Hydrophilic Pores Research Articles

Hydrophilic-hydrophobic heterogeneous interface enables the formation of a high-performance polyamide membrane for water purification

Polyamide reverse osmosis (RO) membranes possessing high water permeance and high salt rejection are highly beneficial for efficient desalination and wastewater treatment. However, achieving desired membrane properties toward both fast water transport and outstanding salt rejection remains a great challenge. Herein, we report the fabrication of high-performance polyamide RO membrane via interfacial polymerization (IP) on a heterogeneous substrate featuring a hydrophobic surface and polyaniline modified hydrophilic pores. The heterogeneous substrate, combining the advantages of conventional hydrophilic and hydrophobic substrates for IP process, leads to the formation of an ultra-thin polyamide film with rough morphology. The obtained RO membranes thereby not only have simultaneously enhanced water permeance (3.28 L m−2h−1 bar−1) and salt rejection (NaCl rejection 99.5 %), but also exhibit outstanding pH stability, anti-fouling performance, and long-term stability. In addition, the regulation mechanism of the heterogeneous substrate on IP was comprehensively investigated by combing molecular simulation and experiments. Our work provides a novel design direction of substrate used for fabricating RO membrane with outstanding performance.

Porous Antimicrobial Coatings for Killing Microbes within Minutes

Antimicrobial coatings can be used to reduce the transmission of infectious agents that are spread by contact. An effective coating should kill microbes in the time between users, which is sometimes minutes or less. Fast killing requires fast transport, and our proposed method of fast transport is a porous coating where the contaminated liquid imbibes (infiltrates) into the pores to achieve rapid contact with active material inside the pores. We test the hypothesis that a porous antimicrobial coating will enable faster inactivation of microorganisms than a planar coating of the same material. We use hydrophilic pores with dimensions of 5-100 μm such that liquid droplets imbibe in seconds, and from there transport distances and times are short, defined by the pore size rather than the droplet size. Our coating has two levels of structure: (A) a porous scaffold and (B) an antimicrobial coating within the pore structure containing the active ingredient. Two scaffolds are studied: stainless steel and poly(methyl methacrylate) (PMMA). The active ingredient is electrolessly deposited copper. To enhance adhesion and growth of copper, a layer of polydopamine (PDA) is deposited on the scaffold prior to deposition of the copper. This porous copper coating kills 99.84% of Pseudomonas aeruginosa within 3 min, which is equivalent to a half-life of 27 s. In contrast, the same layer of PDA/copper on a nonporous coating kills 79.65% in the same time frame, consistent with the hypothesis that the killing rate is increased by the addition of porosity. Using the porous PMMA scaffold, the porous antimicrobial coating kills >99.99% P. aeruginosa in 5 min, which is equivalent to a half-life of 21 s. The higher rate of kill on the porous antimicrobial solid is appropriate for hindering the spread of infectious agents on common-use objects.

Nanoparticle-Enhanced PVDF Flat-Sheet Membranes for Seawater Desalination in Direct Contact Membrane Distillation

In this study, hydrophobic functionalized carbon nanotubes (fCNTs) and silica nanoparticles (fSiO2NPs) were incorporated into polyvinylidene fluoride (PVDF) flat-sheet membranes to improve their performance in membrane distillation (MD). The performance of the as-synthesized membranes was evaluated against commercial reference polytetrafluoroethylene (PTFE) flat-sheet membranes. The water contact angle (WCA) and liquid entry pressure (LEP) of the PVDF membrane were compromised after incorporation of hydrophilic pore forming polyvinylpyrrolidone (PVP). These parameters were key in ensuring high salt rejections in MD processes. Upon incorporation of fCNTS and fSiO2NPs, WCA and LEP improved to 103.61° and 590 kPa, respectively. Moreover, the NP additives enhanced membrane surface roughness. Thus, an increase in membrane roughness improved WCA and resistance to membrane wetting. High salt rejection (>99%) and stable fluxes (39.77 kg m-2 h-1) were recorded throughout a 3 h process evaluation where 3.5 wt% NaCl solution was used as feed. These findings were recorded at feed temperature of 60 ℃. Evidently, this study substantiated the necessity of high feed temperatures towards high rates of water recovery.

