Formation Of Porous Structure Research Articles

Facile preparation of MnO/Mn3O4 anode from commercial manganese(II) oxalate dihydrate and its advanced lithium storage performance

Manganese oxides are considered a highly promising anode material in lithium ion batteries (LIBs) because of their high theoretical capacity, abundant sources, relatively low voltage hysteresis, nontoxic and cost-effectiveness. Nevertheless, the practical application of these materials faces many challenges such as poor lifespan and serious volume variation during operation. Herein, MnO/Mn3O4–600 composite was obtained based on a single-step pyrolysis procedure from commercial manganese(II) oxalate dihydrate (MOD, C2H4MnO6). The MnO/Mn3O4–600 anode exhibits an exceptionally high reversible capacity of 1041.8 mAh g−1 at the current density of 200 mA g−1, and a remarkable lifespan at 1000 mA g−1. The outstanding performance benefits from the formation of porous structures on nanoparticles, which not only mitigate volume changes and prevent the aggregation of internal MnO/Mn3O4 nanoparticles, but also enhance the ion diffusion. The in-depth insights into the (de)lithiated mechanism of the electrode are investigated by in situ X-ray diffraction (XRD) technique. Moreover, when applied in a full cell, the MnO/Mn3O4–600 anode demonstrates exceptional electrochemical property.

Fabrication and characterization of responsible approach for targeted intestinal releasing and enhancing the effectivity of kidney tea saponin upon porous starch /xanthan gum /sodium alginate-based hydrogel bead

To enhance the intestinal targeted release of kidney tea saponins, a simple delivery system was designed through the use of porous starch (PS), sodium alginate (ALG) and xanthan gum (XG). Porous starch was prepared by hydrolysis with a combination of α-amylase and amyloglucosidase and it was characterized by scanning electron microscopy, which revealed the formation of porous structures in the starch granules. The results of one-way optimisation illustrated that this unique delivery system achieved 79.00 ± 1.22 % of the optimal encapsulation rate. The carrier structure was subjected to analysis using Fourier transform infrared spectroscopy and X-ray diffraction. The α-glucosidase inhibition assay showed better inhibition of kidney tea saponin compared to the positive control acarbose. In addition, the effectiveness of this delivery design was confirmed via an in vitro simulated digestion method. It was showed that only a 15.57 ± 1.27 % release rate of kidney tea saponin was observed in the upper gastrointestinal tract, whereas release rates of 17.51 ± 1.29 % and 41.07 ± 0.76 % were observed for xanthan gum/sodium alginate/kidney tea saponin and sodium alginate/kidney tea saponin beads, respectively. It was concluded that the utilization of PS and a xanthan gum/sodium alginate coating represents an efficacious methodology for the development of an intestinal targeted delivery system.

Impact of diatomit on the transport behavior of unmodified and carboxyl-modified nanoplastics in saturated porous media

Due to the extensive use of plastic products and unreasonable disposal, nanoplastics contamination has become one of the important environmental problems that mankind must face. The composition and structure of porous media can determine the complexity and diversity of the transport behavior of nanoplastics. In this study, the influence of diatomite (DIA) on the nanoplastics transport in porous media is investigated by column experiments combined with XDLVO interaction energy and transport model. Results suggest that the recovery rates of unmodified polystyrene nanoparticles (PSNPs) and carboxyl-modified polystyrene nanoparticles (PSNPs-COOH) in the porous media containing DIA decreases compared with that in the pure quartz sand (QS), and the BTCs showed a “blocking” pattern. The presence of DIA inhibits the transport of both PSNPs and PSNPs-COOH, but the inhibition is not significant. This may be because the presence of DIA provides more favorable deposition sites for PSNPs and PSNPs-COOH to some extent. However, since DIA itself carries a certain negative charge, this can only play a role in compressing the double electric layer for PSNPs and PSNPs-COOH with the same negative charge, and cannot destabilize them. The migration capacity of PSNPs and PSNPs-COOH is strongest in the DIA-QS porous media at pH = 7, and is weak at pH = 9 and pH = 5. The inhibition of migration at pH = 9 can be attributed to the dissolution of the DIA surface under alkaline conditions and the formation of pore and defect structures, which provide more deposition sites for PSNPs and PSNPs-COOH. The presence of humic acid (HA) leads to an increase in the mobility of PSNPs and PSNPs-COOH, and the mobility is enhanced with HA concentration. The mobility of PSNPs and PSNPs-COOH in DIA-QS decreases with ionic valence and ionic strength, and PSNPs-COOH is more significantly inhibited compared to PSNPs.

