Field Of Catalysis Research Articles

Efficient screening of single-atom Porphyrazine-coordinated transition metal catalysts for electrochemical nitric oxide reduction: Insights from first-principles calculations

The electrochemical conversion of NO to NH3 is gaining attention in green energy for its dual benefits of producing ammonia and eliminating toxic NO. However, the lack of efficient and durable electrocatalysts limits its application, highlighting the need for improved catalysts to advance this promising strategy. The emerging transition metal porphyrazine frameworks (TM − Pz), which combine the advantages of single-atom metal (SAC) centers with the coordination of surrounding 4 N ligands, present promising opportunities in the field of electrochemical catalysis. We have designed a series of 3d transition metal single-atom catalysts (SACs) and conducted high-throughput screening, based on first-principles computations, to identify effective catalysts for the electrocatalytic conversion of NO to NH3. Our findings reveal that the Ti − Pz, Fe − Pz, and V − Pz nanosheets exhibit significantly lower UL values of −0.11, −0.24, and −0.31 V, respectively, when compared to the experimentally and theoretically determined criterion of −0.32 V. The correlation between limiting potentials (UL) and a specific descriptor (φ) is particularly significant for constructing a volcano plot, which illustrates the intrinsic properties of metal atoms in various TM − Pz series and their associated remarkable nitric oxide reduction reaction (NORR) performance. Among the range of nanosheets evaluated, the Ti − Pz and Fe − Pz models emerge as particularly noteworthy, demonstrating significantly higher selectivity and NORR activity than their counterparts. This research deepens our comprehension of the distinctive and advantageous properties of SACs, presenting progressive perspectives that can directly facilitate the discovery and optimization of SACs for NORR applications.

Nano-Metal-Organic Frameworks and Nano-Covalent-Organic Frameworks: Controllable Synthesis and Applications.

Nanoscale framework materials have attracted extensive attention due to their diverse morphology and good properties, and synthesis methods of different size structures have been reported. Therefore, the relationship between different sizes and performance has become a research hotspot. This paper reviews the controllable synthesis strategies of nano-metal-organic frameworks (nano-MOFs) and nano-covalent-organic frameworks (nano-COFs). Firstly, the synthetic evolution of nano-frame materials is summarized. Due to their special surface area, regular pores and adjustable structural functions, nano-frame materials have attracted much attention. Then the preparation methods of nanostructures with different dimensions are introduced. These synthetic strategies provide the basis for the design of novel energy storage and catalytic materials. In addition, the latest advances in the field of energy storage and catalysis are reviewed, with emphasis on the application of nano-MOFs/COFs in zinc-, lithium-, and sodium-based batteries, as well as supercapacitors.

Renaissance of Chlorine Evolution Reaction: Emerging Theory and Catalytic Materials

Chlorine (Cl2) is one of the most important commodity chemicals that has found widespread utility in chemical industry. Most Cl2 is currently produced via the chlorine evolution reaction (CER) at the anode of chlor–alkali electrolyzers, for which precious group‐metal‐based mixed metal oxides (MMOs) have been used for more than half a century. However, MMOs suffer from the use of platinum‐group metals, which are costly and scarce, and the selectivity issue arises from the parasitic oxygen evolution reaction. Over the last decade, the field of CER catalysis has seen dramatic advances in both the theory and discovery of new catalysts. Theoretical approaches have enabled a fundamental understanding of CER mechanisms and provided catalyst design principles. The exploration of new materials has led to the discovery of CER catalysts other than MMOs, including non‐PGM‐based oxides, atomically dispersed single‐site catalysts, and organic molecules, with some of which following novel reaction pathways. This minireview provides an overview of the recent advances in CER electrocatalyst research and suggests future directions for this revitalized field.

Active Learning of Boltzmann Samplers and Potential Energies with Quantum Mechanical Accuracy.

