Strong Interfacial Interaction Research Articles

In-situ construction of water-soluble C60 derivative modified cobalt phosphides for efficient electrocatalytic hydrogen evolution in acidic and alkaline media

A zero-dimensional water-soluble ethylenediamine-functionalized C60 derivative (C60(en)n) was used to be in-situ supported on the surface of cobalt phosphides (CoP-Co2P), forming a highly efficient heterostructured electrocatalytic catalyst for the hydrogen evolution reaction (HER). Benefiting from the strong interfacial electronic interaction between C60(en)n and CoP-Co2P, the composite exhibits an exceptional catalytic performance with overpotentials of 129 and 117 mV to achieve a current density of 10 mA cm−2, and Tafel slopes of 59 and 72 mV dec−1 in acidic and alkaline conditions, respectively.

Strong interface interaction enriched surface Co3+ cations on Co3O4-LaCoO3 composite catalyst for highly efficient toluene oxidation

Interface interaction existed in the multicomponent determines the catalytic performance of composite catalysts. Herein, a Co3O4-LaCoO3 (Co-La) composite catalyst with strong spinel-perovskite interface interaction was successfully synthesized via a one-pot sol-gel method for the catalytic oxidation of toluene. The activity test results showed that the optimal 1Co3O4–4LaCoO3 (1Co-4La) catalyst exhibits much higher catalytic activity (T90 = 215 °C, GHSV = 50,000 h−1) than Co3O4 (T90 = 295 °C), LaCoO3 (T90 = 256 °C) and 1Co3O4/4LaCoO3 (1Co/4La) (prepared by mechanical ball-milling, T90 = 285 °C). Characterizations revealed that the strong spinel-perovskite interface interaction generated between the Co3O4 spinel and LaCoO3 perovskite in 1Co-4La facilitates the transfer of interfacial electrons, contributing to the exposure of surface active Co3+ and the enhanced oxidation ability of surface active Co3+ on 1Co-4La. In addition, the reactive lattice oxygen of surface Co3+–O on 1Co-4La effectively promotes the decomposition of toluene into CO2, enabling the low-temperature oxidation of toluene through the Mars-van Krevelen (MvK) mechanism. This work provides insight into the promotional effect of multicomponent interface interaction on enhancing catalytic performance of spinel-perovskite composite catalysts.

A superstable, flexible, and scalable nanofluidic ion regulation composite membrane

Two-dimensional layered membranes with high and stable ion transport properties have various applications in nanofluidic devices; however, their construction remains a considerable challenge. Herein, we develop a superstable aramid nanofiber/graphite composite membrane with numerous one-dimensional and two-dimensional nano-confined interspaces for ultrafast ion transport. The fabricated flexible and scalable membrane exhibits high tensile strength (∼115.3 MPa) even after immersion in water for 90 days. Further, the aramid nanofiber/graphite conductor features the surface-charge-governed ion transport behavior. The ionic conductivity of the membrane at a low potassium chloride concentration of 10−4 mol/L can be enhanced by 16 times that of the bulk counterpart. More importantly, its structure and ionic conductivity remain unchanged even after immersion in different harsh solutions (e.g., acid, base, and ethanol) for over 30 days. Molecular dynamics simulations reveal that the superstability of the membrane is attributable to the robust interchain interactions within the aramid nanofibers and the strong interfacial interactions between the aramid nanofibers and graphite nanosheets. This study highlights the superior structural stability of the proposed flexible and scalable aramid nanofiber/graphite composite membrane, which could be employed in advanced nanofluidic devices for application under extreme working environments.

