Interfacial Sites Research Articles

Designer Nanoreactors for Bioorthogonal Catalysis.

The evolutionary complexity of compartmentalized biostructures (such as cells and organelles) endows life-sustaining multistep chemical cascades and intricate living functionalities. Relatively, within a very short time span, a synthetic paradigm has resulted in tremendous growth in controlling the materials at different length scales (molecular, nano, micro, and macro), improving mechanistic understanding and setting the design principals toward different compositions, configurations, and structures, and in turn fine-tuning their optoelectronic and catalytic properties for targeted applications. Bioorthogonal catalysis offers a highly versatile toolkit for biochemical modulation and the capability to perform new-to-nature reactions inside living systems, endowing augmented functions. However, conventional catalysts have limitations to control the reactions under physiological conditions due to the hostile bioenvironment. The present account details the development of bioapplicable multicomponent designer nanoreactors (NRs), where the compositions, morphologies, interfacial active sites, and microenvironments around different metal nanocatalysts can be precisely controlled by novel nanospace-confined chemistries. Different architectures of porous, hollow, and open-mouth silica-based nano-housings facilitate the accommodation, protection, and selective access of different nanoscale metal-based catalytic sites. The modular porosity/composition, optical transparency, thermal insulation, and nontoxicity of silica are highly useful. Moreover, large macropores or cavities can also be occupied by enzymes (for chemoenzymatic cascades) and selectivity enhancers (for stimuli-responsive gating) along with the metal nanocatalysts. Further, it is crucial to selectively activate and control catalytic reactions by a remotely operable biocompatible energy source. Integration of highly coupled plasmonic (Au) components having few-nanometer structural features (gaps, cavities, and junctions as electromagnetic hot-spots) endows an opportunity to efficiently harness low-power NIR light and selectively supply energy to the interfacial catalytic sites through localized photothermal and electronic effects. Different plasmonically integrated NRs with customizable plasmonic-catalytic components, cavities inside bilayer nanospaces, and metal-laminated nanocrystals inside hollow silica can perform NIR-/light-induced catalytic reactions in complex media including living cells. In addition, magnetothermia-induced NRs by selective growth of catalytic metals on a pre-installed superparamagnetic iron-oxide core inside a hollow-porous silica shell endowed the opportunity to apply AMF as a bioorthogonal stimulus to promote catalytic reactions. By combining "plasmonic-catalytic" and "magnetic-catalytic" components within a single NR, two distinct reaction steps can be desirably controlled by two energy sources (NIR light and AMF) of distinct energy regimes. The capability to perform multistep organic molecular transformations in harmony with the natural living system will reveal novel reaction schemes for in cellulo synthesis of active drug and bioimaging probes. Well-designed nanoscale discrete architectures of NRs can facilitate spatiotemporal control over abiotic chemical synthesis without adversely affecting the cell viability. However, in-depth understanding of heterogeneous surface catalytic reactions, rate induction mechanisms, selectivity control pathways, and targeted nanobio interactions is necessary. The broad field of biomedical engineering can hugely benefit from the aid of novel nanomaterials with chemistry-based designs and the synthesis of engineered NRs performing unique bioorthogonal chemistry functions.

Optimization of Interfacial OH− Accessibility by Constructing a Delayed–Release Membrane Electrode for Ampere–Level Hydrogen Production

AbstractAchieving a high current density during electrochemical overall water splitting is a promising strategy for industrial energy conversion. The mass diffusion rate of OH− ions from the electrolyte to the interfacial active sites strongly influences the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) . Herein, the delayed‐release of OH− ions modulated by a proper organic polymer membrane on the electrode surface can optimize the OH− accessibility to the active sites (as indicated by the molecular dynamics simulations) is demonstrated and that van der Waals interaction force modulates the OH− residence time in the reaction system. The remarkable performance of the membrane‐modified electrode is achieved at ultra‐high current densities of 1.9 A cm−2 (with an HER overpotential of 602 mV) and 2 A cm−2 (with an OER overpotential of 459 mV) in 1 M KOH solution. Consequently, a super‐high current density of 1.3 A cm−2 is obtained for overall water splitting (at a voltage of only 2.2 V), which is 1.9‐fold higher than that of a benchmarked Pt/C‐IrO2 (684 mA cm−2). Therefore, the delayed‐release of OH− has optimized the mass conversion efficiency of the active sites, thus improving the electrochemical performance of overall water splitting.

