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The judicious choice of metal clusters and organic building blocks leads to a wide variety of structures for metal–organic frameworks (MOFs). In this work, we demonstrated that relegating the symme...

Converting CO2 into chemicals with electricity generated by renewable energy is a promising way to achieve the goal of carbon neutrality. Carbon-based materials have the advantages of low cost, wide sources and environmental friendliness. In this work, we prepared a series of boron-doped covalent triazine frameworks and found that boron doping can significantly improve the CO selectivity up to 91.2% in the CO2 electroreduction reactions(CO2RR). The effect of different doping ratios on the activity by adjusting the proportion of doped atoms was systematically investigated. This work proves that the doping modification of non-metallic materials is a very effective way to improve their activity, and also lays a foundation for the study of other element doping in the coming future.

The combined effects of proton irradiation and forward gate-bias stress on the interface traps of AlGaN/GaN heterostructure have been studied in this article. It is found that the effect of proton irradiation and forward gate-bias on the shift of flat band voltage $V_{\mathrm {FB}}$ is independent. By utilizing the frequency-dependent conductance technique, it is found that the trap density $D_{\mathrm {T}}$ at metal/AlGaN interface decreases after proton irradiation and the $D_{\mathrm {T}}$ at most energy levels increases after the following forward gate-bias. The $D_{\mathrm {T}}$ at AlGaN/GaN interface increases after proton irradiation and then decreases after the following forward gate-bias. The energy level range of metal/AlGaN interface traps reduces significantly under the forward gate-bias for the irradiated devices, however, that of AlGaN/GaN interface traps decreases little. In summary, the combined effect of proton irradiation and forward gate-bias stress on the interface traps is more complex than that on the bulk traps in AlGaN layer.

The unique applications of porous metal-organic framework (MOF) liquids with permanent porosity and fluidity have attracted significant attention. However, fabrication of porous MOF liquids remains challenging because of the easy intermolecular self-filling of the cavity or the rapid settlement of porous hosts in hindered solvents that cannot enter their pores. Herein, we report a facile strategy for the fabrication of a MOF liquid (Im-UiO-PL) by surface ionization of an imidazolium-functionalized framework with a sterically hindered poly(ethylene glycol) sulfonate (PEGS) canopy. The Im-UiO-PL obtained in this way has a CO2 adsorption approximately 14 times larger than that of pure PEGS. Distinct from a porous MOF solid counterpart, the stored CO2 in Im-UiO-PL can be slowly released and efficiently utilized to synthesize cyclic carbonates in the atmosphere. This is the first example of the use of a porous MOF liquid as a CO2 storage material for catalysis. It offers a new method for the fabrication of unique porous liquid MOFs with functional behaviors in various fields of gas adsorption and catalysis.

Porous crystalline metal-organic frameworks (MOFs) are one class of promising electrode materials for CO2 electroreduction reaction (CO2RR) by virtue of their large CO2 adsorption capacities and abundant tunable active sites, but their insulating nature usually leads to low current density. Herein, a two-dimensional (2D) Ni-phthalocyanine-based MOF (NiPc-Ni(NH)4) constructed by 2,3,9,10,16,17,23,24-octaaminophthalocyaninato nickel(II) (NiPc-(NH2)8) and nickel(II) ions attained high electrical conductivity due to the high overlap of d-π conjugation orbitals between the nickel node and the Ni-phthalocyanine-substituted o-phenylenediamine. During CO2RR, the NiPc-Ni(NH)4 nanosheets achieved a high CO Faradaic efficiency of 96.4% at −0.7 V and a large CO partial current density of 24.8 mA cm−2 at −1.1 V, which surpassed all the reported two-dimensional MOF electrocatalysts evaluated in an H-cell. The control experiments and density functional theory (DFT) calculations suggested that the Ni-N4 units of the phthalocyanine ring are the catalytic active sites. This work provides a new route to the design of highly efficient porous framework materials for the enhanced electrocatalysis via improving electrical conductivity.

The electrocatalytic conversion of CO2 into value-added chemicals is a promising approach to realize a carbon-energy balance. However, low current density still limits the application of the CO2 electroreduction reaction (CO2 RR). Metal-organic frameworks (MOFs) are one class of promising alternatives for the CO2 RR due to their periodically arranged isolated metal active sites. However, the poor conductivity of traditional MOFs usually results in a low current density in CO2 RR. We have prepared conductive two-dimensional (2D) phthalocyanine-based MOF (NiPc-NiO4 ) nanosheets linked by nickel-catecholate, which can be employed as highly efficient electrocatalysts for the CO2 RR to CO. The obtained NiPc-NiO4 has a good conductivity and exhibited a very high selectivity of 98.4 % toward CO production and a large CO partial current density of 34.5 mA cm-2 , outperforming the reported MOF catalysts. This work highlights the potential of conductive crystalline frameworks in electrocatalysis.