Facile synthesis of inherently nitrogen-doped PAN-derived microporous carbons activated with NaNH2 for selective CO2 adsorption and separation

N-doped porous carbons (PCs) are extensively researched for CO2 capture and separation under flue gas conditions, but their complex and expensive preparation methods hinder widespread industrial use. Herein, we present a direct approach for synthesizing N-doped PCs by utilizing polyacrylonitrile (PAN) and NaNH2 as precursors, without the need for any solvents. The utilization of NaNH2 as both a porogen and nitrogen supply during carbonization is primarily responsible for the formation of the well-developed pore structure and high specific surface area of N-doped PCs. The optimized sample “PN-3” demonstrated excellent textural features with an excellent specific surface area (SSA) of 2490 m2/g, a pore volume of 2.0559 cm3/g, a well-defined pore size distribution (PSD), and abundant micropores (<1 nm). In addition, PN-3 has the highest pyrrolic nitrogen content (∼40.1 at.%), resulting in a significant capacity for CO2 adsorption (7.15 mmol/g at 273 K/1bar, 4.56 mmol/g at 298 K/1 bar, 26.2 mmol/g at 298 K/ 40 bar). Furthermore, it exhibits an outstanding CO2/N2 selectivity (∼102) based on the ideal adsorbed solution theory (IAST) at 273 K, surpassing the performance of most of previously reported biomass and polymer-derived N-doped carbons in terms of CO2 adsorption and separation. In addition, the adsorption process is characterized by a modest heat of adsorption (39.10 kJ/mol) and a steady cyclic pattern of CO2 adsorption–desorption under flue gas settings (15 % CO2 and 85 % N2). This indicates that the adsorption is mostly governed by physisorption, which allows for an energy-efficient regeneration process. In summary, this study showcases the successful production of highly PCs that can effectively adsorb CO2, enlightening the way toward establishment of a cost-effective and facile synthetic protocol for achieving CO2 capture/separation at the commercial scale.

Effect of tailing powder content on dynamic behavior of iron tailing porous concrete: An experimental study

Iron tailing porous concrete (ITPC) is a new type of green-engineered composite that uses iron ore tailing (IOT) powder to partially replace cement in conventional foamed concrete. This study investigates the dynamic properties of ITPC with a range of IOT content (15 % to 35 %) under high-strain rate loads, as well as the hydration products and microstructures of ITPC. Additionally, foamed concrete specimens without IOT powder are prepared and tested as references. The X-ray diffraction (XRD) results indicate that the addition of IOT powder causes the presence of iron oxide (Fe2O3) and silicon dioxide (SiO2) in the ITPC, resulting in a decrease in calcium silicate hydrate (C-S-H) gel and ettringite (AFt). A split Hopkinson pressure bar (SHPB) facility is used to perform impact tests at expected strain rates from 120 to 250 s−1. The experimental results demonstrate that the properties of ITPC obtained in dynamic loading tests exhibit significant IOT content dependence and strain rate effects. Moreover, scanning electron microscopy (SEM) analysis reveals that excessive IOT content results in the formation of numerous micro-cracks and loose pore structures within the ITPC specimens. ITPC with IOT content ranging from 25 % to 30 % achieves the optimal performance with high impact resistance and effective utilization of iron tailing waste. Specifically, at the expected strain rates of 120, 200, and 250 s−1, increasing the IOT content from 15 % to 35 % resulted in reductions of compressive strength by 37.52 %, 51.34 %, and 51.22 %, respectively. The corresponding dynamic increase factors of ITPC achieved the maximum values of 1.25 (25 % IOT content), 2.16 (30 % IOT content) and 3.12 (30 % IOT content), respectively.

