Catalyst For Reaction Research Articles

Manganese doped tailored cobalt sulfide as an accelerated catalyst for oxygen evolution reaction

Developing an efficient, robust, and noble metal-free electrocatalyst that can catalyse oxygen evolution reactions (OER) remains a significant challenge. CoS2, a representative of pyrite form transition metal dichalcogenides, has recently been identified as an economical catalyst. Here, an incredibly quick and scalable technique for novel catalysts synthesized with the use of the microwave method was introduced. Manganese-doped cobalt sulphide (Mn-CoS2) showed outstanding OER with a very low overpotential of 227 mV at 10 mA cm−2. Exposure of surface atoms resulted in high electrochemical activity, where the defects facilitated charge and mass transfer along the nanostructure, allowing surface dependent electrochemical reactions to be performed more efficiently. The electronic properties of pristine and transition-metal-doped CoS2 structures were also investigated using density functional theory (DFT). To better understand transition metal’s dependent impact on crystal structure, orbital electronic participation, charge density, and charge transformation in both pristine and Mn-dopedCoS2 frameworks were calculated and analysized. Our synthesis approach is primarily commercial and extensible, overcoming synthesis challenge of transition metal sulphide nanostructures with prime quality and implying a potential for commercial uses.

Pentagon‐Rich Caged Carbon Catalyst for the Oxygen Reduction Reaction in Acidic Electrolytes

Pentagon‐Rich Caged Carbon Catalyst for the Oxygen Reduction Reaction in Acidic Electrolytes

Construction of NiFe/MnNiCo-LDH heterostructure for enhanced oxygen evolution reaction for efficient water splitting

Developing highly efficient and cost-effective oxygen evolution reaction (OER) catalysts is pivotal for advancing sustainable energy storage and conversion technologies. Herein, NiFe/MnNiCo-LDH was successfully prepared by in-situ growth method. The OER performance of this composite material had been significantly enhanced through bimetallic atom modification and cation doping strategies. These modifications not only enhanced the electronic conductivity but also regulated the electron distribution within the catalyst structure. As a result, NiFe/MnNiCo-LDH can reach a current density of 10 mA cm−2 at an overpotential of only 227 mV in the OER reaction. Moreover, the catalyst exhibited remarkable durability and maintained its high performance over an extended period of 48 h during the water splitting reaction. In this work, the potential of dual modification methods for optimizing catalytic properties of OER materials was investigated.

IPr# Complexes-Highly-Hindered, Sterically-Bulky Cu(I) and Ag(I) N-Heterocyclic Carbenes: Synthesis, Characterization, and Reactivity.

Metal-N-heterocyclic carbene (M-NHC) complexes are well-known as an important class of organometallic compounds widely used in transition-metal catalysis. Taking into account that the steric hindrance around the metal center is one of the major effects in M-NHC catalysis, the development of new, sterically hindered M-NHC complexes is an ongoing interest in this field of research. Herein, we report the synthesis and characterization of exceedingly sterically hindered, well-defined, air- and moisture-stable Cu(I) and Ag(I) complexes, [Cu(NHC)Cl] and [Ag(NHC)Cl], in the recently discovered IPr# family of ligands that hinge upon modular peralkylation of anilines. The complexes in both the BIAN and IPr families of ligands are reported. X-ray crystallographic analyses and computational studies were conducted to determine steric effects, Frontier molecular orbitals, and bond orders. The complexes were evaluated in the model hydroboration of the alkynes. We identified [Cu(BIAN-IPr#)Cl] and [Ag(BIAN-IPr#)Cl] as highly reactive catalysts with the reactivity outperforming the classical IPr and IPr*. Considering the attractive features of well-defined Cu(I)-NHC and Ag(I)-NHC complexes, this class of sterically bulky yet wingtip-flexible complexes will be of interest for catalytic processes in various areas of organic synthesis and catalysis.

