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The atomically dispersed metal is expected as one of the most promising Fenton‐like catalysts for the degradation of recalcitrant organic pollutants (ROPs) by the strong "electronic metal–support interactions" (EMSIs). Here, we develop an atomically dispersed metal–atom alloy made by guest Au atoms substitute host V atoms in the two‐dimensional VO2(B) nanobelt support (Au/VO2) to activate Fenton‐like oxidation for elimination of ROPs. The 2D nanobelt structure enlarges the exposure of atomically Au thus increasing the number of active sites to absorb more S2O82− ions. And the EMSIs regulate the charge density in Au atoms to present positive charge Au+, lowering the energy barrier of S2O82− decomposition to produce SO4.−. The Au/VO2 catalyst possesses excellent durable and reliable characteristics and exhibits record‐breaking efficiency with TOF as high as 21.42 min−1, 16.19 min−1, and 80.89 min−1 for rhodamine, phenol, and bisphenol A degradation, respectively. [ABSTRACT FROM AUTHOR]

We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(I) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(I) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type. [ABSTRACT FROM AUTHOR]

Au nanoparticles (NPs) have been found to be excellent glucose oxidase mimics, while the catalytic processes have rarely been studied. Here, we reveal that the process of glucose oxidation catalyzed by Au NPs is as the same as that of natural glucose oxidase, namely, a two-step reaction including the dehydrogenation of glucose and the subsequent reduction of O2 to H2O2 by two electrons. Pt, Pd, Ru, Rh, and Ir NPs can also catalyze the dehydrogenation of glucose, except that O2 is preferably reduced to H2O. By the electron transfer feature of noble metal NPs, we overcame the limitation that H2O2 must be produced in the traditional two-step glucose assay and realize the rapid colorimetric detections of glucose. Inspired by the electron transport pathway in the catalytic process of natural enzymes, noble metal NPs have also been found to mimic various enzymatic electron transfer reactions including cytochrome c, coenzymes as well as nitrobenzene reductions. Gold nanoparticles (Au NPs) with enzyme-like activities are useful glucose oxidase mimics, but the insights into the mechanism of this reaction are limited. Here, the authors show that the process of glucose oxidation by Au NPs is analogous to the one catalysed by glucose oxidase, involving dehydrogenation and oxygen reduction to H2O2; and that other noble metal NPs also catalyse glucose dehydrogenation, but oxygen is preferably reduced to water. [ABSTRACT FROM AUTHOR]

The renewable-electricity-powered CO2 electroreduction reaction provides a promising means to store intermittent renewable energy in the form of valuable chemicals and dispatchable fuels. Renewable methane produced using CO2 electroreduction attracts interest due to the established global distribution network; however, present-day efficiencies and activities remain below those required for practical application. Here we exploit the fact that the suppression of *CO dimerization and hydrogen evolution promotes methane selectivity: we reason that the introduction of Au in Cu favors *CO protonation vs. C−C coupling under low *CO coverage and weakens the *H adsorption energy of the surface, leading to a reduction in hydrogen evolution. We construct experimentally a suite of Au-Cu catalysts and control *CO availability by regulating CO2 concentration and reaction rate. This strategy leads to a 1.6× improvement in the methane:H2 selectivity ratio compared to the best prior reports operating above 100 mA cm−2. We as a result achieve a CO2-to-methane Faradaic efficiency (FE) of (56 ± 2)% at a production rate of (112 ± 4) mA cm−2. The electroreduction of CO2 offers a promising approach to produce carbon-neutral methane using renewable electricity. This study shows that the introduction of Au in Cu enables selective methane production from CO2 by regulating *CO availability. [ABSTRACT FROM AUTHOR]

The catalytic activity of the size-selected gold clusters Au38(SCH2CH2Ph)24 (abbreviated with Au38) in 3-D nanoporous Ce-metal–organic framework (Ce–UiO-66) was studied. The Au38 nanoclusters were in situ immersed in Ce–UiO-66 with a loading percentage of 1 wt%. The Au38@Ce–UiO-66 catalyst demonstrated excellent catalytic activity for aerobic oxidation of cinnamyl alcohol. The oxidation reaction was tested from 40 to 100 °C utilizing O2 gas (30 ml min−1) as an oxidizing agent in atmospheric pressure. 0.1 mol% of the Au38@Ce–UiO-66 catalyst achieved 65% cinnamyl alcohol conversion at 100 °C within an hour with 100% selectivity toward cinnamaldehyde in toluene. In the case of using an aqueous solvent instead of an organic solvent (toluene), the conversion was increased to 75% under the same reaction condition. The cinnamyl alcohol conversion was increased gradually by increasing the reaction time over Au38@Ce–UiO-66 catalyst, where the conversion was enhanced to 93% after 5 h of heating at 100 °C in water. The catalytic activity of the Au38@Ce–UiO-66 catalyst was largely enhanced after oxygen thermal pretreatment at 100–200 °C, where the catalyst achieved 990 h−1 turnover frequency (TOF) after O2-pretreatment at 175 °C with 92% cinnamaldehyde and 8% cinnamic acid selectivity. The unique atomic packing structure and electronic properties of the size-selected gold nanoclusters (Au38) are responsible for their extraordinary catalytic activity. Moreover, the support (Ce–UiO-66) has a big role in the catalyst activity, since it has a high ability to absorb large quantities from oxygen on the Ce(III)/Ce(IV) centers and generate active oxygen species such as superoxo and peroxo species on the catalyst surface, which help in oxidation of cinnamyl alcohol. For comparison, gold nanoparticles were loaded over the same support, where the Au(III) ions were reduced by two different reduction methods utilizing NaBH4 in the absence of the ligand and hydrogen reduction at 200 °C, 4 h. The particle size of the Au38 clusters and gold nanoparticles over Ce–UiO-66 was investigated by a high-resolution transmission electron microscope (HR-TEM). The charge of the gold clusters and nanoparticles was zero as confirmed by X-ray photoelectron spectroscopy (XPS). The crystallinity and surface texture properties of the prepared catalysts and the pure support were measured by powder X-ray diffraction analysis and N2 gas sorption isotherm at − 196 °C, respectively. [ABSTRACT FROM AUTHOR]

Oxidation of a mixture of glucose and arabinose over Au particles deposited on porous carbons, N-doped carbons and carbon nitrides was investigated at 70 °C, under constant pH of 8, and oxygen partial pressure 0.125 atm. In particular, Au deposited on nitrogen-containing carbon-based mesoporous structures demonstrated activity in the oxidation of the sugars to the corresponding aldonic acids higher than gold deposited on undoped carbon supports (conversion of glucose up to ca. 60%, arabinose–ca. 30% after 200 min). The results can be explained by the basic nature of the supports leading to an increase in the polarity of the carbon surface and the oxygen activation. Glucuronic acid (with selectivity ca. 10–93.5%) together with gluconic acid was formed as a result of glucose oxidation, while arabinose was selectively oxidized to arabinonic acid. [ABSTRACT FROM AUTHOR]