Biphilic Functional Surfaces for Frost Prevention and Efficient Active Defrosting

AbstractThe present work addresses the systematic accurate fabrication and design of biphilic surfaces having superhydrophobic circular islands surrounded by a hydrophilic background by investigating their condensation frosting and defrosting behavior. A significant delay in frost formation is observed on samples with higher superhydrophobicity ratio A*, defined as superhydrophobic area to total area ratio. As the superhydrophobic island diameter D increases from D = 500 µm to D = 700 µm (A* from 19.62% to 38.46%), a 50% improvement/delay is observed in terms of frost formation or densification. Besides delaying icing/frosting, the presence of superhydrophobic areas empowers the formation of porous and nonuniform frost structure, which facilitates ice removal during the defrosting process. To this end, as the surface is recovered the ambient temperature, almost complete passive cleaning performance within only 23 s is observed on the biphilic design having superhydrophobic islands with the diameter of D = 500 µm, that is, a superhydrophobicity ratio A* of 19.62%. This work concludes on the optimum biphilic ratio, which is not only effective as a passive method by hindering frosting but also leads to a slush/water free surface after defrosting eased by the Laplace pressure gradient which is imposed by the different biphilic wettability patterns.

Facile fabrication of a cellulose-based photocatalytic membrane decorated with core-shell heterojunction microspheres for efficient and continuous wastewater remediation

Advanced oxidation processes have extensive applications in the degradation of organic pollutants in wastewater. However, conventional powder photochemical catalysts have limited utility due to their susceptibility to agglomeration, electron-hole recombination, and challenges in recycling. In this work, we herein propose an integration tactic to facilely fabricate a cellulose-based photocatalytic electrospun membrane (ZPP/CA-ENM) via synchronous electrospinning of acetate cellulose (CA) and electrospray of core-shell PMMA@PDA@ZIF-67 (ZPP) photocatalysts. This hybrid membrane is capable of synergistic PMS activation and photocatalytic degradation of tetracycline (TC) and methylene blue (MB). For the ZPP catalysts, the PDA@ZIF-67 heterojunctions greatly promote the adsorption of visible light and the separation of photogenerated electron-hole pairs, leading to excellent catalytic efficiency. The synchronous electrospinning and electrospray not only lead to the formation of porous and spiderweb-like membrane structure, but also facilitates the dispersion and recycling of these catalysts. Results reveal that under the presence of light irradiation and PMS, various oxidative species, including 1O2, SO4−, OH and O2− are generated, resulting in rapid degradations of TC (93.31 % within 30 min) and MB (99.90 % within 15 min), which also exhibits a rapid degradation and high efficiency in a cascade continuous lab setup. This work provides a new strategy for exploring novel and efficient material for wastewater purification.

Three-Dimensional (3D) Porous Reduced Graphene Oxide Aerogel (RGA) Nanoelectrodes Consisted of Palladium Nanoparticles Embedded in Polyethlyenimine (PEI) for Detection of Bisphenol A and H2O2

