Interfacial Sites Research Articles

Interfacial Site Density Engineering of ZnO/Cu Cube Inverse Catalysts for CO2 Hydrogenation Reactions

Interfacial Site Density Engineering of ZnO/Cu Cube Inverse Catalysts for CO₂ Hydrogenation Reactions

Tuning Flame Spray Pyrolysis for Variation of the Crystallite Size in Cu/ZnO/ZrO2 and its Influence on the Performance in CO2‐to‐Methanol Synthesis

CO2 hydrogenation to methanol (MeOH) is a key transformation in the Power‐to‐liquid concept, which aims to store energy in chemical energy carriers and chemicals. Cu/ZnO/ZrO2 (CZZ) shows great promise due to its enhanced stability in the presence of water, a critical by‐product when utilizing CO2‐based feedstocks. The structure‐sensitivity of this reaction, especially for particle sizes below 10 nm and in three‐component systems, remains highly debated. Herein, we systematically prepared a series of CZZ catalysts by flame spray pyrolysis to vary the crystallite size and to study its effect on methanol synthesis in this 3‐component system. FSP enabled us to maintain a fixed Cu/Zn/Zr ratio close to the commercial composition (61/29/10 atomic ratio), while varying the precursor feed rate. This resulted in variation in the crystallinity. The characterization by X‐ray diffraction and electron microscopy revealed an increase in crystallite size with rising feed rate for Cu and t‐ZrO2, whereas ZnO remained mostly unaffected. The testing of the materials in methanol synthesis uncovered an increase in performance, higher space time yield and MeOH selectivity, with decreasing crystallite size for two (Cu, t‐ZrO2) of its three components. The increased selectivity with smaller sizes might be attributed to an increase in interfacial sites.

Single-atom Barium Promoter Enormously Enhanced Non-noble Metal Catalyst for Ammonia Decomposition.

As a well-established topic, single-atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single-atom form, the intrinsic roles of single-atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co-Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co-Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat-1·min-1 at very low temperature (500 °C, GHSV = 840,000 mL·g-1·h-1) and Co-Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non-noble catalysts, and reaches or even exceeds numerous reported Ru-based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co-O-Ba-Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N-H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

Single‐atom Barium Promoter Enormously Enhanced Non‐noble Metal Catalyst for Ammonia Decomposition

As a well‐established topic, single‐atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single‐atom form, the intrinsic roles of single‐atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co‐Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co‐Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat−1·min−1 at very low temperature (500 °C, GHSV = 840,000 mL·g−1·h−1) and Co‐Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non‐noble catalysts, and reaches or even exceeds numerous reported Ru‐based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co‐O‐Ba‐Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N‐H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

The Role of Cholesterol in M2 Clustering and Viral Budding Explained.

The influenza A M2 homotetrameric channel consists of four transmembrane (TM) and four amphipathic helices (AHs). This viral proton channel is suggested to form clusters in the catenoid budding neck areas in raft-like domains of the plasma membrane, resulting in cell membrane scission and viral release. The channel clustering environment is rich in cholesterol. Previous experiments have shown that cholesterol significantly contributes to lipid bilayer undulations in viral buds. However, a clear explanation of membrane curvature from the distribution of cholesterol around the M2TM-AH clusters is lacking. Using coarse-grained molecular dynamics simulations of M2TM-AH in bilayers, we observed that M2 channels form specific, C2-symmetric, clusters with conical shapes driven by the attraction of their AHs. We showed that cholesterol stabilized the formation of M2 channel clusters by filling and bridging the conical gap between M2 channels at specific sites in the N-termini of adjacent channels or via the C-terminal region of TM and AHs, with the latter sites displaying a longer interaction time and higher stability. The potential of mean force calculations showed that when cholesterols occupy the identified interfacial binding sites between two M2 channels, the dimer is stabilized by 11 kJ/mol. This translates to the cholesterol-bound dimer being populated by almost 2 orders of magnitude compared to a dimer lacking cholesterol. We demonstrated that the cholesterol-bridged M2 channels can exert a lateral force on the surrounding membrane to induce the necessary negative Gaussian curvature profile, which permits spontaneous scission of the catenoid membrane neck and leads to viral buds and scission.

