Catalytic Materials Research Articles

In-situ prepared co exsolution nano catalyst for efficient hydrogen generation via ammonia decomposition

Active and durable catalytic material for ammonia (NH3) decomposition reaction is attracting attentions for utilization of NH3 as an innovative hydrogen carrier. In this study, diverse single metal and alloy nano catalysts are prepared via in-situ exsolution method and their NH3 decomposition properties are evaluated. Transition metal cations (Ni, Co, Fe ions) are doped into the La0.43Ca0.37MxNyTi1-(x+y)O3-δ (LCMNT) perovskite oxide structure and exsolved on its surface as supported nano particles under reduction condition. The maximum doping level and chemical composition of exsolution catalysts are investigated to optimize their NH3 decomposition activity. The exsolution catalyst demonstrates improved NH3 decomposition characteristics compared to conventionally prepared infiltration catalysts, indicating higher conversion efficiency and H2 production rate. The exsolved nano catalysts also exhibit great thermochemical stability against catalyst agglomeration or surface nitriding. The results obtained in this study suggest the potential utilization of exsolution catalysts for on-site production of H2 through NH3 decomposition catalysis.

Rapid phenol mineralisation in a low-pressure dead-end light transmitting photocatalytic membrane reactor (LT-PMR)

Photocatalytic membrane reactors (PMRs) are widely studied for wastewater decontamination but reactions are too slow for scaled up application. This PMR study proposes a novel operation involving rapid decontamination in just one pass through the confined space within the membrane. This approach was demonstrated for the first time by light transmitting PMR (LT-PMR), conveniently receiving UV LED light (λpeak = 365 nm) via the permeate side to the photocatalyst P25 TiO2 microfiltration membrane coated on porous glass. A 93 % reduction in model contaminant phenol concentration from a 10 mg/L feed occurred at a flux of 4.7 L/m2/h. The phenol degradation occurred without any additional residence time from external vessels or recirculation. Phenol was almost entirely mineralised, confirmed by total organic carbon (TOC) measurements, with trace by-products identified by high pressure liquid chromatography (HPLC) analysis. Mass transfer and reaction rate constants from Langmuir-Hinshelwood modelling were comparable to literature. Highest reaction rates occurred at lowest permeate phenol concentrations, highlighting potential to destroy recalcitrant pollutants persisting through established treatments. LT-PMR is therefore an effective and practical process that very rapidly destroys phenol. Further work to explore improved flux by enhanced light transmission, tailored catalytic materials and demonstration on other pollutants and water matrices is warranted.

Scalable synthesis of a new {P2Mo18O62}-modified CuI/CuII-based metal–organic complex for multi-center synergistic catalysis of benzyl alcohol to benzoic acid

The scalable production of high-efficiency catalysts derived from polyoxometalates (POMs) is critically significant for advancing the catalysis sector. Herein, the synthesis of a new [P2Mo18O62]6– ({P2Mo18})-based metal–organic complex, (CuIL2)11[(CuIIL2Cl)(P2Mo18O62)2]·2L·0.5H2O (L = benzimidazole) (1), was achieved on a large scale using the one-pot method, and the complex was systematically characterized. Complex 1 is a three-dimensional (3D) supramolecular framework by hydrogen bonding interactions between [CuII0.5LCl0.5]-decorated {P2Mo18} anions and {CuIL2} metal–organic subunits. Benzyl alcohol (BA) was efficiently oxidized to benzoic acid (BZA) with complex 1 as a stable heterogeneous catalyst, exhibiting a remarkable conversion rate of nearly 100 % and an outstanding selectivity of 99.47 %. Notably, the catalytic system exhibits outstanding scalability, with no significant decrease in conversion and selectivity after a 20-fold increase in reaction scale. The remarkable efficiency is attributable to the unique multi-center synergistic catalytic mechanism of CuI, CuII, and MoVI within complex 1. These findings could provide significant insights into the rational design and synthesis of POMs-based catalytic materials with enhanced catalytic efficiency.