Selenized Binary Transition Metals-Mxene Composite for the High-Performance Asymmetric Supercapacitors

The exploration of novel and efficient energy storage materials is crucial for the development of high-performance supercapacitors. Herein, we develop a new composite with multilayered MXene (Ti3C2Tx) nanoparticles and porous NiCo2Se4 nanosheets. The unique accordion-like nanostructure and strong interfacial interactions of MXene introduce the favorable nanocomposite with a larger surface area and reasonable cycling stability. The substitution of Se for the oxyhdryl in the Ni-Co based hydroxides modulates the orbital hybridization with the corresponding metallic cations, which effectively improves the electrochemical activity of Ni/Co and reduces the adsorption/desorption energy barrier of electrolyte ions. Based on the above considerations, we proposed a new Ni-Co TMSe and multilayer Ti3C2Tx MXene nanocomposite on NF (denoted as MXene-NiCo2Se4@NF) that could act as a binder-free electrode for SCs. In this regard, compared with the directly grown pure NiCo2Se4 electrode, the composite electrode exhibits a larger surface area, higher mass-loading, and lower internal resistance by the introduced MXene particles. The well-designed hierarchical structures make it possible for facilitated electrolyte diffusion, more active sites, fast electron transport, and improved nanostructure stability for a longer lifespan. Owing to such multifold attributes, the fabricated composite electrodes enable to attain a specific capacity of 786.25 C/g and 589.22 C/g at the current density at 1 A/g and 20 A/g with a good rate capability, respectively. The selenization improved the inherent conductivity of active materials and contributed to the lower deprotonation energy barrier, resulting in facile electron transfer in the Faradaic reaction process. Furthermore, the composite structure retained over 90% of capacity after 8000 cycles. The assembled asymmetrical device displays a high specific energy density of 64.36 Wh/kg, at a power density of 0.8kW/kg. These results suggest that the proposed composite structure can potentially be used as active material in various practical applications.

High-performance zinc-ion batteries cathode material ZnMn2O4 modified by polypyrrole and reduced graphene oxide

Spinel zinc manganate has great prospects due to its advantages of a high voltage platform, non-toxicity, low cost, and abundant resources as a cathode material for ZIBs. However, its inherent poor conductivity and unsatisfactory long-term cyclic stability seriously restrict its commercial applications. Herein, the highly conductive polymer polypyrrole-coated ZnMn2O4 nanoparticles anchored on reduced graphene oxide with strong interfacial interaction (ZMO/rGO-PPy composite) were successfully synthesized. Compared with the pure ZnMn2O4 nanoparticles, ZMO/rGO-PPy composite displays increased conductivity of 3.89 × 103 S m−1 and higher discharge capacity of 269.6 mAh g−1 at 0.2 A g−1, as well as better rate capability and long-term cycling stability (after 900 cycles at a high current density of 1 A g−1 the specific capacity remains at 147.4 mAh g−1, with a capacity retention rate of 88.7%). The excellent performance is attributed to the shortened ion diffusion pathway, improved electrical conductivity and good structure stability. Furthermore, electrochemical analyses reveal that favorable reaction kinetics towards efficient zinc ion storage is achieved in the composite. These results suggest ZMO/rGO-PPy composites could be a competitive cathode material for ZIBs.

Self-Assembled 2D VS2 /Ti3 C2 Tx MXene Nanostructures with Ultrafast Kinetics for Superior Electrochemical Sodium-Ion Storage.

Constructing nanostructures with high structural stability and ultrafast electrochemical reaction kinetics as anodes for sodium-ion batteries (SIBs) is a big challenge. Herein, the robust 2D VS2 / Ti3 C2 Tx MXene nanostructures with the strong Ti─S covalent bond synthesized by a one-pot self-assembly approach are developed. The strong interfacial interaction renders the material of good structural durability and enhanced reaction kinetics. Meanwhile, the enlarged and few-layered MXene nanosheets can be easily obtained according to this interaction, providing a conductive network for sufficient electrolyte penetration and rapid charge transfer. As predicted, the VS2 /MXene nanostructures exhibit an extremely low sodium diffusion barrier confirmed by DFT calculations and small charge transfer impedance evidenced by electrochemical impedance spectroscopy (EIS) analysis. Therefore, the SIBs based on the VS2 /MXene electrode present first-class electrochemical performance with the ultrahigh average initial columbic efficiency of 95.08% and excellent sodium-ion storage capacity of 424.6mAhg-1 even at 10Ag-1 . It also shows an outstanding sodium-ion storage capacity of 514.2mAhg-1 at 1Ag-1 with a capacity retention of nearly 100% within 500 times high-rate cycling. Such impressive performance demonstrates the successful synthesis strategy and the great potential of interfacial interactions for high-performance energy storage devices.