A novel and highly efficient heterogeneous gold(I)-catalyzed hydroamination of allenamides with arylamines has been developed that proceeds effectively under mild conditions and offers a general and practical route for the synthesis of allylamino E-enamides with good to excellent yields and high stereoselectivity. The supported gold(I) catalyst can be reused at least seven times without any apparent decrease in the catalytic activity. [ABSTRACT FROM AUTHOR]

This work shows the biosynthesis of gold clusters and nanoparticles (AuNPs) from a solution of gold in a mixture of ammonium chloride and nitric acid treated with two different Mexican plants extracts, Toad Leaf (Eryngium heterophyllum, SF) and Cuachalalate (Amphipterygium adstringens, CF) as bioreductants. Subsequently, the gold entities were supported on the ordered mesoporous material SBA-15 functionalized with mercaptopropyl groups (1.6 wt% of sulphur). The gold contents were 0.7 wt% and 1.1 wt% for the CF and SF samples, respectively. UV–vis spectroscopy and TEM show the presence of gold nanoclusters in both samples, while very minor amount of AuNPs is detected only in the sample with the highest Au content (SF). The Au/SBA-15 materials are active in the aerobic oxidation of cyclohexene at 65 °C and atmospheric pressure. Two of the catalytic reaction products come from the addition of oxygen to the double bond of cyclohexene: cyclohexene epoxide and cyclohexanediol, while the other three come from allylic oxidation of the ring, which is the major reaction pathway: 2-cyclohexen-1-ol, 2-cyclohexen-1-one and 2-cyclohexenyl hydroperoxide, being the two first the major stable reaction products, while the enone/enol ratio is nearly 2. It has been found that the gold nanoclusters initially present in the catalysts evolve toward AuNPs during catalytic reaction. [ABSTRACT FROM AUTHOR]

The front cover of the journal "Advanced Synthesis & Catalysis" features an illustration of pandas as gold catalysts on trees, representing the 5¿exo¿dig¿selective cyclization of ¿,ß¿ynones. The illustration highlights the synthesis of 2¿exomethylene indolin¿3¿ones, which can be used to create spiropseudoindoxyl and pyranoindole derivatives. The image suggests that these synthetic materials could have potential applications in the development of new bioactive substances. The details of this research can be found in an article by Tsuyoshi Yamada and co-authors. [Extracted from the article]

DEDMS-silylation induced reduction of zeolite surface hydroxyl (z-OH) groups on USY affects the selective oxidation of benzyl alcohol to benzaldehyde over Au/USY-1 catalysts by altering adsorption effect. [Display omitted] • More Al-associated zeolite hydroxyl groups more strongly adsorb benzyl alcohols. • Stronger adsorption capacity boosted Au-catalyzed conversions of benzyl alcohol. • Diethoxydimethylsilane silylation reduced surface –OH in Al-O(H)-Si and Al-OH. • FT-IR and in-situ DRIFT results proved change in adsorption ability and acidity. Metal-zeolites catalysts are of great importance in selective organic conversions. Zeolites possess features of highly-ordered porous network, adjustable acidic properties (Brønsted/Lewis), spatial nanoconfinement effects, unique shape selectivity and the strong (hydrothermal-) stability. The role of zeolite hydroxyl (z-OH) groups, such as bridging ones in Si-O(H)-Al (B acids) and terminal ones in Al-OH and Si-OH (silanols), in catalysis is an interesting topic, particularly when they are not catalytic active sites, while they affect the catalytic performances. This study comprehensively investigated series of Au/USY catalysts in the selective oxidation of benzyl alcohol to benzaldehyde and clarified the dominating contributions of Al-associated z-OH groups to affecting catalytic conversions and selectivity via altering the Si/Al ratio and reducing z-OH groups by amorphous silica species derived from diethoxydimethylsilane under high-temperature calcination. The catalysts were characterized by XRD, BET, TEM, XPS, UV/Vis, FT-IR and in-situ DRIFT to investigate crystal structures, textural properties, morphologies, size distribution, chemical state of gold, acidity, and adsorptive properties. The experimental results proved that zeolites with a higher amount of z-OH groups tuned by Si/Al ratios or by diethoxydimethylsilane silylation exhibited higher catalytic activity because of the adsorption effect. Finally, a possible mechanism was discussed based on the experimental results and literature. [ABSTRACT FROM AUTHOR]

CO 2 conversion to CO via the reverse water-gas shift (RWGS) reaction is a promising source of syngas for subsequent synthesis of liquid fuels and chemicals. Herein, we present the synthesis of catalysts containing Au supported on hydroxylated Na-modified ZrO 2 , with Au amounts ranging from 0.05 to 1 wt%. Systematic investigations reveal the formation of cooperative Au/Na sites at the interface. These sites cooperate synergistically to activate CO 2 and generate a high surface density of carboxylate-like species, which serve as highly active intermediates for CO formation. It was found that the RWGS reaction on the catalyst with low Au loading proceeds mainly via a carboxylate pathway, with bidentate formate acting as spectators. At higher Au loading, the bidentate formate pathway contributes somewhat to CO formation alongside the carboxylate pathway. Based on temporal analysis of products, we emphasize the significant roles of H 2 spillover and the metal-support interface in the RWGS reaction. [Display omitted] • ZrO2 prepared at high pH with NaOH contains strongly adsorbed surface Na species. • Hydroxylated Na-modified ZrO2 is an excellent support for gold catalysts for RWGS. • Surface Au and Na sites synergistically activate CO2 and boosting CO formation. • In-situ spectroscopic studies reveal carboxylate as active intermediates for RWGS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Moisture promotes low temperature CO oxidation with molecularly-adsorbed O 2 species at NiO-Au interface. • Experimental evidence for OH or H 2 O stabilized O 2 species is obtained. • Adsorbed H 2 O, instead of OH groups, promotes O 2 activation for low temperature CO oxidation. • H 2 O stabilized O 2 species is facilely activated into reactive OOH species, whereas OH stabilized O 2 species not. • Catalytic role of water in NiO-Au catalyzed low temperature CO oxidation is clarified. Water substantially promotes the low-temperature redox reactions catalyzed by gold. However, clarifying the catalytic role of water is challenging due to co-existing OH and H 2 O species on Au catalysts under working conditions. Here, via controlled preparation of OH and adsorbed H 2 O species on a NiO/Au(1 1 1) inverse model surface combined with isotope-labelling reactants, we provide unambiguous spectroscopic experimental evidence to identify adsorbed H 2 O species, instead of OH groups, to promote O 2 activation for low-temperature CO oxidation at the NiO-Au interface. In combination with theoretical calculations, adsorbed H 2 O-stabilized O 2 species was found to be facilely activated into reactive OOH species but OH stabilized-O 2 species could not. These results successfully discriminate the role of adsorbed H 2 O species and OH group in O 2 activation in gold catalysis, which significantly advances our fundamental understanding of both Au catalysis and catalytic role of H 2 O. [ABSTRACT FROM AUTHOR]

