Materials Today Catalysis最新文献

The development of catalytic systems that selectively convert O₂ to water is required to progress fuel cell technology. As an alternative to platinum catalysts, derivatives of iron and cobalt porphyrin molecular catalysts provide one benchmark for catalyst design. However, the inclusion of these catalysts into homogeneous platforms remains a difficulty. Co-porphyrins have been studied as heterogeneous O₂ reduction catalysts; however, they have not been explored much in homogeneous systems. Moreover, they suffer from poor selectivity for the desired four-electron reduction of O₂ to H₂O. Herein, we present two cobalt-based β-fluorinated porphyrin complexes (CoTPF₈(OH)₂ and CoTPF₈(OH)₄) and demonstrate applicability as effective catalysts for the oxygen reduction reaction. Using rotating ring-disk electrochemistry, the catalysts, CoTPF₈(OH)₂ and CoTPF₈(OH)₄, showed maximum Faradaic efficiency for H₂O of 92 % and 97 %, respectively. DFT calculations suggest that the formation of a phlorin intermediate could occur before O₂ reduction and that a stronger H₂O₂ binding in the cobalt-based β-fluorinated porphyrin species compared to the unsubstituted parent compound, CoTP(OH)₂, was responsible for the observed experimental selectivity for H₂O. These results reveal that the β-fluorinated porphyrin catalyst serves as a novel platform for investigating molecular electrocatalytic reactions.

Two-dimensional (2D) materials, such as graphene, hexagonal boron nitride, 2D metal–organic frameworks, layered double hydroxides, transition metal dichalcogenides, and MXenes, have garnered significant attention in catalysis due to their exceptional properties and structures. Notably, recent studies have revealed the promising catalytic activity of MXene-based catalysts for many reactions, including hydrogen evolution, oxygen evolution, oxygen reduction, nitrogen reduction, carbon dioxide reduction, alcohol oxidation, hydrogenation, dehydrogenation, methanol conversion, dry reforming of methane, and CO oxidation. This review offers a summary of recent advances in the field, contextualizing the progress made. Additionally, it delves into existing challenges while presenting prospects for future developments in this domain.

This review delves into the underlying principles, advantages, challenges, and recent developments in photoelectrocatalysis (PEC) processes for wastewater treatment and green hydrogen production. PEC is an emerging technique that holds great promise for addressing two critical challenges simultaneously, namely, the degradation of industrial wastewater pollutants and the generation of clean energy in the form of hydrogen gas. In recent years, many studies have explored the use of photoanodes to harness solar energy for wastewater treatment. These photoanodes facilitate the breakdown of contaminants, while the cathode concurrently produces green hydrogen. The PEC enables the production of both clean water and hydrogen gas from industrial wastewater. This dual benefit makes it an attractive avenue for sustainable industrial wastewater treatment and clean energy generation. The PEC process capitalizes on the constructive interaction between electrochemical reactions and photocatalysis. Solar energy is efficiently converted into electron-hole pairs, which play a pivotal role in water-splitting reactions occurring at the electrode surfaces. Achieving the best performance involves scrutiny of various parameters, including catalyst loading, pH, light intensity, and electrolyte composition. The photoelectrocatalytic system shows commendable stability and durability during extended operation, reinforcing its practical applicability. This review provides a comprehensive overview of the PEC process, catalyst materials, optimization strategies, and driving efficiency. Considering the potential benefits and costs on a larger scale underscores the significance of photoelectrocatalytic hydrogen production in addressing environmental concerns and energy-related issues concurrently. Therefore, PEC is a promising pathway toward sustainable water treatment and clean energy, bridging the gap between environmental stewardship and technological advancement.

Ribbon-like coordination polymers (CP) represents a highly unexplored innovative class of metal-coordination network. Herein, we have developed a highly scalable and chemically robust (pH = 3–10 stable) ribbon-like CP [{Cu(Pim)(L)(H₂O)·H₂O}]_n (1) following a complete environment-friendly green synthesis route. Considering the presence of surface flanked labile coordinated water molecules and their appealing correlation with one-dimensional structural characteristics, such sort of ribbon-like CP was explored for the first time as excellent heterogeneous surface catalyst for largely unexplored three-component Hantzsch condensation for synthesis of different classes of dihydropyridine (DHP). Moreover, 1 is employed to synthesize bio-responsive drug ‘Ethidine’ (possessing high anti-oxidant and anticarcinogenic properties) characterized with Single Crystal X-ray Diffraction (SCXRD) analysis. Several DHP-based products are also analysed through in-depth SCXRD analysis. This report inaugurates the usage of a Cu(II) based ribbon-like CPs as heterogeneous surface catalyst following environmentally benign manner for synthesis of bioactive DHPs and Drugs.