Extracting consistent statistics between relevant free energy minima of a molecular system is essential for physics, chemistry, and biology. Molecular dynamics (MD) simulations can aid in this task but are computationally expensive, especially for systems that require quantum accuracy. To overcome this challenge, we developed an approach combining enhanced sampling with deep generative models and active learning of a machine learning potential (MLP). We introduce an adaptive Markov chain Monte Carlo framework that enables the training of one normalizing flow (NF) and one MLP per state, achieving rapid convergence toward the Boltzmann distribution. Leveraging the trained NF and MLP models, we compute thermodynamic observables such as free energy differences and optical spectra. We apply this method to study the isomerization of an ultrasmall silver nanocluster belonging to a set of systems with diverse applications in the fields of medicine and catalysis.

Renaissance of Chlorine Evolution Reaction: Emerging Theory and Catalytic Materials.

Chlorine (Cl2) is one of the most important commodity chemicals that has found widespread utility in chemical industry. Most Cl2 is currently produced via the chlorine evolution reaction (CER) at the anode of chlor-alkali electrolyzers, for which platinum group-metal (PGM)-based mixed metal oxides (MMOs) have been used for more than half a century. However, MMOs suffer from the use of expensive and scarce PGMs and face selectivity problems due to the parasitic oxygen evolution reaction. Over the last decade, the field of CER catalysis has seen dramatic advances in both the theory and discovery of new catalysts. Theoretical approaches have enabled a fundamental understanding of CER mechanisms and provided catalyst design principles. The exploration of new materials has led to the discovery of CER catalysts other than MMOs, including non-PGM oxides, atomically dispersed single-site catalysts, and organic molecules, with some of which following novel reaction pathways. This minireview provides an overview of the recent advances in CER electrocatalyst research and suggests future directions for this revitalized field.

Limited dissolution of transition metals in the nanocrystalline cerium (IV) oxide

Nanocrystalline cerium (IV) oxides doped with transition metals have gained significant interest recently, mostly in the field of catalysis. Herein, we present the comprehensive studies on ceria doped with 10 mol.% of transition metals (Mn, Fe, Co, Ni or Cu) synthesized by the reverse microemulsion method. The aim of this work is to study the properties of those materials with the use of different complementary methods like XRD, SEM, TPR, and XPS and to determine the possibility of fabrication of single-phase materials with that doping level. Studies presented here prove that despite showing single-phase XRD patterns with high nanocrystallinity, in all obtained materials, the dopants are not fully incorporated in the ceria lattice. Spectroscopy studies show that additional transition metal oxides are present on the surface of all materials. Herein, we also present the analyses of L3,2-edges of transition metals in ceria, as well as high energy Ce K-edge to prove that 10 mol.% of any of those transition metals cannot be incorporated in the ceria host without the formation of additional phases. Using techniques presented here, it was found that the highest share of Mn can be dissolved in the lattice, while Cu is mostly present as a surficial Cu2O. Studies presented are an important contribution to the discussion about the solubility limits in nanocrystalline ceria and its properties which may be utilized for e.g various catalysts or as electrolytes.

One-Step Molten Salt Method For Synthesis of Perovskite-Like Sr2Nb2O7 and Sr5Nb4O15 Ceramics

Abstract In this study, Sr2Nb2O7 and Sr5Nb4O15 layered perovskite-like ceramics were synthesized by a single process using a one-step molten salt method. By optimizing the key parameters, including the choice of molten salt, reaction temperature and residence time, two materials achieve synchronous production. The crystal structures of the synthesized materials were confirmed by X-ray diffraction. It is proved that it has typical perovskite-like structural characteristics. Scanning electron microscopy reveals the morphology of these materials. Sr2Nb2O7 presents a sheet-based structure, and Sr5Nb4O15 presents a rod-based structure. This study provides an efficient and direct method for the synthesis of perovskite materials. One-step molten salt method has great potential in the synthesis of multiphase materials. These findings are expected to promote the application of perovskite materials in the fields of electronics, optics and catalysis.

