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The fabrication of noble metal free catalysts with excellent performance and high stability by a simple, efficient, general and low-cost approach remains an urgent task for solving the problem of resource shortage. Herein, Cu-based metal organic frameworks (MOFs) immobilized on commercial filter papers were used as pyrolysis precursors to synthesize CuxO@C at various calcination temperatures. Notably, the resultant CuxO@C-400 exhibits an excellent catalytic performance toward the reaction of reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). By virtue of the large specific surface area, well-developed porosity, good stability and high dispersity of CuxO nanoparticles, the obtained CuxO@C-400 could complete the reduction reaction within 11 min with a large apparent rate constant κapp value (4.8 × 10−3 s−1). Our strategy therefore opens a new avenue for the preparation of low-cost and high-performance noble metal free catalysts. [ABSTRACT FROM AUTHOR]

Cu nanoparticles (CuNPs) were successfully synthesized in situon ZnO whiskers as a selective scaffold, which were supported in a microstructured paper matrix composed of inorganic fibers; as-prepared paper composites were easy to handle in practical use and demonstrated excellent catalytic performance in the methanol reforming process for effective hydrogen production. [ABSTRACT FROM AUTHOR]

An electrospray ionization mass spectrometer equipped with a quadrupole ion trap as the mass analyzer provided a powerful tool for the investigation of metal ligand affinities of catalysts for atom transfer radical polymerization. It allowed, in particular, (i) the identification, in a library of ligands, of the most stable, and thus active, copper catalysts; (ii) the assessment of the effects of the reaction medium on the relative stabilities of the catalyst complexes; and (iii) the evaluation of the influence of the nature of the ligand on both the complex halogenophilicity and the metal–ligand stabilities in the gas-phase. [ABSTRACT FROM AUTHOR]

A chiral cobalt-catalyzed enantioselective aerobic oxidative kinetic resolution of (±)-α-hydroxy esters, using molecular oxygen as a sole oxidant, is reported and a maximum of selectivity factor (s) 31.9 was achieved with >99% enantiomeric excess for unreacted α-hydroxy esters. [ABSTRACT FROM AUTHOR]

A stereoselective gold-catalyzed [2 + 2 + 2] cycloaddition of ketoenynes substituted at the propargylic position with OR groups has been applied for the synthesis of (+)-orientalol F and pubinernoid B. [ABSTRACT FROM AUTHOR]

By establishing both a highly efficient phosphonamidate formation and a RuCp-catalyzed cleavage of an allyl linker, the solid-phase synthesis of Fmoc-(GlyP(OBn))6-OH/DIEA, a protected form of a new type of unnatural peptide α-amino phosphonic acid oligomer (APO), has been realized. [ABSTRACT FROM AUTHOR]

A chiral zirconium catalyst prepared from Zr(OtBu)4and a chiral tridentate BINOL was found to be effective for asymmetric meso-aziridine ring-opening reactions with aniline derivatives. The N-benzhydryl group on the product obtained was easily cleaved to give the corresponding amine in high yield under reductive conditions. [ABSTRACT FROM AUTHOR]

4-Substituted oxazolines, which are readily synthesized from naturally occurring α-amino acids, are converted efficiently and stereospecifically to β-amidoaldehydes in the presence of synthesis gas and catalytic dicobalt octacarbonyl. [ABSTRACT FROM AUTHOR]

Pd(ii)- and Pt(ii)-catalyzed ring-expansion of enantiomerically pure alkylidenecyclopropane derivatives leads to the formation of cyclobutene species with a complete preservation of the stereogenic center. [ABSTRACT FROM AUTHOR]

We report a new catalytic synthesis of α-pyridones and 32H-isoquinolones from readily available 3-en-5-ynyl nitrones and o-alkynylphenyl nitrones; the reaction mechanism is proposed to involve iminyl ketene species through an oxygen transfer process. [ABSTRACT FROM AUTHOR]

CuO/CeO2 catalysts were widely studied as an alternative to precious metal catalysts, and the Cu–Ce synergy was essential to improve the catalytic performance. In this paper, the effects of CuO loading on Cu–Ce synergy in CuO/CeO2 nanorod catalysts and their performance in toluene combustion were systematically investigated. It was found that non-equilibrium plasma facilitated the dispersion of CuO active species on the CeO2 surface. With the increase of the CuO loading from 1 wt% to 4 wt%, the Cu–Ce synergistic effect was gradually improved, which generated Cu+/Cu2+ and Ce3+/Ce4+ redox electron pairs. The highest oxygen vacancy concentration and Cu+ content of CuCe-4 (4 wt%) resulting from strong Cu–Ce synergy accelerated the activation of chemisorbed oxygen and consequently improved the efficiency of toluene catalytic combustion. [ABSTRACT FROM AUTHOR]

Sustainable production of 1,4-pentanediol (1,4-PDO) from biomass is of great importance because 1,4-PDO is a monomer of degradable polyesters and plastics. This paper reviews the conversion of biomass-derived levulinic acid (LA) and furfural as well as their derivatives alkyl levulinate, γ-valerolactone (GVL) and furfuryl alcohol (FAL) into 1,4-PDO. MoOx or ReOx modified noble metal catalysts and non-noble metal catalysts with core–shell and alloy structures show a high 1,4-PDO yield and stability in LA hydrogenation under severe hydrothermal conditions. The conversion of furfural to 1,4-PDO involves the initial C＝O bond hydrogenation to form FAL, the consecutive acid-catalyzed ring-opening and the final hydrogenation. Therefore, it needs a bifunctional catalyst composed of metallic species and acid sites to improve the 1,4-PDO yield. Efforts are made here to highlight the employed catalysts, structure–performance relationship, reaction pathway and reaction mechanism in detail. The current challenges for large-scale applications of conversion of LA and furfural to 1,4-PDO have been proposed, including process development, catalyst cost, solvent and active site distribution. We believe that this review will provide new opportunities and expand the options for the production of 1,4-PDO via biorefining processes. [ABSTRACT FROM AUTHOR]