Integrated interfacial design of covalent organic framework photocatalysts to promote hydrogen evolution from water

Attempts to develop photocatalysts for hydrogen production from water usually result in low efficiency. Here we report the finding of photocatalysts by integrated interfacial design of stable covalent organic frameworks. We predesigned and constructed different molecular interfaces by fabricating ordered or amorphous π skeletons, installing ligating or non-ligating walls and engineering hydrophobic or hydrophilic pores. This systematic interfacial control over electron transfer, active site immobilisation and water transport enables to identify their distinct roles in the photocatalytic process. The frameworks, combined ordered π skeletons, ligating walls and hydrophilic channels, work under 300–1000 nm with non-noble metal co-catalyst and achieve a hydrogen evolution rate over 11 mmol g–1 h–1, a quantum yield of 3.6% at 600 nm and a three-order-of-magnitude-increased turnover frequency of 18.8 h–1 compared to those obtained with hydrophobic networks. This integrated interfacial design approach is a step towards designing solar-to-chemical energy conversion systems.

A fluorescent N-doped carbon dot-hydrogel composite for concurrent selective detection and local hot spot promoted adsorption of uranium(vi)

N-doped carbon dot-embedded cellulose-based fluorescent hydrogel composite (CMH–NCDs) with 3D hydrophilic hierarchical pore network and confined convection exhibited concurrent selective detection and adsorption of uranium(vi) from nuclear water.

Study on boron removal performance of covalent organic skeleton membrane by hydroxyl groups

Growing demand for water desalination promoted the vigorous development of reverse osmosis (RO) membrane. How to effectively remove boron from seawater is the key problem to be solved by RO membrane. It is important to select suitable membrane materials for experimental design before complicated and expensive experimental attempts. In this paper, we demonstrate that pore chemistry plays a key role in boron removal capability of RO membranes via nonequilibrium molecular dynamics simulations. This study shows that the introduction of hydroxyl (-OH) groups into the Covalent organic frameworks (COFs) pore allows for better boron removal without changing water permeability. The optimal boron rejection of AB-COF membranes is 76.67%, and that of ATFG-COF membranes with hydroxyl groups can achieve 90%. This is caused by the hydrophilic pore of ATFG-COF that will preferentially adsorb water molecules to prevent the passage of boric acid molecules through membrane zone. Additionally, -OH groups on the pore will also adsorb a part of boric acid in the membranes, reducing the amount of boric acid entering into the permeate side. The results obtained in this paper can provide guidance for the rational design of RO membranes to achieve more efficient boron removal.

Multistage Activation of Anthracite Coal-Based Activated Carbon for High-Performance Supercapacitor Applications

An anthracitic coal-derived activated porous carbon is proposed as a promising carbon electrode material for supercapacitor (SC) applications. The specific capacitance of this activated carbon SC electrode is related to the characteristics, such as specific surface area, pore size distribution, wettability, and conductivity. In the present work, a series of anthracite-based activated carbons (ABAC) were prepared via a multistage activation process and used as electrode materials for SCs. The multistage activation experiment was developed by exploring different activation temperatures, precursor/activating agent mass ratios, and process treating environments. The electrochemical performance of ABACs was evaluated in a three-electrode testing system. Multiple electrolytes were utilized, such as 1 M sulfuric acid (H2SO4) and 1 and 6 M potassium hydroxide (KOH) solutions. An optimum ABAC electrode was obtained, characterized by its largest wettability and superior conductivity, and achieved excellent electrochemical performance. The three-electrode system exhibited a specific capacitance of 288.52 and 260.30 F/g at 0.5 A/g in the 1 M H2SO4 and 6 M KOH electrolytes, respectively. It was found that moderate multistage activation temperatures are beneficial for the electrolyte uptake which enhances the specific capacitance. The high content of the oxygen functional groups on the activated carbon surface greatly improved its specific capacitance due to the increase in wettability. In the 1 M H2SO4 electrolyte, the working electrode exhibited better performance than in 1 M KOH because the ion diameter in the acidic electrolyte was more suitable for pore diffusion. The concentrated KOH electrolyte leads to an increase in specific capacitance due to increased ions being adsorbed by a certain number of the hydrophilic pores. Moreover, the specific capacitance of the optimum ABAC sample remained at 95.4% of the initial value after 1000 galvanostatic charge–discharge tests at 0.5 A/g, which is superior to the performance of SC grade commercial carbon.