Tuning Strong Metal‐Support Interactions for Enhancing Direct Deoxygenation of Biomass‐Lignin Derived Phenolics

AbstractCatalytic direct deoxygenation (DDO) of phenolic compounds to aromatics is an appealing approach for utilization of biomass‐lignin with minimal amount of H2 consumption. Metal/reducible metal oxide catalysts provide two functionalities, i. e., C−H bond formation (hydrogenation) and C−O bond breakage (deoxygenation), required for this reaction that takes place at the interfacial perimeter sites. Strong metal‐support interactions (SMSI) can profoundly alter the density and property of such sites. This short review summarized recent advances in tuning SMSI for enhancing DDO of phenolics. The approaches of varying reduction temperature, modulation of crystal facets and crystal phases of metal oxide, and reduction of mixed metal oxide were discussed for the origin for formation of SMSI, the degree of SMSI, and its consequence on the DDO performance. The analysis revealed that intermediate degree of SMSI with maximal density of metal/oxide interfacial perimeter site enhances DDO while minimizing unfavorable side reactions. This short review highlights the concept of tuning the interfacial perimeter sites via SMSI for reactions which require multiple functionalities and take place at the metal/oxide interface.

Tailoring the Brønsted acidity of Ti-OH species by regulating Pt-TiO2 interaction.

Bifunctional catalysts comprising metal and acid sites are commonly used for many reactions. Interfacial acid sites impact intermediate reactions more than other sites. However, controlling the type and amounts of interfacial acid sites by regulating metal-support interaction (MSI) via traditional methods is difficult. Thus, the influence of MSI on interfacial acid sites remains unclear. We prepared Pt-mTiO2/α-Al2O3 (m represents the cycle number of TiO2) catalysts via atomic layer deposition (ALD). New Brønsted acid sites were generated via Pt-TiO2 interaction, and the acidity was precisely regulated by regulating Pt-TiO2 interaction by changing the TiO2 nanolayer thickness. We chose levulinic acid (LA) hydrogenation as a model reaction. The catalytic activity varied with the TiO2 nanolayer thickness and was linearly correlated with the Ti-OH species (Brønsted acid) content. Pt-40TiO2/α-Al2O3, with the highest acid site content of 0.486 mmol/g, exhibited the best catalytic activity. Hydrogen spillover and water dissociation at the Pt-TiO2 interface promoted Ti-OH species generation.

Pt/MnO Interface Induced Defects for High Reverse Water Gas Shift Activity.

The implementation of supported metal catalysts heavily relies on the synergistic interactions between metal nanoparticles and the material they are dispersed on. It is clear that interfacial perimeter sites have outstanding skills for turning catalytic reactions over, however, high activity and selectivity of the designed interface-induced metal distortion can also obtain catalysts for the most crucial industrial processes as evidenced in this paper. Herein, the beneficial synergy established between designed Pt nanoparticles and MnO in the course of the reverse water gas shift (RWGS) reaction resulted in a Pt/MnO catalyst having ≈10 times higher activity compared to the reference Pt/SBA-15 catalyst with >99 % CO selectivity. Under activation, a crystal assembly through the metallic Pt (110) and MnO evolved, where the plane distance differences caused a mismatched-row structure in softer Pt nanoparticles, which was identified by microscopic and surface-sensitive spectroscopic characterizations combined with density functional theory simulations. The generated edge dislocations caused the Pt lattice expansion which led to the weakening of the Pt-CO bond. Even though MnO also exhibited an adverse effect on Pt by lowering the number of exposed metal sites, rapid desorption of the linearly adsorbed CO species governed the performance of the Pt/MnO in the RWGS.