Vinyl sulfones are important structural motifs with a wide range of applications in the biomedical field. Although the hydrosulfonylations of alkynes have provided straightforward strategies for the synthesis of vinyl sulfones, these methods still exhibit several drawbacks, such as the use of large amounts of transition metal catalysts or/and additional additives. Herein, we report an efficient and mild multicomponent reaction (MCR) for the preparation of vinyl sulfones achieved by carrying out hydrosulfonylation of alkynes with the corresponding aryl diazonium salts, K2S2O5 and thiophenols at room temperature without any metal catalysts or additives. This transformation was the first example of a thiophenol as a hydrogen source reacting with vinyl radical with the advantages of high chemoselectivity and step-economy. Notably, the method was found to also be applicable to aliphatic alkynes, circumventing the limitations of existing methods, and a gram-scale experiment proceeded smoothly, proving the practicality of the methodology. [ABSTRACT FROM AUTHOR]

The development of a bifunctional ruthenium-based electrocatalyst that can efficiently and economically drive both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains challenging because ruthenium species can undergo severe agglomeration during preparation which can significantly reduce the catalytic activity. Constructing supported metal catalysts can not only improve the stability of Ru but also improve the catalytic performance by adjusting the electronic structure, which is an effective way to solve the current challenges. In this paper, Ru-loaded MoO2/MoO3 heterostructures (Ru–MoOx) with oxygen vacancies were successfully synthesized by controlling the annealing temperature. This special structure can effectively tune the electronic structure, enhance the electrical conductivity and increase the active sites, thus improving the catalytic activity of the catalyst. Performance studies have shown that Ru–MoOx exhibits excellent HER and OER performance in alkaline media. And it is not surprising that the overall water decomposition performance of Ru–MoOx is also excellent, requiring only a cell voltage of 1.54 V to reach 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Norfloxacin (NOR) is a synthetic antibacterial agent that is extensively applied in the management of various infectious conditions. After entering the human body, most of it cannot be absorbed and is excreted, eventually reaching natural waters. At the same time, it promotes the generation of drug-resistant bacteria, which seriously threatens human health. In this study, a simple mechanical mixing method was employed to synthesize a Ni–MCM composite catalyst with excellent stability, which was utilized for the degradation of NOR. The effects of the mass ratio of Ni–MC to MCM-41, initial pH value, starting NOR concentration, catalyst dosage and inorganic anions on NOR degradation were studied. The findings indicate the superior degradation capability of Ni–MCM towards NOR under diverse conditions. Quenching experiment and electron paramagnetic resonance spectroscopy showed that when dissolved oxygen occupied the active site of the metal in the catalyst, more ˙O2− and 1O2 would be formed, and NOR would be degraded due to the interaction with the mixed system composed of ˙OH and SO4˙− and electron transfer, indicating that the degradation mechanism of the Ni–MCM system was dominated by non-free radicals. The utilization of the Ni–MCM nano-composite catalyst is a promising approach for the treatment of wastewater containing norfloxacin. [ABSTRACT FROM AUTHOR]

Compared with heavy metal catalysts, metal-free catalysts that activate persulfate (PS) for controlling organic pollutants are more economical, environmentally friendly, and safer for human health. Utilizing ZIF-8 particles as templates and polyphosphazene as the precursor, hollow N, P, and O tri-doped carbon microspheres (NPOC) with a hierarchical pore structure were successfully synthesized from ZIF-8@polyphosphazene. Their morphology and structure were investigated by SEM, TEM, TGA, XPS, BET, and FT-IR. Otherwise, NPOC were used as catalysts to activate PS for the oxidative degradation of tetracycline. The dosage of catalyst and oxidant, tetracycline concentration, carbonization temperature, and pH can all have a substantial influence on the oxidative degradation of tetracycline. Free radical testing by EPR reveals that HO˙ and SO4˙− are generated and the radical pathway is dominant in the oxidative degradation process. NPOC exhibited superior catalytic oxidation performance and good reusability, indicating their potential for application for eliminating TC from aqueous solution. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER), as a pivotal half-reaction, significantly hinders the advancement of energy conversion efficiency. Metal electrodeposition on catalysts has been demonstrated to effectively enhance the HER reactivity. Here, Ni3S2–Fe–Ni with a multilayer structure was obtained by the electrodeposition of Ni3S2 with dopants Fe/Ni, in which a number of active sites were achieved and the intrinsic conductivity of the catalyst was well improved. Elemental analyses revealed the multilayer structure consisting of Ni3S2, NiS, and Fe. The Ni3S2–Fe–Ni catalyst exhibited impressive electrochemical performance due to optimization of its structure with the overpotentials of the HER and OER of only 83 and 190 mV. Notably, at a higher current density of 100 mA cm−2, the overpotentials for the HER and OER are only 339 and 365 mV. As a bifunctional electrocatalyst, its total splitting voltage was only 1.55 V. The catalysis performance remained nearly unchanged even after 48 h of stability testing. Finally, density functional theory (DFT) calculations revealed that the potential barriers in each reaction step of the OER are evenly distributed, and optimizing the Ni3S2 structure with iron and nickel atoms reduced the reaction energy barriers during the electrochemical process, improving the OER/HER performance. [ABSTRACT FROM AUTHOR]