A series of chiral, C 3 -symmetric tris(binaphthyl) phosphite ligands was synthesized and tested in palladium-catalyzed asymmetric Suzuki-Miyaura coupling reactions and gold-catalyzed asymmetric intramolecular hydroaminations of allenes. Enantioselectivity differences were attributed to variations in conformational rigidity based on crystallographic, DFT, and DOSY NMR analyses of differently substituted chiral phosphites and their gold complexes. [Display omitted] Five new C 3 -symmetric tris(binaphthyl) phosphites with different substituents at the binaphthyl 2ʹ positions were synthesized and tested as ligands in palladium-catalyzed asymmetric Suzuki-Miyaura coupling reactions and gold-catalyzed asymmetric intramolecular hydroamination of allenes. The nature of the 2ʹ-substituent had a strong effect on yields and enantioselectivities in both reactions, with phosphites bearing CF 3 -substituted aryl groups performing best and giving up to 52–53% ee. Crystal structures of two phosphites and three gold(I) phosphite complexes were obtained, and the latter revealed highly encumbered chiral steric pockets around the metal center that are enforced by the presence of 2ʹ-aryl substituents. A diffusion-ordered spectroscopy (DOSY NMR) study suggested that the ligands undergo dynamic conformational processes in solution but become more rigid upon binding to a metal. X-ray and DFT-calculated structures supported the hypothesis that intramolecular CF 3 -π interactions between neighboring 2ʹ-aryl group on the ligands further rigidify their conformations, stabilizing the encumbered, C 3 -symmetric steric environment surrounding the catalytic metal center and thus increasing chiral induction for phosphites with CF 3 -containing 2ʹ-aryl groups. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coupling of Au and m -ZrO 2 is a bifunctional catalyst for dehydrogenation of ethanol. • Activity of Au/ZrO 2 was accompanied by decrease of in situ R Au-Au bond distance. • The increase of catalytic activity towards 2D Au species, evidenced by R Au-Au values. • The structural and electronic properties are correlated by R Au-Au and Au4f 7/2 BE. • DFT studies indicate that ethoxy at the interface Au-ZrO 2 is feasible pathway. Efficient Au/m-ZrO 2 catalysts for the conversion of ethanol to acetaldehyde and ethyl acetate were obtained by the deposition precipitation method. The present work investigates the impact of the electronic properties of Au supports on m-ZrO 2 catalysts on ethanol dehydrogenation. The Au4f 7/2 binding energy (BE) and the average Au-Au nearest-neighbor distances (R Au-Au) were associated with surface defects characterized by CO adsorption. The BE and R Au-Au properties are correlated among themselves, changing by Au loading and pretreatments in an inert atmosphere at different temperatures. Although the R Au-Au unveils a boost of the reaction rates for shorter distances, the coupling of Au and m-ZrO 2 produced a bifunctional catalyst. Theoretical studies indicate that molecular ethanol adsorption and formation of the ethoxy intermediate represented a feasible pathway for the activation of ethanol on the Au-ZrO 2 interface. The R Au-Au toward of 2D clusters conferred high catalytic activity and low apparent activation energy for ethanol dehydrogenation. [ABSTRACT FROM AUTHOR]

[Display omitted] Single-atom alloy (SAA) attracts great interest recently as excellent heterogeneous catalyst. Herein, the catalysis of Ni-based Au SAA for NO-CO reaction is investigated using DFT calculations. Under lean conditions, N 2 formation occurs to produce NiO x surface, as observed experimentally, because CO 2 formation cannot occur due to easy desorption of CO. Under rich conditions, CO 2 formation occurs with small E a value to afford (N) 2 -adsorbed surface. Next catalytic cycle starts with (N) 2 (NO) 2 -adsorbed surface because N 2 formation needs larger E a value but NO adsorption readily occurs with considerable energy stabilization. As Au-content increases, d -valence-band center lowers in energy to increase activation barrier for N–O bond cleavage of NO but decrease those of CO 2 and N 2 formations. Thus, rate-limiting step is N 2 formation in low Au-content but N–O bond cleavage in high Au-content. A volcano-plot is presented against Au-content. The optimal Au-content is about 6 % on catalyst surface. [ABSTRACT FROM AUTHOR]

Porous C 3 N 4 nanosheets supported Au single atoms photocatalyst (Au 1 @CN) with Au N 4 coordination favors CO 2 adsorption/activation, *COOH generation, and dynamic transfer of photogenerated charge carriers, thereby significantly enhancing the CO 2 photoreduction activity and CO selectivity. [Display omitted] • Porous C 3 N 4 supported Au single atoms photocatalyst Au 1 @CN for efficient CO 2 reduction. • Au 1 @CN exhibits CO evolution rate of 0.58 μmol h−1, CO selectivity of 94 %, and TOF of 10.0 h−1. • Au N 4 coordination facilitates adsorption/activation of CO 2 and generation of *COOH. • Au N 4 coordination promotes dynamic transfer of photogenerated charge carriers. Artificial photosynthesis utilizing solar energy to convert carbon dioxide (CO 2) and water (H 2 O) into fuels and high-value chemicals offers a promising technology for mitigating energy consumption and environmental pollution. However, the development of efficient photocatalysts with high product selectivity remains a big challenge due to the sluggish dynamic transfer of photogenerated charge carriers. Herein, porous C 3 N 4 nanosheet supported Au single atoms photocatalyst (Au 1 @CN) with Au N 4 coordination is fabricated via a facile "impregnation + freeze-drying" process. The as-synthesized Au 1 @CN exhibits efficient and stable CO 2 photoreduction activity with a CO evolution rate of 0.58 μmol h−1 (amount of catalyst: 10 mg), CO selectivity of 94 %, and a turnover frequency (TOF) of 10.0 h−1 using H 2 O as the reductant, which exceed most previous works on C 3 N 4 -based single-atom photocatalysts for CO 2 reduction. Experimental studies and density functional theory (DFT) calculations reveal that the unique Au—N 4 coordination promotes the dynamic transfer of photogenerated charge carriers, facilitates the adsorption/activation of CO 2 molecules and generation of *COOH intermediate, thereby significantly enhancing the CO 2 photoreduction activity with high CO selectivity. This study demonstrates an effective strategy for the design of M—N 4 coordinated single-atom catalyst toward efficient and selective photoreduction of CO 2 to CO. [ABSTRACT FROM AUTHOR]

