RSS 1.0Chemical Science Program
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Recent Submissions
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Atomically Dispersed NiNx Site with High Oxygen Electrocatalysis Performance Facilely Produced via a Surface Immobilization Strategy(ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2023-03-27) [Article]Nonprecious-metal heterogeneous catalysts with atomically dispersed active sites demonstrated high activity and selectivity in different reactions, and the rational design and large-scale preparation of such catalysts are of great interest but remain a huge challenge. Current approaches usually involve extremely high-temperature and tedious procedures. Here, we demonstrated a straightforward and scalable preparation strategy. In two simple steps, the atomically dispersed Ni electrocatalyst can be synthesized in a tens grams scale with quantitative yield under mild conditions, and the active Ni sites were produced by immobilizing preorganized NiNx complex on the substrate surface via organic thermal reactions. This catalyst exhibits excellent catalysis performances in both oxygen evolution and reduction reactions. It also exhibited tunable catalysis activity, high catalysis reproducibility, and high stability. The atomically dispersed NiNx sites are tolerant at high Ni concentration, as the random reactions and metal nanoparticle formation that generally occurred at high temperatures were avoided. This strategy illustrated a practical and green method for the industrial manufacture of nonprecious-metal single-site catalysts with a predictable structure.
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Bioengineering of air-filled protein nanoparticles by genetic and chemical functionalization.(Journal of nanobiotechnology, Springer Science and Business Media LLC, 2023-03-25) [Article]Background: Various bacteria and archaea, including halophilic archaeon Halobacterium sp. NRC-1 produce gas vesicle nanoparticles (GVNPs), a unique class of stable, air-filled intracellular proteinaceous nanostructures. GVNPs are an attractive tool for biotechnological applications due to their readily production, purification, and unique physical properties. GVNPs are spindle- or cylinder-shaped, typically with a length of 100 nm to 1.5 μm and a width of 30–250 nm. Multiple monomeric subunits of GvpA and GvpC proteins form the GVNP shell, and several additional proteins are required as minor structural or assembly proteins. The haloarchaeal genetic system has been successfully used to produce and bioengineer GVNPs by fusing several foreign proteins with GvpC and has shown various applications, such as biocatalysis, diagnostics, bioimaging, drug delivery, and vaccine development. Results: We demonstrated that native GvpC can be removed in a low salt buffer during the GVNP purification, leaving the GvpA-based GVNP's shell intact and stable under physiological conditions. Here, we report a genetic engineering and chemical modification approach for functionalizing the major GVNP protein, GvpA. This novel approach is based on combinatorial cysteine mutagenesis within GvpA and genetic expansion of the N-terminal and C-terminal regions. Consequently, we generated GvpA single, double, and triple cysteine variant libraries and investigated the impact of mutations on the structure and physical shape of the GVNPs formed. We used a thiol–maleimide chemistry strategy to introduce the biotechnological relevant activity by maleimide-activated streptavidin–biotin and maleimide-activated SpyTag003-SpyCatcher003 mediated functionalization of GVNPs. Conclusion: The merger of these genetic and chemical functionalization approaches significantly extends these novel protein nanomaterials' bioengineering and functionalization potential to assemble catalytically active proteins, biomaterials, and vaccines onto one nanoparticle in a modular fashion.
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Polyoxometalate-cyclodextrin supramolecular entities for real-time in situ monitoring of dopamine released from neuroblastoma cells(Biosensors & bioelectronics, Elsevier BV, 2023-03-23) [Article]Optimized and sensitive biomarker detection has recently been shown to have a critical impact on quality of diagnosis and medical care options. In this research study, polyoxometalate-γ-cyclodextrin metal-organic framework (POM-γCD MOF) was utilized as an electrocatalyst to fabricate highly selective sensors to detect in-situ released dopamine. The POM-γCD MOF produced multiple modes of signals for dopamine including electrochemical, colorimetric, and smartphone read-outs. Real-time quantitative monitoring of SH-SY5Y neuroblastoma cellular dopamine production was successfully demonstrated under various stimuli at different time intervals. The POM-CD MOF sensor and linear regression model were used to develop a smartphone read-out platform, which converts dopamine visual signals to digital signals within a few seconds. Ultimately, POM-γCD MOFs can play a significant role in the diagnosis and treatment of various diseases that involve dopamine as a significant biomarker.