Tuning the Dynamic Properties of Epoxy Vitrimers via Bioinspired Polymer-Nanoparticle Bond Dynamics.

In this work, Fe3O4 nanoparticles anchored with dopamine molecules were developed via bioinspired iron-catechol coordination interactions, and the dopamine-modified Fe3O4 surface was linked to the matrix through strong interfacial interactions between the nanoparticles and the epoxy vitrimer. Results showed that the typical dynamic parameters of vitrimer could be readily adjusted in the epoxy vitrimer composites. These findings demonstrate that it is efficient to adjust the dynamic properties of vitrimers by introducing the metal-coordination bonds into epoxy vitrimer networks. The synergy of metal-catechol coordination and transesterification enriched the mechanism of dynamic regulation. In addition, the epoxy vitrimer composites were responsive to temperature and near-infrared light. The scratch could be successfully healed with 1 min on the surface of vitrimer composites under NIR irradiation even for the 1% addition of Fe3O4 nanoparticles. This approach shows potential to be generally applicable to different types of metal-coordination systems.

Bio-derived phosphorous-nitrogen-silicon decorated halloysite nanotube towards enhancing flame retardant, UV-blocking and mechanical properties of poly(lactic acid)

Developing flame retardant and UV-blocking polylactide (PLA) with reinforced mechanical properties is important but challenging. Herein, bio-derived phytic acid was decorated on halloysite nanotube though silane grafting, ring-opening reaction with melamine and then electrostatic interactions with phytic acid. The obtained phopsphorous-nitrogen-silicon decorated halloysite nanotube (PNSiHNT) was incorporated into PLA to prepare PLA composites. The surface modification significantly improved the compatibility between PNSiHNT and PLA, and the flame retardant, UV-shielding and mechanical properties of the composites were enhanced. At 5% mass loading, the peak heat release and total heat release were reduced by 18% and 12% compared to pure PLA, respectively, superior to most phytic acid-based flame retardants. The relevant mechanism analysis showed that PNSiHNT can restrain the emission of combustible volatiles and promote the formation of protective char layer. Moreover, the flame-retardant PLA showed excellent UV-shielding ability with an ultraviolet protection factor (UPF) value of around 120. Due to the reinforcing effect of PNSiHNT and the strong interfacial interactions between PNSiHNT and PLA matrix, the PLA/PNSiHNT showed 77% and 116% increase in tensile strength and elongation at break compared to the bulk PLA. This study provides a strategy for designing bio-derived organic/inorganic systems for enhancing flame retardant, UV-blocking and reinforced PLA.

Balancing the Strength-Impact Relationship and Other Key Properties in Polypropylene Copolymer-Natural CaSO4 (Anhydrite)-Filled Composites.

To develop novel mineral-filled composites and assess their enhanced properties (stiffness, a good balance between mechanical strength and impact resistance, greater temperature stability), a high-impact polypropylene copolymer (PPc) matrix containing an elastomeric discrete phase was melt mixed with natural CaSO4 β-anhydrite II (AII) produced from gypsum rocks. First, in a prior investigation, the PPc composites filled with AII (without any modification) displayed enhanced stiffness, which is correlated with the relative content of the filler. The tensile and impact strengths dramatically decreased, especially at high filling (40 wt.%). Therefore, two key methods were considered to tune up their properties: (a) the ionomeric modification of PPc composites by reactive extrusion (REx) with zinc diacrylate (ZA), and (b) the melt mixing of PPc with AII surface modified with ethylenebis(stearamide) (EBS), which is a multifunctional processing/dispersant additive. The properties of composites produced with twin-screw extruders (TSEs) were deeply assessed in terms of morphology, mechanical, and thermal performance, including characterizations under dynamic mechanical solicitations at low and high temperatures. Two categories of products with distinct properties are obtained. The ionomeric modification by Rex (evaluated by FTIR) led to composites characterized by remarkable thermal stability, a higher temperature of crystallization, stronger interfacial interactions, and therefore noticeable mechanical properties (high tensile strength (i.e., 28 MPa), increased stiffness, moderate (3.3 kJ/m2) to good (5.0 kJ/m2) impact resistance) as well as advanced heat deflection temperature (HDT). On the other hand, the surface modification of AII with EBS facilitated the dispersion and debonding of microparticles, leading to composites revealing improved ductility (strain at break from 50% to 260%) and enhanced impact properties (4.3-5.3 kJ/m2), even at high filling. Characterized by notable mechanical and thermal performances, high whiteness, and a good processing ability, these new PPc-AII composites may be tailored to meet the requirements of end-use applications, ranging from packaging to automotive components.