Cu-S-Mo Interfacial Sites in CuO2@MoS2/PLLA Scaffolds for Robust Synergistic Antibacterial Efficacy via CDT and PTT

Bacterial infections considerably limit the success of scaffold transplantation. CuO2 may generate hydroxyl radicals through a self-cascade catalytic process, which is effective for sterilization. However, reducing CuO2-derived Cu+ ions to Cu° can lead to a decline in catalytic activity. To overcome these limitations, we anchored CuO2 onto MoS2 to establish stable Cu-S-Mo interfacial sites. The CuO2/MoS2 nanozyme was fabricated using a low-temperature co-precipitation technique and introduced into poly-L-lactic acid scaffolds using selective laser sintering. The Cu-S-Mo interfacial sites showed a triad of functions that synergistically enhanced catalytic performance. These sites stabilized the Cu atoms, augmented catalytic activity by facilitating efficient electron transfer through the Mo4+/Mo6+ redox couple, and improved the conduction of heat derived from the photothermal response of MoS2 to the Cu catalyst. The synergistic action of chemodynamic and photothermal therapy, mediated by the Cu-S-Mo sites, resulted in remarkable antibacterial efficacy, with 92.3% and 93.5% inhibition rates against Staphylococcus aureus and Escherichia coli, respectively. Experimental evidence and simulations demonstrated that Cu-S-Mo structure stabilized the Cu atoms and improved electron transfer via interatomic charge transfer. These results highlight the potential of the CuO2@MoS2/PLLA scaffold in eliminating bacterial infections.

Ru/TiO2 Catalyzed High‐Yield Synthesis of Furanic Diols by 5‐Hydroxymethylfurfural Hydrogenation with Switchable Selectivity

Abstract5‐Hydroxymethylfurfural (HMF) is a versatile platform molecule that can be derived from biomass feedstocks and catalytically converted into various value‐added chemicals. In this work, selective hydrogenation of HMF is investigated to produce valuable furan‐based diols, namely 2,5‐bis‐hydroxymethylfuran (BHMF) and 2,5‐bis‐hydroxymethyltetrahydrofuran (BHMTHF), using TiO2 supported Ru catalysts. The catalyst performance was fine‐tuned to achieve over 98% yield to BHMF and BHMTHF under optimized reaction conditions with very good recyclability. We pointed out several key factors allowing to maximize the yield towards the respective diols. Features such as the Ru nanoparticle size, the strength of metal‐support interactions and the presence of residual chlorine were found to significantly influence the reaction. A characteristic volcano‐shaped relationship was obtained between the particle size and the catalytic activity giving the highest diol yield for an optimum Ru nanoparticle size of 1.6 nm. Further, metal‐support interactions were found to be responsible for providing optimum Ru‐TiOx interfacial surface sites and chlorine was affecting the electronic properties of Ru nanoparticles, potentially benefiting to the selective formation of BHMF. The reaction time was shown to control the hydrogenation of the furan ring and the selectivity of the reaction, that can be directed optimally towards BHMF or BHMTHF.

Quantifying Interface‐Performance Relationships in Electrochemical CO2 Reduction through Mixed‐Dimensional Assembly of Nanocrystal‐on‐Nanowire Superstructures

AbstractFine‐tuning the interfacial sites within heterogeneous catalysts is pivotal for unravelling the intricate structure–property relationship and optimizing their catalytic performance. Herein, a simple and versatile mixed‐dimensional assembly approach is proposed to create nanocrystal‐on‐nanowire superstructures with precisely adjustable numbers of biphasic interfaces. This method leverages an efficient self‐assembly process in which colloidal nanocrystals spontaneously organize onto Ag nanowires, driven by the solvophobic effect. Importantly, varying the ratio of the two components during assembly allows for accurate control over both the quantity and contact perimeter of biphasic interfaces. As a proof‐of‐concept demonstration, a series of Au‐on‐Ag superstructures with varying numbers of Au/Ag interfaces are constructed and employed as electrocatalysts for electrochemical CO2‐to‐CO conversion. Experimental results reveal a logarithmic linear relationship between catalytic activity and the number of Au/Ag interfaces per unit mass of Au‐on‐Ag superstructures. This work presents a straightforward approach for precise interface engineering, paving the way for systematic exploration of interface‐dependent catalytic behaviors in heterogeneous catalysts.

Manipulating Pt-ZnO interface for fast selective oxidation of glycerol to glyceric acid in base-free medium