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Zero-dimensional Cu(i)-based organometallic halide with green cluster-centred emission for high resolution X-ray imaging screens(Chemical Communications, Royal Society of Chemistry (RSC), 2023-03-22) [Article]In this communication, we report a low-dimensional perovskite-related structure based on Cu(I) organometallic halide with strong green cluster-centred emission and near-unity photoluminescence quantum yield. The 0D [Rb(18-crown-6)]2Cu4I6 was sucessfully applied for X-ray imaging screens which exhibit high spatial resolution of 16.8 lp mm−1 and low detection limit of 458 nGy s−1.
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Artificial Leaf for Solar-Driven Ammonia Conversion at Milligram-Scale Using Triple Junction III-V Photoelectrode(Advanced Science, Wiley, 2023-03-22) [Article]Developing a green and energy-saving alternative to the traditional Haber-Bosch process for converting nitrogen into ammonia is urgently needed. Imitating from biological nitrogen fixation and photosynthesis processes, this work develops a monolithic artificial leaf based on triple junction (3J) InGaP/GaAs/Ge cell for solar-driven ammonia conversion under ambient conditions. A gold layer serves as the catalytic site for nitrogen fixation with photogenerated electrons. The Au/Ti/3J InGaP/GaAs/Ge photoelectrochemical (PEC) device achieves high ammonia production rates and Faradaic efficiencies in a two-electrode system without applying external potential. For example, at 0.2 sunlight intensity, the solar-to-ammonia (STA) conversion efficiency reaches 1.11% and the corresponding Faradaic efficiency is up to 28.9%. By integrating a Ni foil on the anode side for the oxygen evolution reaction (OER), the monolithic artificial leaf exhibits an ammonia production rate of 8.5 µg cm<sup>-2</sup> h at 1.5 sunlight intensity. Additionally, a 3 × 3 cm unassisted wireless PEC device is fabricated that produces 1.0039 mg of ammonia in the 36-h durability test. Thus, the new artificial leaf can successfully and directly convert solar energy into chemical energy and generate useful products in an environmentally friendly approach.
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Zero-dimensional Cu(i)-based organometallic halide with green cluster-centred emission for high resolution X-ray imaging screens(Chemical Communications, Royal Society of Chemistry (RSC), 2023-03-22) [Article]In this communication, we report a low-dimensional perovskite-related structure based on Cu(I) organometallic halide with strong green cluster-centred emission and near-unity photoluminescence quantum yield. The 0D [Rb(18-crown-6)]2Cu4I6 was sucessfully applied for X-ray imaging screens which exhibit high spatial resolution of 16.8 lp mm−1 and low detection limit of 458 nGy s−1.
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Visualization of Surface Charge Carrier Diffusion Lengths in Different Perovskite Crystal Orientations Using 4D Electron Imaging(Advanced Optical Materials, Wiley, 2023-03-20) [Article]Understanding charge carrier dynamics on the surface of materials at the nanometer and femtosecond scales is one of the key elements to optimizing the performance of light-conversion devices, including solar cells. Unfortunately, most of the pump-probe characterization techniques are surface-insensitive and obtain information from the bulk due to the large penetration depth of the pulses. However, ultrafast scanning electron microscopy (USEM) is superior in visualizing carrier dynamics at the surface with high spatial-temporal resolution. Here, the authors successfully used USEM to uncover the tremendous effect of surface orientations and termination on the charge carrier of MAPbI3 perovskite single crystals. Time-resolved secondary electrons snapshots and density functional theory calculations clearly demonstrate that charge carrier diffusion, surface trap density, surface work function, and carrier concentration are strongly facet-dependent. The results display a diffusion length of 22 micrometers within 6.0 nanoseconds along (001) orientation. While (100) facet forms defect states that prevent carrier diffusion and shows an increase in the surface work function leading to dark contrast and fast charge carrier recombination. These findings provide a new key component to optimizing the surface of perovskites, thus paving the way for even more efficient and stable solar-cell devices based on perovskite single crystals.