Performance of cobalt doped two dimensional black phosphorus (Co-2D BP) for bifunctional hydrolysis in alkaline solution

The present study contributes to the exploration of transition metal phosphides with specific composition and structure to enhance electrocatalytic ability. Cobalt doped two dimensional black phosphorus (Co-2D BP) with layered structure exhibits excellent electrocatalytic activity for hydrogen evolution reaction (HER) in alkaline solutions, and demonstrates an overpotential of 86.42 mv at a current density of 10 mA cm−2, requiring only 140.29 mv, 198 mv, and 238.89 mv to reach 20, 50, and 100 mA cm−2 respectively. The catalytic performance was stable even after 10 h using in alkaline electrolytes, demonstrating good chemical stability. Co-2D BP can also improve the catalytic performance for oxygen evolution reaction (OER). This study provides a novel strategy for the design of multifunctional 2D BP-based catalytic materials for hydrolysis.

Carbon-based materials for low concentration CO2 capture and electrocatalytic reduction

The gradual increase in carbon dioxide (CO2) concentration in the atmosphere has been recognized as a significant problem for humankind. CO2 flue gas is one of the most apparent contributing sources of emissions. CO2 capture and conversion are environmental-friendly and efficient ways to reduce atmospheric carbon dioxide emissions from flue gases. Considering the traditional expensive gas purification process of low-concentration CO2, the low-cost capturing and electrocatalytic CO2 reduction (ECR) at low concentration by newly-developed carbon-based materials provide an attractive approach to convert low-concentration CO2 in flue gas into high-value fuels and chemicals. Developing and integrating carbon-based capturing and catalytic materials with an understanding of the mechanism has a promising future and will promote this technology toward practical application. This review describes recent progress in the design, preparation, and structural characterization of existing carbon-based materials for the capture and catalysis of low-concentration CO2. The crucial factors of capturing and catalysis performance of all the carbon-based materials are also summarized. Furthermore, the review identifies existing research problems and challenges, and outlines future research directions. We also discuss the prospects for the industrialization of low-concentration CO2 capture and ECR. The remaining technological challenges and future directions for enhancing and applying of carbon-based materials for CO2 capture and electrocatalytic reduction are highlighted.

Measuring the capacity of yeast for surface display of cell wall-anchored protein isoforms by using β-lactamase as a reporter enzyme.

Yeast surface display is a promising biotechnological tool that uses genetically modified yeast cell wall proteins as anchors for enzymes of interest, thereby transforming yeast cell wall into a living catalytic material. Here, we present a comprehensive protocol for quantifying surface-displayed β-lactamase on the cell wall of model yeast Saccharomyces cerevisiae. We use β-lactamase as a reporter enzyme, which we tagged to be anchored to the cell wall closer to its N or C terminus, through the portion of the Pir2 or Ccw12 cell wall proteins, respectively. The catalytic activity of surface-displayed β-lactamase is assessed by its ability to hydrolyze nitrocefin, which produces a colorimetric change that is quantitatively measured by spectrophotometric analysis at 482 nm. This system enables precise quantification of the potential of S. cerevisiae strains for surface display, continuous real-time monitoring of enzyme activity, and facilitates the study of enzyme kinetics and interactions with inhibitors within the cell's native environment. In addition, the system provides a platform for high-throughput screening of potential β-lactamase inhibitors and can be adapted for the visualization of other enzymes, making it a versatile tool for drug discovery and bioprocess development.

Bioinspired Proton Pump on Ferroelectric HfO2-Coupled Ir Catalysts with Bidirectional Hydrogen Spillover for pH-Universal and Superior Hydrogen Production.