This research focuses on the development of three-dimensional (3D), hierarchically porous nanoelectrodes, which incorporate palladium nanoparticles within a polyethyleneimine-reduced graphene oxide aerogel (RGA-PEI-Pd). These nanoelectrodes are designed for sensitive detection of bisphenol A (BPA) and hydrogen peroxide (H2O2). The abundant positive charges in polyethyleneimine (PEI) facilitate the formation of a 3D porous structure by connecting to the reduced graphene oxide through carbon-nitrogen bonds, while also anchoring palladium nanoparticles uniformly across the aerogel. This structure maintains the aerogel's porosity.Palladium in its zero-valent (Pd0) and divalent (Pd2+) states plays a crucial role in the catalyst's performance, undergoing redox reactions to alternate between Pd2+ and Pd4+ states. This dynamic contributes to the electrode's ability to effectively oxidize BPA and reduce H2O2. The modified electrode showed low detection limits for BPA (25.5 nM) and H2O2 (16.2 nM) under optimal conditions. Extensive analytical methods, including electrochemical spectroscopy, were employed to delve into the unique electrocatalytic properties of these electrodes.The practical applicability of these electrodes was further demonstrated by their successful use in real-world environmental and biological samples, such as BPA-contaminated water from rivers and lakes, and clinical samples containing MCF-7 cells. The electrodes also exhibited impressive reusability, with recovery rates ranging from 96% to 104.3%.

Novel flexible chemiresistive ammonia sensors based on rGO/ZIF-8 composites deposited on conductive graphite sheets

This work presents novel investigations on room temperature chemiresistive ammonia (NH3) gas sensing capability of composite materials based on reduced graphene oxide (rGO) and ZIF-8 metal organic framework (MOF), deposited on flexible graphite substrate. These rGO/ZIF-8 composites synthesized via a facile one-pot wet chemical route were found to exhibit a fast, highly sensitive and reversible response over successive exposure cycles towards various concentrations of NH3. The enhanced response is attributable to the synergistic performance of the appreciably conductive rGO and the highly porous ZIF-8. ZIF-8 with its high specific surface area, microporous structure and hydrophobicity, serves to provide greater gas adsorptive capacity as well as resistance to effects of ambient moisture. rGO, on the other hand, has limited specific surface area due to π-π restacking of its sheets but it is capable of providing a conductive template to the hybrid material. Consequently, the NH3 gas sensing performance parameters of rGO/ZIF-8 were measured to be exceedingly better than those of bare rGO and ZIF-8 synthesized separately. A response of 15.98 % was recorded towards 10 ppm NH3 with response/recovery times as 2.8/6 s for the rGO/ZIF-8 composites. The enhanced gas sensing performance is credited to the formation of hierarchical pore structure which allows for greater adsorption at the micropore sites and faster diffusion through the mesopores. The effect of rGO loading in the hybrid materials was also assessed. The composite materials exhibited appreciable stability with respect to ambient aging. The adsorption behaviors and the resultant gas sensing mechanisms have also been discussed for the investigated materials.

Effects of probiotics fermentation on physicochemical properties of plum (Pruni domesticae semen) seed protein-based gel

The plum seed protein isolates (PSPI) were used to prepare a gel by probiotics fermentation. The effects of fermentation time (from 0 to 12 h) on the physicochemical properties of PSPI gel were evaluated. The results showed that PSPI started to form a gel after 6 h of fermentation, as evidenced by a decrease in pH from 6.6 to 5.2, an increase in particle size from 10 μm to 40 μm, appearance of a new peak with retention time of 10 min in gel filtration high-performance liquid chromatography, and formation of aggregation and porous structure observed by fluorescence and scanning electron microscope. The PSPI gel from 9 h of fermentation exhibited the highest viscosity (318 Pa.s), storage modulus (18,000 Pa), water holding capacity (37 %), and gel strength (21.5 g) due to stronger molecular interactions such as hydrogen bond, electrostatic, hydrophobic interaction and disulfide bond. However, increasing fermentation time over 9 h led to disrupture of PSPI gel. Furthermore, the subunit around 15 kDa of PSPI disappeared after fermentation, indicating that the formation of PSPI gel was induced by both acidification and partial hydrolysis. Our results suggest that PSPI can provide an alternative for developing plant-based gel products.