Prediction of catalytic performance of metal oxide catalysts for alkyne hydrogenation reaction based on machine learning

In the field of catalyst design, machine learning is gaining significant attention, especially in situations where data is limited. Facing this challenge, we have developed a neural network model that enhances predictive accuracy through the careful selection of catalyst descriptors and feature engineering, aiming to predict the conversion rate and selectivity of the acetylene semi-hydrogenation reaction. Our model has identified promising metal oxide catalysts, such as CuO, ZnO, and V2O5, for the acetylene semi-hydrogenation reaction, and these predictions have been experimentally validated. Among them, CuO achieved an acetylene conversion of 99.6 % and an ethylene selectivity of 90 % at 50–100°C, which is unprecedented at the reaction space velocity we tested. This high activity at relatively low temperatures indicates a more promising industrial application. Looking ahead, machine learning will play a pivotal role in catalyst design, accelerating the discovery and industrial application of new materials.

The interfacial engineering of seaurchin-like CoP/Ni2P heterostructure for highly efficient alkaline hydrogen evolution

Creating efficient, cost-effective catalysts for the hydrogen evolution reaction (HER) with low overpotential is crucial for advancing the hydrogen energy cycle. Herein, the CoP is introduced into the Ni2P system to attract the transfer of electrons from Ni2P to the CoP. Interfacial electronic structure optimization enabled the binder-free sea urchin-like CoP/Ni2P/NF electrocatalysts present superb performance in HER within 1.0 M KOH, characterized by a minimal overpotential of 67.4 mV and a reduced Tafel slope of 73.9 mV dec-1 under a current density of 10 mA cm−2. The as-fabricated catalyst also demonstrates significant long-term HER stability. The reallocation of charge across the heterogeneous interface of CoP/Ni2P catalyst was further investigated via DFT calculation. The addition of CoP effectively accelerates the electron transfer and optimized the heterogeneous interface inside CoP/Ni2P for *H adsorption/H2 desorption, reduced the water decomposition energy barrier, thereby, promoting the HER process. The microstructural construction as well as synergistic effect of interfacial electrons of CoP/Ni2P catalyst paves the way to design electrocatalysts with highly HER activity.

Effect of Iron Doping in Ordered Nickel Oxide Thin Film Catalyst for the Oxygen Evolution Reaction.

Water splitting has emerged as a promising route for generating hydrogen as an alternative to conventional production methods. Finding affordable and scalable catalysts for the anodic half-reaction, the oxygen evolution reaction (OER), could help with its industrial widespread implementation. Iron-containing Ni-based catalysts have a competitive performance for the use in commercial alkaline electrolyzers. Due to the complexity of studying the catalysts at working conditions, the active phase and the role that iron exerts in conjunction with Ni are still a matter of investigation. Here, we study this topic with NiO(001) and Ni0.75Fe0.25O x (001) thin film model electrocatalysts employing surface-sensitive techniques. We show that iron constrains the growth of the oxyhydroxide phase formed on top of the Ni or NiFe oxide, which is considered the active phase for the OER. Besides, operando Raman and grazing incidence X-ray absorption spectroscopy experiments reveal that the presence of iron affects both, the disorder level of the active phase and the oxidative charge around Ni during OER. The observed compositional, structural, and electronic properties of each system have been correlated with their electrochemical performance.

Understanding the Roles and Regulation Methods of Key Adsorption Species on Ni‐Based Catalysts for Efficient Hydrogen Oxidation Reactions in Alkaline Media

This review focuses on recent advancements in the development and understanding of nickel‐based catalysts for the hydrogen oxidation reaction in alkaline media. Given the economic and environmental limitations associated with platinum group metals , nickel‐based catalysts have emerged as promising alternatives due to their abundance, lower cost, and comparable catalytic properties. The review begins with an exploration of the fundamental HOR mechanisms, emphasizing the key roles of the reactive species in optimizing the catalytic activity of Ni‐based catalysts. Thermodynamic and stability optimizations of nickel‐based catalysts are thoroughly examined, focusing on alloying strategies, heteroatom incorporation, and the use of various support materials to enhance their catalytic performance and durability. The review also addresses the challenge of catalyst poisoning, particularly by carbon monoxide, and evaluates the effectiveness of different approaches to improve poison resistance. Finally, the review concludes by summarizing the key findings and proposing future research directions to further enhance the efficiency and stability of nickel‐based catalysts for practical applications in anion exchange membrane fuel cells. The insights gained from this comprehensive analysis aim to contribute to the development of cost‐effective and sustainable catalysts and facilitate the broader adoption of AEMFCs in the quest for clean energy solutions.