Fabrication of highly active carbon-supported atomically isolated metal catalysts with maximized atomic efficiency is significant but remains a big challenge because the adjacent metal species are ...

The effect of gamma ( $\gamma $ )-irradiation on AlGaN-based light-emitting diodes (LEDs) in the short-wavelength ultraviolet (UVC, 210–280 nm) spectral range under electrical stress is characterized by electroluminescence and current–voltage measurement. Different from previous reports that $\gamma $ -irradiation can hardly damage nitride devices, we observe that the optical power decreases and leakage current increases obviously after electrical stress under $\gamma $ -irradiation. To delve into the nature of degradation, variation of defects is studied using temperature-dependent low-frequency noise measurement. After stress, the ~0.78-eV defects attributed to N antisite are generated and lead to device degradation, which is accompanied by a reduction of the intrinsic Ga vacancy with an energy level of ~0.38 eV. The variation of defects after stress in $\gamma $ -irradiated environment is more evident than that in nonirradiated environment, which is well corresponding to the performance degradation behavior. In conclusion, $\gamma $ -irradiation is found to accelerate degradation induced by electrical stress, and the study can help improve irradiation resistance in AlGaN-based UVC LEDs.

Metal–organic framework (MOFs) films have a wide range of applications in gas separation and chemical sensing. By contrast, MOF films have rarely been reported in the field of photocatalysis. Compa...

The design and synthesis of a hydrogen-bonded organic framework (HOF) based on tetrathiafulvalene tetracarboxylic acid is reported. The resultant HOF can undergo single-crystal-to-single-crystal transformation to form another two isomers. The structural characteristics and the redox properties of the HOFs were conveniently tailored utilizing the transformation of the phases.

The construction of Z-scheme heterojunctions has been demonstrated as an effective strategy to improve photocatalytic hydrogen (H2) production efficiency. Herein, a Zn vacancy defect-mediated direct Z-scheme CdS/ZnS (CSZS–VZn) heterojunction was developed to optimize the H2 production performance, and the introduction of cation defects in ZnS could regulate the band structure of the photocatalyst by forming additional energy levels within the band gap and help to form ohmic contacts. The CSZS–VZn heterojunction exhibited a H2 evolution rate of 46.63 mmol h−1 g−1 under visible light illumination in an aqueous Na2S/Na2SO3 system, which was about 388 and 1727 times higher than those of CdS and Zn-vacancy ZnS (ZnS–VZn), respectively. The enhanced photocatalytic activity of CSZS–VZn was mainly attributed to the presence of Zn vacancy defects upon the formation of the Z-scheme heterojunction structure, by which the photogenerated electrons were trapped in the Zn vacancy defect levels of ZnS and recombined with holes in the valence bands of CdS at heterojunction interfaces through ohmic contacts. In such a way, electrons in the conduction bands of CdS were boosted to participate in H2 evolution reactions and photocorrosion was suppressed. This work provides a viable design strategy via the engineering of cation defects in Z-scheme photocatalysts for photocatalytic H2 evolution.

Atomically dispersed transition metal ion doped CdZnS nanocrystals were synthesized to delicately tune the selectivity for CO2 photoreduction to CH4, among which the CZS–Cu2+ achieved an excellent CO2-to-CH4 conversion rate of ca. 665.9 μL h−1 g−1 with a high selectivity of ca. 79.7% under visible irradiation.

The construction of heterostructures is a universal method to hinder the radiative recombination of hot electrons and hot holes, which can effectively enhance the photothermal effect of semiconductors. In this work, a one-pot method was employed to prepare a composite named Bi2Se3@ZIF-8 NPs, which incredibly increased the photothermal conversion efficiency of Bi2Se3 NPs. The temperature elevation of Bi2Se3@ZIF-8 NPs was almost double that of the Bi2Se3 NPs; specifically, the temperature of the irradiated Bi2Se3@ZIF-8 NPs was strikingly increased to 130 °C within 6 seconds, and finally stabilized at 165 °C. Furthermore, the photothermal conversion ability was maintained over multiple irradiation cycles, which endows this composite with great potential to be an excellent photothermal agent.

Ultrafine silver (Ag) nanoparticles (NPs) were successfully loaded on a robust aluminum (Al) metal–organic framework (MOF), NOTT-300(Al), by means of a double-solvent method (DSM), and the construc...

