Catalytic Production Research Articles

Plasmonic Pt-PPCN/TiN Ohmic Junction for Photo-Thermo Catalytic Hydrogen Production.

The rational design of photocatalysts for improving the conversion of solar energy into hydrogen is a promising route for achieving carbon neutrality. Herein, we couple plasmonic titanium nitride (TiN) with highly crystalline potassium-doped polymeric carbon nitride (PPCN) to construct a PPCN/TiN ohmic junction. Such an ohmic junction not only broadens the absorption spectrum but also inhibits the recombination of electrons and holes. In addition, Pt nanoparticles are introduced into this ohmic junction to form plasmonic Pt-PPCN/TiN, improving the capture of hot electrons generated by TiN and thereby promoting the dissociation of the O-H bond in H2O. The energy barrier decreases from 0.7 to 0.2 eV. Enhanced separation of carrier, activation of water molecules, and capture of hot electrons are jointly promoting photo-thermo catalytic hydrogen production. Therefore, under full-spectrum irradiation, the hydrogen production rate of Pt-PPCN/TiN reaches 19 085 μmol g-1 h-1. This novel plasmonic photocatalyst is promising for full-spectrum photo-thermo catalytic hydrogen production.

Modification of metals and ligands in two-dimensional conjugated metal-organic frameworks for CO2 electroreduction: A combined density functional theory and machine learning study

Electrochemical carbon dioxide reduction reaction (CO2RR) is a promising technology to establish an artificial carbon cycle. Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) with high electrical conductivity have great potential as catalysts. Herein, we designed a range of 2D c-MOFs with different transition metal atoms and organic ligands, TMNxO4-x-HDQ (TM = Cr∼Cu, Mo, Ru∼Ag, W∼Au; x = 0, 2, 4; HDQ = hexadipyrazinoquinoxaline), and systematically studied their catalytic performance using density functional theory (DFT). Calculation results indicated that all of TMNxO4-x-HDQ structures possess good thermodynamic and electrochemical stability. Notably, among the examined 37 MOFs, 6 catalysts outperformed the Cu(211) surface in terms of catalytic activity and product selectivity. Specifically, NiN4-HDQ emerged as an exceptional electrocatalyst for CO production in CO2RR, yielding a remarkable low limiting potential (UL) of −0.04 V. CuN4-HDQ, NiN2O2-HDQ, and PtN2O2-HDQ also exhibited high activity for HCOOH production, with UL values of −0.27, −0.29, and −0.27 V, respectively, while MnN4-HDQ, and NiO4-HDQ mainly produced CH4 with UL values of −0.58 and −0.24 V, respectively. Furthermore, these 6 catalysts efficiently suppressed the competitive hydrogen evolution reaction. Machine learning (ML) analysis revealed that the key intrinsic factors influencing CO2RR performance of these 2D c-MOFs include electron affinity (EA), electronegativity (χ), the first ionization energy (Ie), p-band center of the coordinated N/O atom (εp), the radius of metal atom (r), and d-band center (εd). Our findings may provide valuable insights for the exploration of highly active and selective CO2RR electrocatalysts.

A Review on the Influence of Crystal Facets on the Product Selectivity of CO2RR over Cu Metal Catalysts.

The electrocatalytic carbon dioxide reduction reaction (ECRR) is promising in converting environmentally harmful CO2 into useful chemicals, but the large-scale application of this technology is seriously limited by its low efficiency and selectivity. Cu-based electrocatalysts displayed attractive ability in converting CO2 to multiple products, and the product selectivity can be manipulated through various approaches. Among them, exposing specific crystal facets through crystal facet engineering has been proven to be highly effective in obtaining specific products and has attracted numerous researchers. However, to our knowledge, few reports have systematically summarized the relationship between the crystal facet control of Cu catalysts and the catalytic products. This review begins by outlining the general mechanism of CO2 electrocatalytic reduction on Cu-based catalysts, and then summarizes the preferences of low-index and high-index Cu facets regarding product selectivity and delves into the synergistic effects between facets (including different Cu facets and interactions between Cu and non-Cu facets) and their impact on CO2 reduction reaction (CO2RR). In addition, the study of the recently developed Cu single-atom catalysts in ECRR was also introduced. Finally, we provide an outlook on the development of high-performance Cu-based catalysts for applications in CO2RR. The purpose of this review is to provide a clear vein and meaningful guidance for the following studies over the crystal facet control of Cu-based electrocatalysts.