A theoretical chemistry framework to unravel the monolayer adsorption of geogenic anions on UiO-66 and ZIF-8 organometallic structures

The arsenic and fluoride adsorption equilibria of UiO-66 and ZIF-8 organometallic structures were analyzed and interpreted. Experimental isotherms were quantified at 20–40 °C and pH 7 for both geogenic pollutants. Density functional theory and statistical physics simulations were carried out to explain and characterize the interfacial interaction forces for the adsorption of these toxic geogenic anions. The adsorption properties of UiO-66 were superior to those of ZIF-8 for both geogenic anions. The maximum fluoride and arsenic adsorption capacities were 4.3 and 2.8 mmol/g, respectively. The best adsorption of fluoride and arsenic was obtained using UiO-66 at 20 °C and pH 7. These MOFs showed adsorption capacities up to double those reported for several adsorbents used in the depollution of water containing these geogenic pollutants. The adsorption of arsenic and fluoride on ZIF-8 structure was endothermic (16–31 kJ/mol), while the removal of both pollutants using UiO-66 MOF was exothermic (−26 – −41 kJ/mol). This adsorption behavior was associated with the presence of a multi-anionic mechanism for both arsenic and fluoride on ZIF-8 surface. On the other hand, a double monodentate interaction was found for the arsenic adsorption on the external UiO-66 surface due to steric restrictions for mass transfer, while the fluoride adsorption corresponded mainly to a mono-anionic interaction where the internal pore diffusion played a relevant role. The calculated energies for fluoride adsorption were higher than those obtained for arsenic removal indicating stronger interfacial interactions. These results demonstrate the promising potential of these MOF structures for developing cost-effective water treatment processes to remove arsenic and fluoride from groundwater.

Soy protein isolate/kappa-carrageenan/cellulose nanofibrils composite film incorporated with zenian essential oil-loaded MOFs for food packaging

Edible films applied in food packaging must possess excellent inhibitory and mechanical properties. Protein-based films exhibit a high capacity for film formation and offer good gas barrier properties. However, they have weak mechanical and water barrier characteristics. The objective of this research was to develop active composite films based on reinforced soy protein isolate (SPI)/Kappa-carrageenan (K) with varying concentrations of bacterial cellulose nanofibrils (BCN). Increasing the BCN concentration improved the morphological, structural, mechanical, water vapor barrier, and moisture content properties. In comparison to the pure SPI film (S), the film with a high BCN concentration demonstrated a significant decrease in WS (22.98 ± 0.78 %), MC (21.72 ± 0.68 %), WVP (1.22 ± 0.14 g mm-1 S-1 Pa-1 10-10), and EAB (57.77 ± 5.25 %) properties. It should be emphasized that there was no significant alteration in the physicomechanical properties of the optimal film (SKB0.75) containing Zenian-loaded metal-organic frameworks (ZM). However, it substantially enhanced the thermal stability of this film, which can be attributed to the strong interfacial interactions between polymer chains and ZM. Furthermore, the ZM films inhibited the growth of pathogenic bacteria and increased the DPPH antioxidant activity. Thus, SKB0.75-ZM2 films can be utilized as practical components in food packaging.