To address the shortage of fossil energy, the development of affordable and efficient non-precious metal catalysts for oxygen evolution reaction (OER) from electrocatalytic water splitting is still a crucial challenge. Herein, the bimetallic NiFe metal–organic frameworks (MOFs) are synthesized by hydrothermal and electro-deposition. Benefiting from the synergistic effect of Fe and Ni, the catalyst demonstrates extraordinary activity, which exhibits favorable OER catalytic activity in 1 M KOH solution with an overpotential of 206 mV at 10 mA cm−2. Meanwhile, the obtained NiFe-NDC presents promising stability in the 20 h test at 50 mA cm−2. [ABSTRACT FROM AUTHOR]

Due to the high oxidation potential of arenes and alkenes, previous methods of benzylic and allylic C–H oxidation necessitated the use of strong oxidizing agents, metal catalysts, or free radical initiators (such as photocatalysts or hydrogen atom transfer reagents) to be effective. Herein, we employ oxygen to generate a triple-spin charge transfer state with π-conjugated compounds effectively accessing the triplet excited states of arenes, followed by energy transfer to form singlet oxygen facilitating C–H bond oxidation. Distinct from previous oxidations, it is the first time that a series of natural products and drug molecules (27 examples) are selectively oxidized without any catalysts or additives. The transformation can be implemented under sunlight to produce valuable unsaturated (aromatic) ketones and only water as waste, which meets every one of the 12 principles of green chemistry. [ABSTRACT FROM AUTHOR]

N-Substituted 5-(hydroxymethyl)-2-furfuryl amines have been obtained through the reductive amination of 5-hydroxymethylfurfural (HMF) with a variety of primary amines using a non-noble metal catalyst based on monodisperse Co nanoparticles covered by a thin carbon layer. The Co@C catalyst was highly active, selective and stable, allowing us to perform the reductive amination of HMF under very mild reaction conditions (60 °C and 4 bar H2) using ethanol as a green solvent and achieve the corresponding amino-alcohol in yields ranging from 80 to 99%. Moreover, the reaction was extended to other furanic aldehydes with excellent success. Furthermore, in order to synthesize amino-ester derivatives, precursors of ammonium salt-based surfactants, the reductive amination of HMF with methylamine was coupled with the selective esterification of the hydroxymethyl group of the furan ring with fatty acids using lipase CALB (Novozym 435) as a biocatalyst in 2-methyltetrahydrofuran as a green and enzyme compatible solvent, achieving practically total conversion to the corresponding amino-esters. The process was implemented in flow reactors by combining two consecutive fixed bed reactors, achieving a global yield of the amino-ester derivative of 85%, which was maintained over 86 h of operation. [ABSTRACT FROM AUTHOR]

Photocatalytic ammonia production holds immense promise as an environmentally sustainable approach to nitrogen fixation. In this study, In2O3/In2S3-ZnCdS ternary heterostructures were successfully constructed through an innovative in situ anion exchange process, coupled with a low-temperature hydrothermal method for ZnCdS (ZCS) incorporation. The resulting In2O3/In2S3-ZCS photocatalyst was proved to be highly efficient in converting N2 to NH3 under mild conditions, eliminating the need for sacrificial agents or precious metal catalysts. Notably, the NH4+ yield of In2O3/In2S3-0.5ZCS reached a significant level of 71.2 μmol g−1 h−1, which was 10.47 times higher than that of In2O3 (6.8 μmol g−1 h−1) and 3.22 times higher than that of In2O3/In2S3 (22.1 μmol g−1 h−1). This outstanding performance can be attributed to the ternary heterojunction configuration, which significantly extends the lifetime of photogenerated carriers and enhances the spatial separation of electrons and holes. The synergistic interplay between CdZnS, In2S3, and In2O3 in the heterojunction facilitates electron transport, thereby boosting the rate of the photocatalytic nitrogen fixation reaction. Our study not only validates the efficacy of ternary heterojunctions in photocatalytic nitrogen fixation but also offers valuable insights for the design and construction of such catalysts for future applications. [ABSTRACT FROM AUTHOR]

Exploring efficient non-noble metal catalysts for the hydrogen evolution reaction (HER) will contribute to the development of clean and green energy technologies. Herein, we adopted a "waste utilization" strategy by using readily available and inexpensive coconut shell waste as a carbon source to synthesize carbon materials anchored with a Cu7Co alloy (Cu7Co/C) as a potential electrocatalyst for the hydrogen evolution reaction (HER). Utilizing a combination of hydrothermal and pyrolysis methods, the synthesized Cu7Co/C catalyst showcases superior HER electrocatalytic performance in alkaline solutions, with an overpotential of 134 mV at 10 mA cm−2 and a Tafel slope of 94 mV dec−1. The alloying of Cu and Co within Cu7Co/C markedly improves charge transfer capabilities, enhancing HER electrocatalysis. This research underscores the exceptional catalytic performance and stability of Cu7Co/C nanocomposites in alkaline media for the HER, attributed to a synergistic effect between the carbon derived from coconut shells and the bimetallic Cu7Co alloy. [ABSTRACT FROM AUTHOR]

Noble-metal-free heterogeneous catalysts for deoxydehydration (DODH) using H2 as a reductant were developed. Among various transition metals examined as additives to modify the MoOx/TiO2 catalyst, Cu showed good conversion and selectivity in the transformation of 1,4-anhydroerythritol (1,4-AHERY) to 2,5-dihydrofuran (2,5-DHF). The performance of the MoOx–Cu/TiO2 catalysts was comparable to those modified with either Ag or Au instead of Cu. Upon the combination of two Mo precursors, i.e. (NH4)6Mo7O24 and Na2MoO4, the selectivity of the catalyst (MoOx–Cu–Na/TiO2) was further enhanced to achieve 81% yield of 2,5-DHF. This catalyst also exhibited broad substrate scope including cyclic and linear alkyl vicinal diols and tartaric ester. Furthermore, MoOx–Cu–Na/TiO2 was reusable at least three times after its calcination as regeneration. The reaction was almost zero-order with respect to the H2 pressure and 1,4-AHERY concentration, suggesting that the release of the alkene is the rate-determining step. The comprehensive characterization using STEM, XRD and XAFS provided insights into the surface structure of the catalyst, revealing that H2 is activated over Cu particles and subsequently transferred to Mo cluster species on the TiO2 surface via the spillover effect to proceed with the DODH reaction. [ABSTRACT FROM AUTHOR]