Development of Thermoelectric Nanomaterials with Photothermal Effect to Enhance Thermalcatalysts Sterilization Applications

Reactive oxygen species (ROS) are widely used in environmental and health-related fields due to their high reactivity. Among them, hydrogen peroxide (H2O2) is the most mild, stable, and environmentally friendly oxidant with only H2O and O2 as the decomposition products. Therefore, it is widely used in bleaching, wastewater treatment, fuel cells, and medical which can using on sterilization or infective wound healing and so on. However, the traditional anthraquinone method for producing H2O2 requires precious metal catalysts、high energy consumption and produces a large amount of wastewater. In addition, the catalytic production of H2O2 is mainly achieved by photocatalysis, piezocatalysis, or electrocatalysis procresses, which limits the application environment. To solve this problem, thermocatalysis based on temperature difference by using thermoelectric materials is a promising solution. However, the current H2O2 production efficiency is still low, which limits the application scenarios. Therefore, we propose to use Au nanoparticles and MoS2 nanosheets with Bi2Te3 nanoplates as the thermocatalytic material. Bi2Te3 nanoplates have high Seebeck coefficient at room temperaturea and high specific surface area. Moreover, Au nanoparticles and MoS2 nanosheets are known as great photothermal property materials which can be used to increase the temperature difference of the material to improve the H2O2 production efficiency. The temperature difference is the most common environmental factor in daily life, which makes thermoelectric nanomaterials have great potential for practical applications in the field of thermalcatalysts.

Product Selection Toward High-Value Hydrogen and Bamboo-Shaped Carbon Nanotubes from Plastic Waste by Catalytic Microwave Processing.

The escalating levels of plastic waste and energy crises underscore the urgent need for effective waste-to-energy strategies. This study focused on converting polypropylene wastes into high-value products employing various iron-based catalysts and microwave radiative thermal processing. The Al-Fe catalysts exhibited exceptional performance, achieving a hydrogen utilization efficiency of 97.65% and a yield of 44.07 mmol/g PP. The gas yields increased from 19.99 to 94.21 wt % compared to noncatalytic experiments. Furthermore, this catalytic system produced high-value bamboo-shaped carbon nanotubes that were absent in other catalysts. The mechanism analysis on catalytic properties and product yields highlighted the significance of oxygen vacancies in selecting high-value products through two adsorption pathways. Moreover, the investigation examined the variations in product distribution mechanisms between conventional and microwave pyrolysis, in which microwave conditions resulted in 4 times higher hydrogen yields. The technoeconomic assessment and Monte Carlo risk analysis further compared the disparity. The microwave technique had a remarkable internal rate of return (IRR) of 39%, leading to an income of $577/t of plastic with a short payback period of 2.5 years. This research offered sustainable solutions for the plastic crisis, validating the potential applicability of commercializing the research outcomes in real-world scenarios.

Zeolite Membrane-Based Low-Temperature Dehydrogenation of a Liquid Organic Hydrogen Carrier: A Key Step in the Development of a Hydrogen Economy.

Methylcyclohexane (MCH) dehydrogenation is an equilibrium-limited reaction that requires high temperatures (>300°C) for complete conversion. However, high-temperature operation can degrade catalytic activity and produce unwanted side products. Thus, a hybrid zeolite membrane (Z) is prepared on the inner surface of a tubular support and used it as a wall in a membrane reactor (MR) configuration. Pt/C catalysts is packed diluted with quartz sand inside the Z-coated tube and applied the MR for MCH dehydrogenation at low temperatures (190-250°C). Z showed a remarkable H2-permselectivity in the presence of both toluene and MCH, yielding separation factors over 350. The Z-based MR achieved higher MCH conversion (75.3%±0.8% at 220°C) than the conventional packed-bed reactor (56.4%±0.3%) and the equilibrium state (53.2%), owing to the selective removal of H2 through Z. In summary, the hybrid zeolite MR enhances MCH dehydrogenation at low temperatures by overcoming thermodynamic limitations and improves the catalytic performance and product selectivity of the reaction.

