Increase In Specific Surface Area Research Articles

Green biomediated synthesis of anodized WO3 nanocatalysts using Melia azedarach leaves extract for the energetic transition: Solar hydrogen and Li-ion batteries

This study reports the bio-mediated synthesis of tungsten trioxide nanostructures from aqueous extracts of Melia azedarach (L.) dry leaves. The synthesis was carried out by electrochemical anodization of tungsten foils in the presence of different volume percentages of leaves extracts. These nanostructures were afterwards completely characterized by Field-Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy (HR-TEM), impedance measurements, linear sweep voltammetry in the presence of simulated solar light and UV-Vis spectroscopy. Finally, these nanoelectrodes were used as (photo)electrocatalysts in the photoelectrochemical water splitting process to obtain green hydrogen and as anodes in Li-ion rechargeable batteries. Nanostructures fabricated with 5% M. azedarach leaves extract provided the best (photo)electrocatalytic behavior for both applications, since in that biogenic electrolyte, thin nanorods arranged in very porous and spongy layers were formed. Therefore, the significant increase in specific surface area found for nanostructures fabricated following this green route, in comparison with the blank sample (i.e., nanostructure formed following a non-green route), was essential to enhance their performance as promising efficient (photo)electrocatalysts.

Facile and green hydrothermal synthesis of MgAl/NiAl/ZnAl layered double hydroxide nanosheets: a physiochemical comparison

Abstract Layered double hydroxide (LDH) exhibits a remarkable trait referred to as the ‘memory effect,’ demonstrating its capacity to reconstruct its layered structure from calcined oxides through hydrothermal treatment. Its uniqueness has garnered significant interest from researchers in both industrial and academic domains. Various methods have been utilized to synthesize LDH but most LDH studies still utilize alkali precipitants which might taint the final LDH product. Thus, in this study, layered double hydroxides involving MgAl/NiAl/ZnAl were synthesized via an alkali-free hydrothermal approach in which the formed precipitates of LDH were thermally destroyed via calcination at 450 °C before undergoing a rehydration treatment at 110 °C for 24 h to restore its original structure. Particularly, the physiochemical properties of MgAl/NiAl/ZnAl LDH have been undertaken by multiple techniques such as Powder X-ray Diffraction (PXRD), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscope (FESEM) and Fourier-transform infrared spectroscopy (FTIR). The resultant products exhibited exceptional crystallinity, accompanied by notably larger crystallite sizes and crystallinity index, particularly post-hydrothermal treatment. Among the fresh and calcined products studied, those subjected to HTM (4:1) treatment demonstrated the highest specific surface area and crystallinity surpassing both the fresh and calcined samples. In essence, this research showcased how utilizing the hydrothermal approach resulted in the most substantial increase in crystallite size and specific surface area.

Zn and Ni doped hydroxyapatite: Study of the influence of the type of energy source on the photocatalytic activity and antimicrobial properties

The present work aimed to produce HAp nanoparticles doped with Zn and Ni in order to analyze the incorporation of these elements in the catalytic and antimicrobial properties of HAp. The samples were obtained by the microwave-assisted hydrothermal method in 30 min at 150 °C. XRD and FTIR results showed that HAp was formed without the presence of secondary phases, and Rietveld refinement indicated a reduction in crystallite size after doping. Nanorod-like morphologies were observed by SEM-FEG with reduction in particle size and increase in specific surface area. Furthermore, the hidden gap at 3.26 eV, photoluminescence indicated that there was a predominance of deep defects and XPS showed the presence of dopants on the HAp surface. The catalytic results in the degradation of methylene blue dye indicated that the zinc-doped sample removed 97.85 % under sunlight, 66.81 % under UV light and 70.64 % under ultrasound. After four cycles of reuse under sunlight, good photocatalytic performance was maintained, and inhibition tests indicated that holes and hydroxyls are the active radicals. Antimicrobial activity tests showed that zinc-doped and co-doped samples were efficient in inhibiting Gram-negative bacteria (Escherichia coli). This work brings a promising alternative application for hydroxyapatite in environmental and microbial remediation.