Experimental study on pore structure evolution of thermally treated shales: implications for CO2 storage in underground thermally treated shale horizons

Extracting gas from unconventional shale reservoirs with low permeability is challenging. To overcome this, hydraulic fracturing (HF) is employed. Despite enhancing shale gas production, HF has drawbacks like groundwater pollution and induced earthquakes. Such issues highlight the need for ongoing exploration of novel shale gas extraction methods such as in situ heating through combustion or pyrolysis to mitigate operational and environmental concerns. In this study, thermally immature shales of contrasting organic richness from Rajmahal Basin of India were heated to different temperatures (pyrolysis at 350, 500 and 650 °C) to assess the temperature protocols necessary for hydrocarbon liberation and investigate the evolution of pore structural facets with implications for CO2 sequestration in underground thermally treated shale horizons. Our results from low-pressure N2 adsorption reveal reduced adsorption capacity in the shale splits treated at 350 and 500 ºC, which can be attributed to structural reworking of the organic matter within the samples leading to formation of complex pore structures that limits the access of nitrogen at low experimental temperatures. Consequently, for both the studied samples BET SSA decreased by ∼58% and 72% at 350 °C, and ∼67% and 68% at 500 °C, whereas average pore diameter increased by ∼45% and 91% at 350 °C, and ∼100% and 94% at 500 °C compared to their untreated counterparts. CO2 adsorption results, unlike N2, revealed a pronounced rise in micropore properties (surface area and volume) at 500 and 650 ºC (∼30%–35% and ∼41%–63%, respectively for both samples), contradicting the N2 adsorption outcomes. Scanning electron microscope (SEM) images complemented the findings, showing pore structures evolving from microcracks to collapsed pores with increasing thermal treatment. Analysis of the SEM images of both samples revealed a notable increase in average pore width (short axis): by ∼4 and 10 times at 350 °C, ∼5 and 12 times at 500 °C, and ∼10 and 28 times at 650 °C compared to the untreated samples. Rock-Eval analysis demonstrated the liberation of almost all pyrolyzable kerogen components in the shales heated to 650 °C. Additionally, the maximum micropore capacity, identified from CO2 gas adsorption analysis, indicated 650 °C as the ideal temperature for in situ conversion and CO2 sequestration. Nevertheless, project viability hinges on assessing other relevant aspects of shale gas development such as geomechanical stability and supercritical CO2 interactions in addition to thermal treatment.

Efficient separation of oil-in-water emulsion using (MgCoNiCuZn)O high-entropy ceramic membrane

In this study, we have successfully prepared (MgCoNiCuZn)O high-entropy ceramic membrane by the combination of diffusion-induced phase transformation and high temperature sintering. The membrane was used to separate oil/water emulsions. The results showed that the phase transformation between solvent DMAc and non-solvent H2O resulted in the formation of asymmetric pore structure including finger-like pores and sponge-like pores. After calcination, the porous structure was remained, and the transformation of high-entropy phase was completed. As the calcination temperature increased, the porosity decreased, resulting in densification of the membrane. However, the nanopore with the pore size of 3.433 nm was obtained after calcination at 850 ℃. The membrane exhibited good hydrophilicity in air and underwater oleophobicity, yielding the high pure water flux and separation efficiency simultaneously. After the calcination was performed at 900 ℃, a pure water flux of 6333 L/(m2⋅h) was obtained, and the separation efficiency of oil-in-water emulsion reached 99.87 %. The long-term stability of high-entropy ceramic membrane was studied. A flux of 520 L/(m2⋅h) was achieved even though the separation operation was performed for 10 h. After 10 h, the rejection rate consistently remained above 99 %, which proved that the membrane has excellent long-term stability.