Cascade Electrocatalytic Reduction of Nitrate to Ammonia Using a Heterobimetallic Covalent Organic Framework Composed of Cu-Porphyrin and Co-Bipyridine.

The electrocatalytic reduction of nitrate (NO3-) to ammonia (NH3) not only offers an effective solution to environmental problems caused by the accumulation of NO3- but also provides a sustainable alternative to the Haber-Bosch process. However, the conversion of NO3- to NH3 is a complicated process involving multiple steps, leading to a low Faradaic efficiency (FE) for NH3 production. The structural designability of covalent organic frameworks (COFs) renders feasible and precise modulation at the molecular level, facilitating the incorporation of multiple well-defined catalytic sites with different reactivities into a cohesive entity. This promotes the efficiency of the overall reaction through the coupling of multistep reactions. Herein, heterobimetallic CuP-CoBpy was prepared by postmodification, involving the anchoring of cobalt ions to the CuP-Bpy structure. As a result of the cascade effect of the bimetallic sites, CuP-CoBpy achieved an outstanding NH3 yield of 13.9 mg h-1 mgcat.-1 with a high FE of 96.7% at -0.70 V versus the reversible hydrogen electrode and exhibited excellent stability during catalysis. A series of experimental and theoretical studies revealed that the CuP unit facilitates the conversion of NO3- to NO2-, while the CoBpy moiety significantly prompts the reduction of NO2- to NH3. This study demonstrates that tailoring the structural units for the construction of COFs based on each step in the multistep reaction can enhance both the catalytic activity and product selectivity of the overall process.

A Comprehensive Review of Solar Photocatalysis & Photothermal Catalysis for Hydrogen Production from Biomass: from Material Characteristics to Engineering Application.

Biomass photoreforming is a promising way of producing sustainable hydrogen thanks to the abundant sources of biomass feedstocks. Solar energy provides the heat and driven force to initial biomass oxidation coupled with H2 evolution. Currently, biomass photoreforming is still far from plant-scale applications due to the lower solar energy utilization efficiencies, the low H2 yield, and the lack of appropriate photoreactors. The production of H2 from photoreforming of native biomass and platform molecules was summarized and discussed with particular attention to the prospects of scaling up the catalysis technology for mass hydrogen production. The types of photoreforming, including photocatalysis and photothermal catalysis, were discussed, consequently considering the different requirements for photoreactors. We also reviewed the photoreactors that support biomass photoreforming. Numerical simulation methods were implemented for the solid-liquid two-phase flow and inter-particle radiative transfer involved in the reaction process. Developing concentrated photothermal catalytic flowed reactors is beneficial to scale-up catalytic hydrogen production from biomass.

Watching a Single Enzyme at Work Using Single-Molecule Surface-Enhanced Raman Scattering and DNA Origami-Based Plasmonic Antennas.

The detection of a single-enzyme catalytic reaction by surfaced-enhanced Raman scattering (SERS) is presented by utilizing DNA origami-based plasmonic antennas. A single horseradish peroxidase (HRP) was accommodated on a DNA origami nanofork plasmonic antenna (DONA) containing gold nanoparticles, enabling the tracing of single-molecule SERS signals during the peroxide reduction reaction. This allows monitoring of the structure of a single enzymatic catalytic center and products under suitable liquid conditions. Herein, we demonstrate the chemical changes of HRP and the appearance of tetramethylbenzidine (TMB), which works as a hydrogen donor before and after the catalytic reaction. The results show that the iron in HRP adopts Fe4+ and low spin states with the introduction of H2O2, indicating compound-I formation. Density functional theory (DFT) calculations were performed for later catalytic steps to rationalize the experimental Raman/SERS spectra. The presented data provide several possibilities for tracking single biomolecules in situ during a chemical reaction and further developing plasmon-enhanced biocatalysis.

Catalytic Mode and Product Specificity of an α-Agarase Reveal Its Direct Catalysis for the Production of Agarooligosaccharides.

