Catalytic Activity Of Materials Research Articles

Electrode design for ammonia synthesis

A rapid and efficient electrochemical reaction requires active catalytic material, as well as proper electrode and cell design. Now, a gas diffusion electrode based on a stainless steel cloth successfully overcomes gas transport limitations for high-current ammonia electrosynthesis in non-aqueous solvents at ambient conditions.

Influence of Binder on Porous Structure of Zeolite Compositions and Their Catalytic Activity

The work is devoted to studying the parameters of the porous structure and catalytic activity of materials containing zeolites of the structural types ZSM-5 and BEA and aluminum hydroxides from various manufacturers. It is shown that it is possible to purposefully control the parameters of the porous structure of zeolite compositions, which serve as the basis for the catalysts of many processes, by varying the nature of the zeolite, carrier, peptizer, and their amount. The relationship of the textural characteristics of the compositions with their catalytic activity in the reaction of isomerization of n-hexane is established.

Pyrolysis-free approach towards synthesis of oxygen reduction electrocatalysts

The accelerated consumption of traditional fossil energy has aggravated the energy crisis and environmental pressure worldwide, so clean and renewable energy technologies have been attracting increasing interest. The development of fuel cell technology, metal air batteries, etc., is an important way to deal with the crisis and relieve pressure. As an important part in the operation of battery system, oxygen reduction reaction (ORR) electrochemical catalysts have become the focus of more and more researchers. At present, the commercial catalysts are metal base, especially the electrocatalysts based on precious metals (platinum, ruthenium, etc.) show excellent electrochemical catalytic performance and good stability in ORR. However, the introduction of precious metals increases the cost of battery systems, and the scarcity of raw materials greatly limits the large-scale commercial application of such catalysts. Therefore, the development of high efficiency, stability and low cost non-noble metal based electrocatalysts is the current research target. Recently, a large number of non-precious metal carbon-based catalysts (Fe, Co and other transition metals) have been developed. As early as 1964, scientists found that cobalt phthalocyanine with M-N4 structure in alkaline electrolyte showed ORR properties, but the stability and catalytic activity of the material were poor. On the basis of this research, M-N x /C electrocatalysts prepared by high-temperature pyrolysis with materials with non-noble metals, N and C sources as precursors have been widely studied in the field of new energy materials. Non-noble metal carbon oxygen reduction catalyst is the current popular fuel cell catalysts, the traditional preparation process, most of the carbon catalyst with high temperature carbonization decomposition (usually in 800−1100°C) carbonization process to improve the conductivity and catalytic activity of material, but because of the high temperature in the process of sheet metal atoms to reunite, pyrolysis carbonization of artificial is high, the preparation conditions demanding, not guaranteed, reproducibility and subsequent brings environmental pollution problems such as acid treatment process, is not conducive to practical production applications. In the process of high-temperature carbonization, the material structure may change unpredictably or even be reconstructed, and the catalytic activity potential is unclear and difficult to control, which brings great challenges to understand the reaction and deactivation mechanism and subsequently develop large-scale preparation approach. The research and development of non-carbonization method can avoid the change of material structure caused by high temperature from the source of production. This method can not only effectively reduce energy consumption and improve the repeatability of material preparation, but also realize the controllable construction of high-density, high-activity center and multi-function, and even realize the centralized appearance of different catalytic active centers in the same catalyst, providing a model catalyst for the study of catalytic mechanism. More and more researchers have been working on the preparation of carbon-based catalysts by non-carbonized methods. This paper systematically introduces the preparation and application of non-carbonization strategy to construct new oxygen reduction catalytic materials. Although the non-carbonization strategy is still in its infancy, it is playing an important role in promoting the research of active sites and catalytic mechanism.