Molecular dissolution behaviors on porous membrane surface using hierarchical metal–organic framework lamellar membrane

AbstractLamellar membranes, especially assembled by microporous framework nanosheets, have excited interest for fast molecular permeation. However, the underlying molecular dissolution behaviors on membrane surface, especially at pore entrances, remain unclear. Here, hierarchical metal–organic framework (MOF) lamellar membranes with 7 nm‐thick surface layer and 553 nm‐thick support layer are prepared. Hydrophilic (–NH2) or hydrophobic (–CH3) groups are decorated at pore entrances on surface layer to manipulate wettability, while –CH3 groups on support layer provide comparable, low‐resistance paths. We demonstrate that molecular dissolution behaviors are determined by molecule–molecule and molecule–pore interactions, derived from intrinsic parameters of molecule and membrane. Importantly, two dissolution model equations are established: for hydrophobic membrane surface, dissolution activation energy (ES) obeys ES = Kmln[(γL‐γC)μd2], while turns to ES=Kaln[(γL‐γC)δeμd2] for hydrophilic one. Particularly, hydrophilic pore entrances exert strong interaction with polar molecules, thus compensating the energy consumed by molecule rearrangement, giving fast permeation (>270 L m−2 h−1 bar−1).

Treatment of cervical cancer by electrochemotherapy with bleomycin, cisplatin, and calcium: an in vitro experimental study.

Low-dose chemotherapy in advanced stages of cancer does not give a positive response in treatment. The use of high-dose antineoplastic drugs creates significant side effects. The limiting situation in treatment creates a need for new generation drugs with less side effects and new treatment methods that will enable low-dose drug use. Electroporation (EP), a phenomenon, is a technique in which the membrane permeability is increased by the establishment of hydrophilic pores in the cell membrane with short and high-voltage electrical pulses. In the present investigation study, we aimed to inspect the effects of EP plus bleomycin, cisplatin, and calcium administration (CaEP) on cell viability, apoptotic activity, gene expression p53, Bax/Bcl-2 rate mitochondrial membrane potential (ΔΨm), and cell cycle in HeLa cervical cancer cell line. The permeabilization of the membrane was evaluated in flow cytometry with the PI method, and cell viability was measured in an ELISA reader with the WST-8 method. For bleomycin and cisplatin doses applied to HeLa cells, the concentration values (IC50) that inhibited 50% of the cells were found to be 214.11 ± 4.7µM and 35.16 ± 3.3µM, respectively. The IC50 values of the groups administered together with EP were calculated as 0.44 ± 0.3µM for bleomycin and 20.55 ± 4.3µM for cisplatin. There was no change in cell viability in calcium alone application, but a statistically notable reduction in cell vitality was observed in CaEP application. An increase in ΔΨm was found in bleomycin and CaEP exposure with EP. It was determined that EP exposure caused G0/G1 arrest in the cell cycle at all electric field intensities. It was determined that EP application in HeLa cells increased bleomycin cytotoxicity 487 times and cisplatin cytotoxicity 1.71 times, and CaEP could be an alternative treatment method.