Efficiently Catalyzing Xylose to Furfural by Synthesizing Solid Acid Catalysts from Lignocellulosic Residues

AbstractThe utilization of biomass as a carbon source for the synthesis of renewable solid acid catalysts (SA) has emerged as a prominent research direction in the field of heterogeneous catalysis. Based on the challenges associated with reusing residues from lignocellulosic biorefining, the biomass‐based SA (BCSA) were prepared using poplar sawdust (PS), hydrothermally pretreated PS (PPS), and the residue of PPS's enzymatic hydrolysis (ER). The characterization revealed that all three types of BCSA were loaded with catalytic groups, and the BCSA synthesized using ER rich in lignin components exhibited a highly efficient catalytic structure. Furthermore, the catalysis of a 20 g/L xylose solution with BCSA‐ER as SA also achieved the highest furfural yield (89.3%) and furfural selectivity (90.3%). The findings of this study suggested that lignin holds significant potential as a carbon carrier for SA, thereby offering a viable solution for utilizing by‐products from lignocellulosic biorefining.

Palladium‐Catalyzed Remote C−H Functionalization: Non‐Covalent Interactions and Reversibly Bound Templates

AbstractPd‐catalysis has stood as a pivotal force in synthetic transformations for decades, maintaining its status as a paramount tool in the realm of C−H bond activation. While functionalization at proximal positions has become commonplace, achieving selective and sustainable access to distal positions continues to captivate scientific endeavors. Recently, a noteworthy trend has emerged, focusing on the utilization of non‐covalent interactions to address the challenges associated with remote functionalization. The integration of these non‐covalent interactions into palladium catalysis stands as a justified response to the demands of achieving selective transformations at distal positions. This review delves into the latest advancements and trends surrounding the incorporation of non‐covalent interactions within the field of palladium catalysis. Furthermore, it is noteworthy to emphasize that multifunctional templates, particularly those harnessing hydrogen bonding, present an elegant and sophisticated approach to activate C−H bonds in a highly directed fashion. These templates showcase versatility and demonstrate potential applications across diverse contexts within the area of remote functionalization.

Palladium-Catalyzed Remote C-H Functionalization: Non-Covalent Interactions and Reversibly Bound Templates.

Pd-catalysis has stood as a pivotal force in synthetic transformations for decades, maintaining its status as a paramount tool in the realm of C-H bond activation. While functionalization at proximal positions has become commonplace, achieving selective and sustainable access to distal positions continues to captivate scientific endeavors. Recently, a noteworthy trend has emerged, focusing on the utilization of non-covalent interactions to address the challenges associated with remote functionalization. The integration of these non-covalent interactions into palladium catalysis stands as a justified response to the demands of achieving selective transformations at distal positions. This review delves into the latest advancements and trends surrounding the incorporation of non-covalent interactions within the field of palladium catalysis. Furthermore, it is noteworthy to emphasize that multifunctional templates, particularly those harnessing hydrogen bonding, present an elegant and sophisticated approach to activate C-H bonds in a highly directed fashion. These templates showcase versatility and demonstrate potential applications across diverse contexts within the area of remote functionalization.

High-Entropy Alloys in Catalysis: Progress, Challenges, and Prospects.

High-entropy alloys (HEAs) have become pivotal materials in the field of catalysis, offering unique advantages due to their diverse elemental compositions and complex atomic structures. Recent advances in computational techniques, particularly density functional theory (DFT) and machine learning (ML), have significantly enhanced our understanding and design of HEAs for use in catalysis. These innovative atomistic simulations shed light on the properties of HEAs, enabling the discovery and optimization of catalysis materials for solid-solution structures. This Perspective discusses recent studies that illustrate the progress of HEAs in catalysis. It offers an overview of the properties, constraints, and prospects of HEAs, emphasizing their roles in catalysis to enhance catalytic activity and selectivity. The discussion underscores the capabilities of HEAs as multifunctional catalysts with stable structures. The presented insights aim to inspire future computational and experimental efforts to address the challenges in fine-tuning HEAs properties for improved catalytic performance.