Pt/MnO Interface Induced Defects for High Reverse Water Gas Shift Activity

AbstractThe implementation of supported metal catalysts heavily relies on the synergistic interactions between metal nanoparticles and the material they are dispersed on. It is clear that interfacial perimeter sites have outstanding skills for turning catalytic reactions over, however, high activity and selectivity of the designed interface‐induced metal distortion can also obtain catalysts for the most crucial industrial processes as evidenced in this paper. Herein, the beneficial synergy established between designed Pt nanoparticles and MnO in the course of the reverse water gas shift (RWGS) reaction resulted in a Pt/MnO catalyst having ≈10 times higher activity compared to the reference Pt/SBA‐15 catalyst with >99 % CO selectivity. Under activation, a crystal assembly through the metallic Pt (110) and MnO evolved, where the plane distance differences caused a mismatched‐row structure in softer Pt nanoparticles, which was identified by microscopic and surface‐sensitive spectroscopic characterizations combined with density functional theory simulations. The generated edge dislocations caused the Pt lattice expansion which led to the weakening of the Pt−CO bond. Even though MnO also exhibited an adverse effect on Pt by lowering the number of exposed metal sites, rapid desorption of the linearly adsorbed CO species governed the performance of the Pt/MnO in the RWGS.

Cu/ZnO/CeO2 Supported on MOF-5 as a Novel Catalyst for the CO2 Hydrogenation to Methanol: A Mechanistic Study on the Effect of CeO2 and MOF-5 on Active Sites

Cu/ZnO/CeO2 nanocomposite was supported on metal organic framework (MOF-5) to enhance active sites dispersion and control the nanoparticles agglomeration during synthesis through strong metal-support interactions. The incorporation of MOF-5 alleviated the obstacle facing the commercial ternary Cu/ZnO/Al2O3 regarding low surface area due to nanoparticles agglomeration. In addition, Cu/ZnO/CeO2@MOF-5 gave higher methanol selectivity than the commercial catalyst which can be accounted for by the interfacial sites generated between MOF-5 and Cu/ZnO which favour methanol synthesis over carbon monoxide through regulating the intermediates bonding energies. CeO2 as support for Cu/ZnO nanoparticles was also compared with commercial support and showed to have led to smaller particle size and superior dispersion of Cu active sites as well. Cu/ZnO/CeO2@MOF-5 resulted in methanol STY of 23.3 mg gcat h−1 and selectivity of 79% at mild reaction temperature (260 °C) and pressure (10 bar). Two different MOFs including cerium based MOF and ZIF-8 demonstrated inferior performance compared to MOF-5.Graphical

Homologous heterostructure CdSe/CdS nanoflowers to enhance photocatalytic hydrogen production

The study of nano-heterostructures as light-capturing system applied in photocatalytic water splitting is a current research hotspot. In this study, a simple in situ anion exchange method was proposed for the synthesis of homologous heterostructure CdSe/CdS nanoflowers. Series of CdSe/CdS composites were obtained by controlling the amounts of Se powder. The optimum ratio 5 wt% CdSe loading on CdS nanosheets achieved the maximum H2 production rate of 16.03 mmol g−1 h−1, which was 1.5 times higher than that of pure CdS. Mechanism study with UV–vis DRS, and photoluminescence revealed the excellent photocatalytic property was attributed to the expansion the absorption range of CdS with the introduction of CdSe, the construction of the Z-scheme heterojunction between CdS and CdSe, and the rich catalytic reaction interfacial sites provided by the hierarchical structure with 2D nanosheets and 3D nanoflowers. This work provided the design and synthesis of homologous heterostructure photocatalysts for high efficiency hydrogen production.

Oxygen-incorporated crystalline/amorphous heterophase cobalt vanadium selenide nanoplates with dense interfacial sites for robust lithium–sulfur batteries

Oxygen-incorporated heterophase cobalt vanadium selenide nanoplates with dense crystalline/amorphous interfacial sites (DC/A O-CoVSe NPs) are developed as high-efficiency sulfur electrocatalysts for lithium–sulfur batteries.

Metal substrate engineering to modulate CO2 hydrogenation to methanol on inverse Zr3O6/CuPd catalysts.