The electrocatalytic urea oxidation reaction (UOR) provides a promising alternative pathway for oxygen evolution in water electrolysis due to its lower thermodynamic barriers. Developing efficient nonprecious metal UOR catalysts is important. Rational design of heterogeneous structures to regulate the morphology and electronic structure is an effective method to improve the activity of electrocatalysts. Herein, a unique heterostructure of ultrathin NiCo-LDH supported by FeNiCoS4 was constructed for the UOR via a facile hydrothermal followed by electrodeposition process. The electrode exhibits superior activity and stability in a solution of 1 M KOH containing 0.33 M urea, with a potential of 1.366 V at 50 mA cm−2 and excellent durability over 48 h. The outstanding performance is attributed to the high conductivity of FeNiCoS4, ultrathin NiCo-LDH and the strong interface interaction between the two components, regulating the local electronic structure of the active metals. This work represents an effective strategy for the preparation of an efficient UOR catalyst with promising applications. [ABSTRACT FROM AUTHOR]

Electrocatalysts for hydrogen production play a crucial role in advancing the green economy. However, the sluggish kinetics of the hydrogen evolution reaction (HER) limited its application. Therefore, efficient strategies with a tailored d-band center adjustment are highly desirable. In this study, we synthesized N, P-doped carbon matrix-confined Mo-doped FeP nanoparticles using a simple strategy to optimize the catalyst's d-band center. Mo-FeP@NPC presents an excellent HER performance of 63 mV (H2SO4) and 116 mV (KOH) at −10 mA cm−2 in acid and alkaline electrolytes, separately. Theoretical calculations confirm that the outstanding HER performance originates from the strong electronic coupling between atoms, thus upshifting the d-band center and increasing H intermediate adsorption on the active sites. Furthermore, the N, P-doped carbon matrix protects the Mo-doped FeP nanoparticles from aggregation, exposing more active sites during hydrogen production. This work provides new avenues for applying highly efficient metal phosphide catalysts for the HER. [ABSTRACT FROM AUTHOR]

To replace depleting freshwater resources, seawater, with its abundance and economy, has become a more favourable option for water electrolysis. However, seawater electrolysis necessitates electrocatalysts with excellent activity as well as resistance to Cl− corrosion. Herein, we utilized a biowaste, eggshell membranes, as a versatile platform to fabricate sulfide electrocatalysts for the oxygen revolution reaction (OER). Structural analyses including X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy tests indicated that the introduction of iron into the cobalt sulfide lattice greatly modified the structures of the sulfide. Electrochemical tests and operando electrochemical Raman spectroscopy showed that the introduction of Fe adjusted the electronic structure of Co9S8, facilitating the formation of Co4+ species, which serve as the major active sites for OER, thereby effectively improving the catalyst performance. The optimal Co8FeS8/ESM-900 sample can achieve a current density of 10 mA cm−2 in alkaline freshwater, simulated seawater, and natural seawater at overpotentials of 270, 271, and 324 mV, respectively, which are lower than the overpotentials of 273, 272, and 337 mV obtained from IrO2. The sulphate passivation layer formed during the OER process can effectively repel Cl−, leading to outstanding corrosion resistance. The Co8FeS8/ESM-900 catalyst can be continuously operated in seawater electrolysis for 200 000 s. A (−)Pt/C‖‖Co8FeS8/ESM-900(+) electrolyzer required only 1.629, 1.623, and 1.648 V to yield a current density of 10 mA cm−2 for the electrolysis of alkaline freshwater, simulated seawater, and natural seawater, respectively, which are superior to the performance of the (−)Pt/C‖‖IrO2(+) electrolyzer. In virtue of its low cost, high efficiency and outstanding stability, the catalyst reported in this study is promising in practical seawater electrolysis. [ABSTRACT FROM AUTHOR]

The utilization of plant polyphenols as catalyst carriers holds promise for environmentally friendly catalysis. However, challenges such as the inhomogeneous distribution of organic ligands often hinder their effectiveness. In this study, lignin–metal supramolecular framework were formed through ionic coordination self-assembly, achieved by oxidative ammonolysis modified lignin. The specific spatial domain-limiting effect of lignin–metal supramolecular framework ensures the dispersion and stability of catalyst active sites. Carbon-coated trimetallic catalysts (Ru–FeNi@OALC) derived from lignin–metal supramolecules exhibit promising performance, with low overpotentials for the oxygen evolution reaction (OER, η10 = 290 mV) and the hydrogen evolution reaction (HER, η10 = 52 mV), surpassing commercial noble metal catalysts. Additionally, these catalysts demonstrate long-lasting water-splitting performance, highlighting their potential for sustainable catalytic reactions. Molecular simulations and DFT theoretical calculations elucidate the feasibility of lignin oxidative ammonolysis modification and reveal the coordination mechanism. Furthermore, the abundant defects and disorder in the coordination polymer-derived carbon materials optimize electron transfer processes and accelerate reaction kinetics. This construction strategy towards designable polyphenol–metal supramolecular framework presents a promising avenue for the green synthesis of a variety of metal/carbon composite catalysts, contributing to sustainable catalysis and environmental protection. [ABSTRACT FROM AUTHOR]