Ethanol Oxidation Reaction on Electrodeposited Pd and Sb‒Pd Catalysts in Alkaline Solution Containing Na or Li Cations

Abstract This work reports the galvanostatical electrodeposition of Pd and Sb‒Pd catalysts on rotating glassy carbon (GC) electrode using surfactant-free electrolytes and the prepared catalysts were tested is the electro-oxidation reactions in alkaline solutions. Characterization of Pd and Sb‒Pd catalysts was performed with scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) technique. Cyclic voltammetry (CV) and chronoamperometry were applied in order to study the electrocatalytic behavior of Pd and Sb‒Pd catalysts in the ethanol oxidation reaction (EOR) in alkaline solution containing Na+ or Li+ cations from the point of the impact of the selected alkali metal cations on the electrocatalytic activity. The peak current of EOR at Pd and Sb‒Pd catalysts in the solution with Li+ cations is 2.5 times higher compared to the values obtained in the solution with Na+ cations. EOR starts at rather negative potentials in LiOH solution regarding NaOH for approximately 0.03 V indicating the active role of OHad and the impact of the nature of alkali metal cations which consequently arises from the formation of OHad ‒ cation clusters. The role of Sb in bimetallic catalyst was established by adjusting the extent and persistence of OHad surface coverage.

In Situ generated PdNPs immobilized on polystyrene supported DABCO Dicationic ionic liquid: An efficient and reusable catalyst for Suzuki and Heck coupling reactions

A catalyst named PdNPs-DDIL@PS has been synthesized by immobilizing PdNPs on a DABCO Dicationic Ionic Liquid (DDIL) supported on Merrifield Resin (PS). The PdNPs (∼4.16 nm size) generated in situ were fully characterized using different techniques such as SEM, TEM, TGA-DTA, and XPS. It has been found that the catalyst is highly active in the Suzuki coupling reaction of various aryl bromides and aryl boronic acids in 70 % aqueous ethanol at room temperature. The catalyst produced the desired Suzuki coupling products in good to excellent yields. Additionally, the protocol was extended for the Heck coupling reactions in DMF at 80 °C with good to excellent yields. The catalyst attained a good turnover number (TON) of 160.00–189.92 and a turnover frequency (TOF) of 8.493–18.992 min−1 for the Suzuki and TON of 173.33–189.77 and TOF of 3.952–6.325 min−1 for the Heck coupling reactions. The catalyst displayed at least four times recyclability for the Suzuki coupling without a substantial decrease in product yields. Additionally, it boosts impressive environmentally-friendly credentials in Suzuki coupling reactions.

Optimizing bimetallic and multimetallic Cu-based catalysts by promoters for enhanced reverse Water-Gas Shift reaction: Insights and stability assessments

This study investigates bimetallic and multimetallic catalysts tailored for the reverse water gas shift (RWGS) reaction. Promoting with potassium and iron, while maintaining a constant copper content of 15 wt% on γ-alumina, revealed that bimetallic catalysts containing 7.5 wt% iron and 5 wt% potassium exhibit superior catalytic activity and stability. Among the multimetallic catalysts, the optimal composition was found to be in the 15 wt% Cu-5 wt% Fe-2.5 wt% K/γ-Al2O3 catalyst for the RWGS reaction. The prepared catalysts underwent assessments using various techniques such as N2 adsorption-desorption, XRD, H2-TPR, CO2-TPD, and FESEM. Stability assessments conducted over 72 hours showcased sustained long-term performance for the optimized catalysts, highlighting the influential role of the hierarchical structure. Mesopores extended the catalyst lifetime by reducing permeation limits, while macropores facilitated diffusion process, enhancing selectivity and stability. This hierarchical design also improved mass transfer, amplifying reaction rates. The synthesized catalysts exhibited exceptional specificity, demonstrating 100 % selectivity for the RWGS reaction. Particularly, under H2/CO2=1, these catalysts displayed remarkable carbon dioxide conversion rates, indicating potential for enhancing Cu-based catalysts in RWGS reactions by maximizing active sites.