It is well known that the performance of some key catalytic reactions has a strong dependence on metal catalyst surfaces. In the current work, this concept is further extended to the CuPd alloy-supported zirconium oxide inverse catalyst for CO2 hydrogenation to methanol. A combined DFT and microkinetic simulation study reveal that both the metal substrate surface and the precise exposed Cu or Pd metal atoms on the substrate have a pivotal influence on the catalytic mechanism and performance of the inverse catalyst for CO2 hydrogenation to methanol. Herein, CuPd(100), (111), and (110) surfaces with either Cu and Pd terminations have been examined, which provided five metal substrates as support for the inverse catalyst. Three different mechanisms, including the formate pathway, RWGS + CO-hydro pathway, and CO2 direct activation pathway, are explored under the same conditions; they take place at the interfacial sites between the metal alloy and oxide. The calculations indicated that the inverse catalyst with the CuPd(100) substrate demonstrates better performance than those with CuPd(110) and (111) for both formate and RWGS + CO-hydro mechanisms. Conversely, the reaction pathway is more sensitive to exposed atoms on the metal substrate. The best inverse catalyst, Zr3O6/CuPd(100) with either Cu or Pd terminations, demonstrated a methanol formation TOF above 0.30 site-1 s-1 and the selectivity was above 90% at 573 K, as evaluated from microkinetic simulation. The coverage analysis indicates the most populated species is HCOO*, which is consistent with experimental reports. Both kinetic and thermodynamics control steps are identified from DRC analysis for the best performing catalysts. Overall, the current study confirms the catalytic performance of the inverse Zr3O6/CuPd catalyst and demonstrates the tunable effects of the metal alloy substrate, which can facilitate effective optimization.

UV-modification of Ag nanoparticles on α-MoCx for interface polarization engineering in electromagnetic wave absorption.

The design of electromagnetic wave absorbing materials (EWAMs) has aroused great attention with the express development of electromagnetic devices, which pose a severe EM pollution risk to human health. Herein, an Ag-doped MoCx composite was designed and constructed through a UV-light-induced self-reduction process. The UV-reduction time was controlled on the α-MoC polymer for 0.5-2 hours for modifying different amounts of Ag. As a result, α-MoC@Ag-1.5 exhibited the strongest RLmin of -56.51 dB at 8.8 GHz under a thickness of 3.0 mm and the widest EAB of 4.96 GHz (12.16-17.12 GHz) covering a substantial portion of the Ku-band at a thickness of 2.0 mm due to the synergy of the conductivity loss and abundant interfacial polarization sites. Additionally, a new strategy for computer simulation technology was proposed to simulate substantial radar cross-sectional reduction values with real far-field conditions, whereby absorbing coatings with α-MoC@Ag-1.5 were proved to contribute to a remarkable radar cross-sectional reduction of 37.4 dB m2.

Electrochemical conversion of 5-hydroxymethylfurfural over CuNi bimetallic catalysts: the synergistic effect of interfacial active sites

ECO of HMF to FDCA and ECR to BHMF with high yield have been studied on CuNi-based bimetallic catalysts. The presence of the Cu–O–Ni interfacial area was beneficial for promoting the catalytic performance in ECO.

The Cu–Al2O3 interface: an unignorable active site for methanol steam reforming hydrogen production

Formate species are the crucial intermediates that determine the methanol steam reforming reaction rate. Cu0–Al2O3 interfacial sites greatly promote the decomposition of formate species and methanol steam reforming performance.

Enhanced H2 production at the atomic Ni–Ce interface following methanol steam reforming

As the active component for MSR, the atomically dispersed Ni–CeOx interfacial sites connect the MD and WGS, in which the Ni sites and Ov in CeOx contribute to the activation of methanol and water, respectively, resulting in excellent MSR activity.

NiS/NiCo2O4 Cooperative Interfaces Enable Fast Sulfur Redox Kinetics for Lithium-Sulfur Battery.