[Display omitted] • For Au catalyst the preparation methods are very important. • Gold can be an active catalyst as cations, clusters and nanoparticles. • Cooperative Redox enhancement (CORE) effect is important for redox reactions. • Chemo and enzyme catalysts can be combined effectively for oxidation reactions. This perspective article is based on a plenary lecture delivered by the author at Europacat 2023 in Prague on 29th August in recognition of the Boudart Award of EFCATS in 2021. The article charts the journey taken by the author in the discovery and application of gold catalysts over the preceding 40 years of research. Five topics are discussed. The first three parts describe three facets of monometallic gold catalysts. (1) CO oxidation and the hierarchy of activity of gold species supported on a reducible oxide Fe 2 O 3 ; (2) acetylene hydrochlorination for the manufacture of vinyl chloride monomer using highly dispersed gold cations supported on carbon; (3) methane oxidation using molecular oxygen with gold nanoparticles dispersed on the zeolite H-ZSM-5. These first three parts emphasise that the active species of a gold catalyst is dependent on the reaction being catalysed and it is not a one size fits all for this catalysis. The final two parts concern gold palladium bimetallic catalysts. (4) alcohol oxidation and the new Cooperative Redox Enhancement effect (CORE); and (5) the use of in situ generation of hydrogen peroxide to enable new oxidative cascade processes. These examples demonstrate the rich tapestry that catalysis by gold can provide to the catalysis community globally, both from an academic and an industrial perspective as well as the societal impact that has been achieved by the commercialisation of gold catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Strong morphology-dependent Au-CuO interactions and catalysis were observed. • Au-CuO interactions over Au-CuO/c-Cu 2 O (cubes) are stronger. • Au-CuO interfaces over Au-CuO/c-Cu 2 O are more active in CO oxidation. • A Langmuir-Hinshelwood (LH) mechanism was proceeded over Au-CuO/c-Cu 2 O. • Au-CuO/o-Cu 2 O (octahedra) involves both LH and Mars-van-Krevelen mechanisms. Tailoring metal-oxide interfaces with controllable structures are challenging due to the complexity of interfacial structures involving multiple influence factors. Herein, both Au-CuO/Cu 2 O catalysts with different Au-CuO interfaces tuned by altering original Cu 2 O morphologies were prepared via a colloid-deposition method followed by restructuring in 1 %CO/Air atmosphere at 240 °C. Strong morphology dependence on original Cu 2 O nanocrystals was observed. The Au-CuO interactions over Au-CuO/c-Cu 2 O (cubes) catalyst are stronger than those over Au-CuO/o-Cu 2 O (octahedra), resulting in less electron-rich Au species formed. Catalytic performance of different Au-CuO interfaces in CO oxidation follows an order of Au-CuO/c-Cu 2 O > Au-CuO/o-Cu 2 O. Kinetic results together with in situ DRIFTS spectra demonstrate that a Langmuir-Hinshelwood (LH) mechanism was proceeded over Au-CuO/c-Cu 2 O catalyst, whose excellent activity could arise from the fleet desorption of adsorbed surface carbonate species to produce CO 2 , while Au-CuO/o-Cu 2 O catalyzing CO oxidation was involved with both LH and Mars-van-Krevelen mechanisms. These results greatly deepen the fundamental understanding of Au-CuO interfacial catalysis in CO oxidation and broaden the concept of morphology engineering strategy in developing efficient heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

• The surface microchemical environment of Au NPs was modulated by the doping engineering of PANI for the first time. • The readily microchemical environment tuning realized the accurate regulation of the surface electronic state of Au by virtue of the electronic metal support interaction (EMSI). • The less positive charged Au can adsorb the appropriate amount of 4-NP molecules and further increase the catalytic performance. Polyaniline (PANI) support was doped by acids including HCl acid, 10-camphorsulfonic acid (CSA), thioglycollic acid (TA), and citric acid (CA), to modulate the environment of Au. The catalytic activities refer to the following sequence of Au/CA-PANI > Au/TA-PANI > Au/HCl-PANI ≈ Au/CSA-PANI > Au/EB-PANI toward the 4-nitrophenol (4-NP) reduction. It is found that a less positively charged Au surface can adsorb an appropriate 4-NP molecules and further increase the catalytic performance. The Au/CA-PANI with the lowest positively charged Au surface displayed the highest activity in 4-NP reduction with a reaction rate of 0.035 s−1 and a turnover frequency of 1997 h−1. The electronic state of Au likely played a decisive role for the catalytic activity differences. The readily microchemical environment tuning enabled for the accurate regulation of the electronic state of Au. This work provides a strategy for designing Au catalysts with an accurate electronic state surface. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl 4 –H 2 Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (Apt AFB1) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to Apt AFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005–0.225 μg/L and a detection limit of 0.002 μg/L. Principle of aptamer-mediated SERS/RRS for AFB1 based on AgSAC catalysis. [Display omitted] • A highly active silver single-atom catalyst (AgSAC) was synthesized with AgMOF. • A new AgSAC-HAuCl 4 -H 2 Mi catalytic indicator was constructed. • The nanocatalytic amplification reaction was coupled with aptamer mediation. • A highly sensitive SERS/RRS platform was proposed for trace Aflatoxin B1. [ABSTRACT FROM AUTHOR]

Three morphologies of ZnO [spherical (S), rod (R) and disk (D)] were synthesized and tested as supports for Au nanoparticles for the selective oxidation of glycerol, 1,2-propanediol, 1,2-butanediol, and isopropanol at their secondary hydroxyl group to produce the corresponding ketones. The Au-ZnO(0 0 1) interface exhibits a strong electron sink effect and abundant oxygen vacancies, greatly promoting the adsorption of O 2 and the adsorption and conversion of polyols at their secondary hydroxyl moiety. Moreover, the as-formed Auδ+-OH* site resulting from O 2 activation can efficiently extract the hydrogen of the C-H bond of the key RCHO*CH 2 OH intermediate on the Zn-O v site of ZnO(0 0 1) surfaces. Therefore, the Au/ZnO-D exhibits superior catalytic activity (turnover frequency >500h−1) and ketone selectivity (>80 %) than other catalysts with different ZnO facets exposed. [Display omitted] • Three morphologies of ZnO [spherical (S), rod (R) and disk (D)] were synthesized to support Au nanoparticles. • Au/ZnO-D exhibits superior catalytic activity and ketone selectivity. • Au-ZnO(0 0 1) interface exhibits a strong electron sink effect and abundant oxygen vacancies. • Auδ+-OH* site can efficiently extract the hydrogen of the C-H bond of the key RCHO*CH 2 OH intermediate. In-depth understanding and precise tuning of the crystal facet-dependent catalytic properties of supported catalysts are critical for polyol oxidation. Herein, we report a crystal-facet-dependent study of Au-ZnO interfaces for the selective promotion of the oxidation of various polyols and alcohols (glycerol, 1,2-propanediol, 1,2-butanediol, and isopropanol) at the secondary hydroxyl position to produce the corresponding ketones. Three facets of the zinc oxide support, ZnO(1 0 1), ZnO(1 0 0) and ZnO(0 0 1), associated with nanoparticles of various morphologies (spherical (S), rod (R) and disk (D), respectively), were found to induce different electronic local environments and surface oxygen vacancy contents at the Au-ZnO interface. In particular, the ZnO(0 0 1) facet dominating in the Au/ZnO-D nanoparticles can store more electrons from Au, and such electron sink effect, together with the generation of oxygen vacancies (Zn-O v), synergistically enhances the adsorption of O 2 and polyols at the secondary hydroxyl position. Moreover, it was determined that the as-formed Auδ+-OH* site resulting from O 2 activation can efficiently extract the hydrogen of the C-H bond of the key RCHO*CH 2 OH intermediate on the Zn-O v site of ZnO(0 0 1) surfaces. Consequently, the Au/ZnO-D catalyst exhibits unprecedented catalytic activity (turnover frequency >500 h−1) and ketone selectivity (>80 %) for glycerol oxidation. [ABSTRACT FROM AUTHOR]