In vitro Biomineralization Ability of Magnesium-Doped Coral Hydroxyapatite Coating Prepared by Pulsed Laser Deposition

Coral hydroxyapatite (CHA) is a calcium phosphate that has a similar inorganic composition to human bone and the porous structure of coral stone. Due to its interconnected network like pore structure, it can serve as a framework for bone conduction. In this study, CHA films and Mg-CHA films were deposited on titanium and silicon substrates by Pulsed laser deposition, and then the films were heat treated respectively. Studies on the adhesion of the coating showed that the heat-treated Mg-CHA film adhered better to the titanium substrate. The experimental study on biomineralization in vitro showed that a small amount of porous structure appeared in the heat-treated Mg-CHA after immersion in SBF for three days, and the porous structure was visible after immersion for seven days. After 14 days, a new apatite layer formed on the surface. This suggested that magnesium undergoes chemical corrosion in SBF, leading to rapid ion exchange, which results in the formation of porous structures and promotes the development of an apatite-like layer. In summary, the heat-treated Mg-CHA films had superior biomineralization properties.

Construction of Co9S8/SnS heterostructures encapsulated in multi-channel carbon nanofibers as long-term stable anodes for sodium-ion batteries

This study presents the design and fabrication of multi-channel self-supported anode materials Co9S8/SnS@MCNFs, through the electrospinning technique. The high compatibility of Co9S8 and SnS at the interface enables the synthesis of a more complete heterostructure within the material, enhancing the electrochemical reaction process through rational heterostructure design. Additionally, the incorporation of high theoretical capacity SnS improves sodium storage performance. The design of multi-channel carbon nanofibers (MCNFs) effectively addresses challenges such as material volume expansion and metal particle aggregation during cycling by providing large specific surface areas and enabling carbon encapsulation. The resulting pore structure and heterostructure formation, coupled with introduction of more defects, enhance the availability of Na+ active sites for electrochemically reversible processes. As expected, Co9S8/SnS@MCNFs exhibit remarkable initial coulombic efficiency (ICE = 92.6 %) and demonstrate stable long-term cycling performance (222.5 mA h g−1 at 2 A g−1 after 400 cycles) for sodium storage, with only a 0.18 % decay rate per cycle. These findings suggest promising application for the electrode material in sustained high-current discharges and long-endurance performance.

Investigation of adhesion status of Candida species to the surface of resin materials produced at different angles with additive manufacturing

BackgroundThe aim of this study was to evaluate the adhesion of Candida glabrata, Candida albicans, Candida krusei, Candida parapsilosis and Candida tropicalis yeasts to disk-shaped resin materials produced from resin which used in the production of surgical guide with 0, 45 and 90-degrees printing orientations by Liquid Crystal Display additive manufacturing technology.MethodsDisk-shaped specimens were printed with surgical guide resin using the Liquid Crystal Display production technique in 3 printing orientations (0, 45 and 90-degrees). Surface roughness and contact angle values were evaluated. Real-Time PCR analysis was performed to evaluate Candida adhesion (C. glabrata, C. albicans, C. krusei, C. parapsilosis and C. tropicalis) Field emission scanning electron microscope (FESEM) images of the materials were obtained.ResultsSpecimens oriented at 45-degrees demonstrated higher surface roughness (P < .05) and lower contact angle values than other groups. No significant difference was found in the adhesion of C. glabrata, C. albicans, and C. parapsilosis among specimens printed at 0, 45, and 90-degrees orientations (P > .05). A higher proportion of C. krusei and C. tropicalis was found in the specimens printed at orientation degrees of 45 = 90 < 0 with statistical significance. Analyzing the adhesion of all Candida species reveals no statistical disparity among the printing orientations.ConclusionsThe surface roughness, contact angle, and adhesion of certain Candida species are affected by printing orientations. Hence, careful consideration of the printing orientation is crucial for fabricating products with desirable properties. In 45-degree production, roughness increases due to the layered production forming steps, whereas in 0-degree production, certain Candida species exhibit high adhesion due to the formation of porous structures. Consequently, considering these factors, it is advisable to opt for production at 90-degrees, while also considering other anticipated characteristics.