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Engineering grain boundaries in monolayer molybdenum disulfide for an efficient water/ion separation(Research Square Platform LLC, 2023-03-20) [Preprint]Atomically thin two-dimensional (2D) materials have long been considered as ideal platforms for developing separation membranes. However, it is difficult to generate uniform subnanometer pores over large areas on 2D materials. Herein, we report that the well-defined defect structure of monolayer MoS2, namely, eight-membered ring (8-MR) pores typically formed at the boundaries of two antiparallel grains, can serve as molecular sieves for efficient water/ion separation. The 8-MR pores (4.2 × 2.4 Å) in monolayer MoS2 allow rapid single-file water transport while rejecting various hydrated ions. Further, the density of grain boundaries and, consequently, the density of pores can be tuned by regulating the nucleation density and size of MoS2 grains during the chemical vapor deposition process. The optimized MoS2 membrane exhibited an ultrahigh water/NaCl selectivity of ~6.5 × 104 at a water permeance of 232 mol m−2 h−1 bar−1, outperforming the state-of-the-art desalination membranes. When used for direct hydrogen production from seawater by combining the forward osmosis and electrochemical water splitting processes, the membrane achieved ~40 times the energy conversion efficiency of commercial polymeric membranes. It also exhibited a rapid and selective proton transport behavior desirable for fuel cells and electrolysis. The bottom-up approach of creating precise pore structures on atomically thin films via grain boundary engineering presents a promising route for producing large-area membranes suitable for various applications.
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Sintering-free catalytic ammonia cracking by vertically standing 2D porous framework supported Ru nanocatalysts(Chemical Engineering Journal, Elsevier BV, 2023-03-18) [Article]Catalytic ammonia decomposition enables ammonia to be a hydrogen gas carrier for a carbon-free fuel economy. The challenge is to obtain high conversion yields and rates at low temperatures for a prolonged time. A promising approach is to engineer a catalyst support to minimize deleterious effects like sintering. Here, we compared a conventional 2D planar porous framework support with a vertically standing 2D structure to ascertain the effects of support geometry on the catalytic performance. The catalysts were made by loading ruthenium (Ru) nanoparticles onto the structures, and the catalytic activities were monitored by varying the ammonia (NH3) feeding rate and reaction temperature. Unlike the planar version, the vertically standing 2D support prevented nanoparticle aggregation, retained the original nanoparticle size, and showed an excellent hydrogen production rate (95.17 mmol gRu-1min-1) at a high flow rate of 32,000 ml gcat-1h-1 at a temperature of 450 ℃.
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Efficient capture of iodine and methyl iodide using all-silica EMM-17 zeolite(Nano Research, Springer Science and Business Media LLC, 2023-03-18) [Article]Hydrophobic zeolites have been identified as suitable adsorbents for capturing radioactive iodine species from nuclear-power-plant off-gas because of their high stability and strong water resistance. However, only the most common zeolites have been investigated for the capture of molecular iodine to date. Herein, we demonstrate that the composition and pore structure of zeolites considerably affect their iodine adsorption performance. A novel all-silica ExxonMobil material-17 (EMM-17) zeolite having a unique three-dimensional 10(12) × 10(12) × 11-ring channel system exhibits a high adsorption capacity for iodine and methyl iodide in the presence of water. EMM-17 outperforms previously reported zeolites in terms of gravimetric and volumetric adsorption capacity in dynamic adsorption measurements. The excellent iodine/methyl iodide capture properties are attributed to the combination of optimal pore size, high pore volume, strong hydrophobicity, and suitable particle morphology. This study provides useful insights for designing efficient adsorbents for iodine capture.