Fine constructing the desirable active sites of catalysts is critical for the efficient polyol oxidation. Herein, we conceptually manipulate the Pt-ZnO interfacial active site instead of traditional Pt-Pt active site to isolate oxidation reaction and carboxylic acid desorption for fast selective oxidation of glycerol to glyceric acid in base-free medium. Multiple characterizations (including in-situ spectroscopy, reaction kinetics and density functional theory calculation, etc.) revealed that the strong electronic delocalization of Pt d-partial and the synergistic effect of ZnO adsorption could collectively strengthen the adsorption of glycerol and then promote the C-H bond of RCH2O intermediate in the primary hydroxyl group oxidation, resulting in higher catalytic activity over the Pt-ZnO interface. Meanwhile, the abundant oxygen vacancy of well-dispersed nano-ZnO could preferentially adsorb the formed glyceric acid product, preventing the coverage of the efficient Pt-Pt and Pt-O-Zn active sites by carboxylic acid products. Such tailored interface strategy achieves 80.4 % glycerol conversion and 84.6 % glyceric acid selectivity in only 1 h, and the turnover frequency could also be as high as 1338.4 h−1 over the optimal Pt/ZnO-MCM-41 (200) catalyst. The methodology provided here constitutes a promising basis for highly efficient polyol oxidation catalysis under mild and green conditions.

Restructuring the interfacial active sites to generalize the volcano curves for platinum-cobalt synergistic catalysis

Computationally derived volcano curve has become the gold standard in catalysis, whose practical application usually relies on empirical interpretations of composition or size effects by the identical active site assumption. Here, we present a proof-of-concept study on disclosing both the support- and adsorbate-induced restructuring of Pt-Co bimetallic catalysts, and the related interplays among different interfacial sites to propose the synergy-dependent volcano curves. Multiple characterizations, isotopic kinetic investigations, and multiscale simulations unravel that the progressive incorporation of Co into Pt catalysts, driven by strong Pt-C bonding (metal-support interfaces) and Co-O bonding (metal-adsorbate interfaces), initiates the formation of Pt-rich alloys accompanied by isolated Co species, then Co segregation to epitaxial CoOx overlayers and adjacent Co3O4 clusters, and ultimately structural collapse into amorphous alloys. Accordingly, three distinct synergies, involving lattice oxygen redox from Pt-Co alloy/Co3O4 clusters, dual-active sites engineering via Pt-rich alloy/CoOx overlayer, and electron coupling within exposed alloy, are identified and quantified for CO oxidation (gas-phase), ammonia borane hydrolysis (liquid-phase), and hydrogen evolution reaction (electrocatalysis), respectively. The resultant synergy-dependent volcano curves represent an advancement over traditional composition-/size-dependent ones, serving as a bridge between theoretical models and experimental observations in bimetallic catalysis.

Highly active ternary Ir/In2O3-ZrO2 catalyst for CO2 hydrogenation towards methanol: The role of zirconia

Indium oxide supported iridium catalyst has been verified to be highly active and selective for CO2 hydrogenation to methanol. In this work, zirconia is introduced into the Ir/In2O3 system as a novel Ir/In2O3-ZrO2 ternary catalyst. The solid solution generated between ZrO2 and In2O3 exhibits a strong electronic metal-support interaction with iridium, rendering the supported iridium species highly dispersed in a form of clusters. Thereout, an active interface between iridium and the solid-solution carrier is thus generated, on which electron transport is more feasible with a stronger CO2 adsorption than that of on the Ir−In2O3 interfacial site. Moreover, compared to Ir/In2O3, this ternary catalyst exhibits better catalytic activity as well as the stability. Density functional theory (DFT) simulations, combined with the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies, further demonstrate the CO-hydrogenation pathway is the most favored for methanol synthesis, providing a rationale for the superior methanol selectivity of the Ir/In2O3-ZrO2 catalyst during CO2 hydrogenation.

Steam-Assisted Selective CO2 Hydrogenation to Ethanol over Ru-In Catalysts.

Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. We here unveil how reducibility and mobility of indium oxide species in Ru-based catalysts crucially control the direct, selective conversion of CO2 to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation. With the addition of steam as a mild oxidant and using porous polymer layers to control In mobility, Ru-In2O3 interface sites are stabilized, and ethanol can be produced with superior overall selectivity (70 %, rest CO). Our work highlights how engineering of bifunctional active ensembles enables cooperativity and synergy at tailored interfaces, which unlocks unprecedented performance in heterogeneous catalysts.

Morphology effect of In2O3/Co3O4 on Co–In2O3 interface formation to drive the hydrogenation of CO2 to methanol

In2O3 is loaded onto Co3O4 with diverse morphologies to prepare In2O3/Co3O4 for better understanding of the interaction between metallic Co and In2O3 in CO2 hydrogenation to methanol. After in-depth characterizations, we found that loading In2O3 on platelike Co3O4 (P–Co) can achieve more uniformly dispersed surface hexagonal In2O3 (h-In2O3) and stronger electron transfer between In2O3 and Co3O4 than Co3O4 with other morphologies. Under reaction stabilization, Co3O4 is transformed into metallic Co0, which can promote the reactivity of h-In2O3 to form cubic In2O3 (c-In2O3), accompanied by the formation of Co3InC0.75 carbide. Especially for In2O3/P–Co, stronger interaction between Co0 and c-In2O3 is formed to produce more oxygen vacancies in comparison with other samples owing to the absent of h-In2O3. Furthermore, density functional theory calculation reveals that H2 and CO2 molecules are more easily adsorbed on Co-c-In2O3 interfacial site. As a result, In2O3/P–Co exhibits the best methanol space-time yield of 11.6 mmol · gcat−1 · h−1 and excellent thermal stability for an additional continuous run of 64 h after reaction stabilization.