Methoxy management of side chains on the carbazole-diphenylamine derivatives based hole transport materials for perovskite solar cells: A theoretical design and experimental research

Molecular design is the important approach for realizing the improvement of performance for hole transport materials (HTMs) in perovskite solar cells (PSCs). In this work, starting from the carbazole-diphenylamine derivatives based HTMs, three molecules (CX1-CX3) are designed through methoxy management on the side chains. The calculated results indicated that CX1-CX3 yield different molecular arrangements through methoxy management on the side chains, resulting in adjusting the intermolecular coupling strength and hole transport capabilities. In comparison with the designed CX2 and CX3, CX1 exhibits a higher hole mobility, stronger interfacial interactions and more efficient charge transfer at perovskite/HTMs interface. Hence, under the same conditions, PSC devices based on CX1 yields a PCE of 22.13% higher than those of other molecules CX2 (20.96%) and CX3 (19.72%). These findings highlight the significance of methoxy management on the side chains in HTMs for the photovoltaic performance of PSCs, and reveal the potential of molecular engineering for the design of efficient HTMs.

Size transformation of Au nanoclusters for enhanced photocatalytic hydrogen generation: Interaction behavior at nanocluster/semiconductor interface

Recently, atomically precise metal nanoclusters (NCs) become a new class of photosensitizer for light energy conversion in metal-cluster-sensitized semiconductor (MCSS) system. However, fundamental understanding for the suitable combination of NCs and semiconductor is still unclear. Aside from aspects of light harvesting, energy level alignment and catalytic activity, interfacial interaction behavior at NCs/semiconductor interface is also crucial due to its important influence in charge transportation. In this work, the interface interaction between Au NCs and TiO2 is examined by precise transformation of Au NCs from Au22(SG)18 to Au18(SG)14, as well as its effect on photocatalytic hydrogen production activity. From the optical, charge transport and solid-states spectroscopy analyses, it is able to display that precisely tuning the number of core atoms from Au22(SG)18 to Au18(SG)14 results in the strong interface interaction between Au NCs and TiO2, reflecting in high difference of work function and modified surface band bending of TiO2, therefore promoting the injection of electrons from NCs to TiO2 and reducing interfacial charges recombination. As a result, Au18(SG)14/TiO2 shows higher hydrogen generation rate than Au22(SG)18/TiO2 under light irradiation. This work would provide new insights into rational combination of metal NCs with semiconductor and highlights the overlooked effect of interfacial interaction behavior on light energy conversion.

Enhanced catalytic ozonation performance by CuOx nanoclusters/TiO2 nanotube and an insight into the catalytic mechanism

Highly reactive nanoclusters of metal oxides are extremely difficult to be synthesized due to their thermodynamic instability. For the first time, CuOx nanoclusters supported on anatase TiO2 nanotubes (NT) with many defects as anchoring sites were successfully prepared. Although the copper loading reached as high as 2.5 %, the size of CuOx nanoclusters in the sample of 2.5 %CuOx/NT were mainly around 1.0 nm. The aggregation of copper species during the calcination process was undoubtedly hampered by the anchoring effects of the abundant defects in NT support. Due to the highly exposed undercoordinated atoms of CuOx nanoclusters, the mixed valences of copper, and the strong interface interaction between CuOx nanoclusters and NT support, 2.5 %CuOx/NT-catalyzed ozonation showed the highest pseudo-first-order reaction rate constant of 8.5 × 10−2 min−1, 2.2 and 4.0 times that of NT-catalyzed ozonation and ozonation alone, respectively. Finally, the catalytic mechanism was revealed by both experiments and density functional theory calculations (DFT). The results demonstrated that the undercoordinated Cu in CuOx/NT could highly promote the adsorption of ozone with a high adsorption energy of −125.16 eV and the adsorbed ozone was activated immediately, tending to dissociate into a O2 molecule and a surface O atom. Thus, abundant reactive oxygen species, e.g., hydroxyl radical (·OH), superoxide radical (·O2–) and singlet oxygen (1O2), could be generated via chain reactions. Especially, ·OH mainly contributed to the removal of ibuprofen pollutants. This work sheds a light on the design and preparation of highly reactive nanoclusters of metal oxide catalysts for catalytic ozonation of refractory organic pollutants.