Heterostructure engineering of In2O3/ErVO4 hairy curd for high-performance TEA gas sensors

Triethylamine (TEA) is a mephitic volatile organic compound, which has huge damage to human body. Therefore, the development of gas sensitive materials for the effective detection of TEA has important application value. In this paper, In2O3, ErVO4 and In2O3/ErVO4 composite samples were successfully synthesized by hydrothermal method. The In2O3/ErVO4 composite of In2O3 and ErVO4 has a spherical structure with a rough surface, and forms a variety of porous structures, which effectively increases the specific surface area of the composite (58.9551m2/g), thereby improving the gas sensitivity to TEA. In2O3/ErVO4 composites can achieve a higher response to 100 ppm TEA (S = 54.73), have a lower optimal operating temperature (250 °C) compared with In2O3 pure samples, and have a faster recovery time (52 s) compared with ErVO4 pure samples. In addition, In2O3/ErVO4 sensors also achieve good selectivity, excellent moisture resistance, long-term stability. The microstructure of the sample was significantly changed by ErVO4 recombination. These alterations include an increase in specific surface area, a decrease in particle size, an increase in the utilization of the sensitive body, an increase in the proportion of vacancy oxygen, a decrease in the optical band gap, and an increase in electron transport efficiency. These results show that the combination of ErVO4 and In2O3 to construct heterojunction can achieve excellent sensor for TEA gas detection.

Triclosan-loaded aged microplastics exacerbate oxidative stress and neurotoxicity in Xenopus tropicalis tadpoles via increased bioaccumulation

Microplastics and chlorine-containing triclosan (TCS) are widespread in aquatic environments and may pose health risks to organisms. However, studies on the combined toxicity of aged microplastics and TCS are limited. To investigate the toxic effects and potential mechanisms associated with co-exposure to TCS adsorbed on aged polyethylene microplastics (aPE-MPs) at environmentally relevant concentrations, a 7-day chronic exposure experiment was conducted using Xenopus tropicalis tadpoles. The results showed that the overall particle size of aPE-MPs decreased after 30 days of UV aging, whereas the increase in specific surface area improved the adsorption capacity of aPE-MPs for TCS, resulting in the bioaccumulation of TCS under dual-exposure conditions in the order of aPE-TCS > PE-TCS > TCS. Co-exposure to aPE-MPs and TCS exacerbated oxidative stress and neurotoxicity to a greater extent than a single exposure. Significant upregulation of pro-symptomatic factors (IL-β and IL-6) and antioxidant enzyme activities (SOD and CAT) indicated that the aPE-TCS combination caused more severe oxidative stress and inflammation. Molecular docking revealed the molecular mechanism of the direct interaction between TCS and SOD, CAT, and AChE proteins, which explains why aPE-MPs promote the bioaccumulation of TCS, causing increased toxicity upon combined exposure. These results emphasize the need to be aware of the combined toxicity caused by the increased ability of aged microplastics to carry contaminants.

Significantly Optimized Piezoelectric Catalytic Properties of Surface Functionalized Nano-BaTiO3

In piezoelectric catalysis, the interaction between reaction molecules and the catalyst surface is of great significance for designing highly selective reaction processes. In this study, chemically functionalized BaTiO3 nanoparticles were fabricated using the hydrothermal method, and the piezoelectric catalytic activity was evaluated for degradation dye reactants by ultrasonic vibration. Due to surface modification of BaTiO3 nanoparticles, the carboxyl groups will be applied on the surface of BaTiO3 nanoparticles, resulting in the reduction in particle size and an increase in specific surface area. The adsorption of the carboxyl groups on the surface can also improve the ability of the BaTiO3 nanoparticles to capture the organic dyes. A high piezoelectric catalytic reaction rate constant of 0.0716 min-1, together with a degradation efficiency of > 90% was achieved within 30 min under 60 kHz and 100 W ultrasonic conditions. These results show that the surface modification of BaTiO3 nanoparticles brought excellent performance of piezoelectric catalysis by controlling the precursor and hydrothermal parameters. This study provides a new method for the preparation of chemically functionalized piezoelectric catalysts and design of other new highly selective catalysts.