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Poly(heptazine imide) ligand exchange enables remarkable low catalyst loadings in heterogeneous metallaphotocatalysis(Nature Communications, Springer Science and Business Media LLC, 2023-03-17) [Article]The development of heterogeneous metallaphotocatalysis is of great interest for sustainable organic synthesis. The rational design and controllable preparation of well-defined (site-isolated) metal/photo bifunctional solid catalysts to meet such goal remains a critical challenge. Herein, we demonstrate the incorporation of privileged homogeneous bipyridyl-based Ni-catalysts into highly ordered and crystalline potassium poly(heptazine imide) (K-PHI). A variety of PHI-supported cationic bipyridyl-based Ni-catalysts (LnNi-PHI) have been prepared and fully characterized by various techniques including NMR, ICP-OES, XPS, HAADF-STEM and XAS. The LnNi-PHI catalysts exhibit exceptional chemical stability and recyclability in diverse C−P, C−S, C−O and C−N cross-coupling reactions. The proximity and cooperativity effects in LnNi-PHI significantly enhances the photo/Ni dual catalytic activity, thus resulting in low catalyst loadings and high turnover numbers.
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Ultra-Highly Active Ni-Doped MOF-5 Heterogeneous Catalysts for Ethylene Dimerization.(Small (Weinheim an der Bergstrasse, Germany), Wiley, 2023-03-15) [Article]Here, an ultra-highly active Ni-MOF-5 catalyst with high Ni loading for ethylene dimerization is reported. The Ni-MOF-5 catalysts are synthesized by a facile one-pot co-precipitation method at room temperature, where Ni2+ replaces Zn2+ in MOF-5. Unlike Zn2+ with tetrahedral coordination in MOF-5, Ni2+ is coordinated with extra solvent molecules except for four-oxygen from the framework. After removing coordinated solvent molecules, Ni-MOF-5 achieves an ethylene turnover frequency of 352 000 h−1, corresponding to 9040 g of product per gram of catalyst per hour, at 35 °C and 50 bar, far exceeding the activities of all reported heterogeneous catalysts. The high Ni loading and full exposure structure account for the excellent catalytic performance. Isotope labeling experiments reveal that the catalytic process follows the Cossee–Arlman mechanism, rationalizing the high activity and selectivity of the catalyst. These results demonstrate that Ni-MOF-5 catalysts are very promising for industrial catalytic ethylene dimerization.
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A monolithic composite based on zeolite-like metal-organic framework@divinylbenzene polymer separates azeotropic fluorocarbon mixture efficiently.(Journal of chromatography. A, Elsevier BV, 2023-03-15) [Article]Organic monolithic columns are mainly used to separate macromolecules; however, many attempts to extend their performance toward small molecules were examined by incorporating micro- and nanoparticles. The incorporation technique enabled utilizing organic monoliths in gas chromatography (GC) for small molecules, which are still scarce. Here, we prepared a composite matrix of capillary monolithic columns of a zeolite-like metal-organic framework with a sodalite topology (sod-ZMOF) and Divinylbenzene polymer (DVB) for GC separations under 0.5 MPa. Relatively short DVB monolithic columns (18 cm long × 0.25 mm i.d.) incorporated with a tiny amount of sod-ZMOF nanoparticles (0.7 and 1.17 wt%) with an average particle size of 225 nm were successfully fabricated and used to separate linear alkanes and polar probes mixtures with increasing resolution up to 3.7 and 5.1 times, respectively, compared to a blank DVB monolithic column. A high-performance separation of linear alkanes series mixture (methane to decane) was exhibited in less than 2 min. McReynolds constants revealed that sod-ZMOF provided the composite monolith with a nonpolar character yielding a negative average polarity value smaller than the standard squalene column. An Excellent retention time of pentane and octane day-to-day reproducibility was achieved during 16 days and over more than 500 runs with RSD% of 2.25% and 3.3% using a composite monolithic column with 5 mg mL−1 sod-ZMOF (5-ZMOF@DVB). In addition, a qualitative determination of the gas mixture content of three commercially available Lighter gas cartridges was performed via the 5-ZMOF@DVB column. Finally, successfully separating an azeotropic freon mixture of difluoromethane (R-32) and pentafluoroethane (R-125) was achieved with a selectivity of up to 4.84. A further thermodynamic study related the preferential adsorption of R-125 to entropic factors rather than enthalpic while trapping inside ZMOF pores. This work sheds light on utilizing the infinite diversity of MOFs and combining their properties with high permeability and easily fabricated organic monoliths for GC separations of light molecules and gasses. Furthermore, the study highlights the role of GC as an easy and fast approach for the preliminary evaluation of the separation efficiency of porous polymers.