Recovering noble metals from waste streams using porous organic frameworks for heterogeneous catalysis

AbstractRecovering noble metals from waste resources and incorporating them into catalysts stands out as a promising strategy for advancing sustainability within the catalysis field. This review provides a comprehensive overview of recent investigations into noble metal recovery from waste streams, specifically employing porous organic frameworks (POFs). Additionally, the study delves into the utilization of the resultant composites, enriched with noble metals, in heterogeneous catalysis. Moreover, we offer insights into the challenges faced and outline prospects for the practical implementation of extracting noble metal catalysts from waste streams using POFs, aiming to develop cost-effective, sustainable, and efficient heterogeneous catalysts.

Oxygen atom activated ZIF-67/carbon cloth in plasma system for CO2 reduction

ZIF-67 was grown in situ on carbon cloth (CC) using a simple one-step method. The prepared ZIF-67/CC electrodes exhibited excellent CO2 reduction reaction (CO2RR) performance in a dielectric barrier discharge plasma reactor. The highest concentrations of produced formic acid and formaldehyde were 9.16 and 0.068 mmol L−1 at a reaction time of 1 h, respectively. The high performance is related to the unique high aspect ratio structure and pad-like cavity of ZIF-67, which results not only in an increase in the specific surface area for CO2 adsorption but also in the hydrophobicity of the electrode. Unexpectedly, the superoxide radical (·O2−) greatly affects the reduction performance of the electrode. In addition, the ZIF-67/CC electrode maintained good CO2RR performance in the presence of different pollutants, and the production of formic acid and formaldehyde increased to 10.81 and 0.11 mmol L−1 at 1 h with the addition of 10 mg L−1 phenol. This research provides new directions in the field of plasma catalysis.

Ultrafast Synthesis of Transition Metal Phosphides in Air via Pulsed Laser Shock.

Transition metal phosphide nanoparticles (TMP NPs) represent a promising class of nanomaterials in the field of energy; however, a universal, time-saving, energy-efficient, and scalable synthesis method is currently lacking. Here, a facile synthesis approach is first introduced using a pulsed laser shock (PLS) process mediated by metal-organic frameworks, free of any inert gas protection, enabling the synthesis of diverse TMP NPs. Additionally, through thermodynamic calculations and experimental validation, the phase selection and competition behavior between phosphorus and oxygen have been elucidated, dictated by the redox potential and electronegativity. The resulting composites exhibit a balanced performance and extended durability. When employed as electrocatalysts for overall water splitting, the as-constructed electrolyzer achieves a low cell voltage of 1.54 V at a current density of 10 mA cm-2. This laser method for phosphide synthesis provides clear guidelines and holds potential for the preparation of nanomaterials applicable in catalysis, energy storage, biosensors, and other fields.

Oxidative Cleavage of Alkoxyamines for Nucleophilic Substitution Reactions

Photoredox catalysis and synthetic electrochemistry have begun to find their spot in a synthetic chemist’s toolbox. Apart from its use of renewable reagents (light and electricity respectively), these methods have enabled pathways that were previously viewed as near impossible. It is therefore essential to develop methods to further advance the field of photoredox catalysis and synthetic electrochemistry. Alkoxyamines previously used for initiation of polymerization reactions are now viewed as prime building blocks for photoredox and synthetic electrochemists for their facile reactivity to oxidatively cleave C‐O bonds. This review begins with addressing the first method developed for generating carbocations via a mesolytic cleavage pathway, and then highlights the recent approaches to utilizing photoredox and synthetic electrochemistry on oxidative cleavage of alkoxyamines for nucleophilic substitution reactions. To demonstrate its applicability, this review also highlights its utilization in the enantioselective synthesis of (‐)‐calycanthidine and (‐)‐psychotriasine.

Manipulating d-Band Center of Nickel by Single-Iodine-Atom Strategy for Boosted Alkaline Hydrogen Evolution Reaction.