Performance of anaerobic fluidized bed microbial fuel cell with different porous anodes

Abstract Anode materials were used to construct microbial fuel cells (MFCs), and the characteristics of the anodes were important for successful applied performance of the MFCs. Via the cyclic voltammetry (CV) method, the experiments showed that 5 wt% multiwalled carbon nanotubes (MWNTs) were optimal for the PANI/MWNT film anodes prepared using 24 polymerization cycles. The maximum output voltage of the PANI/MWNT film anodes reached 967.7 mV with a power density of 286.63 mW·m−2. Stable output voltages of 860 mV, 850 mV, and 870 mV were achieved when the anaerobic fluidized bed microbial fuel cell (AFBMFC) anodes consisted of carbon cloth with carbon black on one side, copper foam and carbon brushes, respectively. Pretreatment of the anodes before starting the AFBMFC by immersion in a stirred bacterial fluid significantly shortened the AFBMFC startup time. After the AFBMFC was continuously run, the anode surfaces generated active microbial catalytic material.

Bulk, Surface and Interface Promotion of Co3O4 for the Low-Temperature N2O Decomposition Catalysis

Nanocrystalline cobalt spinel has been recognized as a very active catalytic material for N2O decomposition. Its catalytic performance can be substantially modified by proper doping with alien cations with precise control of their loading and location (spinel surface, bulk, and spinel-dopant interface). Various doping scenarios for a rational design of the optimal catalyst for low-temperature N2O decomposition are analyzed in detail and the key reactivity descriptors are identified (content and topological localization of dopants, their redox vs. non-redox nature and catalyst work function). The obtained results are discussed in the broader context of the available literature data to establish general guidelines for the rational design of the N2O decomposition catalyst based on a cobalt spinel platform.

Impact of surface loading on catalytic activity of regular and low micropore SBA‐15 in the Knoevenagel condensation

AbstractThe mesopores of SBA‐15 are well‐suited for immobilizing catalytic aminosilanes for converting substrates for fine chemicals, but these materials have micropores that could impact the observed reaction rate of immobilized catalysts. Materials are synthesized with conventional methods that produce micropores (Regular Micropore SBA‐15; REG) and compared to materials with limited to no micropore volume (NMP SBA‐15). These materials are functionalized with aminosilanes for testing in the Knoevenagel condensation. For low amine loadings, NMP materials have a higher observed reaction rate compared to REG materials, achieving twice the conversion in the same time. As the surface density increases, the reaction rate for NMP materials decreases since organosilane functionalization consumes surface silanols that interact cooperatively with the amine. Regardless of surface density, the NMP materials have higher observed reaction rate than the REG materials. These results demonstrate the importance of reducing micropore volume to create highly active catalytic materials.

Tuning redox and chemical characteristics of Mo-based catalysts for bioenergy applications – The case of catalysts supported on TiO2 or ZrO2

A series of MoO3-MoS2 catalysts supported on TiO2 or ZrO2 were synthesized and studied. The aim of this work is to understand the main aspects that influence the catalytic performance of Mo-based catalysts in bioenergy applications. We used two sulfidation temperatures for changing the Mo species in both supports. The catalysts were characterized by N2 physisorption, XRD, SEM, H2-TPR, Raman spectroscopy and XPS. We found important changes in the chemical species of Mo, S and O atoms present in the catalytic materials at 200 or 400 °C of sulfidation temperature. The materials were tested in the hydrodeoxygenation (HDO) of palmitic acid as a model compound of fatty acids. We found some structure-activity relationships of these materials. For instance, the promotion of mixtures of Mo6+, Mo5+ and Mo4+ species increased the catalytic activity for all the materials. MoO3/TiO2 catalyst exhibits higher activity than its counterpart supported on ZrO2. However, the sulfidation of these materials resulted in highly active catalysts, specially using ZrO2. Oxygen vacancies are formed for the catalysts supported on ZrO2 upon sulfidation. Molecular models were employed for a better understanding of the interaction between palmitic acid and the catalytic surfaces. We found that a combination of Mon+ species with S-containing compounds and oxygen vacancies in the catalytic materials is key to develop new highly active catalytic materials for HDO of fatty acids.