Enhancing the Electrical Conductivity and Strength of PET by Single-Wall Carbon Nanotube Film Coating.

Single-wall carbon nanotubes (SWCNTs) with excellent physicochemical properties are considered a promising candidate for the electrical and mechanical reinforcements of polymers. However, the poor dispersion of SWCNTs in plastics seriously limits their application and their achieved performance enhancement. Here, we coat a freestanding, highly conductive SWCNT film onto the surface of a polyethylene terephthalate (PET) film by a hot-pressing method. Due to the uniform SWCNT network structure and strong interfacial interaction, the SWCNT/PET hybrid film showed notably enhanced electrical and mechanical properties even though with a very low SWCNT weight fraction of 0.066%. The surface square resistance of the SWCNT/PET film decreased to 120-140 Ω/□ from 1016 Ω. In addition, Young's modulus and tensile strength of the SWCNT/PET film reached 4.6 GPa and 148 MPa, which are 31.3 and 24.4%, respectively, higher than the pure PET film. The SWCNT/PET film shows excellent mechanical durability and thermal stability, demonstrating its potential use as an antistatic material.

Improved proton conductivity and mechanical performance of phosphoric acid doped aminated PAF-1 reinforced OPBI for high temperature proton exchange membranes

High-temperature proton exchange membranes (HT-PEMs) doped with phosphoric acid (PA) can achieve high proton conduction at high phosphoric acid doping level (ADL). However, polybenzimidazole (PBI) membranes have problems with PA loss, poor mechanical properties, and other issues at high ADL. Herein, PAF-1-NH2 was obtained through an amination of porous aromatic frameworks with an ultrahigh specific surface area (PAF-1), and APAF-1 was prepared by vacuum injection of PA on PAF-1-NH2 to increase the ADL through the high basic site amount and specific area. APAF-1/OPBI composite HT-PEMs was prepared by solution casting method. The composite membrane maintained superior mechanical properties, high proton conductivity and low dimensional swelling ratio (166.2%) even with a high PA doping rate (328.5%), due to the rigid structure of APAF-1 and the strong interfacial interaction between APAF-1 and OPBI. The mechanical strength and proton conductivity of the 10%APAF-1/OPBI were 20.86 MPa and 0.107 S cm−1 at 200 °C, respectively, which was about 2.43 times that of the OPBI membrane (0.044 S cm−1). When the catalyst Pt dosage was only 0.3 mg cm−2, the peak power density of the H2/O2 fuel cell at 180 °C was 366.6 mW cm−2. Therefore, this work presented a new approach for preparing HT-PEMs with excellent comprehensive properties.

Study on the evolution of impermeability and mechanical properties of epoxy composite coatings

AbstractThe permeation of marine water can lead to severe degradation of the protective properties of polymer composite coatings. At present, experimental studies on the anticorrosive and mechanical properties of polymer composite coatings are relatively mature, but the impermeability and mechanical property changes of the coating during the permeation process are challenging tasks to be studied only by experiments. In this paper, molecular dynamics (MD) models of composite coatings consisting of pure epoxy resin (EP), graphene/epoxy resin (Gr/EP), and graphene oxide/epoxy resin (GO/EP) were constructed respectively. MD simulations were performed to reveal the impermeability and mechanical property changes of composite coatings from an atomic perspective. The results show that GO has strong interfacial interaction with EP and the best effect to enhance the impermeability and mechanical properties of epoxy coatings. NaCl solutions can damage the coating microstructure and occupy the Gr and GO surfaces, causing them to no longer have an enhancing effect. The study of GO/EP coatings with different permeation degrees shows that the mechanical properties of the coating decrease as the penetration degree increases.