Many α-agarases have been characterized and are utilized for producing agarooligosaccharides through the degradation of agar and agarose, which are considered valuable for applications in the food and medicine industries. However, the catalytic mechanism and product transformation process of α-agarase remain unclear, limiting further enzyme engineering for industrial applications. In this study, an α-agarase from Catenovulum maritimus STB14 (Cm-AGA) was employed to degrade agarose oligosaccharides (AGOs) with varying degrees of polymerization (DPs) to investigate the catalytic mechanism of α-agarases. The results demonstrated that Cm-AGA could degrade agarose into agarotetraose and agarohexaose. The reducing ends of agarotetraose and agarohexaose spontaneously release unstable 3,6-anhydro-α-l-galactose molecules, which were further degraded into agarotriose and agaropentose. Cm-AGA cannot act on α-1,3-glucoside bonds in agarotriose, agarotetraose, neoagarobiose, and neoagarotetraose but can act on AGOs with a DP greater than four. The product analysis was further verified by β-galactosidase hydrolysis, which specifically cleaves the non-reducing glycosidic bond of agarooligosaccharides. Multiple sequence alignment results showed that two conserved residues, Asp994 and Glu1129, were proposed as catalytic residues and were further identified by site-directed mutagenesis. Molecular docking of Cm-AGA with agaroheptose revealed the potential substrate binding mode of the α-agarase. These findings enhance the understanding of Cm-AGA's catalytic mode and could guide enzyme engineering for modulating the production of agarooligosaccharides.

THE EFFECT OF ASPHALTENES QUANTITY ON THERMAL AND CATALYTIC CRACKING PRODUCT YIELD OF HEAVY OIL FROM KARMALSKOYE FIELD

The study investigated the composition of products resulting from thermal and catalytic cracking of mixtures of deasphaltenized oil from the Karmalskoye field with asphaltenes content of 0.0, 5.2, and 10.4wt.%. The experiments were conducted at a temperature of 450 °C for a duration of 100 min. The catalyst used was a mixture of tungsten carbide and nichrome powders (NiCrWC), in an amount of 0.1%wt. The presence of the NiCrWC additive during cracking of mixtures of deasphaltenized oil with different asphaltenes content has been shown to increase the yield of oils, gasoline, and diesel fractions while reducing the yield of coke and asphaltenes compared to thermal cracking. During the catalytic cracking of all the mixtures studied, the combined yield of gasoline and diesel fractions exceeds 70%wt. It is important to note that an increase in asphaltenes content during catalytic cracking results in a decrease in the yield of gasoline fractions and an increase in the yield of diesel fractions. Studies have demonstrated that the thermal cracking of heavy oil mixtures with different asphaltene contents results in a decrease in the contents of saturated and monoaromatic hydrocarbons, while the contents of biaromatic and triaromatic hydrocarbons increase. Additionally, the presence of asphaltenes has been found to impact the formation of polyaromatic hydrocarbons. During catalytic cracking, the content of saturated, monoaromatic, and biaromatic hydrocarbons increases, while the content of triaromatic and polyaromatic hydrocarbons decreases. During catalytic cracking, the average structure of asphaltene molecules undergoes significant changes. The molecules become smaller, more aromatic, and monoblock, with fewer carbon atoms in the saturated moieties. This catalyst also helps reduce the amount of heteroatoms in the resulting asphaltenes. For citation: Sviridenko N.N., Urazov Kh.Kh., Sergeyev N.S. The effect of asphaltenes quantity on thermal and catalytic cracking product yield of heavy oil from Karmalskoye field. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 76-84. DOI: 10.6060/ivkkt.20246708.6t.

Inhibitory mechanism of xanthine oxidase by 6-, 8- and 10-gingerol: Enzyme kinetics, multi-spectroscopy and molecular simulations

In this study, the inhibitory activity and mechanism of three gingerols (6-, 8- and 10-gingerol) on xanthine oxidase (XOD), a key enzyme responsible for the formation of uric acid, were evaluated. The three gingerols reversibly inhibited XOD activity in a mixed manner with IC50 values of (13.16 ± 0.41), (10.18 ± 0.22) and (6.88 ± 0.11) μM, respectively. 10-gingerol exhibited stronger inhibitory ability, which might contribute to its superior antioxidant properties, higher binding affinity and more significant conformational changes for XOD compared to other gingerols. Fluorescence quenching and molecular docking results indicated that gingerols acted in the vicinity of the flavin adenine dinucleotide in XOD, interacting with the surrounding key amino acid residues through hydrogen bonding and van der Waals forces, thereby preventing substrate entry and the release of catalytic products. Molecular dynamics simulations showed that the addition of gingerol decreased the stability and increased the structural density of XOD. These findings could provide valuable data for the application of gingerols in new XOD inhibitors and hypouricemic functional foods.