Hydrogen-bonded organic frameworks (HOFs) possess various merits, such as high porosity, tunable structure, facile modification, and ready regeneration. These properties have yet to be explored in the context of new functional HOF materials. The facile and inexpensive electrophoretic deposition (EPD) method applied in this study generated a transparent HOF film at room temperature in just 2 min and is applicable to other HOFs. The resulting film exhibited reversible electrochromism with the advantage of long cycle life (>500 cycles). More strikingly, this all-organic film could be readily regenerated (through rinsing with DMF and redeposition) and showed tunable electrochromic behavior (through low-cost postsynthetic modification) with the ability to undergo successive color changes, which is difficult to achieve with conventional electrochromic materials. An electrochromic device was manufactured to further demonstrate the application potential of the film.

Photocatalytic hydrogen production coupled with selective oxidation of organic substrates to produce high-value-added fine chemicals has drawn increasing attention. Herein, we report a noble metal-free photocatalyst for the highly efficient and simultaneous generation of hydrogen and the selective oxidation of benzyl alcohol into benzaldehyde over CdS@MoS2 heterostructures under visible light. Without the need for a sacrificial agent, CdS@MoS2 displayed an excellent hydrogen production rate of 4233 µmol g−1 h−1 with 0.3 mmol benzyl alcohol, which is approximately 53 times higher than that of bare CdS nanorods (80 µmol g−1 h−1). The reaction system was highly selective for the oxidation of benzyl alcohol into benzaldehyde. When the amount of benzyl alcohol increased to 1.0 mmol, the hydrogen production reached 9033 µmol g−1 h−1. Scanning electron microscopy and transmission electron microscopy images revealed that p-type MoS2 sheets with a flower-like structure closely adhered to n-type semiconductor CdS nanorods through the formation of a p-n heterojunction. As a potential Z-scheme photocatalyst, the CdS@MoS2 heterostructure effectively produces and separates electron-hole pairs under visible light. Thus, the electrons are used for reduction to generate hydrogen, and the holes oxidize benzyl alcohol into benzaldehyde. Moreover, a mechanism of photogenerated charge transfer and separation was proposed and verified by photoluminescence, electrochemical impedance spectroscopy, photocurrent and Mott-Schottky measurements. The results reveal that the CdS@MoS2 heterojunctions have rapid and efficient charge separation and transfer, thereby greatly improving benzyl alcohol dehydrogenation. This work provides insight into the rational design of high-performance Z-scheme photocatalysts and the use of holes and electrons to obtain two valuable chemicals simultaneously.

A novel sandwich-like structure material was exploited for the fabrication of an effective corrosion resistance system. An environmentally friendly composite material was synthesized by installing 8-hydroxyquinoline (8-HQ) on the surface of graphene oxide (GO). In order to prevent leakage of corrosion inhibitor 8-HQ, GO/8-HQ was modified by polydopamine (PDA), denoted as GO/8-HQ/PDA. A sandwich-like structure (GO/8-HQ/PDA) enables long-term stable storage of corrosion inhibitor in the protective matrix. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized to verify the sandwich-like structure of GO/8-HQ/PDA. The electrochemical tests in a 3.5 wt% NaCl solution showed that the addition of well-dispersed GO/8-HQ/PDA into epoxy system (GO/8-HQ/PDA-EP) remarkably improved corrosion protection of AZ31b magnesium alloy compared with pure epoxy (EP) coating. The sandwich structure protects the activity and structural integrity of the corrosion inhibitor (8-HQ). The corrosion inhibitor (8-HQ) of the GO/8-HQ/PDA sandwich structure cuts off the ion exchange between the metal alloy and the electrolyte solution, which hinders the electrochemical corrosion of the metal. A possible corrosion resistance mechanism of GO/8-HQ/PDA is fully discussed. This study provides feasibilities for the immobilization of corrosion inhibitors on the metal surface.

Traditional polymer membranes exhibit a constant structure that makes adjustment of the filtration process difficult, such as flux changing and contaminant cleaning. Inspired by the automatically c...

Charge transport mechanisms of forward and reverse leakage currents in vertical GaN Schottky barrier diodes are investigated by measuring the temperature-dependent current–voltage characteristics. The results show that the leakage current is primarily governed by dislocation-associated thermionic field emission (TFE). The primary transport path is the reduced, localized conduction band around the dislocation core rather than the continuum defect states. A refined phenomenological physical model is developed for conductive dislocations in GaN, emphasizing that: 1) surface donors, surrounding the core of dislocations, can significantly shrink the barrier region after ionization, causing severe TFE leakage; 2) the $\text{O}_{N}$ donors likely to be responsible for TFE have a typical density of $\sim 1\,\,\!\times \! \,\,10^{{18}}$ cm $^{-{3}}$ at 300 K and activation energy of 78 meV; and 3) the barrier height at donor sites is ~0.65 eV at 300 K, which is reduced by ~0.4 eV with respect to the dislocation-free region.