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Nanometer-thick crystalline and amorphous zeolitic imidazolate framework films for membrane and patterning applications(Research Square Platform LLC, 2023-03-14) [Preprint]Zeolitic imidazolate frameworks (ZIFs) are a subset of metal-organic frameworks (MOFs) with more than 200 characterized crystalline and amorphous networks made of divalent transition metal centers (e.g., Zn2+ and Co2+) linked by imidazolate linkers. ZIF thin films have been pursued intensively motivated by the desire to prepare membranes for selective gas and liquid separations. To achieve membranes with high throughput, as in Å-scale biological channels with nanometer-scale pathlengths, ZIF films with the minimum possible thickness, down to just one unit cell, are highly desired. Control of ZIF film thickness at the 10-nm-scale may also enable emerging, MOF-inspired, applications including patterned crystalline MOF films, and amorphous organic-inorganic resists for high-resolution electron-beam (e-beam) and extreme UV (EUV) lithography. However, the state-of-the-art methods yield ZIF films with thicknesses exceeding 40 nanometers. Here, we report a deposition method from ultra-dilute precursor mixtures that within minutes yields uniform ZIF deposits with nm-scale thickness control. On crystalline substrate such as graphene, two-dimensional crystalline ZIF (2DZIF) film with thickness of a unit-cell could be achieved, which composed of a six-membered zincimidazolate coordination ring enabling record-high H2 permselective separation performance. Deposition under identical conditions on amorphous substrates yields macroscopically smooth amorphous ZIF (aZIF) films, which can be used as negative- and positive-tone resists yielding pattern features down to 20 nm. The method reported here will likely accelerate the development of 2D crystalline and ultrathin amorphous MOF films for applications ranging from separation membranes to sensors and patterning for microelectronic applications.
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Copper Organometallic Iodide Arrays for Efficient X-ray Imaging Scintillators(ACS Central Science, American Chemical Society (ACS), 2023-03-10) [Article]Lead-free organic metal halide scintillators with low-dimensional electronic structures have demonstrated great potential in X-ray detection and imaging due to their excellent optoelectronic properties. Herein, the zero-dimensional organic copper halide (18-crown-6)2Na2(H2O)3Cu4I6 (CNCI) which exhibits negligible self-absorption and near-unity green-light emission was successfully deployed into X-ray imaging scintillators with outstanding X-ray sensitivity and imaging resolution. In particular, we fabricated a CNCI/polymer composite scintillator with an ultrahigh light yield of ∼109,000 photons/MeV, representing one of the highest values reported so far for scintillation materials. In addition, an ultralow detection limit of 59.4 nGy/s was achieved, which is approximately 92 times lower than the dosage for a standard medical examination. Moreover, the spatial imaging resolution of the CNCI scintillator was further improved by using a silicon template due to the wave-guiding of light through CNCI-filled pores. The pixelated CNCI-silicon array scintillation screen displays an impressive spatial resolution of 24.8 line pairs per millimeter (lp/mm) compared to the resolution of 16.3 lp/mm for CNCI-polymer film screens, representing the highest resolutions reported so far for organometallic-based X-ray imaging screens. This design represents a new approach to fabricating high-performance X-ray imaging scintillators based on organic metal halides for applications in medical radiography and security screening.
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Ambivalent Role of Rotamers in Cyclic(alkyl)(amino)carbene Ruthenium Complexes for Enantioselective Ring-Opening Cross-Metathesis(Organometallics, American Chemical Society (ACS), 2023-03-07) [Article]The development of highly efficient enantioselective olefin metathesis catalysts is a significant challenge. Using optically pure chiral cyclic (alkyl)(amino)carbene (ChiCAAC) ligands combined with preliminary mechanistic insights and density functional theory (DFT) computations, we show that catalytic performances in this field can be impaired by the formation of rotamers before the enantio-determining step. Using DFT, we also demonstrate that these results can help accelerate the process of ligand discovery by providing faster methods to discriminate potential candidates.