Monitoring Enzymatic Reaction Kinetics and Activity Assays in Confined Nanospace.

Enzyme-mediating biotransformations commonly occur in micro- and nanospace, which is crucial to maintain the essential biochemical processes and physiological functions in living systems. Probing enzyme-catalytic reactions in a biomimetic fashion remains challenging due to the lack of competent tools and methodology. Here, we show that studying enzymatic reaction kinetics can be readily achieved by a well-designed solid-state nanopore. Using tyrosine as a classical substrate, we quantitatively characterize the catalytic activity of tyrosinase (TYR) and tyrosine decarboxylase (TDC) in a nanoconfined space. Tyrosine was first immobilized in the nanopipette, wherein the active sites of tyrosine were left unoccupied. When successively exposed to TYR and TDC, a two-step cascade reaction can spontaneously take place. In this process, the surface wettability and charge of the nanopipette stemming from the catalytic products can sensitively regulate ion transport and ionic current rectification behavior, which were monitored by ionic current signal. In this biomimetic scenario, we obtained the enzymatic reaction kinetics of monophenyl oxidase that were not previously actualized in the conventional macroenvironment. Significantly, TYR showed higher enzyme activity, with a Km value of 1.59 mM, which was lower than that measured in a free and open space (with a Km of 3.01 mM). This suggests that tyrosine should be the most appropriate substrate of TYR, thus improving our understanding of tyrosine-associated biochemical reactions. This work offers an applicable technical platform to mimic enzyme-mediated biotransformations and biometabolisms.

Preparation of catalyst for CO2 hydrogenation reaction based on the idea of element sharing and preliminary exploration of catalytic mechanism.

Under the background of the continuous rise of CO2 annual emissions, the development of CO2 capture and utilization technology is urgent. This study focuses on improving the catalytic capacity of the catalyst for CO2 hydrogenation, improving the efficiency of CO2 conversion to methanol, and converting H2 into chemical substances to avoid the danger of H2 storage. Based on the concept of element sharing, the ASMZ (Aluminum Shares Metal Zeolite catalysts) series catalyst was prepared by combining the CuO-ZnO-Al2O3 catalyst with the ZSM-5 zeolite using the amphoteric metal properties of the Al element. The basic structural properties of ASMZ catalysts were compared by XRD, FTIR, and BET characterization. Catalytic properties of samples were measured on a micro fixed-bed reactor. The catalytic mechanism of the catalyst was further analyzed by SEM, TEM, XPS, H2-TPR, and NH3-TPD. The results show that the ASMZ3 catalyst had the highest CO2 conversion rate (26.4%), the highest methanol selectivity (76.0%), and the lowest CO selectivity (15.3%) in this study. This is mainly due to the fact that the preparation method in this study promotes the exposure of effective weakly acidic sites and medium strength acidic sites (facilitating the hydrogenation of CO2 to methanol). At the same time, the close binding of Cu-ZnO-Al2O3 (CZA) and ZSM-5 zeolite also ensures the timely transfer of catalytic products and ensures the timely play of various catalytic active centers. The preparation method of the catalyst in this study also provides ideas for the preparation of other catalysts.

Liposome-Papain Conjugates for Catalytic Digestion of Antibody Producing Fab Fragments.