Single atom-based catalysts (SACs), due to their exceptional electrocatalytic behavior, have been explored for numerous applications such as the oxygen reduction reaction, thermo-catalytic CO2 reduction, and other catalytic activities. Ammonia is one of the most used chemical compounds, and its electrochemical synthesis is a promising alternative as it is simple and cost-effective and shows selective tunability towards the synthesis. Utilizing single-atom electrocatalysts with comparatively low metal mass loading yet exceptional activity could be a better approach to maximize ammonia production. Herein, we report a practically viable magnesium SAC (MgNxC) for the promising reduction of nitrate to ammonia. The catalyst was prepared using green leaf extracts of Spinacia oleracea via simple one-step pyrolysis. We optimized their synthesis temperature to scrutinize the effect of SAC formation and their variation on the catalysis efficacy. The MgNxC650 catalyst, anchored on a defective graphitic matrix, exhibits the best-optimized potential of −0.58 V vs. RHE, a faradaic efficiency of 81.5 ± 2.9% and a yield rate of 392.5 ± 41.2 μmol h−1 mg−1cat. with excellent repeatability. A comprehensive study of the nature of the heterojunction formed at the reactive interface of MgNxC catalysts was carried out by Mott–Schottky analysis to probe the band structure of the intrinsically induced metal–semiconductor junction in the MgNxC catalysts, followed by the analysis of parameters like flat band potential and carrier density correlation. DFT is employed to optimize the most stable reactive site and various reaction pathways for favorable nitrate reduction reaction with probable reaction intermediates were explored. Collectively, our work demonstrates a simple, cost-effective, and convenient way to synthesize SACs. Moreover, it provides clear evidence that chlorophyll moieties can be used as a template to prepare metal catalysts singly anchored on the graphitic carbon matrix. [ABSTRACT FROM AUTHOR]

A green strategy for the selective alkylation of cysteine-containing peptides in a continuous flow reactor has been developed, providing an efficient pathway to alkylated cysteine-containing peptides under mild conditions. This process does not need light, metal catalysts, or oxidative reagents. It provides a useful method for the modification of amino acids and peptides. As one of the low cost and synthetic versatile raw materials, the alkyl thianthenium salt can be used as an alkylation source in the preparation of alkylated cysteine-containing peptides. In addition, the microfluidics technology can shorten the reaction time and improve the efficiency, thus reducing the costs and energy consumption of the synthesis process. A series of alkylated cysteine-containing peptides (41 examples) has been synthesized here with a short residence time (14.0 min), and with good to excellent yields. [ABSTRACT FROM AUTHOR]

Hydrazones as organometallic equivalents have emerged as a general and sustainable strategy to utilize naturally abundant aldehydes and ketones as feedstocks while only releasing water and nitrogen gas as byproducts. Yet the addition of these carbanion equivalents to carbonyl compounds has been limited to the use of precious metals as catalysts and hazardous solvents under an inert atmosphere. Herein, we report the development of a manganese-based catalyst system for the addition of aldehydes to carbonyl compounds producing secondary and tertiary alcohols with yields of up to 91%. Furthermore, this method has proven robust and reproducible under aqueous and aerobic conditions to employ an earth-abundant metal catalyst, hence advancing hydrazone umpolung chemistry to be more sustainable and operationally simple. [ABSTRACT FROM AUTHOR]

Si NWs@C core/shell anodes for lithium-ion batteries were synthesized via a one-step environmentalpressure chemical vapor deposition (CVD) process utilizing nano-silicon and methane as raw materials. In this structure, the silicon nanowire core is obtained by controlling the temperature above 900 °C to catalyze the growth of nano-silicon particles coated with a natural oxide layer according to the oxide-assisted growth (OAG) mechanism, while the carbon as a protective coating shell is derived from methane cracking. In contrast to the conventional nanowire catalytic approach, this method obviates the addition of metal catalysts while ensuring a straightforward and scalable process. This Si NWs@C electrode displayed excellent electrochemical performance, exhibiting high reversible capacity (745.8 mA h g-1) and excellent cycling stability (91.3% after 100 cycles at 0.5 A g-1). [ABSTRACT FROM AUTHOR]

Reducing the utilization of precious metals and minimizing their depletion has been a pivotal concern in precious metal catalyst research. Hence, we employed a wet impregnation method to fabricate hollow carbon and silicon nanospheres (PdFe/NxC@mSiO2), encapsulating PdFe bimetallic nanoparticles. These bimetallic nanoparticles were enclosed within the hollow spheres, forming an alloy facilitated by nitrogen anchoring. The Pd4Fe1/NxC@mSiO2 catalyst exhibited enhanced dispersion of Pd, strengthened metalcarrier interaction, and superior ability for CO adsorption enrichment compared to single Pd catalysts. In situ DRIFTS analysis further revealed that the PdFe alloy catalysts, prepared via Fe doping, exerted reduced force on CO and improved CO insertion efficiency. Consequently, the Pd4Fe1/NxC@mSiO2 catalyst demonstrated heightened catalytic activity. In comparison to the individual Pd catalyst, this catalyst showed exceptional catalytic activity in the acetylene dialkoxycarbonylation process, with strong selectivity for 1,4-dicarboxylate (485%) and considerable acetylene conversion (490%). Moreover, this catalyst displayed remarkable recyclability, remaining active even after five cycles. [ABSTRACT FROM AUTHOR]