The improvement of hydrogen evolution reaction kinetics can be largely accelerated by introducing a well-designed hydrogen spillover pathway into the catalysts. However, the driving force and mechanism of hydrogen migration on the surface of catalysts are poorly understood and are rarely explored in depth. Here, inspired by the specific ferroelectric property of HfO2, Mn-O-Ca sites in Mn4CaO5, and Fe-Fe sites in hydrogenases, we constructed a bioinspired HfO2 coupled with Ir catalysts (Ir/HfO2@C) with an alkaline hydrogen reverse spillover effect from HfO2 to interface and acid hydrogen spillover effect from Ir to interface. Benefiting from the bidirectional hydrogen spillover pathways controlled by pH, Ir/HfO2@C displays a narrow overpotential difference between acidic and alkaline electrolytes. Remarkably, Ir/HfO2@C shows a remarkable mass current density and turnover frequency value, far exceeding the benchmark Ir/C by 20.6 times. More importantly, this Ir/HfO2@C achieves extraordinarily low overpotentials of 146 and 39 mV at 10 mV cm-2 in seawater and alkaline seawater, respectively. The anion-exchange membrane water electrolyzer equipped with Ir/HfO2@C as a cathode exhibits excellent and stable H2-evolution performance on 2.22 V at 1.0 A cm-2. We expect that the bioinspired strategy will provide a new concept for designing catalytic materials for efficient and pH-universal electrochemical hydrogen production.

Mechanism insights into the upgrading of xylose to furfural over the carbon-based catalysts in aqueous media

Exploring low-cost and high-efficient solid acid catalysts and elucidating complete reaction mechanisms are critically important for the sustainable transformation of biomass-derived molecules to bio-fuels and high-value chemicals. Here, we design a renewable strategy to construct carbon-supported solid acid catalysts (M@FRC, M=Sn, Al, Fe, Zn, and Mg) by using biomass waste resources (furfural residue, FR) as the carbon source and tested for dehydration of xylose to furfural (FAL) in the aqueous medium. Kinetic studies revealed the relationship between the main reaction (target product FAL) and the side reaction (other by-products) in the dehydration of xylose under different catalysts. Deuterium-labeling reactions and density functional theory calculations elucidate that the aldehyde carbon of FAL was derived from the C1 of xylose. Furthermore, the C1 of xylose could be broken to form formic acid. While the C1 atom from xylose was converted into formic acid, other carbon atoms could be transformed to tetra-, tri-, di- and mono-carbon compounds. This study offers a prospect for the sustainable catalytic upgrading of biomass by the development of renewable catalytic materials from waste lignocellulosic biomass and an in-depth understanding of the xylose conversion mechanism to develop tailored processes.

A review on algae-mediated adsorption and catalytic processes for organic water pollution remediation

Wastewaters consist of organic pollutants that have environmental concerns. Wastewaters are treated by different methods, but efficient, low-cost, and sustainable techniques still need to be developed. Algae-based water pollution remediation techniques are considered to be sustainable approaches. This review exclusively discusses the facets of macro and microalgae in the treatment of organic toxicants. The current trends of algae-mediated water treatments have been discussed under adsorption and degradation methods. A focus on algae fuel cell, algae mediated activation of oxidizing agents, Fenton-like reactions, and photocatalysis was given. The need of algae-based adsorptive and catalytic materials was mentioned. The role of algae in the synthesis of catalysts which were employed in pollutant removal methods was also explained. The integrated algae-mediated water treatment techniques were also highlighted. The toxicant removal performances of different algae-based materials in the water medium were summarized. The conclusion and future prospects derived from the literature survey were described. This review will be helpful for researchers who are working in the field of sustainable water pollution remediation.

The “d-p orbital hybridization”-guided design of novel two-dimensional MOFs with high anchoring and catalytic capacities in Lithium − Sulfur batteries

The energy system of lithium-sulfur batteries is quite promising, however, lithium-sulfur batteries still suffer from considerable problems, such as the abominable shuttle effect of polysulfides (LiPSs), the low conductivity of the solid-phase products, the slow redox kinetics during charging and discharging, and the volume expansion. Herein, the hybridization pattern between the d-orbitals of various transition metal atoms and the p-orbitals of sulfides is revealed grounded in the theory of density function, which explains the high adsorption strength of two-dimensional metal–organic frameworks (MOFs) with LiPSs and accelerates the screening of high-performance anchoring and catalytic materials. The results elucidate that the coordinated transition metal–organic frameworks (Mo-NH MOF) monolayers increase the capacity of LiPSs to anchor by forming more π-bonds from the hybridization of the S p orbitals and Mo d orbitals. Notably, Mo-NH MOF exhibits bifunctional catalytic activity for sulfur reduction as well as Li2S decomposition reactions during charging and discharging, which improves the conversion efficiency of redox reactions. As a result, new MOF materials featuring unique active centers and the potential mechanism by which the active centers modulate the performance of the substrate materials are revealed, and this finding may accelerate the development of high-performance Li-S batteries.