Those catalysts are engineered for conventional thermal oxidation catalysis but also sequential adsorption-catalytic, photocatalytic, and plasma-catalytic oxidation processes. This Special Issue collects three reviews, eight articles, and two communications related to the design of catalysts for environmental applications, such as the transformation of several pollutants into harmless or valuable products. The authors showed that the addition of Au improved the activity of the Al SB 2 sb O SB 3 sb -supported Cu and Pt catalysts and had a positive effect on SO SB 2 sb production by widening its production window, especially for the platinum-based catalyst. [Extracted from the article]

An emerging approach in the field of targeted drug delivery is the establishment of abiotic metal‐triggered prodrug mechanisms that can control the release of bioactive drugs. Currently, the design of prodrugs that use abiotic metals as a trigger relies heavily on uncaging strategies. Here, we introduce a strategy based on the gold‐catalyzed activation of a phenanthridinium‐based prodrug via hydroamination under physiological conditions. To make the prodrug strategy biocompatible, a gold artificial metalloenzyme (ArM) based on human serum albumin, rather than the free gold metal complex, was used as a trigger for prodrug activation. The albumin‐based gold ArM protected the catalytic activity of the bound gold metal even in the presence of up to 1 mM glutathione in vitro. The drug synthesized via the gold ArM exerted a therapeutic effect in cell‐based assays, highlighting the potential usefulness of the gold ArM in anticancer applications. [ABSTRACT FROM AUTHOR]

The heterogeneous gold(I)-catalyzed oxidative ring expansion of alkynyl quinols has been achieved by using a benzyldiphenylphosphine-modified MCM-41-immobilized gold(I) complex [MCM-41–BnPh2P–AuNTf2] as the catalyst and 8-methylquinoline N-oxide as the oxidant under mild reaction conditions, yielding a variety of functionalized tropone derivatives in good to excellent yields. Extension of this methodology allows for facile construction of other seven- or six-membered ring systems including dibenzotropones, dibenzooxepines, phenanthrenes, and quinolin-2(1H)-ones. This new heterogeneous gold(I) complex can be readily recovered through a simple filtration process and recycled at least eight times without any apparent decrease in catalytic efficiency. [ABSTRACT FROM AUTHOR]

Prussian blue nanoparticles (PBNPs) have peroxidase‐like activity for H2O2. However, PB alone have poor electrochemical performances. Herein, a strategy was proposed by direct in‐situ growth PBNPs onto gold nanowires (AuNWs) surface to obtain the peroxidase‐like activity with about 4.05 times higher than that of PBNPs alone. PBNPs@AuNWs was employed to construct a non ‐ enzymatic electrochemical H2O2 sensor with the detection limit of 5.3×10−9 mol/L (S/N=3). The sensor was successfully used to detect H2O2 in human serum samples or secreted from living HeLa cells. It may be a competitive candidate for H2O2 assaying in biological samples or cellular investigation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using the USP method, Au supported ZnO particles were generated. • Au nanoparticles were dispersed inner and outer portions of the ZnO particles. • The optimal photocatalytic activity occurs with 0.1 mass% Au supported. • The optimal photolysis activity was exhibited at a dose of 10 mg of Ag/ZnO. Environmental pollution by organic dyes used in industry is a serious problem in developing countries. Environmentally friendly treatment methods are being studied because conventional methods require chemical or additional decomposition treatment. In particular, oxidation via a photocatalyst is a promising alternative due to its chemical and physical stabilities and low cost. However, electron-hole recombination limits the photocatalytic activity in semiconductor photocatalysts such as ZnO and TiO 2. This study investigates control of electron-hole recombination of the photocatalyst by loading Au on ZnO (Au/ZnO). Using the Ultrasonic Spray Pyrolysis (USP) method, Au/ZnO particle generation is easily achieved under various conditions. XRD analysis confirms the crystal peaks of ZnO and Au. The EDX mapping and STEM images of the particles show that the Au crystals are well dispersed in the inner and outer portions of ZnO. The photocatalytic decomposition rate of organic dye (Rhodamine-B) is faster than that of ZnO in all Au/ZnO particles, and the best photocatalytic activity occurs in particles with 0.1 mass% Au supported on ZnO particles. In addition, optimal photolysis activity occurs in 100 mL of 5 mg/L RhB aqueous solution and 10 mg dose of Au/ZnO particles. [ABSTRACT FROM AUTHOR]

Bottom-up grown single-crystalline silicon nanowires (SiNWs) are highly intriguing to build nanoscale probes, for instance for atomic force microscopy (AFM), due to their mechanical robustness and high aspect ratio geometry. Several strategies to build such nanowire-equipped probes were explored but their fabrication is still elaborate, time-consuming and relies partly on single-crystalline substrates. Here, we explore a new strategy to fabricate AFM probes that are equipped with single-SiNW scanning tips. The conceptual evaluation begins with a discussion on the overall design and softness of such probes based on finite-element-method simulations. For the experimental realization, SiNWs were grown by the well-established gold-catalyzed vapor–liquid–solid method employing gaseous monosilane. As-grown SiNWs were subsequently transferred onto flexible membranes and even freestanding AFM microcantilever beams via mechanical nanowire contact printing. Elongation of the deposited nanowires by so-called regrowth was triggered by reusing the original gold catalyst to yield the prospective AFM scanning tip. SiNW-equipped scanning probes were created in this manner and were successfully employed for topography imaging. Although a multitude of challenges remains, the created probes showed an overall convincing performance and a superior durability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A "Au antenna-Pd reactor" catalytic system was designed and constructed. • Au antennas enhance Pd activity to Suzuki–Miyaura cross-coupling reactions. • The reactive center electron cloud density of the substrates affects the enhancement. • The enhancement is also decided by the electromagnetic hot spot interactions. It is well documented that placing a plasmonic antenna close to catalytically active nanoparticles can enhance their catalytic activity in chemical reactions via the near-field enhancement effect. Less known is whether and how the near-field enhances the reactivity of the reactant substrates involved in these reactions. Herein, we prepared an "antenna-reactor" catalyst with Au nanoparticles absorbing light as an optical antenna and the adjacent Pd nanoparticles acting as a chemical reactor to study the near-field enhancement effect in Suzuki–Miyaura cross-coupling reaction involving various substrates. The results showed that the activity of Pd nanoparticles were significantly enhanced in the presence of Au antennas. Excessively increasing the density of Au antennas, however, suppressed the reaction due to the interaction between neighboring electromagnetic hot spots. Moreover, the near-field affected different substrates in different extents, enhancing more to reactions that involve substrates with higher electron cloud density at the reactive center. The overall effect of the near-field to the catalytic reactions was proved to be an integrated result of the effect of Au nanoparticle density and reactive center electron cloud density. This study provides enriched understanding for the near-field enhancement effect in photocatalytic reactions with various substrates, and deepened insights for new "antenna-reactor" photocatalyst design. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxidation of betulin to oxo-derivatives over gold catalysts under mild conditions. • Gold catalyzed betulin oxidation is a structure sensitive reaction. • An optimum gold particle size of 3.3 nm gave the highest TOF in betulin oxidation. • Alumina materials are suitable supports for gold nanoparticles. • A certain oxo-derivative of betulin be preferentially formed by adjusting the experimental conditions. Liquid-phase oxidation of betulin extracted from birch bark was studied over gold catalysts supported on a range of supports (hydrotalcite, ZrO 2 , ZnO, MgO, CeO 2 , La 2 O 3 , HMS and various alumina) with different morphology and properties. Gold catalysts as well as the corresponding supports were characterized by XRD, BET, ICP-OES, XPS and TEM. It was found that the nature of the support plays a decisive role in betulin oxidation over gold-based catalysts, expressed in the influence on the average size and distribution of gold nanoparticles and, thereby, on their catalytic performance (activity and selectivity) in betulin oxidation. Moreover, it was revealed that betulin oxidation catalyzed by gold is a structure sensitive reaction, requiring an optimal size of gold nanoparticles of ca. 3.3 nm. The most suitable support for gold was found to be alumina. Kinetic studies allowed determination of reaction orders and conditions favorable for selective formation of a particular oxo-derivative of betulin (betulone, betulinic and betulonic aldehydes, betulinic acid). [ABSTRACT FROM AUTHOR]

