ChemCatChem最新文献

Lignins, abundant aromatic biopolymers and one of the major components of lignocellulosic biomass, remain the most underutilized renewable bioresources of aromatics and hydrocarbons on the Earth. Numerous physical and chemical processes have been developed for lignin valorization; however, they generally suffer from environmentally unfriendly, harsh conditions and lack reaction specificity. On the other hand, milder methods involving biocatalysts exist but are impeded by many limitations, such as cofactor regeneration, deleterious enzyme–lignin interactions, and low stability. In this work, we attempt to eliminate the constrains encountered in enzyme-based lignin valorization processes through the development of a novel electrochemically assisted bioprocess. This “all-in-one” biocathode incorporates a hybrid electrocatalytic interface combining a hydrogen peroxide-generating passive air-breathing gas diffusion electrode with an immobilized hydrogen peroxide-consuming lignin peroxidase on a single surface and catalyzing the depolymerization of lignins. The ligninolytic potential of this bioelectrochemical device is demonstrated using both lignin models (veratryl alcohol and veratrylglycerol β-guaiacyl ether) and a technical lignin at room temperature in aqueous media with the reaction efficiency of 14.9% per hour.

Non-benzenoid PAHs with pentagon/heptagon pairs have unique electronic structures and promising opto-electronic properties. However, the construction of pentagon/heptagon pair units in these PAHs is challenging. Herein, we developed a Pd-catalyzed (3+2) alkyne annulation reaction of heptagons, and constructed heptagon/pentagon pairs. The substrate scope is wide and the yield is good to moderate. A series of dibenzoauzlene derivatives were synthesized and their opto-electronic properties were systematically studied by UV-vis absorption and cyclic voltammetry. In addition, the dibenzoazulene derivative was further transformed to tropylium cation and tropyl radical, which showed bathochromic shifted absorption and switched aromaticity.

The one-carbon degradation  of aliphatic carboxylic acids has been studied using a H₂IrCl₆-Ru(CO)₄I₂ bimetallic catalyst. Alkanes, RH, have been obtained from the corresponding RCOOH in good to near quantitative yields via a process that is thought to involve (i) a decarbonylation process that involves the formation of alkenes along with CO and H₂O, (ii) a water–gas shift (WGS) reaction to give H₂ and CO₂, and (iii) the hydrogenation of the resulting alkenes.

Hantzsch ester (HEH) is a bench-stable compound used in hydrogenation and photoinduced reactions, where it acts as a photoreductant and an electron donor. In this study, we describe a new use of this classical reductant in the visible-light-induced desulfurative coupling of alkyl benzothiazolyl sulfides with electron-deficient alkenes/alkynes via activation with base additives. C(sp³)─S scission is achieved through catalyst-free HEH anion-mediated reactions and organo-photocatalysis. The synthetic utility is illustrated with several examples of derivatization of natural products, including monosaccharides. In addition, mechanistic investigations reveal that the HEH anion acts as a photoreductant in catalyst-free reactions and as a sacrificial reductant in the organo-photocatalysis.

Oxygen evolution reaction (OER) represents a significant bottleneck in many energy technologies such as electrochemical water splitting, metal-oxygen (O) batteries, and solid oxide fuel cells (SOFCs) because of the complexity of the reaction process. Double perovskite oxides (ABO₃), recognized for their compositional flexibility, have emerged as excellent OER activity and stability. This study investigates the catalytic potential of A-site-ordered double ABO₃ with (PrBa)_xCo_1.5Fe_0.5O_6δ (PBCF_−x, x = 0.9–1.1) in alkaline media. The results reveal that PBCF_−0.9, characterized by an A-site-deficient composition, exhibits exceptional OER activity. It demonstrates a low Tafel slope of 76.12 mV⋅dec⁻¹ and a low overpotential (η) of 270 mV at 10 mA⋅cm⁻². Notably, the intrinsic OER activity of PBCF_−0.9 is 25% higher than that of the stoichiometric PBCF_−1.0. Additionally, PBCF_−0.9 exhibits remarkable durability, as evidenced by its stable performance during a 6-h chronopotentiometry (CP) test and minimal microstructural changes. These results underscore the effectiveness of A-site deficiency in optimizing the structure of double ABO₃ for improved OER performance. This approach presents a promising strategy for designing highly efficient, stable, and inexpensive catalysts for energy-related applications.