A simple surface engineering to develop the potential of carbon nitride nanosheets in high-performance polymer nanocomposites conducted by first-principles calculations

The incompatible interface between carbon nitride (CN) nanosheets and polymer resin is a huge challenge to develop high-performance polymer/CN nanocomposites. Recently, the complicated surface functionalization methods reported severely hinder the commercial production and practical application of polymer/CN nanocomposites. Herein, conducted by the first-principles calculations, a simple surface engineering is put forward to change the surface characteristic of CN nanosheets by rapidly introducing oxygen atoms with a chemical oxidation method. Presented by the first-principles calculations, it is found that the introduction of oxygen atoms can enhance the adsorption energy between oxygen-doping carbon nitride nanosheets (OCN) and waterborne polyurethane (WPU) resin. As a result, a stronger interfacial interaction and better dispersion state are presented in WPU/OCN nanocomposites, thus laying the foundation for the properties enhancement. Further, effective suppression effects for thermal pyrolysis and fire hazards of WPU resin are demonstrated by OCN nanosheets. As presented by cone calorimeter results, the peak values of heat release rate and total heat release in WPU/OCN-2 are decreased to 806 kW/m2 and 43.3 MJ/m2, significantly less than those of pure WPU (1028 kW/m2 and 55.9 MJ/m2). Meanwhile, more char residue, lower signal intensity of pyrolysis gas, and a prolonged time for signal peak also confirm that the addition of 2.0 wt% OCN nanosheets can hinder the thermal degradation behavior of WPU resin. In addition, the introduction of oxygen atoms promotes the formation of hydrogen bond interactions between OCN nanosheets and WPU matrix, thus enhancing interfacial compatibility and overcoming the re-stack problem. As a result, break strength and elongation at break of WPU/OCN-2 are up to 621% and 24.4 MPa, respectively. The combination of first-principles calculations and surface engineering opens a new approach for designing and developing high-performance polymer nanocomposites.

Self-introduction of carbon nitride quantum dots into carbon nitride planar structure for enhanced photocatalytic hydrogen production

The separation efficiency and migration rate of photogenerated carriers are important factors determining the activity of photocatalysts. In this work, CN/CNQDs were prepared by self-introducing carbon nitride quantum dots (CNQDs) into the planar structure of carbon nitride (CN) using a novel photo-triggered self-assembly strategy. Different from conventional interfacial modification strategies based on van der Waals forces or hydrogen bonding, CN/CNQDs atomic junctions formed chemical bonds between the two components, which have stronger interfacial interactions and facilitate efficient carrier migration between the two components. The continuous π-conjugated structure of CN/CNQDs also provided unique conditions for carrier migration. In addition, the presence of in-plane electric field (IEF) in CN/CNQDs acted as a direct driving force for the migration of electrons and holes in the opposite directions, which greatly facilitates the separation and transfer of photogenerated carriers in CN/CNQDs. This work provides an atomic-level strategy for the construction of heterojunction photocatalyst systems.

Visible light-assisted hydrogen generation from ammonia borane over Z-Scheme NiO-CuO heterostructures

The design and fabrication of cheap and high-efficiency catalysts for ammonia borane (AB) hydrolysis for hydrogen production is crucial for its commercial applications. Improvement of the catalytic performance of the catalysts with the assistance of sunlight, a costless resource, is extremely attractive. Herein, we have constructed Z-scheme heterostructured VO-NiO-CuO catalysts with strong interfacial electronic interactions and abundant oxygen vacancies to enhance hydrogen production from NH3BH3 solution under visible light illumination. The as-prepared VO-NiO-CuO catalysts exhibit excellent catalytic activity with a high turnover frequency (TOF) of 35.3 molH2 molcat.-1 min−1 toward AB hydrolysis under visible light. It is demonstrated that excellent catalytic performance is highly related to the effective separation and migration of charge on the catalyst surface. As a result, dual active sites were created, making it easier for various reactants to be adsorbed and activated on the catalyst surface. Furthermore, the density functional theory (DFT) calculations indicate that the adsorption and activation of H2O occurred mainly at the Ni site of VO-NiO-CuO. When the VO-NiO-CuO is irradiated with visible light, the photogenerated electrons assembled on the conduction band were transferred to the O atom through the Ni-O bond, which made the bond length of H2O molecules longer and OH bonds more prone to breaking, thus facilitating AB hydrolysis under illumination. The findings in this work pave the way to design novel and efficient heterostructured catalysts for fast hydrogen release from NH3BH3 under visible light irradiation.