Currently, Zr-alloys are widely used in nuclear power reactors for fuel cladding and structural components. Many types of zr-based alloys were developed to overcome the challenges encountered in the progress of nuclear reactors (high-burnup and high-duty). Oxygen diffused into the cladding, hydrogen absorbed in the cladding (breakaway oxidation and ruptured balloons) and rapid oxidation rate are results of chemical interaction of cladding material with steam at high temperature. Zirconium alloys seem to be the most suitable for use in fuel cladding, if they can overcome the rapid oxidation at temperature higher than 1200 °C. Previous studies on the oxidation behavior for some Zr-alloys nuclear fuel cladding tubes in steam and steam–air atmospheres at high temperatures are reviewed. The oxidation behavior of zirconium-alloys is strongly affected by the chemical composition of alloys and its surface conditions.

We report a facile and scalable synthesis of Pt-Co truncated octahedral nanocrystals (TONs) by employing Pt(acac)2 and Co(acac)2 as precursors, together with CO molecules and Mn atoms derived from the decomposition of Mn2(CO)10 as a reductant and a {111} facet-directing agent, respectively. Both the composition and yield of the Pt-Co TONs could be varied through the introduction of CHCl3. When tested at 80 °C using membrane electrode assembly (MEA), the 4 nm Pt2.6Co TONs gave a mass activity of 294 A gPt-1 at beginning-of-life (BOL) and it increased to 384 A gPt-1 during recovery cycles. The mass activity at BOL only dropped by 24% after 30 000 voltage cycles at end-of-life (EOL) in a metal dissolution accelerated stress test. The Pt2.6Co/C catalyst outperformed the commercial TKK Pt3Co/C (230 A gPt-1 at BOL and 40% loss after 30 000 cycles at EOL) in terms of both activity and durability. Our systematic analysis suggested that the enhancement in activity can be attributed to the combination of small, uniform size and well-defined {111} facets. This new class of catalysts holds promise for applications in proton-exchange membrane fuel cells.

Total-ionizing-dose (TID) effects and low-frequency noise are evaluated in 30-nm gate-length bulk and silicon-on-insulator (SOI) FinFETs for devices with fin widths of 10–40 nm. Minimal threshold voltage shifts are observed at 2 Mrad(SiO2), but large increases in low-frequency noise are found, and significant changes in defect-energy distributions are inferred. Radiation-induced leakage current is enhanced for narrow- and short-channel bulk FinFETs. Short-channel SOI FinFETs show enhanced degradation compared with longer-channel devices. Narrow- and short-channel SOI devices exhibit high radiation tolerance. Significant random telegraph noise (RTN) is observed in smaller devices due to prominent individual defects.

Doping, introducing traces of impurity into a material to alter its original electrical or optical properties, constitutes the fundamental basis for a number of electronic devices that are used in materials science. In this study, we demonstrate that doping trace amounts of organic molecules into metal–organic frameworks (MOFs) dramatically alters the electrical structure and optical property of the bulky material without disturbing the original frameworks, as confirmed by both powder and single-crystal X-ray diffraction. This method is applicable to various dopants and different types of MOFs. Theoretical calculations suggested that the dopant introduces an impurity level in the host band structure, which considerably narrows the band gap and increases the photogenerated electron–hole separation. Therefore, photocatalytically inert MOFs can achieve excellent activity for water splitting into hydrogen through molecular doping. The findings presented here provide a powerful yet facile strategy toward regulating the electronic band structure of MOFs for improved catalytic activity without necessarily changing the original chemical components, topology, and porosity.

A facile method, post-synthetic exchange of modulators (PSEm), has been demonstrated here to prepare chiral metal-organic frameworks for enantioseparation. Based on this method, three chiral porous Zr-based metal-organic frameworks have been prepared through exchanging the coordinated modulators on metal clusters of MOFs with commercially available chiral carboxylic acid molecules. In addition, the obtained materials show enantioselectivity toward three different enantiomers, which presents a proof of concept for the design of MOF materials for enantioseparation by an easy and low-cost method.