Optimization of 4-chlorophenol decomposition by H2O2 activate catalytic magnetic iron oxide an activated carbon carrier

Wastewater from chemical plants that produce pesticides always carries a large amount of organic matter that is difficult to decompose. One of them is the compound 4-chlorophenol, which has difficult-to-decompose properties, is durable in the environment, and is also listed in the group of substances that are likely to cause cancer in humans. In this study, the 4-chlorophenol compound was treated with heterogeneous Fenton by H2O2 activated by magnetic iron oxide nanoparticles on activated carbon. Magnetic iron oxide nanoparticles were successfully synthesized and mounted on activated carbon 10-15 nm in size with material surface morphological parameters such as specific surface area 330.28 cm2/g; total pore volume 0.16 cm3/g; magnetization 8.19 emu/g. The optimization of the 4-chlorophenols decomposition reaction with pH parameters, the content of catalytic materials, and the initial concentration of 4-chlorophenol is carried out using the Box-Behnken Design. The results showed that the removal efficiency of 4-chlorophenol was 96.5% achieved with optimum parameters pH 2.9; catalytic concentration 0.32 g/L; initial concentration of 4-chlorophenol 92.3 mg/L. The results of the study show the efficiency of the decomposition of an organic compound using magnetic activated carbon.

Novel Ni-doped dual MOF-derived urchin-like Co-Fe layered double hydroxides for oxygen evolution reaction

The oxygen evolution reaction (OER) plays a vital role in water splitting for renewable energy generation, making the development of cost-effective electrocatalysts essential in tackling global energy challenges. In this study, we synthesized ZIF-67@MIL-88 using a self-assembly method, with ZIF-67 serving as the precursor, followed by an aging process. The incorporation of iron-based MIL-88 significantly enhanced the surface morphology and porous structure of the catalytic material. Additionally, we prepared urchin-like CoNi@FeNi layered double hydroxides (LDHs) by etching ZIF-67@MIL-88. LDHs are known for their unique two-dimensional sheet structure and corrosion resistance. We achieved efficient OER catalytic activity through interlayer anion exchange by substituting metal cations at high temperatures. This study highlights recent advancements in the rational design of structurally unique and highly effective CoNi@FeNi-LDH composite materials using a synergistic strategy.

Ultrafine ruthenium-based nanoclusters regulated by a three-phase heterogeneous interface exhibiting superior mass activity for alkaline hydrogen evolution

Platinum-based catalysts are considered the most effective catalysts for the hydrogen evolution reaction (HER) in acidic media; however, they exhibit poor performance in alkaline electrolysis waters, which are currently more commercially developed, due to their sluggish water dissociation ability. Small-sized metal Ru nanoparticles, with metal-hydrogen bond strength close to Pt (approximately 65 kcal/mol) and a relatively lower water dissociation barrier, are considered one of the most promising alternatives to the noble metal Pt for alkaline HER. Based on the above statements, the present study innovatively combines the effective strategies of "heterogeneous interface engineering" and "construction of ultrafine active sites" to develop a highly efficient Ru-based catalyst with a three-phase heterogeneous interface, aiming to form its application in alkaline HER. Characterization analysis and DFT calculations demonstrated that the "Rux-Ni(OH)2NiO" three-phase heterogeneous interface constructed around ultrafine Rux clusters effectively modulated the electronic structure of the overall material and optimized the HER kinetic steps. This catalytic material, Rux@NOH/NO, exhibited outstanding electrocatalytic activity in alkaline HER, requiring only 44.2 mV to drive a current density of 10 mA·cm−2, with excellent long-term stability and extremely low active material loading (1.36 wt%-Ru). Specially, its mass activity reached an impressive 18,897.1 A/gRu at 150 mV, which is 10.2 times higher than that of commercial 20wt% Pt/C. In summary, this study synergistically constructs an ultrafine metal ruthenium-based catalyst based on a three-phase heterogeneous interface using a composite strategy, which provides an effective catalyst system for alkaline HER catalytic reactions and holds significance for the rational construction and design of efficient heterogeneous interface electrocatalysts.