The highly active and selective oxygen reduction reaction (ORR) is vital to promote the performance of advanced energy conversion systems, such as fuel cells and other electrochemical devices. Porous framework materials have the capability to combine the catalytic performance of catalytic active units with their porous characteristics, making them promising oxygen reduction catalysts. However, due to the difficulty in designing and synthesizing catalytic active units, the pore size modulation of framework materials is primarily achieved by altering the linkers. We herein report the design and synthesis of three cobalt-corrole-based porous organic polymers (Co-POP-1, Co-POP-2 and Co-POP-3) with different pore sizes, which were obtained by extending 5,15-meso substituents of Co corroles. Compared to Co-POP-1 and Co-POP-2, Co-POP-3 has the largest pore size. Benefiting from the enhanced mass transfer and the highly exposed active sites, Co-POP-3 displayed remarkably boosted activity for the selective four-electron/four-proton (4e⁻/4 H⁺) ORR with a half-wave potential of E_1/2 = 0.89 V versus reversible hydrogen electrode (RHE) in 0.1 M KOH solutions. This work not only presents a cobalt-corrole-based porous organic polymer catalyst with high ORR activity and selectivity but also provides a new strategy to moderate the pore size of porous framework materials.

The conversion of carbon dioxide (CO₂) into valuable chemicals, specifically C₂ and C₃, through metal-free electrocatalysis remains a formidable challenge. Breaking away from traditional transition metal complexes, the focus is on designing and selecting efficient organic catalysts. In this pursuit, a diazo-based organic bulky ligand emerges as a promising candidate, offering a solution that is both sustainable and renewable. The key feature of this ligand is its low-lying π* (LUMO), enabling it to readily accept an electron in an electrochemical environment when a potential is applied. The synthesized Diazo-based ligands have been meticulously characterized using various techniques, including ¹H NMR, ¹³C NMR, UV-Vis, and IR spectroscopy. This diazo-based ligand serves as an electrocatalyst, undergoing reduction to a triplet diradical that acts as a nucleophile. In an aqueous medium, it forms an adduct with CO₂, leading to the generation of a formyl radical. This radical further couples to produce acetic acid and acetone with efficiencies of 19.6% and 24.2%, respectively, at pH 5.5. To provide a deeper understanding, we present a proposed mechanism pathway supported by in-situ UV-Vis spectroscopy and a comprehensive Density Functional Theory (DFT) study. These findings mark a significant step forward in the field of metal-free electrocatalysis, offering a sustainable approach to the conversion of CO₂ into valuable chemicals, contributing to the development of renewable and environmentally friendly systems.

Although single-atom catalysts (SACs) are emerging as potential contenders for heterogeneous catalysis, interactions between metal single-atom active sites and support matrix remain uncertain. In a recent issue of Nature, Zhang and coworkers revealed the phase-dependent growth of single atom Pt on 1 T′ phase MoS₂ for efficient hydrogen evolution. However, some analyses of the nature of catalyst structure and properties are still lacking, and the relevant large-scale commercial application is still difficult.

The electrochemical carbon dioxide reduction (ECR) to profoundly diminished chemical entities offers a compelling avenue for transforming sporadic energy resources into enduring fuels while forging an enclosed anthropogenic carbon cycle. Metal-organic frameworks (MOFs) has been extensively investigated as a promising multifunctional material for ECR. Notably, two-dimensional (2D) MOFs attract particular research attention due to their specific chemical and structural properties, i.e., enhanced electrical conductivity, increased open sites, improved mass transport and tunable interfacial environments. In this review, the recent progress of 2D MOFs for ECR is summarized. We begin with the introduction of the synthetic strategies of 2D MOFs. Then, we mainly focus on the advanced 2D MOF electrocatalysts for ECR in recent years, which are clarified by the products. The mechanism underlying the conversion of carbon dioxide (CO₂) into carbon products, the factors influencing product formation and a summary of selected 2D MOF catalysts and their synthetic methods are presented. By consolidating the potential factors contributing to the products, we anticipate that the review will offer fresh opportunities for further advancements in CO₂ reduction with 2D MOF catalysts.