The substantial expense associated with catalysts significantly hampers the progress of electrolytic water-based hydrogen production technology. There is an urgent need to find non-precious metal catalysts that are both cost-effective and highly efficient. Here, the porous Ni2P–FePx nanomaterials were successfully prepared by hydrothermal method, nickel foam as the base, iron nitrate solution as the caustic agent and iron source, and finally phosphating at low temperature. The obtained porous Ni2P–FePx nanosheets showed excellent catalytic activity under alkaline PH = 14, and an overpotential of merely 241 mV was required to achieve a current density of 50 mA cm−2. The morphology of the nanosheet can still be flawlessly presented on the screen after 50 h of working at high current density. [ABSTRACT FROM AUTHOR]

Carbon-supported non-precious metal catalysts with highly exposed active sites have great potential for applications in the hydrogenation reduction of nitro compounds. Herein, a strategy for the preparation of carbon-supported Mo-based catalysts (Mo@C/MC) is proposed. Protein–Mo ion networks are first coated on the surface of microsphere carbons (MC). The coated MC employed as a precursor is then pyrolyzed to produce carbon-supported Mo-based catalysts. Notably, neither pore-forming agents nor post-treatment is required in the preparation of the catalyst. The active sites tend to disperse uniformly on the surface of the carbon matrix, facilitating the exposure of the active sites of the catalyst. The as-prepared catalyst Mo@C/MC shows high conversion (>99%) and selectivity (>98%) for the hydrogenation of nitro compounds under mild reaction conditions (100 °C, 5 bar H2). [ABSTRACT FROM AUTHOR]

Non-precious metal catalysts play a significant role in the field of hydrogenation. This study synthesized Co-BTC from cobalt nitrate hexahydrate and 1,3,5-tricarboxylic acid benzene. By changing the calcination temperature of Co-BTC in an inert atmosphere, a series of novel non-precious metal Co/C microsphere catalysts were successfully prepared. The composition and structure of the Co/C-n catalysts were characterised by FESEM, TEM, XRD, IR, XPS and BET. These results confirm that 1,3,5-benzenetricarboxylic acid provides a rich carbon matrix and metallic Co nanoparticles are generated by self-reduction on the carbon matrix. The graphite matrix formed during the calcination process has a rich pore structure and good dispersion of active components on the catalyst surface, which is very favourable for the catalytic reaction. In the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN), the Co/C-500 catalyst showed the best catalytic performance. At 80 °C and 2 MPa H2 for 60 minutes, the conversion rate of o-CNB reached 99% and the selectivity reached 99%. When the reaction takes 5 minutes, the conversion rate reaches 10.5%, and the TOF value reaches 36.3 h−1. The Co/C-500 catalyst can be easily recycled and reused after reaction with the help of a magnetic field. Moreover, this catalyst is also effective in the selective hydrogenation of other nitroaromatic hydrocarbons containing halogen or unsaturated groups to corresponding aniline. This simple and direct synthesis method may lead to the economic production of large-scale Co/C catalysts, which is an attractive prospect for the industrial trial production of corresponding aniline. [ABSTRACT FROM AUTHOR]

Although silane diamine copolymers have captured the attention of the catalysis community, the optimization of their synthesis and end uses have yet to be explored. In this study, a well-defined Earth-abundant metal catalyst, [(2,6-iPr2PhBDI)Mn(μ-H)]2, has been found to couple organosilanes to diamines to prepare networks that feature varied silane substitution and diamine chain lengths. By performing dehydrocoupling in the absence of solvent with 0.01 mol% catalyst loading, substrate utilisation turnover frequencies of up to 300 s-1 have been achieved at early reaction times, the highest Si--N dehydrocoupling activity to be observed on a per catalyst basis. These networks have been employed as absorbents for common organic solvents, a property that had not been studied for this class of materials. By incorporating a longchain hydrophobic linker, one network has been found to absorb 7.7x its original mass in THF and recycling has been demonstrated upon solvent removal. Controlling the degree of dehydrocoupling also offered an opportunity to deposit coatings from freshly-prepared silane diamine polymer solutions and monitor their integrity upon curing in air. While uniform and persistent coatings have been obtained from 1,6-diaminohexane derived polymers, the need to prepare dilute solutions that have a short shelf-life and the tackiness associated with extended dry times have been identified as potential limitations. [ABSTRACT FROM AUTHOR]

The application of non-noble metal catalysts to photocatalytic hydrogen production from water holds a high practical application value. In this study, photocatalysts were obtained by the hydrothermal and photodeposition methods. The optimal photocatalytic hydrogen production from water decomposition was 2641 μmol g−1 h−1. The results showed that compared with traditional composites, a ZnCdS(Two-Step)/Ni photocatalyst synthesized with Prussian blue analogue (PBA) as the precursor shows better photocatalytic performance for hydrogen evolution. Moreover, the introduction of Ni is found to be a feasible strategy to modulate the performance of photocatalysts, providing a reference for the construction of materials with excellent photocatalytic properties. [ABSTRACT FROM AUTHOR]

The preparation of alanine from waste polylactic acid (PLA) is not only an effective way to recycle waste plastics, but also of great significance to develop a green, clean and efficient amino acid production process. In this work, we studied the synthesis of alanine by amination of PLA with ammonia solution over different types of supported bimetallic catalysts without external hydrogen. It was found that the bimetallic catalyst consisting of Ru and a non-precious metal Co supported on TiO2 (Ru–Co/TiO2) was efficient for the reaction. The selectivity of alanine and turnover frequency (TOF) were 65.2% and 1.5 h−1, respectively. The synergistic effect existing between Ru and Co in the catalyst was crucial for the catalytic performance, and the content of precious metal Ru in the catalyst was lower. This was the first attempt to introduce a non-precious metal component into the catalyst for the amination of polylactic acid to alanine through thermocatalysis. [ABSTRACT FROM AUTHOR]