In the perspective of visible-light-driven hydrogen evolution, photocatalysts with suitable band energy levels and wide-range responses are particularly promising. Herein, CdxZn1−xS (x = 0.2, 0.4, 0.6 and 0.8) nanocrystal solid solutions (NCSSs), which integrated twinning crystal structures, rich sulfur vacancies and wurtzite-sphalerite phase-junctions all in one, were prepared via a facile hydrothermal method. With these features, the twinning Cd0.6Zn0.4S performed remarkable photocatalysis for H2 evolution (42.66 mmol h−1 g−1) in Na2S/Na2SO3 aqueous solution, the rate of which was 691 times higher than those of pristine twinning CdS nanocrystals. To the best of our knowledge, this was the highest performance of H2 evolution among the hitherto reported one-fold sulfide photocatalysts. Density functional theory (DFT) calculations suggested the formation of twinning crystal structures improved the separation of photogenerated electron–hole pairs. Meanwhile, stability of the Cd0.6Zn0.4S photocatalyst was largely enhanced due to the fast hole consumption by Na2S/Na2SO3 through sulfur vacancies. This work explores the interplay and mechanism of special structures, sulfur vacancies and catalytic conditions of twinning CdZnS NCSSs, and provides guidance for the design of highly efficient and stable metal-sulfide-based photocatalysts.

Visible-light-driven photocatalysts have shown tremendous prospects in solving the energy crisis and environmental problems, thanks to their wide spectral response and high quantum efficiency. Several strategies including the expansion of visible light response and the improvement of solar energy utilization and photocatalytic quantum efficiency via more effective separation of photogenerated carriers are the current focuses of research that direct the design and fabrication of viable photocatalysts. Herein, a series of composite photocatalysts assembled from plasmonic Cu nanoparticles (NPs) and Zn3In2S6 (ZIS) solid solutions were synthesized by means of a simple solvothermal method. In comparison with the pristine ZIS semiconductor, Cu NP loaded ZIS solid solutions showed greatly enhanced photocatalytic activity, selectivity and stability towards CO2 reduction under visible irradiation. Of note was that the optimized ZIS-Cu2 exhibited an enhanced CH4 production rate of ca. 292 μL g-1 h-1 and a selectivity of ca. 71.1%, which were among the highest numbers reported hitherto. The localized surface plasmon resonance (LSPR) effect, shown by surface Cu NPs, was believed to play a critical role in the enhanced CO2 photoreduction efficiency. More importantly, the introduction of plasmonic Cu NPs could restrain the recombination of photogenerated electron-hole pairs and promote the migration of photogenerated electrons to better participate in the photocatalytic CO2 reduction in the presence of water vapor. This work thus provides a facile means to design robust and flexible composite photocatalysts for visible-light-driven CO2 photoreduction with high efficiency.

The Schottky barrier created at the interface between electron sinks and semiconductors can effectively optimize electron transfer for active photocatalysis. However, heterogeneous photocatalytic organic transformations via the Mott Schottky effect are still rare and their role in the specific photocatalytic system remains ambiguous. Here, a versatile photocatalytic system integrating the Schottky junctions into the TiO2 particles (Degussa, P25) and Pd NP based films has been developed. They were readily available through the facile encapsulation of P25 by Pd–H4BINDI films using an alternating layer-by-layer (LBL) approach (H4BINDI: N,N′-bis(5-isophthalate acid)naphthalene-diimide). After a H2 reduction process under 200 °C, the Pd NPs were obtained, denoted as P25@Pd–H4BINDI-200. Interestingly, the resulting P25@Pd–H4BINDI-200 photocatalyst presented an exceptionally high activity for dehydrogenation and hydrogenolysis of benzyl alcohol under visible light irradiation, which was approximately 17 times higher than that of the parent P25@Pd–H4BINDI and was superior to any other analogous systems reported to date. Specifically, the negative charges accumulated on the Pd NP surface reduce the benzyl alcohol, while the holes left on the valence band oxidize the benzyl alcohol, effectively promoting photocatalytic cycles with enhanced carrier separation. The deeper understanding of the reaction mechanisms revealed that Pd NPs play a vital mediating role in storing and shuttling photogenerated electrons via the Mott Schottky effect, and revealed the highly enhanced carrier separation by direct use of photoexcited electrons and holes for photoredox reactions. This work holds great promise for designing Mott–Schottky catalysts in enabling solar-driven photoredox reactions.

We report for the first time ultrafine Ru nanoclusters (NCs) anchored on thin reduced graphene oxide (rGO) via introduction of the macrocyclic compound cucurbit[6]uril (CB[6]). The nanocomposite exhibits a comparable or better HER performance compared to Pt/C in acidic, alkaline as well as neutral media, which greatly broadens its application in different types of electrolyzers.

Constructing the film with a green corrosion inhibitor is the key to metal corrosion protection. This study reports an environmentally friendly graphene oxide (GO) and carboxymethyl cellulose (CMC) composite films (CMC@GO) with enhanced corrosion protection performance. The CMC@GO composite film was grown on AZ31 magnesium alloy by the layer-by-layer (LbL) assembly method. Fourier transform infrared (FT-IR) spectroscopy and the solid-state NMR Spectrometer reveal the successful modification of CMC on the surface of GO nanosheets. The chemical states and the surface morphology of the CMC@GO composite film were obtained from X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The electrochemical measurements and equivalent circuit fitting results demonstrate that the film containing GO composites has higher corrosion resistance than the film of undoped GO. The CMC@GO composite film exerted the corrosion inhibition effect of GO, owing to the synergistic protective effect of GO and CMC.