Physicochemical Properties of Inorganic and Hybrid Hydroxyapatite-Based Granules Modified with Citric Acid or Polyethylene Glycol.

This study delves into the physicochemical properties of inorganic hydroxyapatite (HAp) and hybrid hydroxyapatite-chitosan (HAp-CTS) granules, also gold-enriched, which can be used as aggregates in biomicroconcrete-type materials. The impact of granules' surface modifications with citric acid (CA) or polyethylene glycol (PEG) was assessed. Citric acid modification induced increased specific surface area and porosity in inorganic granules, contrasting with reduced parameters in hybrid granules. PEG modification resulted in a slight increase in specific surface area for inorganic granules and a substantial rise for hybrid granules with gold nanoparticles. Varied effects on open porosity were observed based on granule type. Microstructural analysis revealed increased roughness for inorganic granules post CA modification, while hybrid granules exhibited smoother surfaces. Novel biomicroconcretes, based on α-tricalcium phosphate (α-TCP) calcium phosphate cement and developed granules as aggregates within, were evaluated for compressive strength. Compressive strength assessments showcased significant enhancement with PEG modification, emphasizing its positive impact. Citric acid modification demonstrated variable effects, depending on granule composition. The incorporation of gold nanoparticles further enriched the multifaceted approach to enhancing calcium phosphate-based biomaterials for potential biomedical applications. This study demonstrates the pivotal role of surface modifications in tailoring the physicochemical properties of granules, paving the way for advanced biomicroconcretes with improved compressive strength for diverse biomedical applications.

Using Fractal Theory to Study the Influence of Movable Oil on the Pore Structure of Different Types of Shale: A Case Study of the Fengcheng Formation Shale in Well X of Mahu Sag, Junggar Basin, China

This study investigated the influence of movable oil on the pore structure of various shale types, analyzing 19 shale samples from Well X in the Mahu Sag of the Junggar Basin. Initially, X-ray diffraction (XRD) analysis classified the shale samples. Subsequently, the geochemical properties and pore structures of the samples, both pre and post oil Soxhlet extraction, were comparatively analyzed through Total Organic Carbon (TOC) content measurement, Rock-Eval pyrolysis, and nitrogen adsorption experiments. Additionally, fractal theory quantitatively described the impact of movable oil on the pore structure of different shale types. Results indicated higher movable oil content in siliceous shale compared to calcareous shale. Oil extraction led to a significant increase in specific surface area and pore volume in all samples, particularly in siliceous shale. Calcareous shale predominantly displays H2–H3 type hysteresis loops, indicating a uniform pore structure with ink-bottle-shaped pores. Conversely, siliceous shale exhibited diverse hysteresis loops, reflecting its complex pore structure. The fractal dimension in calcareous shale correlated primarily with pore structure, exhibiting no significant correlation with TOC content before or after oil extraction. Conversely, the fractal dimension changes in siliceous shale samples do not have a clear correlation with either TOC content or pore structure, suggesting variations may result from both TOC and pore structure.