Synthesis and characterization of porous reduced graphene oxide based geopolymeric membrane with titanium dioxide coating for forward osmosis application

Forward Osmosis (FO) is a promising separation technology with a wide range of applications in water and wastewater treatment. FO membrane is the core of the forward osmosis process. Recently, the organic membrane has been widely used for forward osmosis applications even though inorganic membrane has excellent mechanical properties, decent chemical resistance, high durability, high porosity, and good hydrophilicity. Nevertheless, the utilization of inorganic membrane is hindered by the heat-intensive steps involved in its fabrication and the use of expensive source material. Geopolymerization provides a cost-effective technique for the preparation of inorganic membranes because of its sintering-free steps and utilization of fly ash as source material. Herein, we present a sintering-free, environmentally friendly, and cost-effective synthesis of geopolymeric membrane for application in forward osmosis. Fly ash was mixed with alkaline activator solution and porous reduced graphene oxide (PRGO) to prepare geopolymer slurry. The hydrogen peroxide and egg albumen were used as foaming agent and surfactant, while the membrane surface was coated with titanium dioxide to enhance the hydrophilicity of the membrane surface. The PRGO content improved the mechanical properties of the geopolymeric membrane. The average maximum flux recorded was 21 L/m2 h with geopolymer substrate having a pore size of 1.8 μm and hydrophilic coated layer pore size of 0.25 μm. The varying concentrations of PRGO control the substrate's mechanical properties and pore size, as well as provide new insights for future studies. These preliminary results show that low-cost geopolymer material is a promising candidate for FO membrane fabrication.

Requirement of a functional ion channel for Sindbis virus glycoprotein transport, CPV-II formation, and efficient virus budding.

Many viruses encode ion channel proteins that oligomerize to form hydrophilic pores in membranes of virus-infected cells and the viral membrane in some enveloped viruses. Alphavirus 6K, human immunodeficiency virus type 1 Vpu (HIV-Vpu), influenza A virus M2 (IAV-M2), and hepatitis C virus P7 (HCV-P7) are transmembrane ion channel proteins that play essential roles in virus assembly, budding, and entry. While the oligomeric structures and mechanisms of ion channel activity are well-established for M2 and P7, these remain unknown for 6K. Here we investigated the functional role of the ion channel activity of 6K in alphavirus assembly by utilizing a series of Sindbis virus (SINV) ion channel chimeras expressing the ion channel helix from Vpu or M2 or substituting the entire 6K protein with full-length P7, in cis. We demonstrate that the Vpu helix efficiently complements 6K, whereas M2 and P7 are less efficient. Our results indicate that while SINV is primarily insensitive to the M2 ion channel inhibitor amantadine, the Vpu inhibitor 5-N, N-Hexamethylene amiloride (HMA), significantly reduces SINV release, suggesting that the ion channel activity of 6K similar to Vpu, promotes virus budding. Using live-cell imaging of SINV with a miniSOG-tagged 6K and mCherry-tagged E2, we further demonstrate that 6K and E2 colocalize with the Golgi apparatus in the secretory pathway. To contextualize the localization of 6K in the Golgi, we analyzed cells infected with SINV and SINV-ion channel chimeras using transmission electron microscopy. Our results provide evidence for the first time for the functional role of 6K in type II cytopathic vacuoles (CPV-II) formation. We demonstrate that in the absence of 6K, CPV-II, which originates from the Golgi apparatus, is not detected in infected cells, with a concomitant reduction in the glycoprotein transport to the plasma membrane. Substituting a functional ion channel, M2 or Vpu localizing to Golgi, restores CPV-II production, whereas P7, retained in the ER, is inadequate to induce CPV-II formation. Altogether our results indicate that ion channel activity of 6K is required for the formation of CPV-II from the Golgi apparatus, promoting glycoprotein spike transport to the plasma membrane and efficient virus budding.

Control over the Hydrophilicity in the Pores of Covalent Organic Framework Membranes for High-Flux Separation of Dyes from Water