One-Pot Synthesis of Dimethyl Hexane-1,6-diyldicarbamate from CO2, Methanol, and Diamine over CeO2 Catalysts: A Route to an Isocyanate-Free Feedstock for Polyurethanes

A new one-pot synthesis method of dimethyl hexane-1,6-diyldicarbamate (HDC), a potential intermediate compound in the synthesis of polyurethanes, from CO2, methanol, and 1,6-hexanediamine (HDA) is disclosed. The starting materials are renewable, stable, easily available, and cheap. The process was implemented in 1-methyl-2-pyrrolidinone (NMP) solvent over CeO2 catalysts. Three different CeO2 catalysts (commercial nanospheres, CeO2(c) obtained by direct calcination of (NH4)2Ce(NO3)6, and CeO2 nanorods) were tested in this reaction and their micromorphology and physical–chemical properties were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 adsorption. CeO2 nanorods proved to be the most active catalytic material. The influence of different parameters on reaction outcome was studied. The yield of HDC was about 80% under optimized reaction conditions. Experiments for better understanding of reaction mechanism were also performed.

Electrochemical Method for Graphene Preparation from Multi-Walled Carbon Nanotubes

There are the numerous methods of graphene synthesis from multi-walled carbon nanotubes (MWCNTs): redox reaction, modification via incorporation of nitrogen and alkaline earth atoms; plasma sputtering; unzipping by microwave radiation, ultrasonic and electrical treatment, treatment with metallic catalytic particles, treatment with laser irradiation and scanning tunnelling microscope tip hydrogenation in high-temperature conditions, as well as unrolling by electrochemical methods [1]. Among these technologically advanced methods, the electrochemical process seems to be most promising since it can be easily controlled by selection of three parameters, namely current, voltage and time. As it is known from the literature, it is possible to carry out the electrochemical reduction of graphene oxide (GO) to electrochemical reduced graphene oxide (ERGO) in different media by a two-step electrochemical approach. Some investigators the processes of oxidation and reduction of graphene carried out in dilute sulfuric acid first at the anodic and then at cathodic polarization without changing the electrolyte. In our opinion, for more complete unzipping of nanotubes during their oxidation, more concentrated sulfuric acid should be used. The reduction process is preferably carried out in concentrated alkaline medium to neutralize the acid intercalated during oxidation. Additional cathode treatment in an alkaline medium will lead to an increase in the specific surface area and a more complete reducing to graphene. Therefore, the aim of our study was to develop a simple electrochemical method to produce ERGO as the catalyst carrier for oxygen electrodes for fuel cells using anodic oxidation of MWCNTs in an acidic medium and subsequent reduction in an alkaline medium. MWCNT diameter was 10-30 nm, and the specific surface area was 230 m2g-1. The number of walls ranged from 8 to 15. The anodic oxidation in sulphuric acid and the electrochemical reduction in alkaline electrolyte carried out in a galvanostatic. The materials synthesized via the electrochemical oxidation of MWCNTs with subsequent reduction were characterized using an electron microscopy (JEM-100 CXII), and X-ray diffraction (XRD) (DRON-4, CuKα radiation), Raman spectra and XPS spectra. Molecular species were analysed with FTIR spectroscopy. The obtained materials were investigated as cathode material for the oxygen electrodes of power sources in alkaline electrolyte. We have studied electrochemical characteristics of the oxygen electrodes produced by oxidation of the carbon nanotubes over different time. The MWCNT anodic oxidation was carried out under +3 V over 1.5, 4, and 5 hours. We found that in over conditions the more suitable time for the obtained electrochemical parameters (current density) of the oxygen electrodes is 4-hour oxidation duration. We have also studied the MWCNTs oxidation at various potentials for 4 hours. The potentials were chosen in the range +1.8–+4.5 V. Anodic oxidation during 4 hours at +3.0 V creates an extremely active catalytic material, which best suits for oxygen electrodes compared to those made of electrochemically oxidized MWCNTs at other potentials. The materials obtained by anodic oxidation of the carbon nanotubes were subsequently reduced in the alkaline solution at -1.4 V potential over 4 hours. The Raman spectra of all three measured samples show the presence of the Raman marker bands characteristic of the graphite structure, namely, D, G and 2D modes. Based on the analysis of the shape and position of these bands one can assume that after the anodic oxidation, the MWCNT crystallinity becomes worse while it improves after subsequent electrochemical reduction. This observation is also confirmed by corresponding XRD data. The frequencies for the D mode, G mode, and 2D mode suggest well-crystallized graphene structure. Closely positioned tags of C atoms in the XRD rings suggest that the synthesized sample consists of flat wavy sheets. As follows from the analysis of the Raman and IR spectra, XPS and XRD data, in the result of the MWCNT electrochemically treatment we obtained graphene nanoplatelets (Fig1), which contains carbon oxide groups on its surface. Electrodes based on electrochemically reduced graphene nanoplatelets produced from oxidized MWCNTs have the electrocatalytic characteristics close to those of the electrodes from MWCNTs containing deposited platinum. Obtained graphene nanoplatelets were stable over six months subject to testing in the fuel cell mock-up galvanostatic mode. The electrochemical synthesis of graphene nanoplatelets via anodic oxidation of MWCNTs and it reduction has been confirmed by electron microscopy, XRD, X-ray fluorescence, IR and Raman spectroscopy. Electrochemical studies have shown that the obtained graphene are promising materials as a catalyst carrier for fuel cells oxygen electrodes. M.O. Danilov, et al., Graphene Science Handbook. Fabrication Methods, (Eds. M. Aliofkhazraei, et al.), CRC Press/Taylor & Francis, 2016, pp. 205. Figure 1