Gold(I)‐catalyzed higher‐order [8+2] cycloadditions of 8‐aryl‐8‐azaheptafulvenes 1 with allenamides 2 and ynamides 3 were studied. 1,8‐Dihydrocycloheptapyrroles 4 were achieved by a regioselective [8+2] cycloaddition of azaheptafulvenes 1 and allenamides 2 in the presence of (2,4‐ditBuC6H3O)3PAuNTf2 as catalyst. Besides, ynamides 3 and 8‐aryl‐8‐azaheptafulvenes 1, undergo a regioselective [8+2] cycloaddition, to give 2‐amido‐1,4‐dihydrocycloheptapyrroles 7 in the presence of JohnPhosAuNTf2 as catalyst. Both reactions take place with good yields and with a variety of substituents. A plausible mechanism hypothesis suggests a nucleophilic attack of the 8‐azaheptafulvene to the gold activated electron rich allene or alkyne moieties of the allenamide and ynamide, respectively. [ABSTRACT FROM AUTHOR]

The glycerol oxidation reaction (GLYOR) was evaluated using an Au/C electrocatalyst under alkaline conditions and varying glycerol (GLY) concentration. This electrocatalyst was synthesized by the borohydride reduction method. Au/C was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical techniques associated with in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR). XRD diffractograms showed the presence of Au (fcc). Cyclic voltammetry assisted by ATR-FTIR in situ measurements revealed that GLY oxidation on gold leads to the formation of a high amount of glyceraldehyde (GLYAD) for low GLY concentrations, while a lower amount of GLYAD was observed and the formation of dihydroxyacetone (DHA) was prevalent for high GLY concentrations. For high GLY concentrations DHA is almost stable, whereas for low GLY concentration DHA is fast oxidized to hydroxypyruvate. The excellent GLYOR activity of the Au/C catalyst in low GLY concentrations leads to the formation of deeper oxidized C1 species. • Gliceraldehyde production is favored at lower glycerol concentrations. • Water plays a significant role in lowering the activation energy of glyceraldehyde. • Electrochemical route to production of Dihydroxyacetone. [ABSTRACT FROM AUTHOR]

TiO 2 nanocrystals with controlled facets have been extensively investigated due to their excellent photocatalytic performance in sustainable and green energy field. However, the applications in thermal catalysis without applying UV irradiation are comparably less and the identification of their intrinsic roles, especially the different catalytic behaviors of each crystal facet, remains not fully recognized. In this study, bimetallic AuPd nanoparticles supported on anatase TiO 2 nanosheets exposing {0 0 1} facets or TiO 2 nanospindles exposing {1 0 1} as a catalyst were prepared by sol-immobilization method and used for solvent-free benzyl alcohol oxidation. The experimental results indicated that the exposed facet of the support has a significant effect on the catalytic performance. AuPd/TiO 2 -001 catalyst exhibited a higher benzyl alcohol conversion than that of the AuPd/TiO 2 -101. Meanwhile, all the prepared AuPd/TiO 2 catalysts were characterized by XRD, ICP-AES, XPS, BET, TEM, and HRTEM. The results revealed that the higher number of oxygen vacancies in TiO 2 -sheets with the exposed {0 0 1} facets of higher surface energy could be responsible for the observed enhancement in the catalytic performance of benzyl alcohol oxidation. The present study displays that it is plausible to enhance the catalytic performance for the benzyl alcohol oxidation by tailoring the exposed facet of the TiO 2 as a catalyst support. [ABSTRACT FROM AUTHOR]

Ammonia, as an important chemical, has played an indispensable role in the fields of fertilizer precursors, fuel, and energy carriers over time. The electrocatalytic nitrogen reduction reaction (eNRR) has attracted extensive attention due to the potential availability of clean energy under mild conditions, while electrochemical catalysts still need further optimization and exploration restricted by the strong chemical bonds of NN. In this work, it is proposed that a small amount of noble metal (Au) modified Fe2(MoO4)3 can serve as active sites in eNRR. Density functional theory calculations reveal that the interaction of Au with Fe2(MoO4)3 reduces the reaction energy of the rate determining step and inhibits the hydrogen evolution reaction, which increase the eNRR activity and selectivity of Au/Fe2(MoO4)3. As expected, according to the 1H nuclear magnetic resonance measurement as the exclusive quantitative detection approach, the as‐prepared Au/Fe2(MoO4)3 achieves outstanding eNRR performance with 7.61 µg h−1 mg−1cat. NH3 production rate and 18.79% Faradaic efficiency at −0.4 V versus reversible hydrogen electrode in 0.2 m Na2SO4 under ambient conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-reducible oxides MgO and La 2 O 3 investigated as modifiers of Au/SiO 2 catalysts • Both increase metal-support interaction leading predominantly to 1 nm Au particles • Nature of modifier determines Au electronic states and their nanoparticles stability • Modification by La gives fourfold increase of CO oxidation on prereduced catalysts • Both La and Mg increase slightly 1-octanol oxidation rate without deactivation Gold nanocatalysts, active in several oxidation reactions, suffer of insufficient time-on-stream stability. The easiest way to solve this problem is modifying the support, due to metal-support interaction. This study compares modifying effects of MgO and La 2 O 3 on textural, electronic, and catalytic properties of Au nanoparticles (NPs) supported on inert nanostructured SiO 2 in CO oxidation and liquid phase 1-octanol oxidation. Modification of the silica support surface with La and Mg increased metal support interaction, leading to gold particles with primary size of 1 nm but with different stability: stable under different pretreatment conditions on Mg-modified samples but highly sensible to the pretreatments on La-modified samples. Both modifiers changed electronic properties of supported gold favoring formation and stabilization of Auδ+ states, which are probable gold active sites in catalytic redox processes. Modification with La and Mg oxides changed catalytic properties in CO oxidation before and after pretreatment in H 2 at 300 °C for 1 h. Gold catalysts supported on La- and Mg-modified silica showed similar performance in 1-octanol oxidation with higher conversion than unmodified Au/SiO 2. La and Mg showed better promoting effects of catalytic properties in this reaction than redox modifiers (Fe and Ce) supported on small SiO 2 particles. [ABSTRACT FROM AUTHOR]