Aromatic amines, crucial organic entities, exist in drugs, natural products, organic materials, and catalysts. The introduction of amines to aromatics without using metal catalysts and chemical oxidants poses a formidable challenge. Recent years have witnessed extensive developments in the oxidative aromatization of aniline. In this context, we present the electrochemical cross-dehydrogenation aromatization (ECDA) reaction involving cyclohex-2-enone and amines, culminating in the synthesis of 1,4-phenylenediamine, devoid of supplementary metal catalysts and chemical oxidants. The broad applicability of the reaction substrate is underscored, demonstrating its compatibility with select natural and pharmaceutical molecules, thus showing considerable potential for the synthesis of bioactive compounds. The mechanistic underpinnings of the reaction were probed using online electrochemical mass spectrometry. [ABSTRACT FROM AUTHOR]

The synthesis of propargylamines by traditional methods is limited by several drawbacks such as anhydrous conditions, low temperatures and by-products. A3-coupling reactions (aldehydes, amines, and alkynes), that involve a catalytic amount of metal complexes, have been recently recognized as a powerful alternative for the synthesis of these important scaffolds. In this paper, four new silver and gold complexes (3a, 4a, 3b and 4b), bearing N-heterocyclic carbene (NHC) ligands, were tested in A3-coupling reactions, combining the use of harmless metals as catalysts with sustainable reaction conditions (neat conditions or water as solvent). NHC silver(I) and gold(I) complexes were synthesized and characterized by 1H and 13C NMR spectroscopy, ESI-MS and elemental analysis. The molecular structure of the NHC gold(I) complex 4b was determined by single crystal X-ray diffraction. A comparison of the catalytic behavior in A3-coupling reactions among the synthesized complexes disclosed the higher efficiency of gold catalysts. Computational studies shed light on species possibly involved in the catalytic mechanism. [ABSTRACT FROM AUTHOR]

Precious metal nanoparticles (NPs) are attractive for use in the field of catalysis because of their precisely controlled sizes and shapes. However, NPs exhibit insufficient anti-sintering properties under common operating conditions due to their poor thermal stability at elevated temperatures. In this paper, the preparation of noble metallic NPs (Pd and Au) incorporated inside the pores of an SBA-15 support via a sol-immobilization method, which prevents their aggregation, is reported. The Pd NPs retain their size of ∼5 nm within the channels of SBA-15, even after aging at 800 °C for three days under an air atmosphere. However, Au NPs aggregated at a temperature of calcination above 500 °C. Using a set of characterization methods comprising XRD, STEM, HRTEM, TPR, and DRIFTS analysis, it is revealed that Pd on SBA-15 exhibits better anti-sintering properties than the Au supported system. The catalytic activity and durability of M/SBA-15 (M: Pd or Au) catalysts were studied using CO oxidation with and without steam (10 vol%). Interestingly, a hydrothermally treated (Pd/SBA-15-750-H2O-3d) catalyst leads to the partial re-dispersion of Pd. This helps to attain smaller particles of ∼1.6 nm, which play a prominent role in the catalytic performance. This work provides insight into the design of sintering-resistant metal catalysts, which would be suitable for industrial applications under harsh conditions. [ABSTRACT FROM AUTHOR]

A metal-free C–H functionalization of purines with aldehydes was developed to access C6-acylated purines via green radical reactions. Theoretically, there are many competitive reactions due to the three C–H bonds (C2–H, C6–H, C8–H) in the purine, and the acylation only happens at the purinyl C6-position. This method avoids a metal catalyst and provides a green approach to construct C–C (sp2) bonds at the purinyl C6-position, while maintaining excellent compatibility with various functional groups. Moreover, the protocol features broad substrate scope and easy scale-up. The transformation of the product demonstrates the significant practical value of the method. The primary mechanism was proposed based on controlled experiments. [ABSTRACT FROM AUTHOR]

It is attractive but challenging to develop a cocatalyst for CO2/cyclohexene oxide (CHO) copolymerization with a double metal cyanide (DMC) catalyst. In this study, we synthesized three coordination polymers (CPs) [Cd(3N3PY)(NDC)]·0.58H2O (1), [Zn(3N3PY)(IPA)]·3H2O (2) and [Cd(3N3PY)(NPA)]·2DMF·2H2O (3) (3N3PY = 4′-(4-(1H-1,2,4-triazol-1-yl)phenyl)-2,2′:6′,2′′-terpyridine, H2NDC = 2,6-naphthalene dicarboxylic acid, H2IPA = isophthalic acid, H2NPA = 2,2′-dinitro-4,4′-biphenyldicarboxylic acid). Crystal structural analyses show that 1–3 are different one-dimensional (1D) chains that further assemble into three-dimensional (3D) supramolecular structures by π–π and hydrogen bonding interactions. CPs 1–3 were applied as cocatalysts to assist DMC for CO2/CHO copolymerization and the efficient proportion of carbonate P–OC(O)O– in the product is 59% achieved for 2 at 80 °C in 1 MPa CO2. The proportion of carbonate F(CO2) and conversion rate of CHO (CCHO) are 63% and 93%, respectively. The mechanistic study on structure–activity relationship and chemoselectivity was performed. [ABSTRACT FROM AUTHOR]

An efficient and mild multicomponent reaction (MCR) for the preparation of vinyl sulfone is reported, which is achieved by the hydrogenation/difunctional sulfonylation of an alkynyl ester with the corresponding N-allyl bromodifluoroacetamide, DABSO and H2O under visible light conditions without the need for any metal catalysts or additives. This transformation is the first example of a conversion using H2O as the hydrogen source to interact with DABCO to form [DABCO-H]+, which ultimately reacts with the vinyl group, with the advantage of high chemoselectivity and step economy. Notably, the method produces different sulfonylation products with the same substrate regulated by the presence or absence of H2O, which greatly reduces the cost of the chemical reaction and exhibits good functional group tolerance and substrate range. In addition, gram-scale experiments proceeded smoothly, proving the practicality of the methodology. [ABSTRACT FROM AUTHOR]