Electrical reduction of perovskite electrodes for accelerating exsolution of nanoparticles

Growth of finely dispersed nanocatalysts by exsolution of metal nanoparticles from perovskite oxides under reducing conditions at elevated temperature is a promising approach of producing highly active catalytic materials. An alternative method of exsolution using an applied potential has been recently shown to potentially accelerate the exsolution process of nanoparticles that can be achieved in minutes rather than the hours required in chemical reduction. In the present study, we investigate exsolution of nanoparticles from perovskite oxides of La0.43Ca0.37Ni0.06Ti0.94O3-γ (LCTNi) and La0.43Ca0.37Ni0.03Fe0.03Ti0.94O3-γ (LCTNi-Fe) under applied potentials in carbon dioxide atmosphere. The impedance spectra of single cells measured before and after electrochemical poling at varying voltages showed that the onset of exsolution process occurred at 2 V of potential reduction. An average particle size of the exsolved nanoparticles observed after testing using a scanning electron microscopy was about 30–100 nm. The cells with the reduced electrodes exhibited desirable electrochemical performances not only in pure carbon dioxide (current density of 0.37 A cm−2 for LCTNi and 0.48 A cm−2 for LCTNi-Fe at 1.5 V) but also in dry hydrogen (0.36 W cm−2 for LCTNi and 0.43 W cm−2 for LCTNi-Fe).

Enhanced performance of catalyst pellets for methane dry reforming by engineering pore network structure

Enhancing the utilization and activity of catalytic materials is crucial in designing catalysts for industrial use. This work achieves these performance enhancements in Rh/Al2O3 catalyzed dry reforming of methane (DRM) at the catalyst pellet level, through engineering catalyst pore network structure. A continuum model, describing the coupled mass, heat transfer and reactions, is developed to optimize the monodisperse and bidisperse catalyst pellets under different temperatures, pressures, and CH4/CO2 ratios. The results show that the preferred pore diameter for the monodisperse catalyst and macropore diameter for the bidisperse catalyst are all 300 nm, above which Knudsen diffusion is not important. Besides, the optimal porosities for the monodisperse and bidisperse catalysts are in the ranges of 0.51–0.59 and 0.61–0.64, which is the result of the trade-off between diffusion and reaction. The optimal bidisperse catalyst can be 56–175% more active but uses 10–18% less catalyst materials when compared to the optimal monodisperse catalyst with the same mesopore size, indicating the great advantage of introducing the optimal macroporosity into mesoporous catalyst pellets for DRM. These results should serve to guide the rational design of industrial catalyst pellets.