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Salts as Additives: A Route to Improve Performance and Stability of n-Type Organic Electrochemical Transistors(ACS Materials Au, American Chemical Society (ACS), 2023-03-06) [Article]Organic electrochemical transistors (OECTs) are becoming increasingly ubiquitous in various applications at the interface with biological systems. However, their widespread use is hampered by the scarcity of electron-conducting (n-type) backbones and the poor performance and stability of the existing n-OECTs. Here, we introduce organic salts as a solution additive to improve the transduction capability, shelf life, and operational stability of n-OECTs. We demonstrate that the salt-cast devices present a 10-fold increase in transconductance and achieve at least one year-long stability, while the pristine devices degrade within four months of storage. The salt-added films show improved backbone planarity and greater charge delocalization, leading to higher electronic charge carrier mobility. These films show a distinctly porous morphology where the interconnectivity is affected by the salt type, responsible for OECT speed. The salt-based films display limited changes in morphology and show lower water uptake upon electrochemical doping, a possible reason for the improved device cycling stability. Our work provides a new and easy route to improve n-type OECT performance and stability, which can be adapted for other electrochemical devices with n-type films operating at the aqueous electrolyte interface.
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A Z-scheme Heterojunctional Photocatalyst Engineered with Spatially Separated Dual Redox Sites for Selective CO2 Reduction with Water: Insight by in-situ μs-transient Absorption Spectra(Advanced Materials, Wiley, 2023-03-05) [Article]Solar driven CO2 reduction by water with a Z-scheme heterojunction affords an avenue to access energy storage and to alleviate greenhouse gas (GHG) emission, yet the separation of charge carriers and the integrative regulation of water oxidation and CO2 activation sites remain challenging. Here, a BiVO4/g-C3N4 (BVO/CN) Z-scheme heterojunction as such a prototype has been constructed by spatially separated dual sites with CoOx clusters and imidazolium ionic liquids (IL) towards CO2 photoreduction. The optimized CoOx-BVO/CN-IL delivers a ca. 80-fold CO production rate without H2 evolution compared with urea-C3N4 counterpart, together with nearly stoichiometric O2 gas produced. Experimental results and DFT calculations unveil the cascade Z-scheme charge transfer and subsequently the prominent redox co-catalysis by CoOx and IL for holes-H2O oxidation and electrons-CO2 reduction, respectively. Moreover, in-situ μs-transient absorption spectra clearly show the function of each cocatalyst and quantitatively reveal that the resulting CoOx-BVO/CN-IL reaches up to the electron transfer efficiency of 36.4% for CO2 reduction, far beyond those for BVO/CN (4.0%) and urea-CN (0.8%), underlining an exceptional synergy of dual reaction sites engineering. This work provides deep insights and guidelines to the rational design of highly efficient Z-scheme heterojunction with precise redox catalytic sites toward solar fuel production.
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Editorial: Recent advances and challenges in electron microscopy characterizations of radiation-sensitive nanoparticles.(Frontiers in chemistry, Frontiers Media SA, 2023-03-02) [Article]
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Preferential Pyrolysis Construction of Carbon Anodes with 8400 h Lifespan for High-Energy-Density K-ion Batteries.(Angewandte Chemie (International ed. in English), Wiley, 2023-03-01) [Article]Carbonaceous materials are promising anodes for practical potassium-ion batteries, but fail to meet the requirements for durability and high capacities at low potentials. Herein, we constructed a durable carbon anode for high-energy-density K-ion full cells by a preferential pyrolysis strategy. Utilizing S and N volatilization from a π-π stacked supermolecule, the preferential pyrolysis process introduces low-potential active sites of sp2 hybridized carbon and carbon vacancies, endowing a low-potential "vacancy-adsorption/intercalation" mechanism. The as-prepared carbon anode exhibits a high capacity of 384.2 mAh g-1 (90% capacity locates below 1 V vs. K/K+), which contributes to a high energy density of 163 Wh kg-1 of K-ion full battery. Moreover, abundant vacancies of carbon alleviate volume variation, boosting the cycling stability over 14,000 cycles (8,400 h). Our work provides a new synthesis approach for durable carbon anodes of K-ion full cells with high energy densities.