Due to their high energy density and cost-effectiveness, lithium-sulfur batteries (LSBs) are considered highly promising for the next generation of energy storage technologies. However, the soluble lithium-polysulfides (LiPSs) notorious for causing the shuttle effect and the sluggish redox kinetics have hindered their practical commercialization. To tackle these challenges, a heterostructural catalyst featuring NiS-NiCo2O4 interfaces is developed, which serves as an interlayer for LSBs. These interfacial sites leverage the advantages of polar NiCo2O4 and conductive NiS, enabling smooth Li+ diffusion, rapid electron transport, and effective immobilization of LiPSs. This synergistic approach promotes the conversion of sulfur species, resulting in a high discharge capacity of 526mAhg-1 at 3C for cells with the NiS-NiCo2O4 interlayer. Additionally, remarkable cycling stability is achievable with an areal sulfur loading of ≈5.0mgcm-2. It is believed that this research paves the way for practical applications of LSBs.

Sustainable conversion of agricultural biomass waste into electrode materials with enhanced energy density for aqueous zinc-ion hybrid capacitors

Herein, we demonstrate the facile, economic and highly scalable conversion of (N, O and Fe)-self-doped heteroatom Solanum melongena (SM) biomass into highly electro-active carbon material for symmetric supercapacitor and zinc-ion hybrid capacitor (ZIHC) applications. The SM is ubiquous agri-bio-waste that inherently possess electro-active constituents and upon conversion resulted in high surface area, self-doped heteroatoms (N, O and Fe) through one step pyrolysis. A synergetic combination of N, O and Fe co-doping and relatively high-surface-area features that offers widespread interfacial active sites for charge storage and fast kinetics of electrochemical reactions in both supercapacitor and battery-type capacitor to maximize energy and power output. The symmetric supercapacitor is fabricated using 6 M KOH, delivering high specific capacitance of 154.64 F/g at 0.1 A/g current density. Long cycling performance of device exhibits 99 % retention over 50,000 charge and discharge cycles at 10 A/g. While SM carbon as the cathode in zinc ion hybrid capacitor (ZIHC) endows excellent Zn2+ ion storage capacity with 2 M ZnSO4·7H2O as electrolyte. The ZIHC delivered an excellent specific capacitance of 313.08 F/g, a substantial energy density output of 141.35 W h/kg and a power density of 6935.38 W/kg. In addition, ZIHC exhibited better cyclic stability with 1.92 % loss over 20,000 charge and discharge cycles at 4 A/g. The ZIHC device delivered excellent output in wearable devices and in lightning the LED (25.04 min). This study provides ubiquitous agri-waste-derived carbon that can be outstanding electrode material in energy storage devices owing to their hierarchal pore configuration, graphitization degree and self-doping of heteroatoms.

Defective Auδ−-Ov interfacial sites boost C-H bond activation for enhanced selective oxidation of amino alcohols to amino acids

Designing efficient active sites to facilitate the oxidation of hydroxyl group to carboxylic acid under the influence of nitrogen-containing functional groups is worth exploring, but it is rarely investigated. Herein, we construct defective Au-ZrO2 interfacial structures by tuning the calcination temperature of ZrO2 support to boost the oxidation of amino alcohols to amino acids. Interestingly, the modification of calcination temperature induces the escape of saturated coordination oxygen atoms in ZrO2 support, leaving behind abundant surface oxygen vacancy (Ov). The as-formed Auδ−-Ov interfacial site displays the unique synergistic adsorption effect and electron transfer ability. Specifically, the Ov site voluntarily adsorbs the –NH2 group of amino alcohol, thus ensuring that the electron-rich Auδ− nearby Ov site adsorbs the hydroxyl groups and activates the C-H bond activation of NH2CH2CH2O* intermediates. Consequently, Au/ZrO2-600 catalyst with more defective Auδ−-Ov interfacial sites exhibits 98.8 % product yield for the oxidation of diethanolamine to iminodiacetic acid at only 30 °C. The catalyst system is further extended to the oxidation of other amino alcohols, involving monoethanolamine and triethanolamine, to their corresponding amino acids with excellent catalytic performance.

Highly Stable Pt/CeO2 Catalyst with Embedding Structure toward Water-Gas Shift Reaction.