Preparation and characterization of palladium ceramic alumina membrane for hydrogen permeation

In this study, a tubular palladium membrane has been prepared by an electroless plating method using palladium II chloride as a precursor with the intent of not having a completely dense film since its application does not require high hydrogen selectivity. The support used was a 15 nm pore sized tubular ceramic alumina material that comprised of 77% alumina and 33% titania. It has dimensions of 7 mm inner and 10 mm outer diameters respectively. The catalyst was deposited on the outside tube surface using the electroless deposition process. The membrane was morphologically characterized using scanning electron microscopy/energy dispersive x-ray analysis (SEM/EDXA) and liquid nitrogen adsorption/desorption analysis (BET) to study the shape and nature of the palladium plating on the membrane. The catalytic membrane was then inserted into a tubular stainless-steel holder which was wrapped in heating tapes so as to enable the heating of the membrane in the reactor. The gases used for permeation tests comprised H2, N2, O2 and He. Permeation tests were out at 573 K and at pressure range between 0.05 and 1 barg. The results showed that hydrogen displayed a higher permeation when compared to other gases that permeated through the membrane and its diffusion is also thought to include solution diffusion through the dense portions of the palladium in addition to Knudsen, convective and molecular sieving mechanisms occurring through cracks and voids along the grain boundaries. While high hydrogen selectivity is critically important in connection with hydrogen purification for fuel cells and in catalytic membrane reactors used to increase the yield of thermodynamically limited reactions such as methane steam reforming and water–gas shift reactions whereby the effective and selective removal of the H2 produced from the reaction zone shifts the equilibrium, it is not so important in situations in which the membrane has catalytic activity such that it is possible to carryout the reaction in situations where the premixed reactants are forced-through the membrane on which the catalysts is attached. This type of catalytically active membranes is novel and has not been tested in gas-solid-liquid reactions and liquid-solid reactions before. With such a reactor configuration, it is possible to achieve good feed stream distribution and an optimal usage of the catalytic material. The preparation and characterization of such membrane catalysts has gained increased interest in the process industries because it can be adapted to carryout the chemical reactions if one of the reactants is present in low concentration and an optimal reactant distribution results in a better utilization of the active catalytic material. However, there are concerns in terms of the high cost of palladium membranes and research on how to fabricate membranes with a very low content of the palladium catalyst is still ongoing. Work is currently underway to deploy the Pd/Al2O3 membrane catalysts for the deoxygenating of water for downhole injection for pressure maintenance and in process applications.

Design strategies toward catalytic materials and cathode structures for emerging Li–CO2 batteries

The state-of-the-art design strategies toward highly active catalytic materials and cathode structures for Li–CO2 batteries are reviewed and discussed.

Efficient oxygen evolution electrocatalysis in acid by a perovskite with face-sharing IrO6 octahedral dimers

The widespread use of proton exchange membrane water electrolysis requires the development of more efficient electrocatalysts containing reduced amounts of expensive iridium for the oxygen evolution reaction (OER). Here we present the identification of 6H-phase SrIrO3 perovskite (6H-SrIrO3) as a highly active electrocatalyst with good structural and catalytic stability for OER in acid. 6H-SrIrO3 contains 27.1 wt% less iridium than IrO2, but its iridium mass activity is about 7 times higher than IrO2, a benchmark electrocatalyst for the acidic OER. 6H-SrIrO3 is the most active catalytic material for OER among the iridium-based oxides reported recently, based on its highest iridium mass activity. Theoretical calculations indicate that the existence of face-sharing octahedral dimers is mainly responsible for the superior activity of 6H-SrIrO3 thanks to the weakened surface Ir-O binding that facilitates the potential-determining step involved in the OER (i.e., O* + H2O → HOO* + H+ + e¯).