Papain is useful for the enzymatic digestion of various proteins to produce functional peptides or protein fragments. Immobilized papain being reactive toward proteins and easily removable from a reaction mixture is worth developed. In the present work, liposomes were applied as colloidal carriers of papain for the catalytic digestion of polyclonal immunoglobulin G (IgG). Papain was covalently conjugated at pH = 7.0 via tris-succinimidyl aminotriacetate (TSAT) to liposomes incorporated with 5 mol % poly(ethylene glycol)-tethered lipid with a reactive amino group. The papain-conjugated liposome (liposome-papain) catalyzed the hydrolysis of Nα-benzoyl-l-arginine 4-nitroanilide hydrochloride (BAPNA) at pH = 5.0-7.0. The activity of liposome-papain significantly increased with increasing temperature from 25 to 50 °C. The Michaelis constant Km was determined with respect to the liposome-papain- and free papain-catalyzed reactions with BAPNA at 37 °C as Km = 1.11 ± 0.13 and 11.6 ± 2.9 mM, respectively. Liposome-papain was applied to the catalytic digestion of 10 mg·mL-1 IgG at 37 °C for 24 h at pH = 5.0-7.0. The reaction mixture could be analyzed without pretreatment by using the affinity columns immobilized with the protein A or protein L ligand because colloidal liposome-papain quickly flowed through the chromatographic stationary phase, exhibiting little proteolytic effect on the proteinaceous ligands. The analysis clearly demonstrated the catalytic production of antigen-binding fragments (Fab) from IgG in an enzyme concentration- and pH-dependent manner. Liposome-papain with 15 or 50 mol % anionic lipids also catalyzed the formation of Fab from IgG. The above results demonstrated that liposome-papain was useful to digest IgG and to purify Fab formed with the affinity chromatography.

Exploring the potential of surface-modified alginate beads for catalytic removal of environmental pollutants and hydrogen gas generation

In this study, hydrogel beads were fabricated using alginate (Algt) polymer containing dispersed nickel phthalocyanine (NTC) nanomaterial. The viscous solution of Algt and NTC was poured dropwise into a divalent Ca2+ ions, resulting in the formation of hydrogel beads known as NTC@Algt-BDs. The surface of the NTC@Algt-BDs was further modified by coating them with different types of metal ions, yielding metal-coated M+/NTC@Algt-BDs. The adsorbed metal ions i.e., Cu+2, Ag+, Ni+2, Co+2, and Fe+3 were subsequently reduced to zero-valent metal nanoparticles (M0) by NaBH4. The prepared beads were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Initially, M0/NTC@Algt-BDs were examined for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Among them, Cu0/NTC@Algt-BDs catalyst exhibited the highest reduction rate and therefore, investigated for reduction of different nitrophenols (NPs) and dyes, including 2-nitrophenol (2-NP), 2,6-dinitrophenol (2,6-DNP), methyl orange (MO), potassium ferrocyanide (PFC), congo red (CR), and acridine orange (ArO). The highest reduction rates of 2.019 and 1.394 min−1 were observed for MO and 2-NP, respectively. Furthermore, the fabricated catalysts were employed for the efficient production of H2 gas by NaBH4 methanolysis. Among which the Ag0/NTC@Algt-BDs catalyst showed excellent catalytic production of H2 gas, exhibiting the lowest activation energy (Ea) of 25.169 kJ/mol at ambient temperature. Furthermore, the impact of NaBH4 amount, and catalyst dosage on the reduction of 2-NP and H2 gas production was conducted whereas the effect of temperature on methanolysis of NaBH4 for evolution of H2 gas was studied. The amount of H2 gas was confirmed by GC-TCD system. Additionally, the recyclability of the catalyst was investigated, as it garnered significant research interest.

Interplanar spacing and nanosheet thickness regulation of carbon nitride and its “cold” catalytic hydrogen production performance under 10 W LED irradiation

Investigation of hydrogen production catalysis under low-temperature and low-power light irradiation, such as LEDs, is important for energy conservation in cold natural conditions. Interlayer charge transfer in g-C3N4 nanosheets is influenced by the crystal face spacing and nanosheet thickness, due to rapid photogenerated carrier recombination and slow charge transfer, thus enhancing hydrogen production capabilities. Few studies have controlled both crystal face spacing and nanosheet thickness simultaneously. In this research, copper-phosphorus co-doped g-C3N4 was synthesized through one-step thermal polymerization, achieving both control over nanosheet thickness and crystal surface spacing. The hydrogen production rate of 0.5 %Cu/1 %P doped g-C3N4 was increased by 5.25 times and reached 958.98 μmol/g/h under 10 °C and 10 W LED illumination. Copper and phosphorus doping that reduced (002) surface spacing of g-C3N4, resulting in thinner nanosheets. This structural modification facilitated interlayer charge transfer and suppressed photogenerated carrier recombination. This research provides a novel insight and strategy for designing hydrogen production photocatalyst at low temperatures and with low energy consumption.