Membrane separation is making substantial contributions to water purification. Particularly important is the pore-size control designed for molecular sieving. Regarding water permeation, filtration experiments accentuate the importance of hydrophilic pores in enhancing the water adsorption capacity, while hydrophobic pores enable low-friction water diffusion. To reach both the criteria, we herein precisely design the pore metrics and pore functionalities to prepare a covalent organic framework (COF), termed TUS-46, membrane. Credited with pore sizes befitting for size-selective molecular exclusion and negative electrostatic pore walls, the TUS-46 COF membrane shows excellent rejection performance toward anionic dyes. Attributed to the free aldehyde functionalities in the framework resulting from unbalanced stoichiometry, the TUS-46 COF membrane also shows a 10-fold higher water permeance compared to the analogue COF membrane without free aldehyde functionalities. In particular, the in situ construction of hydrophilic nanospaces partaking in high water uptake and hydrophobic nanospaces facilitating fast water diffusion in a single COF structure endows the TUS-46 membranes with unprecedentedly high water flux. The stoichiometric imbalance approach presented herein offers a different route to COF membrane fabrication and may impart with an unprecedented control handle on the permeability and separation selectivity of COF membranes.

Effect of glycyrrhizin and its derivatives on integrity of human red blood cells

Introduction: The first and most prevailing cells that glycyrrhizin (GL) and glycyrrhetinic acid (GA) encounter are red blood cells (RBCs). However, what follows this event is poorly understood. This study aims to evaluate the effect of GL and its derivatives on the integrity of human RBCs. Methods: The integrity of human RBC was assessed under normal isotonic conditions and following osmotic and nystatin-induced colloid-osmotic stress by measuring the amount of hemoglobin released. The pore size was determined by the osmotic protection method. Results: GL was found to be virtually non-hemolytic. However, removal of the carbohydrate moiety of GL imparted significant RBC lytic activity to the cis-(beta-) but not to the trans-(alpha-) isoform of GA. The hemisuccinate radical at position C3 (carbenoxolone) greatly diminished the hemolytic property of GA. The RBC lysis occurred by colloid-osmotic mechanism due to the formation of hydrophilic pores with the radius of ~2.3 nm. At the sublytic doses, the two stereo-isoforms displayed opposite effects on the osmo-resistivity of human RBC: osmoprotection for alpha-GA and osmotic sensibilization for beta-GA. Similar osmotic sensibilization was also observed for GL and carbenoxolone. The two stereo-isoforms exhibited different but not opposite weakening effects on the resistivity of the RBC to the colloid-osmotic stress induced by nystatin, a pore-former. The weakening effect was found intermediate for GL and absent for carbenoxolone. Conclusion: Upon intestinal digestion and absorption, depending on the structure and dosage, the GL hydrolysis products interact with RBC with both beneficial and detrimental consequences.

A Multi-Fluid Model for Water and Methanol Transport in a Direct Methanol Fuel Cell

Direct-methanol fuel cell (DMFC) systems are comparatively simple, sometimes just requiring a fuel cartridge and a fuel cell stack with appropriate control devices. The key challenge in these systems is the accurate determination and control of the flow rates and the appropriate mixture of methanol and water, and fundamental understanding can be gained by computational fluid dynamics. In this work, a three-dimensional, steady-state, two-phase, multi-component and non-isothermal DMFC model is presented. The model is based on the Eulerian approach, and it can account for gas and liquid transport in porous media subject to mixed wettability, i.e., the simultaneous presence of hydrophilic and hydrophobic pores. Other phenomena considered are variations in surface tension due to water–methanol mixing and the capillary pressure at the gas diffusion layer–channel interface. Another important aspect of DMFC modeling is the transport of methanol and water across the membrane. In this model, non-equilibrium sorption–desorption, diffusion and electro-osmotic drag of both species are included. The DMFC model is validated against experimental measurements, and it is used to study the interaction between volume porosity of the anode gas diffusion layer and the capillary pressure boundary condition at the anode, and how it affects performance and limiting current density.

Synthesis of poly (vinylidene fluoride)/polyacrylonitrile electrospun substrate-based thin-film composite membranes for desalination by forward osmosis process

As a water treatment process that has the potential to require low energy inputs, forward osmosis (FO) has experienced a significant breakthrough in recent decades, particularly in membrane development. This paper focuses on blending poly (vinylidene fluoride) (PVDF) with hydrophilic polyacrylonitrile (PAN) to form PVDF/PAN substrates for thin film composite membranes (TFC). The membranes were characterized using a scanning electron microscopy, iS50 FTIR spectrometer, and contact angle system. With high porosity, low tortuosity, and interconnected hydrophilic pores of their substrates, the obtained TFC membranes showed high water fluxes. These membranes yielded superior water and reverse salt fluxes in FO tests compared to the commercial CTA membrane. The membranes also showed excellent mechanical performance under PRO test conditions.