Gold-catalyzed reactions of conjugated haloacetylenes are well known and usually result in the formation of addition or dimerization products. Herein, we report a gold-catalyzed reaction of non-conjugated- haloacetylenes, which leads exclusively to the halogenated cyclization products. Remarkable is the gold-catalyzed reaction of tritylhaloacetylenes to haloindene derivatives, as mechanistic studies reveal that an 1,2-aryl shift occurs in the initially formed gold complex. The potential functionalization at the halogen atom and the wide scope of these cyclization reactions make them an attractive method for the construction of cyclic systems. [ABSTRACT FROM AUTHOR]

Au/XC-72 nanoparticles prepared via microwave-assisted polyol processes were used as the active materials for methimazole detection. The Au/XC-72 modified electrode shows an excellent catalytic activity toward oxidation of methimazole, the cyclic voltammetry of methimazole displays two pairs of well-defined, quasi-reversible redox peaks. The oxidation of methimazole on Au/XC-72 modified electrode is a diffusion-controlled and a one-electron transfer process. The fixed-potential amperometry technique was used for the determination of methimazole and a linear dependence of anodic current on methimazole concentration was obtained in the range of 19.9–100.91 μM. [ABSTRACT FROM AUTHOR]

Titania supported Au–Co catalysts with nano- and sub-nanoparticles, were prepared with 1% Au and different contents of cobalt by one pot deposition precipitation with urea. Monometallic gold and cobalt catalysts were also prepared by the same method for a comparative purpose. The characterization of bimetallic catalyst evidenced the presence of sub-nanoparticles where 50% of cobalt and 40% of gold particles are smaller than 1 nm and the formation Au–Co particles. The results show a positive effect of cobalt on gold particles size and the catalytic activity. The effectiveness of these catalysts in the synthesis of several propargylamines via amine, CH2Cl2 and alkyne coupling (AHA coupling) was demonstrated. Different propargylamines were synthesized with very good yields (71%–88%). A comparative study of monometallic gold, monometallic cobalt and bimetallic gold–cobalt catalysts was investigated. The most efficient catalyst was reused for up to six reaction cycles without significant activity loss. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au/Cu 2 O composed of Au nanoparticles on Cu 2 O hollow nanospheres were successfully synthesized. • Au/Cu 2 O catalysts have an earlier onset potentials for ethanol production than Cu 2 O. • CH 3 CH 2 OH formation is favored over C 2 H 4 on Au/Cu 2 O and increases as Au amount increased. • Enhanced ethanol formation is due to more CO formation on Au sites to promote C–C coupling. Electrochemical CO 2 reduction (CO 2 RR) to ethanol is a way to advance CO 2 utilization toward a renewable chemical feedstock and fuel. In present study, an approach to promote ethanol production is employed through adding Au, which is favorable toward CO formation, onto Cu 2 O catalysts. Namely, the Cu 2 O hollow nanospheres with a size of 150−180 nm were synthesized by a soft template method, and then Au nanoparticles of ∼7 nm were loaded to obtain Au x /Cu 2 O composites. The Au x /Cu 2 O catalysts have an earlier onset for ethanol production than Cu 2 O. Besides, Au x /Cu 2 O catalysts display the significantly enhanced Faraday efficiencies (FEs) of CO and ethanol, the suppressed hydrogen evolution reaction and the slightly weakened HCOOH formation. Among them, Au 0.17 /Cu 2 O stands out with the highest FEs of ethanol from 10.8%–16.2% throughout the measuring potentials, suggesting an optimal amount of Au. Furthermore, it is found that the FEs of ethanol increase as the atomic ratio of Au/Cu increases at the medium reduction potentials (-1.1 V to -1.3 V). Besides, it is demonstrated that ethanol formation is more favorable over ethylene formation, evidenced by the ratio of FE ethanol /FE ethylene reaching 2.0, 3.3, 4.1 on three Au x /Cu 2 O catalysts, respectively. This correlation between the ethanol production and the Au amount reflects that Au plays a crucial role in promoting ethanol formation. The enhanced ethanol formation is ascribed to more CO formation on Au sites to promote C–C coupling. Our study demonstrates an effective approach to develop Cu-based electrocatalysts for ethanol formation from CO 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ceria nanorod supported AuxPdy NPs are highly stable, showing negligible leaching. • Au-rich Au x Pd y /Ce-NR most active for glucose oxidation. • Glucose conversion dependent on bimetallic composition with a maximum at 61 at.% Au. • Selectivity to gluconic acid is >98% at all bimetallic compositions. The catalytic performance of Au x Pd y nanoparticles prepared by colloidal synthesis and immobilised on ceria nanorods (Ce-NR) in the selective oxidation of glucose has been studied under initially basic and relatively mild conditions. Activity was found to be strongly dependent on the bimetallic composition with Au-rich catalysts being more active in glucose oxidation. Catalyst recycling revealed negligible deactivation or metal loss from leaching, and continuing high selectivity to gluconic acid (≥97.7%). Defects on the Ce-NR surface appear to serve as anchoring sites for Au-Pd NPs giving rise to small and very stable NPs. [ABSTRACT FROM AUTHOR]

H2 adsorption on Au catalysts is weak and reversible, making it difficult to quantitatively study. We demonstrate H2 adsorption on Au/TiO2 catalysts results in electron transfer to the support, inducing shifts in the FTIR background. This broad background absorbance (BBA) signal is used to quantify H2 adsorption; adsorption equilibrium constants are comparable to volumetric adsorption measurements. H2 adsorption kinetics measured with the BBA show a lower Eapp value (23 kJ mol−1) for H2 adsorption than previously reported from proxy H/D exchange (33 kJ mol−1). We also identify a previously unreported H‐O‐H bending vibration associated with proton adsorption on electronically distinct Ti‐OH metal‐support interface sites, providing new insight into the nature and dynamics of H2 adsorption at the Au/TiO2 interface. [ABSTRACT FROM AUTHOR]

Surface‐active and highly stable cobalt nanoparticles generated from alkali ion‐promoted gold catalyst for catalyzed carbonylative [2+2+1] cyclization reaction, is described. The gold nanoparticle's (AuNPs) role was assumed to dissociate the CO and H2 into atomic species on the catalyst surface by spillover, which in‐situ reduces the robust mesoporous cobalt oxide to metallic cobalt (Co3+→Co2+→Co), as the active catalytic species that catalyzed the reaction; thereby providing up to 93 % yield of cyclopentenone adducts. Prior to this, catalyst pre‐treatment with H2 gas (130 °C, 3 h, 20 atm) was performed to reduce the catalyst. It appeared that the low reducibility temperature and increased surface basicity ascribed to the presence of alkali ion‐promoters in the catalyst revealed a strong correlation with the catalyst activity, for the intra‐ and intermolecular reactions under milder reaction conditions. Thus, a sustainable, highly reusable, and environmentally friendly green catalyst for the carbonylation reaction, such as Pauson‐Khand, was developed. [ABSTRACT FROM AUTHOR]

The article presents a study that explores the plasmonic nanoreactors regulating selective oxidation by energetic electrons and nanoconfined thermal fields. It suggests a strategy to rationally use plasmonic nanostructures to optimize chemical processes, thereby achieving high yield with high selectivity at lower temperature under visible light illumination.