Convergent Active Site Evolution in Platinum Single Atom Catalysts for Acetylene Hydrochlorination and Implications for Toxicity Minimization.

Platinum single atoms anchored onto activated carbon enable highly stable Hg-free synthesis of vinyl chloride (VCM) via acetylene hydrochlorination. Compared to gold-based alternatives, platinum catalysts are in initial phases of development. Most synthetic approaches rely on chloroplatinic acid, presenting opportunities to explore other precursors and their impact on catalyst structure, reactivity, and toxicity aspects. Here, we synthesize platinum single atom catalysts (Pt SACs, 0.2-0.8 wt % Pt) employing diverse Pt2+ and Pt4+ complexes with ammine, hydroxyl, nitrate, and chloride ligands, following a scalable impregnation protocol on activated carbon extrudates. X-ray absorption spectroscopy (XAS) reveals that Pt4+ species reduce to Pt2+ upon deposition onto the support. Despite similar oxidation states, the initial activity is precursor dependent, with tetraammine-derived Pt SACs displaying 2-fold higher VCM yield than chlorinated counterparts, linked to superior hydrogen chloride binding abilities by density functional theory (DFT) simulations. Their activity gradually converges due to dynamic active site restructuring, delivering remarkable precursor-independent stability over 150 h. Operando XAS and DFT studies uncover reaction-induced ligand exchange, generating common active and stable Pt-Cl x (x = 2-3) species. Convergent active site evolution enables flexibility in metal precursor selection and thus toxicity minimization through multiparameter assessment. This study advances safe-by-design catalysts for VCM synthesis, highlighting the importance of toxicity analyses in early-stage catalyst development programs.

Engineering peripheral S-doped atomic Fe-N4 in defect-rich porous carbon nanoshells for durable oxygen reduction reaction and Zn-air batteries

Iron-nitrogen-carbon (Fe-N-C) single-atom materials have emerged as the most promising catalysts for the oxygen reduction reaction (ORR), which yet suffers from inadequate stability arising from the attack of ·OH and HO2· radicals generated by H2O2. In this study, density functional theory (DFT) calculations reveal that the presence of peripheral S atoms can regulate the electronic structure of the Fe center and suppress the formation of H2O2 to enhance the catalyst's durability. Thereafter, atomic Fe-N4 with peripheral S doping is intricately engineered in defect-rich porous carbon nanoshells (Fe-NS-C) through an adsorption-pyrolysis method. The incorporation of S not only optimizes the coordination microenvironment of Fe-N4 but also induces a larger specific surface area and richer defects. The Fe-NS-C catalyst displays remarkable ORR performance, featuring a half-wave potential (E1/2) of 0.90 V. Its low H2O2 yield (below 1.1 %) and excellent stability (10 mV day in E1/2 after 10,000 cycles) further underscore the superiority of Fe-NS-C. When employed as the cathode for Zn-air battery, Fe-NS-C achieves an impressive peak power density of 230.1 mW cm−2 and stable charge/discharge potentials over an extended duration of 150 h. This study presents an effective strategy for engineering efficient and durable single-atom electrocatalysts for ORR and Zn-air batteries.