Non-innocent ligands in metal complexes pave the way for more energy-efficient and sustainable catalytic processes by involving both the metal and the ligand in bond activation processes. This issue features selected examples illustrating the role of the ligand in enabling (or disabling) catalytic bond cleavage/formation processes via metal-ligand and metal-metal cooperation.

Clay-based materials are an emerging family of earth-abundant and low-cost inorganic functional materials with an modifiable layered-structure mode similar to hydroxides. They are considered as competitive electrocatalysts for water splitting due to their variable intra-layer ions, exchangeable interlayer molecules/ions, and large reaction surfaces, which demonstrate fascinating engineering opportunities at the microscale, mesoscale, and macroscale levels. We systematically summarized the research progress of clay-based materials by classifying clay-like compounds, clay-based composites, and clay-based derivatives, from the viewpoint of structural geometries towards optimizing functionalities. The design strategies for regulating and optimizing clay-based materials to meet the requirements of electrocatalysts with excellent activity and stability were outlined through representative examples. In addition, the hydrogen production applications of these clay-based materials were discussed reasonably including recent advances. Finally, the future perspectives of clay-based materials for electrocatalytic water splitting were demonstrated.

Fungal natural products (NPs), known for their potent bioactivities, can be utilized as human therapeutics and agrochemicals. These bioactive and structurally complex compounds are biosynthesized through condensation of monomeric building blocks to construct core scaffolds, followed by various modification steps. Recent studies have revealed that a unique class of enzymes from the NTF2-like protein family plays important roles in the biosynthesis of complex fungal NPs. These NTF2-like enzymes belong to a large group of related proteins that share a common fold with nuclear transport factor 2, and are capable of catalyzing various reactions. In this study, we summarize the recent progress in discovering and characterizing the catalytic functions of fungal-derived NTF2-like enzymes, including dehydratases, epimerases, isomerases, semipinacolases, pericyclases, and aldolases. These findings not only provide valuable insights into new catalytic reactions and mechanisms, but also offer opportunities to discover novel NPs and biocatalysts through genome mining.

Driven by the growing global demand for sustainable energy, ammonia is gaining recognition as a crucial energy carrier with the potential for widespread manufacturing. This has spurred the emergence of a “sustainable ammonia economy”. Efficient catalyst development is paramount to achieving this purpose. Although the traditional trial-and-error methods have led to substantial progress, they are inherently time-consuming. In recent years, high-throughput screening strategies are revolutionizing catalyst discovery, offering an efficient and cost-effective approach for identifying high-performance catalysts across various processes within the ammonia economy. This review explores recent advancements in these rapid catalyst screening techniques for ammonia-based processes. By outlining the general screening principles and the key steps involved in the computational analysis of catalysts relevant to different stages of the ammonia economy, this review aims to provide fundamental insights for the development of novel catalysts using these accelerated methods.

In this work, we present an insight into the mechanism of electrochemical hydrogenation of furfural on carbon supported palladium nanoparticles. By directly coupling electrochemistry with mass spectrometry, we were able to, for the first time, deconvolute the hydrogen evolution reaction and electrochemical hydrogenation by measuring the mass signal for hydrogen and 2-methylfuran. This approach also allowed us to extract the Tafel slopes for each reaction and get insights into mechanisms. The results indicate that the hydrogenation occurs by a Langmuir–Hinshelwood type process rather than by proton-coupled electron transfer. Further findings recognize the blocking character of furfuryl alcohol (FA) where the latter or one of its intermediates blocks the electrochemical hydrogenation. Additionally, FA is shown to be a precursor for 2-methyl furan formation. Accordingly, specific guidelines towards improvement of reaction performance are suggested.