A modified Guggenheim-Anderson-Boer model for analyzing water sorption in coal

The presence of water can alter the mechanical properties of coal, which may not only cause roof falls during the coal mining process but also affect the hydraulic fracturing of coalbed methane (CBM) reservoirs. The nature of water adsorption properties in unconventional reservoir rocks has been the subject of several recent papers. However, the adsorption properties and adsorption mechanism of water in coal have not been thoroughly investigated. In this study, we carried out water vapor sorption experiments on four coal samples of different maturities. We found no linear relationship between maturity and water adsorption capacity. Furthermore, we proposed that the water adsorption mechanism in coal can be divided into two types: attached to oxygen functional groups and pore filling, which occur in hydrophilic pores and hydrophobic pores, respectively. Based on the above hypothesis, a modified Guggenheim-Anderson-Boer model was proposed to interpret water adsorption isotherms. It was concluded that the differences in the water adsorption characteristics of different coals under high humidity conditions were caused by the pore volume and the proportion of hydrophilic pores. We further analyzed the influence mechanism of water adsorption on methane adsorption under high relative humidity conditions. We found that the influence of water adsorption on methane adsorption in coal can be attributed to the water adsorption amount and proportion of hydrophilic pores.

Residual oil retention and stripping mechanism of hydrophilic pore surfaces during CO2 and N2 combined gas flooding

The mixed gas of CO2 and N2 can replace the great mass of the remaining oil in the center of the porous media channel, but the surface of the pore channels still retain more residual oil. Most of the previous studies focused on how to displace the residual oil in the center of the pore passages, while ignoring how to enhance the recovery degree of the residual oil on the pore surfaces. Moreover, there are few research results on the mechanism of residual oil retention and stripping on pore surfaces during CO2–N2 combined gas flooding, which need to be improved and supplemented. In this paper, the microscopic interaction process among gas phase, oil phase and pore surfaces were explored by molecular dynamics, the changes in microstructural between n-decane molecules and the spatial distribution of gas molecules and n-decane molecules in the system was clarified. The interaction energy between gas, n-decane and pore surfaces were analyzed to reveal the mechanism of remaining oil retention and stripping. The results indicated that when only CO2 in the gas phase, the oil films were easily divided by CO2 molecules, and the adsorption layer formed by CO2 molecules on the quartz surface could well detach the oil phase from the quartz surfaces. With the increase of the proportion of N2 in the mixed gas, the interaction energy between the gas and n-decane phase and between the gas phase and pore surfaces decreased, and the capacity of the gas phase to peel off the oil films from the pore surfaces was weakened. When the proportion of N2 in the gas phase exceeded 25%, the gas phase has no ability to peel off the oil films from the quartz surfaces. The research results have guiding significance for the CO2-N2 combined gas flooding to further tap the remaining oil.

Ultrasensitive Diamond Microelectrode Application in the Detection of Ca2+ Transport by AnnexinA5-Containing Nanostructured Liposomes.

This report describes the innovative application of high sensitivity Boron-doped nanocrystalline diamond microelectrodes for tracking small changes in Ca2+ concentration due to binding to Annexin-A5 inserted into the lipid bilayer of liposomes (proteoliposomes), which could not be assessed using common Ca2+ selective electrodes. Dispensing proteoliposomes to an electrolyte containing 1 mM Ca2+ resulted in a potential jump that decreased with time, reaching the baseline level after ~300 s, suggesting that Ca2+ ions were incorporated into the vesicle compartment and were no longer detected by the microelectrode. This behavior was not observed when liposomes (vesicles without AnxA5) were dispensed in the presence of Ca2+. The ion transport appears Ca2+-selective, since dispensing proteoliposomes in the presence of Mg2+ did not result in potential drop. The experimental conditions were adjusted to ensure an excess of Ca2+, thus confirming that the potential reduction was not only due to the binding of Ca2+ to AnxA5 but to the transfer of ions to the lumen of the proteoliposomes. Ca2+ uptake stopped immediately after the addition of EDTA. Therefore, our data provide evidence of selective Ca2+ transport into the proteoliposomes and support the possible function of AnxA5 as a hydrophilic pore once incorporated into lipid membrane, mediating the mineralization initiation process occurring in matrix vesicles.