Pd Nanoparticle Supported on N‐Doped Carbon Derived from Sodium Alginate/Melamine Blends as Efficient Heterogeneous Catalyst for Heck Reactions

AbstractN‐doped porous carbon shows great potential in the field of heterogenous supports due to its high porosity, large surface area, rich active sites, and strong chelation with catalytic active metals species. Herein, we successfully prepared a novel N‐doped porous carbon derived from sodium alginate/melamine blends (SAMNC) with different mass ratio through a simple carbonization and activation process. Hierarchical porous structure of the derived N‐doped carbon has been confirmed with the SEM, TEM, and N2 adsorption characterization. After Na2PdCl4 solution impregnation and further reduction process, Pd0 nanoparticles have been uniformly immobilized on the SAMNC support to produce novel Pd@SAMNC catalyst. The optimal Pd@SAMNC‐0.6 possesses a high N content (5.13%), Pd content (5.90%), large BET specific surface area of 1884.5 m2·g−1. Positron annihilation lifetime spectroscopy (PALS) investigation of the porous carbon materials provided the sub‐nano level microporous information proofs of Pd@SAMNC‐0.6 had the capability to provide more active sites for reactions than commercial Pd supported on activated carbon (Pd@AC). Pd@SAMNC‐0.6 catalyst showed superior catalytic efficiency in Heck coupling reaction between aromatic halides and alkenes and can be recycled for 17 runs without significant decrease in catalytic efficiency.

Iron and Nickel Substituted Perovskite Cobaltites for Sustainable Oxygen Evolving Anodes in Alkaline Environment.

Perovskite oxides have great flexibility in their elemental composition, which is accompanied by large adjustability in their electronic properties. Herein, we synthesized twelve perovskites oxide-based catalysts for the oxygen evolution reaction (OER) in alkaline media. The catalysts are based on the parent oxide perovskite Ba0.5Gd0.8La0.7Co2O6-δ (BGLC587) and are synthesized through the sol-gel citrate synthesis route. To reduce the demand on cobalt (Co), but also increase the intrinsic catalytic activity of BGLC587 for the OER, we substitute Co on the B-site with certain amounts of Fe and Ni, synthesizing catalysts of the general formula Ba0.5Gd0.8La0.7Co2-x-yFexNiyO6-δ. A plethora of physicochemical and electrochemical methods suggest that an Fe content between 30% and 70% increases the intrinsic catalytic activity of BGLC587, while Tafel slopes in combination with in-situ Raman spectroscopy suggest the rate determining step is likely a proton-exchange reaction, progressing possibly through the lattice oxygen mechanism (LOM). We apply one of the optimized, Co-substituted perovskites in a monolithic, photovoltaic (PV)-driven electrolysis cell and we achieve an initial solar-to-hydrogen (STH) conversion efficiency of 10.5% under one sun solar simulated illumination.

Nickel sulfide nanorods encapsulated in Nitrogen-Doped carbon on nickel foam in situ derived from Saccharomycetes cerevisiae for the selective oxidation of biomass

The design and development of an efficient catalyst for the electrocatalytic oxidation reaction of 5-hydroxymethylfurfural (HMF) require a novel, cost-effective, environmentally friendly, and safe preparation method. In this study, we synthesized nickel sulfide nanorods encapsulated by nitrogen-doped carbon on a nickel foam substrate (Ni3S2@NC/NF), derived in situ from Saccharomyces cerevisiae. The utilization of a gas-phase route facilitated the binding of C, N and S elements to the NF substrate. The resulting Ni3S2@NC/NF catalyst exhibited excellent electrocatalytic performance in the HMF oxidation reaction (HMFOR), achieving a complete conversion of HMF, a selectivity of 95.6 % for 2,5-furandicarboxylic acid, and a Faraday efficiency of 88.9 % at a potential of 1.45 V. Moreover, in situ electrochemical impedance spectroscopy revealed an enhanced charge transfer rate for the Ni3S2@NC/NF catalyst during the interfacial HMFOR. Additionally, the catalyst demonstrated outstanding stability after five cycles of electrolysis. Therefore, this work provides a valuable guide for using microorganisms as sources of C, N, and S in the targeted synthesis of metallic electrocatalysts.