Low cost biomass porous carbons (BPCs) were herein demonstrated as both reducing agents and material supports in the synthesis of robust CdS@BPC photocatalysts through a simple one-step, solvent-fr...

Aggregation-induced emission (AIE) materials present unique solid-state fluorescence. However, there remains a challenge in the switching of fluorescence quenching/emitting of AIE materials, limiting the application in information encryption. Herein, we report a composite of tetraphenylethylene@graphene oxide (TPE@GO) with switchable microstructure and fluorescence. We choose GO as a fluorescence quencher to control the fluorescence of TPE by controlling the aggregation structure. First, TPE coating with an average thickness of about 31 nm was deposited at the GO layer surface, which is the critical thickness at which the fluorescence can be largely quenched because of the fluorescence resonance energy transfer. After spraying a mixed solvent (good and poor solvents of TPE) on TPE@GO, a blue fluorescence of TPE was emitted during the drying process. During the treatment of mixed solvents, the planar TPE coating was dissolved in THF first and then the TPE molecules aggregated into nanoparticles (an average diameter of 65 nm) in H

The photoreduction of toxic Cr(VI) to environmental Cr(III) driven by visible-light is highly desired. Metal-organic frameworks (MOFs), as one class of outstanding porous materials, had been utilized for photoreduction of Cr(VI). Current methods modulated the photoreduction of Cr(VI) mainly by selection of suitable metal ions or organic ligands in single component MOFs. However, most of them still exhibit limited photoreduction performance due to low Cr(VI) adsorption rate/capacity, weak light harvesting efficiency, and/or poor electronic utilization efficiency. Multivariate metal-organic frameworks with highly visible-light photosensitive unit and strong Cr(VI) adsorption strut into one single phase is therefore expected to be an effective strategy to improve the photoreduction of Cr(VI), but remains unexplored. Herein, intense visible-light absorption porphyrin unit and strong toxic anions adsorption strut were integrated into one single MOF simultaneously via a sequential mixed-ligand and ionization method, which strongly improve the photoreduction performance of Cr(VI). The synergistic effect of strong adsorption of Cr2O72− and efficient utilization of light endowed H2TCPP⊂(I-)Meim-UiO-66 with highly efficient photoreduction activity toward toxic Cr2O72− under visible light in a rate of 13.3 mgCr(VI)/gcatalyst/min, much higher than the reported MOF-based photocatalysts including typical NH2-UiO-66 (0.2 mgCr(VI)/gcatalyst/min) and NH2-MIL-125 (1.6 mgCr(VI)/gcatalyst/min). As far as we know, this is the best catalyst among all the reported MOF-based photocatalysts for Cr(VI) photoreduction, in which the I- in our imidazolium functionalized MOF acts as sacrificial agent. Based on the results from time-resolved photoluminescence spectra, electron spin resonance, and theoretical calculation etc., a photoreduction mechanism of Cr2O72- over H2TCPP⊂(I-)Meim-UiO-66 was also well proposed. This general and facial strategy, combining the advantages of adsorption and photosensitivity in a multivariate MOF, paves the way to design of higher efficient photocatalytic materials.

The photocatalytic performance and the involved mechanism of copper-modified TiO2 have attracted a wide range of scientific interests in recent years. In this study, we fabricate CuOx/TiO2 photocat...

Because of the disparity in dative bond strength, three-dimensional (3D) bulky metal–organic frameworks (MOFs) based on the azolate layers and carboxylate pillars can be exfoliated into ultrathin two-dimensional (2D) nanosheets via alkali-etching exfoliation method. The obtained MOFs nanosheets, as giant secondary building layers (SBLs), can assemble with different linkers to form a series of 3D MOFs, thus facilely incorporating diverse functional groups into structures. The strategy reported here presents a low-cost, convenient, and high-throughput method to prepare ultrathin 2D nanosheets not only for potential applications but also for the generation of giant SBLs for rational MOF construction.