Implementing numerical algorithms to optimize the parameters in Kampmann–Wagner Numerical (KWN) precipitation models

The Kampmann–Wagner Numerical (KWN) model of precipitation is a powerful tool to simulate the precipitation of the second phase considering the nucleation, growth, and coarsening. Some quantities such as interfacial energy and nucleation site number density are required to accomplish the simulation. Practically, those quantities are hard to measure in the experiment directly, and the derivation of those quantities through modeling can also be costly. In this work, we hereby adopt the minimization algorithm implemented in the open-source Scipy Python package to derive that important information in terms of very limited experimental data. The convergence and robustness of different algorithms are discussed. Among those algorithms, the Nelder–Mead and Powell algorithms are successfully applied to optimize multiple parameters during KWN modeling. This work will shed light on the design of experiments/processes and facilitate integrated computational materials engineering (ICME).

Decoupling immunomodulatory properties from lipid binding in the α-pore-forming toxin Sticholysin II

Sticholysin II (StII), a pore-forming toxin from the marine anemone Stichodactyla helianthus, enhances an antigen-specific cytotoxic T lymphocyte (CTL) response when co-encapsulated in liposomes with a model antigen. This capacity does not depend exclusively on its pore-forming activity and is partially supported by its ability to activate Toll-like receptor 4 (TLR4) in dendritic cells, presumably by interacting with this receptor or by triggering signaling cascades upon binding to lipid membrane. In order to investigate whether the lipid binding capacity of StII is required for immunomodulation, we designed a mutant in which the aromatic amino acids from the interfacial binding site Trp110, Tyr111 and Trp114 were substituted by Ala. In the present work, we demonstrated that StII3A keeps the secondary structure composition and global folding of StII, while it loses its lipid binding and permeabilization abilities. Despite this, StII3A upregulates dendritic cells maturation markers, enhances an antigen-specific effector CD8+ T cells response and confers antitumor protection in a preventive scenario in C57BL/6 mice. Our results indicate that a mechanism independent of its lipid binding ability is involved in the immunomodulatory capacity of StII, pointing to StII3A as a promising candidate to improve the reliability of the Sts-based vaccine platform.

Hydroxylated TiO2-induced high-density Ni clusters for breaking the activity-selectivity trade-off of CO2 hydrogenation

The reverse water gas shift reaction can be considered as a promising route to mitigate global warming by converting CO2 into syngas in a large scale, while it is still challenging for non-Cu-based catalysts to break the trade-off between activity and selectivity. Here, the relatively high loading of Ni species is highly dispersed on hydroxylated TiO2 through the strong Ni and −OH interactions, thereby inducing the formation of rich and stable Ni clusters (~1 nm) on anatase TiO2 during the reverse water gas shift reaction. This Ni cluster/TiO2 catalyst shows a simultaneous high CO2 conversion and high CO selectivity. Comprehensive characterizations and theoretical calculations demonstrate Ni cluster/TiO2 interfacial sites with strong CO2 activation capacity and weak CO adsorption are responsible for its unique catalytic performances. This work disentangles the activity-selectivity trade-off of the reverse water gas shift reaction, and emphasizes the importance of metal−OH interactions on surface.

One stone, three birds: The enhanced electrocatalytic sensing for 4-nitrophenol derived from the triple-strategies regulated interface of Co-ZIF-L/NCS/CP