Nanostructured Metal Catalysts for Selective Hydrogenation and Oxidation of Cellulosic Biomass to Chemicals.

Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom-economical and energy-efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed. The perspectives obtained from this review paper will provide insights into rational design of active, selective and stable catalytic materials for sustainable production of value-added chemicals from biomass resources.

Influence of calcination on metallic dispersion and support interactions for NiRu/TiO2 catalyst in the hydrodeoxygenation of phenol

Bio-oil upgrading by hydrotreatment has been considered as a renewable route for fuels production and potential substitutes for fossil oil distillates. Traditional hydrodesulfurization catalysts (sulfided CoMo and NiMo) used in petroleum refining have been evaluated in hydrodeoxygenation reactions with high selectivity to aromatics. However, significant deactivation has been commonly observed, due to the low sulfur content in bio-oil. Thus, the development of different active and stable catalytic materials is needed. In this regard, we have previously reported a synergetic effect between Ni and Ru bimetallic materials supported on Al2O3, TiO2 and ZrO2 in phenol HDO with promising activity and selectivity results. In particular, materials supported TiO2 on displayed the highest activities. Therefore, the aim of this work was to evaluate the effect of calcination on dispersion and metal-support interactions and their impact on activity and selectivity for NiRu/TiO2 catalysts in HDO of phenol as a model compound for bio oil. Catalysts were characterized by hydrogen chemisorption, Temperature- programmed reduction, X-ray photoelectron spectroscopy, High resolution electron microscopy. Additionally, hydrogenation of benzene was used as a structure unsensitive reaction in order to obtain more information about metallic dispersion. A highly active NiRu catalyst was obtained when calcination was avoided prior to reduction. The calcination procedure induced the formation of metallic oxides and it provoked less dispersed NiRu species as compared with catalysts without this previous treatment. On the contrary, the formation of metallic species from direct reduction of precursor salts contributed to produce highly dispersed species.

Cu-Ce-O catalyst revisited for exceptional activity at low temperature CO oxidation reaction

In the present study, CexCu1−xO2−δ (x = 0, 0.3, 0.5, 0.8, 0.9, and 1) catalysts were synthesized using a facile and reproducible combustion method and were evaluated towards the CO oxidation (CO-OX) and CO preferential oxidation (CO-PROX) reactions as inexpensive and active catalytic materials. Pure ceria and copper oxide were compared to CexCu1−xO2−δ mixed metal oxides for benchmarking purposes. The catalysts were prepared using citric acid (C6H8O7) as fuel and nitrate salts of cerium and copper as oxidizers under fuel rich conditions. A variety of techniques including XRD, EDX, BET, SEM, Raman, XPS, H2-TPR and CO2-TPD, were used to analyze the microstructural, thermal and redox properties that may influence CO oxidation performance. A profound effect of Cu content was revealed that not only impacts the structural and redox properties of the catalysts but also affects the catalytic activity. The Ce0.8Cu0.2O2−δ catalyst presented the most promising performance among many similar (Cu-Ce-based catalysts) as well as noble supported catalysts published in the literature with T50 = 62 °C and T100 = 78 °C, an activity that coincides with the availability of labile oxygen species at low temperature (T < 100 °C) and the enhanced CO2 desorption at low temperature (low CO2-philicity) of this catalyst.