Effective Regulation of the Au Spatial Position in a Hierarchically Structured Au/HTS-1 Catalyst: To Boost the Catalytic Performance of Propene Epoxidation with H2 and O2

The traditional deposition–precipitation (DP) method is common but not universal in manipulating Au nanoparticles’ spatial locations in propene epoxidation catalysts, especially for hierarchical hydrophilic TS-1 supports. Directional loading of Au nanoparticles to hierarchical hydrophilic TS-1 pores is challenging because the strong hydrophilicity of the hierarchical TS-1 zeolite would make Au nanoparticles loaded by the DP method tend to be deposited on the hydrophilic support surface, thus blocking the pore mouths and leading to deactivation. Therefore, manipulating Au nanoparticles’ spatial locations on hierarchical hydrophilic TS-1 supports is of great significance to enhance the catalytic performance but is a bottleneck problem. In this work, taking hierarchical hydrophilic HTS-1 supports as an example, we propose a new modified isometric impregnation (NIMG) method to manipulate the spatial location of Au nanoparticles. Moreover, the Au spatial location inside HTS-1 pores is quantitatively reflected by introducing the Vna parameter. Combined with the N2 physisorption, high-angle annular dark-field scanning transmission electron microscopy, inductively coupled plasma, and X-ray photoelectron spectroscopy, it is found that the Au nanoparticles loaded by the NIMG method tend to be uniformly distributed inside the pores of HTS-1 due to the capillary effect. As expected, the Au/HTS-1(NIMG) catalyst (with the Au nanoparticles inside the pores) exhibits a much higher propylene oxide (PO) formation rate, PO selectivity, and H2 efficiency than the Au/HTS-1(DP) catalyst (with the Au nanoparticles on the outer surface). This is possibly because loading Au nanoparticles inside the pores is conducive to the transfer of H2O2 from Au to the nearby abundant Ti active sites, thus weakening the decomposition of H2O2 to H2O, avoiding the ring-opening side reactions, and promoting propene epoxidation into PO. This work sheds new light for controlling the spatial location of Au in hierarchically structured hydrophilic catalysts for direct propene epoxidation.

Magnesium oxide scaffolded preparation of N, O self-doped biochar with super-hydrophilic surface for aqueous supercapacitor with desired energy density

To assemble electrochemical supercapacitor with attractive energy density, heteroatoms self–doped biochar with hydrophilic surface and natural pore system is prepared by pyrolyzing Flammulina velutipes (FV) pickled with Mg(CH3COO)2 for the first time. The resultant biochar FVB-2-900 displays a super hydrophilicity. It also shows specific surface area of 1174.2 m2·g−1 and pore volume up to 1.57 cm3·g−1. Due to its N, O co-doped hydrophilic surface, the electrode based on it displays a specific capacitance of 470.5 F·g−1 at current density of 0.5 A·g−1 in three-electrode system. Its outstanding energy density of 18.0 Wh·kg−1 is calculated at power density of 0.7004 kW·kg−1 in the electrolyte 1.0 M H2SO4 for the assembled symmetric super-capacitor. Furthermore, a higher energy density of 26.1 Wh·kg−1 at power density of 1.0 kW·kg−1 is recorded in the electrolyte 1.0 M Na2SO4. It also exhibits a good cyclic stability of 100 % retention rate after 10,000 cycles at 5.0 A·g−1. The simple synthesis process, outstanding property, and excellent electrochemical super-capacitor performance make the biochar FVB-2-900 a competitive candidate in the green energy storage.