4-nitrophenol (4-NP) is one of the most toxic organic pollutants, which causes severe damages to organism and environment. The electrochemical analysis for 4-NP proceeded slowly due to the hard electrocatalytic reduction of 4-NP, the limited catalytic sites and poor stability of the electrodes. In this paper, by the “one stone with three birds” strategy, a series of three-phase interfaces n-Co-ZIF-L/NCS-X/CP were constructed for the enhanced electrocatalytic sensing for 4-NP. By the dual in-situ strategy, NiCo2S4 (NCS) was first electrodepositing on carbon paper (CP) and then Co-based metal-organic framework (Co-ZIF-L) was grown on the NiCo2S4, which not only introduced abundant metal active sites, but also improved the interfacial stability due to the strong bond interactions; By the dual-regulation strategy, the structures and composites of NiCo2S4 and Co-ZIF-L were precisely regulated. The heterogeneous structure of lamellar and nanoflower-like NiCo2S4, as well as the two-dimensional leaf-like Co-ZIF-L, made more catalytic sites be exposed and improved the electrocatalytic activity; The triple synergistic effect among Co-ZIF-L, NiCo2S4 and CP effectively optimized the electronic structure of the interfacial active sites and widen the electron transport channels, thus accelerated the electrochemical sensing process. In addition, the three-phase interface of 0.3-Co-ZIF-L/NCS-20/CP was successfully applied for 4-NP detection in the practical samples of lake water, seawater and industrial wastewater.

Engineering nanoparticle structure at synergistic Ru-Na interface for integrated CO2 capture and hydrogenation

The development of dual functional material for cyclic CO2 capture and hydrogenation is of great significance for converting diluted CO2 into valuable fuels, but suffers from kinetic limitation and deactivation of adsorbent and catalyst. Herein, we engineered a series of RuNa/γ-Al2O3 materials, varying the size of ruthenium from single atoms to clusters/nanoparticles. The coordination environment and structure sensitivity of ruthenium were quantitatively investigated at atomic scale. Our findings reveal that the reduced Ru nanoparticles, approximately 7.1 nm in diameter with a Ru-Ru coordination number of 5.9, exhibit high methane formation activity and selectivity at 340 °C. The Ru-Na interfacial sites facilitate CO2 migration through a deoxygenation pathway, involving carbonate dissociation, carbonyl formation, and hydrogenation. In-situ experiments and theoretical calculations show that stable carbonyl intermediates on metallic Ru nanoparticles facilitate heterolytic C–O scission and C–H bonding, significantly lowering the energy barrier for activating stored CO2.

Computational Design, Chemical Synthesis, and Bioevaluation of Pyrimidinyl‐Indoles for Targeting Breast Cancer Cells

AbstractCancer is a global health challenge, despite significant advancements in research. Addressing this issue, we report the design, synthesis and biological evaluation of pyrimidinyl indoles as potential antineoplastic agents. Pyrimidinyl indoles interact with pyruvate kinase isoform M2 (PKM2), which is commonly overexpressed in oral, lung, breast and colorectal cancers. In silico studies indicated that these molecules are having affinity towards PKM2 and targeting key residues such as Phe26, Leu27, Tyr390, Gln393, Leu394 and Glu397 at the interfacial active site region between the two chains of PKM2. Thereafter compounds were designed, synthesized and characterized using nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and mass spectrometry (MS). This was followed by in vitro screening using cell lines and enzyme‐coupled assays. One of the designed PKM2 inhibitor demonstrated potent anticancer activity against MCF‐7 (Breast Cancer) cells while sparing normal MCF‐10 A breast cells. Molecular dynamics (MD) simulation studies showed that the developed inhibitor stabilized the PKM2 active site over a 100 ns simulation.

MOF‐on‐MOF Heterostructured Electrocatalysts for Efficient Nitrate Reduction to Ammonia

AbstractElectrocatalytic nitrate reduction reaction (NO3−RR) is an important route for sustainable NH3 synthesis and environmental remediation. Metal–organic frameworks (MOFs) are one family of promising NO3−RR electrocatalysts, however, there is plenty of room to improve in their performance, calling for new design principles. Herein, a MOF‐on‐MOF heterostructured electrocatalyst with interfacial dual active sites and build‐in electric field is fabricated for efficient NO3−RR to NH3 production. By growing Co‐HHTP (HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene) nanorods on Ni‐BDC (BDC=1,4‐benzenedicarboxylate) nanosheets, experimental and theoretical investigations demonstrate the formation of Ni−O−Co bonds at the interface of MOF‐on‐MOF heterostructure, leading to dual active sites tailed for NO3−RR. The Ni sites facilitate the adsorption and activation of NO3−, while the Co sites boost the H2O decomposition to supply active hydrogen (Hads) for N‐containing intermediates hydrogenation on adjacent Ni sites, cooperatively reducing the energy barriers of NO3−RR process. Together with the accelerated electron transfer enabled by built‐in electric field, remarkable NO3−RR performance is achieved with an NH3 yield rate of 11.46 mg h−1 cm−2 and a Faradaic efficiency of 98.4 %, outperforming most reported MOF‐based electrocatalysts. This work provides new insights into the design of high‐performance NO3−RR electrocatalysts.