A synergetic cocatalyst for conversion of carbon dioxide, sunlight, and water into methanol

The conversion of CO2 into liquid fuels, using only sunlight and water, offers a promising path to carbon neutrality. An outstanding challenge is to achieve high efficiency and product selectivity. Here, we introduce a wireless photocatalytic architecture for conversion of CO2 and water into methanol and oxygen. The catalytic material consists of semiconducting nanowires decorated with core-shell nanoparticles, with a copper-rhodium core and a chromium oxide shell. The Rh/CrOOH interface provides a unidirectional channel for proton reduction, enabling hydrogen spillover at the core-shell interface. The vectorial transfer of protons, electrons, and hydrogen atoms allows for switching the mechanism of CO2 reduction from a proton-coupled electron transfer pathway in aqueous solution to hydrogenation of CO2 with a solar-to-methanol efficiency of 0.22%. The reported findings demonstrate a highly efficient, stable, and scalable wireless system for synthesis of methanol from CO2 that could provide a viable path toward carbon neutrality and environmental sustainability.

Photocatalytic degradation of non-steroidal anti-inflammatory drugs with ketoprofen as model compound. Intermediates and total reaction mechanism

Ketoprofen KET and other non-steroidal anti-inflammatory drugs NSAIDs are extensively used throughout the world to reduce pain, fever, and inflammation. As a result of this, they have been detected in environmental waters and represent a potential health risk. There are several reports about KET photocatalytic degradation but most of them deal with experimental conditions or catalytic materials to perform this process. In this study, the mechanisms and intermediates involved in KET photocatalysis with TiO2 in aqueous media were investigated. First, the mineralization rate was assessed by TOC measurements. The formation and eventual degradation of intermediate organic compounds were investigated by HPLC, UV–Vis, IR, 1H NMR and HPLC-MS studies. TOC analysis indicate that KET is quickly transformed into other compounds that eventually are degradated and 70 % mineralization was achieved after five hours of irradiation. UV–Vis and HPLC studies indicate that KET is transformed into some other aromatic compounds within minutes. IR studies demonstrate the conversion of KET into several aromatic compounds which in turn degradate into low molecular saturated and unsaturated acids. 1H NMR studies indicate KET is transformed into several aromatic compounds such as 3-hydroxy-benzophenone, phenol, 1,4-hydroquinone, 1,2,4-benzenetriol, and catechol. HPLC-MS studies indicate KET is degradated by several photochemical and photocatalytic parallel mechanisms. Based on this and previous studies, a unified and complete mechanism for KET photocatalytic degradation is presented.

Properties, Industrial Applications and Future Perspectives of Catalytic Materials Based on Nickel and Alumina: A Critical Review

Properties, Industrial Applications and Future Perspectives of Catalytic Materials Based on Nickel and Alumina: A Critical Review

Microwave-assisted synthesis of Fe–N–C catalysts using novel nitrogen precursors for proton exchange membrane fuel cells

The current study describes a facile, time-effective and cost-viable synthesis of highly efficient Fe–N–C catalysts tailored for PEMFC. In this work, three different Fe–N–C catalysts for oxygen reduction reaction (ORR) have been synthesized by pyrolyzing different organic molecules in a microwave machine. The catalytic materials have been characterized using advanced techniques such as SEM, TEM, EDS, XPS, and BET analysis to elucidate their morphological, compositional, and surface properties. The fabricated materials i.e. Fe–N–C-Urea (Fe–N–C–U), Fe–N–C-Para-Phenylene Diamine (Fe–N–C-pPD) and Fe–N–C-5-Amino-1-(4′-Aminophenyl)-1,3,3-Trimethylindane (Fe–N–C-AAT) exhibit remarkable peak power densities, reaching as high as 0.96 W cm−2, 0.77 W cm−2 and 0.90 W cm−2, respectively, at a flow rate of 0.4 L min−1 of oxygen and 0.2 L min−1 of hydrogen, keeping the temperature constant at 80 °C. The current work emphasizes the deployment of facile and rapid synthetic protocol coupled with exploiting ingenious organic molecules and avoiding the application of any solvent.