The electrochemical bromination of enamide derivatives was developed using inexpensive and non-toxic sodium bromide (NaBr). This transformation enabled the direct stereoselective formation of a C(sp2)−Br bond and was applied to a wide variety of enamides without the need for external hazardous oxidants, reductants or metal catalysts. The protocol showed a general efficiency and tolerance, allowing access to brominated enamides with yields ranging from 56% to 85%. The reaction conditions were applied to the chlorination reaction using sodium chloride (NaCl). The synthetic utility of the products was illustrated through Suzuki and Sonogashira cross-coupling reactions, offering a novel reaction procedure to access complex enamide derivatives. [ABSTRACT FROM AUTHOR]

Selective isomerization of terminal olefins to afford new internal olefins is an atom economic reaction that is usually catalysed by metal catalysts. Here, we present a tris(pentafluorophenyl)borane [B(C6F5)3]-catalysed isomerization of olefins. Linear α-olefins are converted to 2-olefins in high yields with unsatisfactory stereoselectivity under the applied reaction conditions. At the same time, the biorelevant phenylpropenoid products can be obtained with high regio- and stereoselectivity from the isomerization of allylbenzenes. [ABSTRACT FROM AUTHOR]

An electrochemical thioetherification of NH-sulfoximines with disulfides is reported. The use of electrochemistry to promote these oxidative coupling reactions not only obviates the requirement for external oxidants, bases, and metal catalysts but also ensures high environmental friendliness and selectivity to afford N-sulfenyl-sulfoximines. Good functional group tolerance, and readily available substrates offer this strategy incomparable advantages in preparing a variety of valuable N-sulfenyl-sulfoximines. Meanwhile, this reaction features simple operation, mild reaction conditions, and convenience of amplification, and has great potential in the subsequent modifications of pharmaceutical N-(2-thiophenyl)benzamide derivatives. Furthermore, the cytotoxic effects of the expected products toward different tumor cells were investigated in vitro and compared with 5-fluorouracil (5-Fu), the most widely used chemotherapeutic drug against malignant tumors. [ABSTRACT FROM AUTHOR]

Exploring non-noble metal dual-functional electrocatalysts with high activity and stability for water splitting is highly desirable. In this study, using zeolitic imidazolate framework-L (ZIF-L) nanoarrays as the precursor, manganese oxide-decorated porous nickel–cobalt phosphide nanosheet arrays have been prepared on nickel foam (denoted as MnOx/NiCoP/NF) through cation etching, phosphorization and electrodeposition, which are utilized as an efficient dual-functional electrocatalyst for overall water splitting. The hierarchical porous nanosheet arrays provide abundant active sites for the electrochemical process, while the MnOx modification induces strong interfacial interaction, benefiting charge transfer. Thus, the MnOx/NiCoP/NF exhibits excellent electrocatalytic activity toward the hydrogen evolution reaction (HER, overpotential of 93 mV at 10 mA cm−2), oxygen evolution reaction (OER, overpotential of 240 mV at 10 mA cm−2) and overall water splitting (cell voltage of 1.59 V at 10 mA cm−2). Furthermore, it shows superior stability during continuous overall water splitting for 200 h. This work provides a simple and effective approach for developing efficient non-noble metal dual-functional catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

Perovskite oxides are considered promising efficient and cost-effective water splitting electrocatalysts under alkaline conditions because of their excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity. However, due to their poor electron transfer and lack of exposed active sites, their HER activity is still much lower than that of precious metal catalysts. Besides, to date, few studies have been reported on the HER in complex water systems. In this study, a new composite electrocatalyst, SrCo0.7Fe0.3O3−δ@CdS, with a core–shell structure (denoted as SCF@CdS) was successfully prepared using an in situ coprecipitation method, which exhibited efficient HER activity in an alkaline environment and oilfield wastewater. The better electrocatalytic performance of SCF@CdS than pure SCF can be attributed to the larger specific surface area and more exposed active sites in this core–shell structure, and the lone pair electrons from S in CdS can also form coordination bonds with the vacant orbital of Co in the perovskite by sharing electron pairs, thus increasing the concentration of oxygen vacancies. This study provides a strategy to improve the HER performance of perovskite catalysts in complex water systems via the construction of a core–shell structure. [ABSTRACT FROM AUTHOR]

Zn–air batteries have garnered significant interest due to their high capacity, economical cost, and eco-friendly nature. The pursuit of non-noble metal cathode catalysts that offer high activity, exceptional durability, and cost-efficiency as alternatives to noble metal platinum is a prominent research focus. In this investigation, a nitrogen-doped carbon material predominantly constituted of pyridinic nitrogen and graphitic nitrogen was synthesized utilizing the polymer of hexaaminobenzene and hexaketocyclohexane as precursors. In a 0.1 M KOH electrolyte, this catalyst demonstrated ORR catalytic activity on par with commercial Pt/C and showcased enhanced stability compared to Pt/C. When incorporated as a cathode catalyst in a zinc–air battery, the battery exhibited stable discharge for 95 hours at a current density of 5 mA cm−2, achieving a specific capacity as high as 730 mA h g−1. Its discharge efficacy remained consistent even following multiple replacements of the anode zinc plate, facilitating the repeated use of the zinc–air battery. This research underpins the technical foundation and theoretical framework for the advancement of novel carbon-based catalysts characterized by straightforward production techniques, affordability, and superior activity and resilience. [ABSTRACT FROM AUTHOR]