oriented growth of Ni₂P at the edges of a 2D Ni-MOF was achieved for the first time by precisely tuning the phosphorus source content and phosphating temperature. Owing to the formation of the edge mode Ni-MOF/Ni₂P heterostructure, the as-prepared heterostructure showed upregulated d-band center, more robust 4-nitrophenol (4-NP) adsorption capacity, lowered energy barrier of the rate-determining step (RDS), and higher specific surface area, resulting in the best performance of the hydrogenation reduction of 4-NP to 4-aminophenol (4-AP) in the presence of non-precious metal catalysts.

In situ utilization of photogenerated hydrogen for hydrogenation reaction over a covalent organic framework

A fully sp²-carbon conjugated COF (Py-FTP-COF) was designed and synthesized, exhibiting excellent hydrogen evolution rate of 5.22 mmol g^-1 h^-1. More importantly, in situ hydrogenation of nitroarenes under visible-light irradiation without any additional hydrogen source was successfully accomplished for the first time over COF-based materials.

Visible-Light-Driven Porphyrin-Based Bimetallic Metal-Organic Frameworks for Selective Photoreduction of Nitro Compounds under Mild Conditions

Selective reduction of nitroaromatics to the corresponding amines generally requires complex conditions, involving pressurized hydrogen, higher temperatures, or organic acids. In this work, we successfully prepared a series of porphyrin-based MOF photocatalysts (Pd-PMOFs, In-PMOFs, and In/Pd-PMOFs) via a facile solvothermal method for the efficient selective reduction of nitroaromatics to corresponding anilines with deionized water as the hydrogen donor. Being a new structured material (monoclinic, C₅₂H₄₀InN₆O₈Pd), on account of the abundant pore channels, strong light absorption capability, well-matched bandgap, as well as the coordination of indium ions and palladium ions, In/Pd-MOFs have excellent migration efficiency of photo-induced electrons and holes. Specifically, the In/Pd-PMOF photocatalyst manifested superior conversion (100%) and selectivity (≥80%) toward the screened nitro compounds under mild conditions. This work avoids the use of strong reductants, organic acids, and pressurized hydrogen gas as hydrogen sources, providing a promising concept for developing green catalytic systems.

EDA mediated S-N bond coupling of nitroarenes and sodium sulfinate salts

Despite their long-known photochemical properties and their industrial value, the use of nitroarenes as a productive photochemical handle in organic synthesis has remained relatively unexplored. More specifically, the photochemical formation of nitrogen-sulfur bonds from nitroarenes remains to be demonstrated. Herein, we report the design and application of a sulfinate-nitroarene electron donor-acceptor (EDA) complex and its subsequent use in the first light mediated catalyst-free synthesis of N-hydroxy-sulfonamides. The presence of the EDA was assessed spectroscopically and studied via DFT and TD-DFT calculations. A total of 32 examples including both electron withdrawing and electron donating groups were synthesized under our oxygen- and water-tolerant conditions.

Stepwise Coordination-Driven Metal-Phenolic Nanoparticle as a Neuroprotection Enhancer for Alzheimer's Disease Therapy

Current therapeutic strategies for Alzheimer's disease (AD) mainly focus on inhibition of aberrant amyloid-β peptide (Aβ) aggregation. However, these strategies cannot repair the side symptoms (e.g., high neuronal oxidative stress) triggered by Aβ accumulation and thus show limited effects on suppressing Aβ-induced neuronal apoptosis. Herein, we develop a stepwise metal-phenolic coordination approach for the rational design of a neuroprotection enhancer, K8@Fe-Rh/Pda NPs, in which rhein and polydopamine are effectively coupled to enhance the treatment of AD in APPswe/PSEN1dE9 transgenic (APP/PS1) mice. We discover that the polydopamine inhibits the aggregation of Aβ oligomers, and rhein helps repair damage to neurons triggered by Aβ aggregation. Based on molecular docking, we demonstrate that the polydopamine has a strong interaction with Aβ monomers/fibrils through its multiple recognition sites (e.g., catechol groups, imine groups, and indolic/catecholic π-systems), thereby reducing Aβ burden. Further investigation of the antioxidant mechanisms suggests that K8@Fe-Rh/Pda NPs promote the mitochondrial biogenesis via activating the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator 1-alpha pathway. This finally inhibits neuronal apoptosis. Moreover, an intravenous injection of these nanoparticles potently improves the cognitive function in APP/PS1 mice without adverse effects. Overall, our work provides a promising approach to develop advanced nanomaterials for multi-target treatment of AD.

Sulfur Vacancy-Rich Amorphous Rh Metallene Sulfide for Electrocatalytic Selective Synthesis of Aniline Coupled with Efficient Sulfion Degradation

The construction of efficient and stable electrocatalysts is of widespread research significance for electrocatalytic coupling reactions. Herein, an amorphous Rh metallene sulfide with sulfur-rich vacancies (a-RhS_2-x metallene) is synthesized for the cathodic nitrobenzene (Ph-NO₂) electroreduction reaction (ERR) to aniline (Ph-NH₂) coupled with the anodic sulfur ion (S^2-) oxidation reaction (SOR) in a coelectrolysis system. On the one hand, the amorphous Rh metallene structure can provide enough of a reactive site. On the other hand, the amorphization and the introduced S vacancies can generate rich defects and ligand unsaturated sites to improve the intrinsic activity of the active sites. Due to these advantages, the a-RhS_2-x metallene exhibits superior electrocatalytic performance for Ph-NO₂ ERR and SOR. Inspiringly, in the assembled electrocatalytic coupling system, the required overpotential is only 0.442 V at 10 mA cm^-2 to drive the cathodic Ph-NO₂ ERR and anodic SOR, which allows for promising energy-efficient electrolysis to generate high value-added chemicals.

Plasmonic reactivity of halogen thiophenols on gold nanoparticles studied by SERS and XPS

Localized surface plasmon resonances on noble metal nanoparticles (NPs) can efficiently drive reactions of adsorbed ligand molecules and provide versatile opportunities in chemical synthesis. The driving forces of these reactions are typically elevated temperatures, hot charge carriers or enhanced electric fields. In the present work the dehalogenation of halogenated thiophenols on the surface of AuNPs has been studied by surface enhanced Raman scattering (SERS) as a function of the photon energy to track the kinetics and identify reaction products. Reaction rates are found to be surprisingly similar for the different halothiophenols studied here, although the bond dissociation energies of the C-X bonds differ significantly. Complementary information about the electronic properties at the AuNP surface, namely work-function and valence band states, have been determined by X-ray photoelectron spectroscopy (XPS) of isolated AuNPs in the gas-phase. In this way, it is revealed how the electronic properties are altered by the adsorption of the ligand molecules, and we conclude that the reaction rates are mainly determined by the plasmonic properties of the AuNPs. SERS spectra reveal differences in the reaction product formation for the different halogen species and on this basis the possible reaction mechanisms are discussed to approach an understanding of opportunities and limitations in the design of catalytical systems with plasmonic NPs.

Cobalt nanoparticles supported on microporous nitrogen-doped carbon for efficient catalytic transfer hydrogenation reaction between nitroarenes and N-heterocycles

Catalytic transfer hydrogenation reaction between nitroarenes and saturated N-heterocycles to simultaneously synthesize value-added anilines and unsaturated N-heterocycles is attractive due to its low-cost, atomic economic, and environmental-friendly properties. Herein, we...