Our study focused on the synthesis of gold catalysts supported on mixed Ce–ZrO2 (Ce/Zr = 0, 0.1, 0.4 and 0.9) mesoporous, which are mainly potential in the total oxidation of toluene and other volatile organic compounds. The mesoporous Ce–ZrO2 oxides (Ce/Zr = 0, 0.1, 0.4 and 0.9) were prepared via soft template strategy, using a triblock copolymer as a template. 1% of Au was loaded on mixed oxide mesoporous by deposition precipitation method. Ce–ZrO2 and Au/Ce–ZrO2 (Ce/Zr = 0, 0.1, 0.4 and 0.9) samples were characterized by XRD, N2 adsorption–desorption, H2-TPR and MET. The results showed that the dispersion of the gold particles on Ce–ZrO2 depends on the Ce/Zr ratio. These catalysts were then tested in the deep oxidation of toluene oxidation where they exhibited an excellent catalytic activity by complete decomposition of toluene at the reaction temperature equal to 576 K. This activity is correlated with the dispersion of the gold particles; itself is correlated with the Ce/Zr ratio. [ABSTRACT FROM AUTHOR]

Green production of NH3, especially the Li‐mediated electrochemical N2 reduction reaction (NRR) in non‐aqueous solutions, is attracting research interest. Controversies regarding the NRR mechanism greatly impede its optimization and wide applications. To understand the electrocatalytic process, we treated Au coated carbon fibrous paper (Au/CP) as the model catalyst. In situ XRD confirmed the transformation of lithium intermediates during NRR. Au greatly improved electron transfer kinetics to catalyze metallic Li formation, and accordingly highly accelerated spontaneous NRR. The Faradaic efficiency of NRR on Au/CP reached 34.0 %, and NH3 yield was as high as 50 μg h−1 cm−2. Our research shows that the key step of Li‐mediated non‐aqueous NRR is electrocatalytic Li reduction and offers a novel electrocatalyst design method for Li reduction. [ABSTRACT FROM AUTHOR]

The chemoselective hydrogenation from 3‐nitrostyrene to 3‐vinylaniline is quite challenging due to coexistence of the C=C bond and the –NO2 group in the same molecule. Previously, we found that the selectivity to the 3‐vinylaniline is very high in wide temperature and time windows when taking the ZnAl‐hydrotalcite supported Au25 nanoclusters as the precatalyst. Here, we investigated the loading effect of gold on the catalytic performance for the chemoselectivity of this reaction. The loadings of gold ranged from 0.5 to 10 wt%. The results showed that the reaction rate decreased greatly with the increasing loading of gold, and selectivity dropped obviously after the loading of gold attaining 10 wt%. The UV–Vis (ultraviolet visible absorption spectroscopy), XRD (X‐ray diffraction), and HAADF‐STEM (high angle annular dark field‐scanning transmission electronic microscope) results suggested that the gold nanoparticles aggregated with the increasing loading of gold. The X‐ray absorption near edge structure (XANES) and in situ CO‐DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) results indicated that the valent state of gold tended to be slightly positively charged when the loading of gold increased. The origin of the high selectivity to the 3‐vinylaniline was discussed subsequently based on the above results. [ABSTRACT FROM AUTHOR]

A new form of carbon-based ligand supported robust heterogeneous gold nanocatalyst was synthesized and its potential catalytic applications are demonstrated. The high yield (> 90%) synthesis procedure involves ligand exchange between hydrophilic polyvinylpyrrolidone polymer stabilized gold nanoparticles (Au:PVP) with a di-alkyne ligand (1,4-Diethynylbenzene). The ultrasmall stabilized gold nanoparticles (1.8 ± 0.3 nm) are bonded to di-alkyne ligand through acetylenic carbon atom (≡C-Au) with an electronically conjugated 3D network. The synthesized material (Au-P1) was meticulously characterized using several spectroscopic and microscopic techniques, e.g., Fourier transform infrared spectroscopy (FTIR), optical absorption spectroscopy (UV-Vis), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM) and thermogravimetric analysis (TGA). The Au nanocatalyst showed good photocatalytic activity for degradation of several organic dye molecules in aqueous phase under visible light irradiation in presence of oxidizing agent (H2O2). The proposed mechanism involves dye absorption on ligand surface through π-π interaction followed by transfer of electron from excited dye molecules to gold core through electronically conjugated ligand for generation of reactive oxygen species (·OH). The catalyst has also been demonstrated for transfer hydrogenation of organic carbonyl and nitro functional groups (>C=O, -NO2) with potassium formate (HCOOK) as hydrogen source in water. The catalyst could be recovered by simple filtration, and it was reused up to five cycles for both of these catalytic transformations with complete retention of its catalytic activity. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) microtubes supported Au catalysts were prepared and evaluated in the catalytic reduction of nitrophenols to aminophenols with NaBH4 as the reductant. PANI microtubes were prepared through a template-free method with salicylic acid as the dopant. HAuCl4 was used as a gold precursor. Au nanoparticles were loaded on PANI microtubes by an in situ redox reaction between PANI and HAuCl4. The morphology and structure of the as-prepared PANI/Au composite catalyst were investigated using SEM, TEM, FT-IR, XRD and Raman spectra. We found that the metallic Au nanoparticles were loaded on PANI through the in situ redox reaction and located closer to the imine nitrogens of PANI. And the interaction between PANI and Au nanoparticles led the metallic Au negatively charged and favored the improvement of catalytic activities in the reduction of 4-nitrophenol (4-NP). A comparative study for the catalytic reduction of 3-nitrophenol (3-NP) and 2-nitrophenol (2-NP) showed that the activity sequence of PANI/Au was 3-NP > 2-NP > 4-NP. [ABSTRACT FROM AUTHOR]

The modifications of support for the dispersion and immobilization of gold nanoparticles were examined for the selective hydrogenation of acetylene to ethylene. The catalyst, denoted as Au/CNA, was prepared by the carbonization of C and N atom-containing organic precursors on Al2O3, which were subsequently used as supports for gold nanoparticles. The TOF value of Au/CNA was five times higher than that of Au/Al2O3 at 250 °C. The carbonization modification of Al2O3 support without N species showed almost no change in catalytic activity. Therefore, the improved catalytic performance of Au/CNA is related to the interactions of the N species on the CNA support with nano-gold particles. From the XPS analysis, electron transfer between gold and C, N co-doped species may play an important role in the high levels of Au active site utilization. This study may provide new avenues for the construction of organic/inorganic composite materials for efficient catalytic hydrogenation applications. [ABSTRACT FROM AUTHOR]