Universal Predictive Power: Introducing the Electronic Structure Decomposition Approach for CO Adsorption and Activation on Al2O3-Supported Ru Nanoparticles.

Accurate prediction of catalyst performance is crucial for designing materials with specific catalytic functions. While the density functional theory (DFT) method is widely used for its accuracy, modeling heterogeneous systems, especially supported transition metals, poses significant computational challenges. To address these challenges, we introduce the Electronic Structure Decomposition Approach (ESDA), a novel method that identifies specific density of states (DOS) areas responsible for adsorbate interaction and activation on the catalyst. As a case study, we investigate the influence of α-Al2O3(0001) as a support material on CO adsorption energy and the stretching frequency of the C-O bond on Ru nanoparticles (NPs). Using multiple linear regression analysis, ESDA models were trained with data from isolated Ru NPs and adjusted using supported NP sample data. The ESDA models accurately predict the CO adsorption energies and C-O vibrational frequencies, demonstrating strong linear correlations between predicted and DFT-calculated values with low errors across various adsorption sites for both isolated and supported Ru NPs. Beyond pinpointing the DOS areas responsible for CO adsorption and C-O bond activation, this study provides insights into manipulating these DOS areas to control CO activation, hence facilitating CO dissociation. Additionally, ESDA significantly accelerates the characterization and prediction of CO adsorption and activation on both isolated and supported Ru NPs compared to DFT calculations, expediting the design of new catalytic materials and advancing catalysis research. Furthermore, ESDA's reliance on the electronic structure as a descriptor suggests its potential for predicting various properties beyond catalysis, broadening its applicability across diverse scientific domains.

Boosting the lattice oxygen reactivity of perovskite electrocatalyst via less Ru substitution

The successful deployment of efficient oxygen evolution reaction (OER) electrocatalysts is highly essential for multiple clean-energy-related conversion technologies. Perovskite oxides, with compositional diversity and elemental complexity, are a classic kind of OER electrocatalysts, whereas their activity remains insufficient under the traditional adsorbate evolution mechanism (AEM) due to limited scaling relations. Herein, taking the Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite as a model system, we find a less Ru substitution strategy to boost the lattice oxygen reactivity for improved OER. The OER behavior of BSCF is greatly ameliorated as Ru doping reaches an optimal level (BSCFR0.1), delivering a lowered overpotential by 45 mV at 10 mA cm−2. Notably, such doping remarkably triggers the generation of more surface oxygen vacancies, promotes internal charge transfer, and enlarges the surface hydrophilicity, hence facilitating more lattice oxygen to participate in the surface reaction. These results demonstrate the feasibility of Ru incorporation for ameliorating the OER behavior of perovskites, and such strategy can be further leveraged to design other remarkable perovskite-based OER catalytic materials.

Synthesis of Pt-doped CoFe layered double hydroxide derived from zeolitic imidazolate framework for efficient electrochemical oxygen evolution reaction

Zeolitic imidazolate frameworks (ZIFs), a class of promising metal organic frameworks (MOFs) material, display high porosity and chemical/thermal stability. However, there are problems such as few active sites and restricted exposed active areas, which limit the oxygen evolution reaction (OER) performance of catalysts. Here, starting from zeolitic imidazolate framework-67 (ZIF-67), we have successfully synthesized Pt-doped CoFe layered double hydroxide (Pt/CoFe LDH) catalysts for efficient OER catalysis. The obtained Pt/CoFe LDH-4 catalysts provides large surface areas and abundant active sites, which further improves the OER performance. In detail, the Pt/CoFe LDH-4 exhibits a lower overpotential of 263 mV at a current density of 40 mA cm−2, in 1 M KOH solution, the stability of the catalyst exceeds 120 h at this current density, far superior to commercial catalyst RuO2. This study describes a new design idea for synthesis of LDH catalytic materials with low noble metal doping, which broadens the way to the synthesis of robust OER catalysts derived from ZIF-67.