The AlGaN/GaN high-electron mobility transistors (HEMTs) were irradiated with fast and thermal neutrons at various fluences. Output, transfer, and gate-leakage characteristics were analyzed in detail before and after irradiation. After irradiation by 14-MeV neutrons, the electrical characteristics of the devices gradually degraded as the fluence increased. After irradiation by thermal neutrons at a fluence of $2.12 \times 10^{16}$ cm−2, the electrical characteristics of devices significantly decreased. Neutrons are believed to introduce a negatively charged acceptorlike deep level in the AlGaN layer, which can deplete 2DEG in the channel, raise the energy band, and shift the threshold voltage to positive values. Such an enhanced barrier can significantly suppress the gate Schottky leakage current of AlGaN/GaN HEMTs in both the reverse and forward bias regions. After the thermal neutron radiation, the quality of Schottky contacts deteriorated significantly.

Hydrogen generated via photocatalytic water splitting has the potential to be a clean and sustainable energy source, and anatase TiO2 has been widely considered as one of the most promising photoca...

The development of paper-based diagnostics should provide facile fabrication and user-friendliness. A promising solution is to obviate hydrophobic barriers and display intuitive results. Herein, we report a novel “Pen-Writing” technique for providing hydrophobic barrier-free patterned biosensor fabrication and user-friendly bioassay operation. We functionalized the rollerball pen with reagent ink to directly write on-demand patterned paper biosensors of any design. The single-step glucose biosensor and multi-step immunosensor were prepared, and the multi-analyte detection capability was proved. Besides, the reagent ink-based rollerball pen was used to directly write bioassays on paper pre-treated with analytes. To perform continuous, high-throughput fabrication and analysis, we also proposed an automatic platform via combining the reagent ink-based rollerball pen and a desktop pen plotter. Our work provides an easy, affordable and generic solution to prepare customized barrier-free patterned paper biosensors and develop on-site bioassays in low-resource settings.

Metal N-heterocyclic carbenes (M-NHCs) on the pore walls of a porous metal-organic framework (MOF) can be used as active sites for efficient organic catalysis. Traditional approaches that need strong alkaline reagents or insoluble Ag2O are not, however, suitable for the incorporation of NHCs on the backbones of MOFs because such reagents could destroy their frameworks or result in low reactivity. Accordingly, development of facile strategies toward functional MOFs with covalently bound M-NHCs for catalysis is needed. Herein, we describe the development of a general and facile approach to preparing MOFs with covalently linked active M-NHC (M = Pd, Ir) single-site catalysts by using a soluble Ag salt AgOC(CF3)3 as the source and subsequent transmetalation. The well-defined M-NHC-MOF (M = Pd, Ir) catalysts obtained in this way have shown excellent catalytic activity and stability in Suzuki reactions and hydrogen transfer reactions. This provides a general and facile strategy for anchoring functional M-NHC single-site catalysts onto functionalized MOFs for different reactions.

For low-speed and large-thrust situations, the single-layer winding permanent magnet linear motor is inefficient because of its large distance, and the thrust fluctuation is large. In order to solve this problem, a finite element analysis model of cylindrical permanent magnet linear motor is established in a cylindrical permanent magnet linear motor, and the Ansoft software simulation is used to ensure the positioning force and thrust of the double-layer winding motor and single-layer winding motor under the same key parameters. The performance of double-layer winding motor and Single-layer winding motor at different frequencies is compared and analyzed. The simulation results show that the cylindrical linear motor with double-layer fractional-slot winding structure is more suitable for occasions with low speed and large thrust, and has higher operation efficiency.

The poor electrical conductivity of metal-organic frameworks (MOFs) has been a stumbling block for its applications in many important fields. Therefore, exploring a simple and effective strategy to regulate the conductivity of MOFs is highly desired. Herein, anionic guest molecules are incorporated inside the pores of a cationic MOF (PFC-8), which increases its conductivity by five orders of magnitude while maintaining the original porosity. In contrast, the same operation in an isoreticular neutral framework (PFC-9) does not bring such a significant change. Theoretical studies reveal that the guest molecules, stabilized inside pores through electrostatic interaction, play the role of electron donors as do in semiconductors, bringing in an analogous n-type semiconductor mechanism for electron conduction. Therefore, we demonstrate that harnessing electrostatic interaction provides a new way to regulate the conductivity of MOFs without necessarily altering the original porous structure. This strategy would greatly broaden MOFs’ application potential in electronic and optoelectronic technologies.