Ni-based electrocatalysts have been predicted as highly potential candidates for hydrogen evolution reaction (HER); however, their applicability is hindered by an unfavorable d-band energy level (Ed). Moreover, precise d-band structural engineering of Ni-based materials is deterred by appropriative synthesis methods and experimental characterization. Herein, we meticulously synthesize a special single-iodine-atom structure (I-Ni@C) and characterize the Ed manipulation via resonant inelastic X-ray scattering (RIXS) spectroscopy to fill this gap. The complex catalytic mechanism has been elucidated via synchrotron radiation-based multitechniques (SRMS) including X-ray absorption fine structure (XAFS), in situ synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectroscopy, and near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). In particular, RIXS is innovatively applied to reveal the precise regulation of Ni Ed of I-Ni@C. Consequently, the role of such single-iodine-atom strategy is confirmed to not only facilitate the moderate Ed of the Ni site for balancing the adsorption/desorption capacities of key intermediates but also act as a bridge to enhance the electronic interaction between Ni and the carbon shell for forming a localized polarized electric field conducive to H2O dissociation. As a result, I-Ni@C exhibits an enhanced alkaline hydrogen evolution performance with an overpotential of 78 mV at 10 mA/cm2 and superior stability, surpassing the majority of the reported Ni-based catalysts. Overall, this study has managed to successfully tailor the d-band center of materials from the SRMS perspective, which has crucial implications for nanotechnology, chemistry, catalysis, and other fields.

Enhanced oxygen evolution on A-site defect perovskite oxide through interfacial engineering

Perovskite oxides are emerging as promising alternative to precious metal-based electrocatalysts for oxygen evolution reactions. Despite their potential, their catalytic activity is often insufficient for practical applications. In this study, we demonstrate that introducing A-site defects in LaNiO3 perovskite oxides promotes B-site exsolution during the reduction process. Subsequent chemical vapor deposition introduces selenium, forming an electrocatalyst with a heterojunction structure. Comprehensive characterization and electrochemical testing reveal that the r-La0.9NiO3/NiSex heterojunction structure, resulting from B-site exsolution induced by A-site defects, significantly enhances the electrocatalytic performance of the La0.9NiO3 electrocatalyst. This novel structure not only increases oxygen vacancy concentration but also improves the wettability of the electrocatalyst, as indicated by a reduced bubble contact angle in water. These modifications lead to a notable improvement in the electrochemical performance of the r-La0.9NiO3/NiSex electrocatalyst. At a current density of 10 mA·cm−2, the electrocatalyst exhibits an overpotential of 297.6 mV, with substantially increased mass activity. This study presents a novel approach to catalyst design in electrocatalysis, leveraging A-site defect induced B-site exsolution in perovskite oxides. The strategy of reduction followed by doping offers a robust framework for developing more efficient electrocatalysts, paving the way for advancements in the field of heterogeneous catalysis.

N, P Dual-Doped Carbons as Metal-Free Catalysts for Hydrogenation.

The activation of molecule hydrogen (H2) by metal-free catalysts is always a challenge in the field of catalysis. Herein, a series of N, P dual-doped carbon catalysts were constructed by the pyrolysis of chitosan and phytic acid and utilized as metal-free catalysts for the hydrogenation of nitrobenzene. The characterization indicated that the doping of phosphorus atoms not only formed the species with catalytic activity for hydrogenation reaction but also promoted the doping of N. The experimental results indicated that their catalytic performance could be improved by the regulation of pyrolysis temperature and heating rate. CP-900-1 (pyrolysis at 900 °C with a heating rate of 1 °C/min) exhibited a promising catalytic activity with >99% nitrobenzene conversion. N, P codoping was the key factor to its catalytic performance. All results indicated that the excellent catalytic activity of CP-900-1 was attributed to the synergistic interaction among pyridinic N, P-C species, and graphitic N. This work provides an effective route for the rational design and construction of highly efficient metal-free catalysts for hydrogenation.

Toward Methanol Production by CO2 Hydrogenation beyond Formic Acid Formation.