Strong metal-support interaction (SMSI) has been extensively studied in heterogeneous catalysis because of its significance in stabilizing active metals and tuning catalytic performance, but the origin of SMSI is not fully revealed. Herein, by using Pt/CeO2 as a model catalyst, we report an embedding structure at the interface between Pt and (110) plane of CeO2, where Pt clusters (∼1.6 nm) are embedded into the lattice of ceria within 3-4 atomic layers. In contrast, this phenomenon is absent in the CeO2(100) support. This unique geometric structure, as an effective motivator, triggers more significant electron transfer from Pt clusters to CeO2(110) support accompanied by the formation of interfacial structure (Ptδ+-Ov-Ce3+), which plays a crucial role in stabilizing Pt nanoclusters. A comprehensive investigation based on experimental studies and theoretical calculations substantiates that the interfacial sites serve as the intrinsic active center toward water-gas shift reaction (WGSR), featuring a moderate strength CO activation adsorption and largely decreased energy barrier of H2O dissociation, accounting for the prominent catalytic activity of Pt/CeO2(110) (a reaction rate of 15.76 molCO gPt-1 h-1 and a turnover frequency value of 2.19 s-1 at 250 °C). In addition, the Pt/CeO2(110) catalyst shows a prominent durability within a 120 h time-on-stream test, far outperforming the Pt/CeO2(100) one, which demonstrates the advantages of this embedding structure for improving catalyst stability.

Niobium Modification of CeO2 Tuning Electron Density of Nickel-Ceria Interfacial Sites for Enhanced CO2 Methanation.

CO2 methanation has attracted considerable attention as a promising strategy for recycling CO2 and generating valuable methane. This study presents a niobium-doped CeO2-supported Ni catalyst (Ni/NbCe), which demonstrates remarkable performance in terms of CO2 conversion and CH4 selectivity, even when operating at a low temperature of 250 °C. Structural analysis reveals the incorporation of Nb species into the CeO2 lattice, resulting in the formation of a Nb-Ce-O solid solution. Compared with the Ni/CeO2 catalyst, this solid solution demonstrates an improved spatial distribution. To comprehend the impact of the Nb-Ce-O solid solution on refining the electronic properties of the Ni-Ce interfacial sites, facilitating H2 activation, and accelerating the hydrogenation of CO2* into HCOO*, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis and density functional theory (DFT) calculations were conducted. These investigations shed light on the mechanism through which the activity of CO2 methanation is enhanced, which differs from the commonly observed CO* pathway triggered by oxygen vacancies (OV). Consequently, this study provides a comprehensive understanding of the intricate interplay between the electronic properties of the catalyst's active sites and the reaction pathway in CO2 methanation over Ni-based catalysts.

The role of oxide supports in constructing plasma-treated gold nanocatalysts for visible light photocatalytic oxidation of CO

Supported Au nanocatalysts are highly attractive plasmonic nanostructures for visible light (VL) photocatalysis due to their significant promise in direct conversion of solar to chemical energy. A promising strategy to prepare high-performance supported plasmonic Au nanocatalysts is treating the catalysts with plasma, where the support holds the key to constructing active Au-support interfaces by interacting with Au nanoparticles. Herein the role of oxide supports in constructing plasma-treated plasmonic Au nanocatalysts for VL photocatalytic oxidation of CO is studied by comparing effect of plasma treatment on typical oxides of TiO2, CeO2 and Al2O3 supported Au nanocatalysts. After O2 plasma treatment, CeO2 supported Au nanocatalyst obtains the highest intrinsic catalytic activity due to its high dispersion of Au nanoparticles induced by strong interaction between CeO2 and Au and strong oxygen activation ability. The O2 plasma treatment enables TiO2 supported Au nanocatalyst to exhibit the largest enhancement in catalytic activity under VL irradiation, which originates from the favorable hot-electron transfer process. This process is not only attributed to the strong surface plasmon resonance of Au nanoparticles and large numbers of Au-TiO2 interfacial sites that result from moderate interaction between TiO2 and Au, but also depends on the low Schottky barrier height at Au-TiO2 interface due to the small work function difference between TiO2 and metallic Au. This investigation deepens the understanding of the role of oxide supports in constructing plasma-treated supported Au nanocatalysts, and can be instructive for the design and optimization of plasmonic Au nanocatalysts for VL photocatalytic reactions.