Low pressure and anoxia are the main characteristics of the environment in the Tibetan Plateau, which means people living there have a large demand for oxygen to reduce the symptoms of altitude sickness. Pressure swing adsorption (PSA) is a competitive oxygen production technology in plateau areas, which relies on the molecular sieves for the separation of N2 and O2 in industry and portable medical equipment. The adsorption characteristics of the Faujasite-type (FAU) molecular sieves, as one kind of the most widely used adsorbents for O2 production, depend on the properties, amount, and distribution of the skeleton cations and atoms. In this paper, we explore the isomorphic substitution effect on the adsorption properties of N2 in FAU molecular sieves using the computational approaches based on the density functional theory (DFT). The structural analysis and adsorption energy calculated for the Zn, Ca, and Ga substitutions at the Si/Al skeleton sites in the β-cage structure, the basic unit of FAU molecular sieves, prove that the isomorphic substitution effect can strengthen the adsorption of N2. The Bader charge and density of states analysis validate the formation of electron-deficient holes near the Fermi level and hence strengthen the local polarity of the pore structure and enhance the adsorption of N2 molecules. The work about isomorphic substitution on the FAU molecular sieves might provide an insight into heteroatom isomorphic modification mechanisms and designing excellent air separation materials.

A new strategy for preparing mesoporous metal-doped bioactive glass fibers (MBGFs) was designed, which included electrospinning and sulfonating mesoporous PS fibers, precipitating metal ions and bioactive glass sol–gel precursor into the mesoporous polystyrene (PS) fibers and calcinations. Silver-doped mesoporous BGFs (Ag-MBGFs) with a uniform diameter of 1–2 μm and a specific surface area of 40.22 m2 g−1 were prepared as an example and characterized by SEM, XRD, TG, ICP and FTIR. These Ag-MBGFs showed excellent bioactivity, antibacterial properties and drug loading and release performance due to their special mesoporous and fibrous structure. The concentration of Staphylococcus aureus decreased from 1 × 108 colony-forming units per mL (CFU mL−1) to 2.5 × 106 CFU mL−1 in 2 h and then to 2 × 102 CFU mL−1 in 12 h when the concentration of the Ag-MBGFs reached 16 mg mL−1. BGFs of different compositions and functions could be prepared by the same strategy in a mesoporous PS fiber template, which could enrich materials for constructing orthopedic implants.

The shape memory properties of sulfur crosslinked natural rubber/beeswax (NR/BW) bio-blends and nanocomposites at three blending compositions (8:2, 6:4, and 4:6) were investigated. The melting temperature of beeswax was used as the switching temperature in the one-way shape memory process. The addition of multi-walled carbon nanotube (CNT) into the NR/BW matrix was helpful in not only improving the beeswax dispersion but also serving the near-infrared absorber to remotely trigger the shape memory process. Most surprisingly, the crystal orientation of beeswax in the natural rubber matrix was parallel to the stretching direction. In addition, the NR/BW blends and nanocomposites demonstrated the THF and acetone solvent vapor-triggered reversible shape memory behavior, which was hardly achieved without applying external stress and pre-soaking treatment as seen in the literature. This simple blending approach offers tremendous possibilities to prepare bio-based blends and nanocomposites with reversible shape memory properties.

Enhancement of the detection signal of fluorescence microscopy in highly diluted solutions is of great importance in chemical analysis, sensing, and bioassay applications. Surface nanodroplets with atto- to femto-liter volumes are promising tools for sensitive online detection by integrating their extremely efficient nano-extraction and optical advantages. In this paper, the development of novel basic units of nanodroplets-in-a-microdroplet by simple solvent exchange is reported. The encapsulated nanodroplets are applied for ultrasensitive and online detection in fluorescence imaging. The biphasic nature of the droplet composite enables simultaneous extraction and enrichment of both hydrophobic and hydrophilic compounds. Furthermore, the desirable lensing effect of the curved surface of the nanodroplets enhances the collection of light emitted from the fluorophore extracted in the droplets by ≈60-fold, allowing sensitive and quantitative analysis of the fluorophore using fluorescence microscopy. The results highlight the potential of encapsulated nanodroplets as a simple and innovative method of signal enhancement in chemical analysis. By integrating selective concentration, extraction, and sensitive detection, the encapsulated nanodroplets reported here may have broad applications in many chemical and biological matrices.

A one-dimensional Cd0.6Zn0.4S nanorod (CZS NR) solid solution with rich sulfur vacancies achieved an excellent photocatalytic hydrogen production activity of 59.3 mmol h-1 g-1 under visible irradiation, which is the highest number observed for CdZnS solid solution nanomaterials to date.

Developing a noncontact ratiometric luminescent temperature sensor with high sensitivity, widely available emission range, and reliable performance is a challenge in materials science. Herein, we demonstrated that this goal can be achieved by fabricating a lanthanide-functionalized hydrogen-bonded organic framework film (named the Eu@HOF-TCBP film). The unbonded carboxylic groups that existed in the structure not only enable lanthanide ions to bind with the framework for bringing dual emission but also allow for preparing a hydrogen-bonded organic framework (HOF) film through the facile electrophoretic deposition. The obtained film exhibits ratiometric temperature sensing performance in the range of 297-377 K with a maximum relative sensitivity of 5.787% K