Rescrutinizing the Iron Effect on Oxygen Evolution Reaction Catalysts under Industrially Relevant Working Conditions: Overlooked Mass Transfer Limitation Driven by the Iron Incorporation

Rescrutinizing the Iron Effect on Oxygen Evolution Reaction Catalysts under Industrially Relevant Working Conditions: Overlooked Mass Transfer Limitation Driven by the Iron Incorporation

Advancing Heterogeneous Organic Synthesis With Coordination Chemistry-Empowered Single-Atom Catalysts.

For traditional metal complexes, intricate chemistry is required to acquire appropriate ligands for controlling the electron and steric hindrance of metal active centers. Comparatively, the preparation of single-atom catalysts is much easier with more straightforward and effective accesses for the arrangement and control of metal active centers. The presence of coordination atoms or neighboring functional atoms on the supports' surface ensures the stability of metal single-atoms and their interactions with individual metal atoms substantially regulate the performance of metal active centers. Therefore, the collaborative interaction between metal and the surrounding coordination environment enhances the initiation of reaction substrates and the formation and transformation of crucial intermediate compounds, which imparts single-atom catalysts with significant catalytic efficacy, rendering them a valuable framework for investigating the correlation between structure and activity, as well as the reaction mechanism of catalysts in organic reactions. Herein, comprehensive overviews of the coordination interaction for both homogeneous metal complexes and single-atom catalysts in organic reactions are provided. Additionally, reflective conjectures about the advancement of single-atom catalysts in organic synthesis are also proposed to present as a reference for later development.

Hydrothermal growth of Zn2GeO4 nanorods for optical and (Photo)Catalytic applications: An experimental and theoretical study

From the material design perspective, we reported a systematic investigation based on theoretical and experimental approaches to explore the physical properties of Zn2GeO4 nanorods prepared by hydrothermal method with different zinc precursors for optical and (photo)catalytic applications. All ZGO samples exhibited uniform nanorod morphology with high purity and crystallinity. A negative zeta potential ranging from −13 mV to −16 mV have been observed for these nanorods. Bandgap values indicated variations among samples synthesized with different precursors. The photoluminescence and photocatalytic activities for these nanorods, have been attributed to the presence of oxygen vacancies on the Zn2GeO4 surfaces. Experimental evidence suggests that these surface defects favor the formation of hydroxyl radicals identified as primary reactive oxygen species responsible for the methylene blue photodegradation. Toxicity testing of photocatalytic residues showed minimal phytotoxic effect on lettuce seed (Lactuca sativa) germination. Additionally, Zn2GeO4 was utilized as an acid catalyst for synthesizing isoxazol-5(4H)-ones, resulting in an increase in the yield from 69 % to 92 % by using this catalyst in multicomponent reactions. Lastly, the theoretical efforts outlined in the study aim to enhance the comprehension of the material design with well-defined morphology using realist theoretical models for the Zn2GeO4 nanorods for the first time.

Combination of nanoparticles with single-metal sites synergistically boosts co-catalyzed formic acid dehydrogenation

The development of hydrogen technologies is at the heart of a green economy. As prerequisite for implementation of hydrogen storage, active and stable catalysts for (de)hydrogenation reactions are needed. So far, the use of precious metals associated with expensive costs dominates in this area. Herein, we present a new class of lower-cost Co-based catalysts (Co-SAs/NPs@NC) in which highly distributed single-metal sites are synergistically combined with small defined nanoparticles allowing efficient formic acid dehydrogenation. The optimal material with atomically dispersed CoN2C2 units and encapsulated 7-8 nm nanoparticles achieves an excellent gas yield of 1403.8 mL·g−1·h−1 using propylene carbonate as solvent, with no activity loss after 5 cycles, which is 15 times higher than that of the commercial Pd/C. In situ analytic experiments show that Co-SAs/NPs@NC enhances the adsorption and activation of the key intermediate monodentate HCOO*, thereby facilitating the following C-H bond breaking, compared to related single metal atom and nanoparticle catalysts. Theoretical calculations show that the integration of cobalt nanoparticles elevates the d-band center of the Co single atoms as the active center, which consequently enhances the coupling of the carbonyl O of the HCOO* intermediate to the Co centers, thereby lowering the energy barrier.