Dynamic fabrication of porous polymeric coating for efficient passive daytime radiative cooling using in-situ pore-formation strategy

Porous polymeric material has emerged as promising choice for making passive daytime radiative cooling (PDRC) emitter. However, it is still an unmet challenge to establish a flexible method to achieve dynamic pore-formation for the purpose of studying the relationships between the porous structure and the resultant cooling performance. The current study reports a novel strategy to construct asymmetric multi-layered porous structure in situ within the matrix of pre-formed polystyrene coating. The modified procedure of inverse emulsion - breath figure method is adopted, and solvent-nonsolvent exchanging process is also involved during the pore-formation process, leading to the formation of hierarchical porous structure with rather high porosity. Geometrical features of the generated pores are effectively regulated by simple adjustment of the experimental parameters of the water ratio of the emulsion and the humidity. The relationship between the pore structure and optical & cooling properties has been established based on experimental facts. By tuning of optimal conditions, the in-situ pore-formation can endow the polymeric coating with high solar reflectance (∼85 %) and infrared emittance (∼98.4 %), resulting in passive temperature drop of 12 °C and cooling power of 91 W/m2. This study provides experimental information to get some insight into the designing principle of porous polymeric PDRC materials, and formulates unique strategy of in-situ functionalization via structural transformation upon polymeric objects or devices.

Impact of the thermo-alkaline pretreatment on the anaerobic digestion of poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) blended plastics

Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable plastic that is difficult to degrade under both mesophilic and thermophilic anaerobic conditions. In this study, the impact of the thermo-alkaline pretreatment (48 h, 70 °C, 1 % w/v NaOH) on the anaerobic degradation (AD) of PBAT, poly(lactic acid) (PLA) and PBAT/PLA blended plastics was investigated. Under mesophilic conditions, pretreatment only improved the methane yield of PBAT/PLA/starch plastic (100 days, 51 and 34 NmL/g VSadd for the treated and original plastics, respectively). Under thermophilic conditions, the pretreatment increased the methanogenic rate of PLA, PBAT and PBAT/PLA/starch plastic at the beginning stage (22 days, 35 and 79 NmL/g VSadd for original and treated PBAT, respectively), but did not change the methane yield at the end of the incubation (100 days, 91 NmL/g VSadd for original and treated PBAT). The reduction in the molecular weight and the formation of pore structures on the plastic surface accelerated the utilization of plastics by microorganisms. Furthermore, the pretreated plastics tend to form microplastics (MPs) with size predominantly below 500 µm (>90 %). The numbers of MPs dynamically changed with the degradation time. Several genera of bacteria showed specific degradation of biodegradable plastics under thermophilic conditions, including Desulfitibacter, Coprothermobacter, Tepidimicrobium, c_ D8A-2 and Thermacetogenium. The results suggest that more attention should be paid to the problem of MPs arising from the thermo-alkaline pretreatment.

Boron/nitrogen-trapping and regulative electronic states around Ru nanoparticles towards bifunctional hydrogen production

Developing a straightforward and general strategy to regulate the surface microenvironment of a carbon matrix enriched with N/B motifs for efficient atomic utilization and electronic state of metal sites in bifunctional hydrogen production via ammonia-borane hydrolysis (ABH) and water electrolysis is a persistent challenge. Herein, we present a simple, green, and universal approach to fabricate B/N co-doped porous carbons using ammonia-borane (AB) as a triple functional agent, eliminating the need for hazardous and explosive functional agents and complicated procedures. The pyrolysis of AB induces the regulation of the surface microenvironment of the carbon matrix, leading to the formation of abundant surface functional groups, defects, and pore structures. This regulation enhances the efficiency of atom utilization and the electronic state of the active component, resulting in improved bifunctional hydrogen evolution. Among the catalysts, B/N co-doped vulcan carbon (Ru/BNC) with 2.1 wt% Ru loading demonstrates the highest performance in catalytic hydrogen production from ABH, achieving an ultrahigh turnover frequency of 1854 min−1 (depending on the dispersion of Ru). Furthermore, this catalyst shows remarkable electrochemical activity for hydrogen evolution in alkaline water electrolysis with a low overpotential of 31 mV at 10 mA cm−2. The present study provides a simple, green, and universal method to regulate the surface microenvironment of various carbons with B/N modulators, thereby adjusting the atomic utilization and electronic state of active metals for enhanced bifunctional hydrogen evolution.