TEMPO-Based Organocatalyst Design

Recently there has been an increased interest in the development of small molecule electrooxidation catalysts such as (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), for multistep electrochemical alcohol oxidation. Several TEMPO derivatives have long been used to electrochemically oxidize short chain alcohols and various sugars to the corresponding aldehydes and carboxylic acids under physiological aqueous conditions. However, many nitroxyl radical-containing species decompose rapidly in an oxidized state and are therefore ineffective as alcohol oxidation catalysts. Furthermore, building libraries of such a catalyst is difficult due to the limited number of commercially available TEMPO derivatives and the lack of modular synthetic pathways for more complicated TEMPO structures. A promising alternative to the physical preparation of such libraries is the use of computational modeling to allow for in silico catalytic screening of a much wider range of TEMPO compounds. We have recently developed a descriptive model that correlates the electrocatalytic activity of nitroxyl radical catalysts to their redox potentials under aqueous conditions. Based on fundamental insights derived from this model, we have designed several highly active and promiscuous catalytic materials in the form of redox polymers capable of oxidizing a wide range of primary and secondary alcohols as well as several amines. In addition, we have recently aimed at enhancing the selectivity of nitroxyl radical catalysts by incorporating highly active TEMPO derivatives into the active site of an artificial thermostable protein.

Nanostructured Nickel Selenides for High Efficiency Water Oxidation Electrocatalysis

While oxygen evolution reaction (OER) taking place at the anode during water splitting reaction, is a very promising route towards clean and renewable energy, synthesis of highly efficient OER catalysts from earth-abundant, precious metal-free resources is the most challenging aspect of the field. We have synthesized a series of nanostructured nickel selenides, NiSe, NiSe2, Ni3Se2 and Ni3Se4 as active catalytic materials for the OER in alkaline medium. While Ni has been proven to show promising catalytic activity, the significant improvement in efficiency observed in this series towards OER can also be partly due to the formed nanostructured interface which increases the exposed surface area of the catalyst. These pure nickel selenides were synthesized by hydrothermal reactions and showed low overpotential at 10 mA cm-2 current density, early onset of catalytic activity, as well as high overall current density during the OER electrocatalytic activity in 1.0 M KOH. The overpotentials at 10 mA cm-2 current density for the above series of nickel selenides are 220, 200, 240 and 250 mV, for NiSe, NiSe2, Ni­3Se2 and Ni3Se4, respectively. Additionally, we have also investigated the stability of this catalyst during long-term OER conditions under 1.0 M KOH, which confirmed that these electrocatalysts maintained their structural and compositional integrity under operational condition for extended period of time. In this presentation we will discuss about the effect of nanostructured morphology on electrocatalytic performance and will offer some insight about designing better electrocatalysts incorporating morphology control. The synthesis of nanostructured electrocatalysts, characterization techniques such as XRD, SEM, TEM and STEM, and detailed electrochemical investigations for catalytic activity will be also discussed.

Designed Meso‐macroporous Silica Framework Impregnated with Copper Oxide Nanoparticles for Enhanced Catalytic Performance

AbstractThe template efficacy of solid lipid nanoparticles for generating porous silica materials with the amalgamation of Cu‐functionalized cetylpyridinium chloride (CPC; as a co‐emulsifier and as a metal source for generation of CuO oxide nanoparticles) has been explored. Impregnation of CuO nanoparticles (∼10–12 nm) onto the silica matrix proffers to be a propitious route for the fabrication of twin sized porous, highly active catalytic materials. The surface morphology and structural characterization of the synthesized CuO@meso‐macroporous silica framework was elucidated by TEM, field ‐emission (FE)‐SEM, energy‐dispersive X‐ray (EDX), wavelength dispersive (WD)‐XRF, X‐ray photoelectron spectroscopy (XPS), small‐angle X‐ray scattering (SAXS), XRD, and N2 adsorption/desorption studies. All the results have shown that there exists a structural network interconnecting the mesopores with macropores. The catalytic performance of the synthesized framework (ascribed catalyst) was checked for two model reactions. For the reduction of p‐nitrophenol to p‐aminophenol, only 0.25 % (w/v) catalyst was sufficient to accomplish the reaction in 6 min, giving 99.9 % yield. On the other hand, the redox reaction of potassium hexacyanoferrate(III) and sodium thiosulfate utilized 5 % (w/v) catalyst and completed the reaction in 40 min, yielding 98.43 %. Therefore, CuO@meso‐macroporous silica materials could hold great importance in the world of nanocatalysis owing to the present promising results.