ConspectusThe Paradigm shift in considering CO2 as an alternative carbon feedstock as opposed to a waste product has recently prompted intense research activities. The implementation of CO2 utilization may be achieved by designing highly efficient catalysts, exploring processes that minimize energy consumption and simplifying product purification and separation. Among possible target products derived from CO2, methanol is highly valuable because it can be used in various chemical feedstocks and as a fuel. Although it is currently produced on a plant scale by heterogeneous catalysis using a Cu/ZnO-based catalyst, a limited theoretical conversion ratio at high reaction temperatures remains an issue. In addition, a catalytic system that can be adjusted to accommodate a variable renewable energy source for the synthesis of methanol is more desirable than current continuous-operation systems, which require a reliable energy supply. Recently, significant progress has been made in the field of homogeneous catalysis, which primarily relies on an indirect route to synthesize methanol via the hydrogenation of carbonate or formate derivatives in the presence of additives and solvents. However, homogeneous catalysis is inappropriate for industrial-scale methanol production because of the inefficient separation and purification processes involved.In this Account, we demonstrate a novel approach for methanol production under mild reaction conditions by CO2 hydrogenation catalyzed by multinuclear iridium complexes under heterogeneous gas-solid phase conditions without any additives and solvents. One of the aims of this Account provides insights for overcoming the barriers for efficient CO2 hydrogenation by focusing on catalyst design, specifically by incorporating varying functionalities into the ligand. The fundamental strategy entails activating hydrogen molecule and enhancing the hydricity of the resulting metal-hydride species, which is based on the following two concepts of catalyst design: (i) Activating a metal-hydride by electronic effects; and (ii) accelerating H2 heterolysis. We have elucidated the mechanism for accelerating H2 heterolysis using a state-of-the-art catalyst that contains an actor-ligand that responds to or participates in catalysis as opposed to a classical spectator-ligand.We have also demonstrated a novel heterogeneous catalysis using a molecular catalyst as a key step for the hydrogenation of CO2 to methanol beyond formic acid formation. The dehydrogenation of formic acid as a reverse reaction of formic acid hydrogenation is strongly favored in acidic aqueous solution. To circumvent the equilibrium limitation, we have envisioned an alternative route that both prevents the liberation of formic acid into the reaction medium, and develops a multinuclear complex to facilitate the transfer of multiple reactive hydrides. The unconventional gas-solid phase catalysis is capable of preventing the liberation of formate species and promoting further hydrogenation of formic acid through multihydride transfer.This novel catalytic system, which is the fusion of a molecular catalyst in heterogeneous catalysis, provides high performance for methanol synthesis through a sophisticated catalyst design and straightforward separation processes. A detailed mechanistic analysis of molecular catalysts in the gas phase would lead to significant progress in the field of Surface Organometallic Chemistry (SOMC).

Click Chemistry for the Generation of Combination of Triazole Core and Thioether Donor Site in Organosulfur Ligands: Applications of Metal Complexes in Catalysis.

During the last two decades, organosulfur compounds have been used in the field of transition metal catalysis. Some of such compounds are known for their ability to withstand their exposure to air and moisture. These compounds are very important ligands. They may be obtained using simple and smooth modular synthetic protocols which include nucleophilic substitution reactions. The development of click chemistry represents a new era of innovation. It is a lighthouse of reliable and efficient reactions. In recent past, click chemistry has also been applied for the synthesis of such organosulfur ligands specifically suited for the dynamic field of transition metal catalysis. In order to synthesize novel compounds containing sulfur and triazole ring, click chemistry is an advantageous methodology over other approaches. This article covers the general features and uses of this methodology for the development of catalytically active organosulfur compounds. The significant advances in the design of transition metal catalytic systems utilizing such ligands, their use in the catalysis of many chemical transformations are also covered in this article. Effort has also been made to present a comparative overview of the performances of such catalysts vis-à-vis the catalysts designed commonly used ligands. Catalytic performances have been discussed thoroughly in order to identify the impact of ligand architecture on efficacy of the catalyst. Effect of reaction conditions (such as time, temperature etc.) and mechanistic aspects have also been rationalized.