Characterization and fractal characteristics of nano-scale pore structure in shale gas reservoirs: a case study of the deep Longmaxi Formation, Zigong region, Southern Sichuan Basin, China

Taking the Longmaxi deep-marine shale gas reservoir in Zigong region as the research target, this paper aimed to characterize the nano-scale pore structure and investigate the reservoirs’ heterogeneity based on fractal theory. By conducting a series of experimental studies, mainly including TOC, XRD, gas adsorption (N2 and CH4), we were able to clarify the main controlling factors for the heterogeneity of deep shale pore structure. Our results indicated that the deep marine shale possessed a significant amount of organic matter, as the average TOC value is 3.68%. The XRD analysis results show that quartz and clay were the main mineral types, and the total content of these two minerals averaged 77.5%. Positive correlations were observed between TOC and quartz, while TOC decreases as the clay mineral increases, this discovery indicating that quartz is biogenic. Based on FHH (Frenkele-Halseye-Hill) method, by using the LTNA adsorption isotherms, we took relative pressure P/P0=0.5 as the boundary, then two separate fractal dimension were deduced, D1 and D2 represent the fractal characteristics of small and large pores, respectively. Our study revealed that both D1 and D2 demonstrated positive correlations with N2 adsorption pore volume and adsorption specific surface area, while negatively correlated with the adsorption average pore diameter. Moreover, the two fractal dimensions showed positive associations with TOC and quartz and negative associations with clay. Additionally, D1 and D2 also demonstrated a positive correlation with Langmuir volume. The presence of micropores was found to significantly influence the formation of an irregular pore structure in shale. As the pore size decreased, the adsorption specific surface area increased, resulting in a more intricate pore structure, and the fractal dimension of the pores elevated, ultimately. This intricate structure is beneficial for the accumulation of shale gas. These research findings offer valuable insights for the comprehensive assessment of deep shale gas, and enrich our knowledge of enrichment mechanisms in deep shale gas reservoirs.

Porous Prussian blue nanolayers formed in situ on Fe-MOFs-modified electrode surfaces by electrochemically triggered dual-templating effect for ultrasensitive detection of lead ions and Staphylococcus aureus

In this study, introducing Fe-MOFs as reactants to the electrode surface creates a novel mode for modulating interface performance that can lead to rapid enrichment of reactants in the proximity of electrodes by electrochemical-induced confinement effect. A facile, controllable, and room temperature electrochemical approach utilizes Fe-MOFs as nanotemplates to produce porous Prussian blue (PB) nanolayers on the electrode surfaces. Unlike conventional chemical conversion that needs a supply of exogenous acid regents, the electrochemical method creates a solid acidic condition in the oxygen evolution reaction cycle to release Fe3+ from the Fe-MOFs, improving conversion efficiency and electrochemical activity of PB. Furthermore, small oxygen bubbles generated by splitting H2O near the electrodes are also good templates, promoting the formation of porous structures that can increase effective surface area and mass-transfer efficiency. As a conceptional application, using Fe-MOFs as self-sacrificial tags, an ultrasensitive electrochemical platform with triple amplification is developed to detect Pb2+ and S. aureus based on DNAzyme-CHA cascade reaction. The designed platform shows low detection limits of 8.5 fM and 1 CFU/mL for Pb2+ and S. aureus, respectively. Moreover, the platform has high selectivity, stability and reproducibility, and also shows satisfactory recovery rates when validated using actual samples.