Pt atomic clusters/MoS2 nanosheets/Co-doped hollow carbon nanofibers for high-current–density alkaline hydrogen production

The application of layered molybdenum disulfide (MoS2) in catalytic hydrogen production has attracted great interest, while their catalytic properties are limited by poor electron conductivity and a few catalytically active sites. In this work, we demonstrated a highly active electrocatalyst for large-scale hydrogen production, consisting of two-dimensional (2D) Pt-MoS2 nanosheets along one-dimensional (1D) cobalt nanoparticle integrated carbon hollow nanofibers (Co@CHNF). The as-prepared Pt-MoS2-Co@CHNF had a large specific surface area (44.5 m2 g−1). X-ray photoelectron spectrometer (XPS) and spherical aberration corrected transmission electron microscope (AC-STEM) demonstrated that Pt atomic clusters (Pt ACs) were doped on MoS2 nanosheets by thermodynamically induced spontaneous interfacial redox between MoS2 and H₂PtCl₆. The Pt-MoS2-Co@CHNF based catalysts exhibited an overpotential as low as 91 mV for 10 mA cm−2 and 258 mV for 200 mA cm−2 in 1 M KOH electrolyte, and there is no significant floating for catalytic active with 14 h continuous operation, which demonstrates its excellent long-term operation durability, significantly superior to the previously reported state-of-the-art Co-based or Mo-based catalysts. In particular, the self-supporting binder-free Pt-MoS2-Co@CHNF catalyst-based electrode showed an ultra-high current density of 500 mA cm−2 at a low overpotential of 301 mV, without any decrease after 24 h operation at 500 mA cm−2 in 1 M KOH seawater electrolyte, representing a great potential for large-scale seawater hydrogen production.

Revisiting hydrotalcite synthesis: Efficient combined mechanochemical/coprecipitation synthesis to design advanced tunable basic catalysts

Abstract Hydrotalcite materials (HTs) were synthesized by a facile and swift combined mechanochemistry/coprecipitation approach, and their catalytic activity was evaluated and compared with conventionally synthesized hydrotalcites (co-precipitation method) in the Knoevenagel condensation between furfural and ethyl cyanoacetate/malononitrile. Characterization and catalytic activity results clearly demonstrate that the proposed combined mechanochemical/coprecipitation approach provides an improvement in crystallinity, morphology, tunable basicity, and textural properties (higher surface area and enhanced surface properties) as compared to HTs obtained via conventional coprecipitation methods. In addition, mechanochemically synthesized HTs largely improve catalytic activities, including conversion and product selectivity to Knoevenagel condensation products under solventless conditions, short reaction times, or reaction at room temperature as compared to conventional counterparts (e.g., 30–40 vs > 99% product yields).

Palladium‐Silver Alloys Deposited on Different Carriers for Dehydrogenation of Formic Acid

AbstractHydrogen (H2) is recognized as a clean energy carrier with great potential for the future energy systems. Given the existing challenges in direct H2 storage and delivery, the current option for utilizing hydrogen energy is to produce hydrogen from its storage carriers on‐site, and the development of a highly active, highly selective, and highly stable catalyst for H2 production is an important part of this. Herein, PdAg alloy was deposited on mesoporous carbon nitride (mpg‐C3N4) as a catalyst for the dehydrogenation of the formic acid (FA). The synergistic effect of Pd and Ag metals for catalysis was explored. The role of the supports on the catalytic performance was also demonstrated by depositing PdAg alloy on several carriers of Silica@Resorcinol‐Formaldehyde Spheres, Carbon Flower Particles and SBA‐15. Pd1Ag1/2/mpg‐C3N4 showed a considerable activity during FA dehydrogenation with a turnover frequency (TOF) value of 887 h−1 at 333 K, demonstrating that carbon nitride as a carrier has a significant enhancement on the catalytic hydrogen production from formic acid.