Characterisation, activation, and reactivity of heterogenous natural clays

Although thermal and mechanochemical activations of natural clays are well-documented, there exists a dual research gap. Firstly, a thorough investigation into the interrelationship between these activation methods and the governing parameters of reactivity for various clays has been notably lacking. Secondly, there is a distinct scarcity of studies specifically focusing on heterogeneous clays compared to the extensive research dedicated to single-layer clays specially kaolinitic clays. This study investigates the correlation of activation methods, and changes in the clay mineralogy, particle size distributions, morphology, specific surface area, and the reactivity of heterogeneous clays. Traditional thermal and mechanochemical activation methods often fall short in achieving complete dehydroxylation of heterogeneous clay minerals and improving their reactivity beyond predefined low thresholds. The results in this paper emphasize that, despite these limitations, combining these activation methods brings about significant modifications in crucial parameters. Notably, integrating 20 min of mechanochemical activation at 500 rpm with prior thermal treatment leads to 158% increase in specific surface area compared to mechanochemical activation conducted on un-calcined clays. Simultaneously, these combined activations result in up to 127% improvement in reactivity levels of heterogenous clays compared to standalone mechanochemical activation. The results underscore that, even with the advancements brought about by combined activations, the presence of impurities like iron oxides and calcite remains a noteworthy factor influencing the reactivity of kaolinitic natural clays. The study concludes by highlighting the potential of combined treatments to enhance the pozzolanicity of low-reactive heterogeneous clays, unlocking avenues for future clinker supplementation with this abundant resource.

Effects of erythromycin on biofilm formation and resistance mutation of Escherichia coli on pristine and UV-aged polystyrene microplastics

Microplastics (MPs) and antibiotics co-occur widely in the environment and pose combined risk to microbial communities. The present study investigated the effects of erythromycin on biofilm formation and resistance mutation of a model bacterium, E. coli, on the surface of pristine and UV-aged polystyrene (PS) MPs sized 1–2 mm. The properties of UV-aged PS were significantly altered compared to pristine PS, with notable increases in specific surface area, carbonyl index, hydrophilicity, and hydroxyl radical content. Importantly, the adsorption capacity of UV-aged PS towards erythromycin was approximately 8-fold higher than that of pristine PS. Biofilms colonizing on UV-aged PS had a greater cell count (5.6 × 108 CFU mg−1) and a higher frequency of resistance mutation (1.0 × 10−7) than those on pristine PS (1.4 × 108 CFU mg−1 and 1.4 × 10−8, respectively). Moreover, erythromycin at 0.1 and 1.0 mg L−1 significantly (p < 0.05) promoted the formation and resistance mutation of biofilm on both pristine and UV-aged PS. DNA sequencing results confirmed that the biofilm resistance was attributed to point mutations in rpoB segment of the bacterial genome. qPCR results demonstrated that both UV aging and erythromycin repressed the expression levels of a global regulator rpoS in biofilm bacteria, as well as two DNA mismatch repair genes mutS and uvrD, which was likely to contribute to increased resistance mutation frequency.

Ultrafast and low-hysteresis humidity sensors based on mesoporous LaFe0.925Ti0.075O3 perovskite

Humidity sensors are omnipresent. Thus, significant efforts have been undertaken to advance their performance, for example, to have a fast detection time, negligible hysteresis, and excellent stability. Despite numerous active research endeavors, establishing a sensor that excels in all these key performances is still challenging. Here, we address this challenge by designing a capacitive-based humidity sensor employing porous LaFeO3 perovskite. Integrating Ti into the perovskite using a sol-gel method, i.e., LaFe0.925Ti0.075O3, results in a 400% increase in specific surface area achieved through pore formation, translating to a 2094% response parameter. Furthermore, due to the rapid equilibrium between adsorption and desorption processes, the sensor achieves ultrafast 4.4 s response time and 1.4 s recovery time, with <1% hysteresis and excellent stability over 28 days, when assessed at 300 K. Our work significantly advances current humidity sensor performance and, in a broader context, emphasizes the efficacy of porous (perovskite) materials for high performance gas detection.

Green synthesis of biomass-derived porous carbon with hierarchical pores and enhanced surface area for superior VOCs adsorption

The release of volatile organic compounds (VOCs) during the production, storage, and transportation of petroleum and its derivatives can be hazardous to human health and lead to secondary pollution. Addressing this challenge, this study introduces a sustainable and low-energy approach for synthesizing high-efficiency porous carbon materials, leveraging the abundant and renewable watermelon rinds as a carbon source. The carbonization and activation processes were optimized to minimize energy consumption while maximizing adsorptive performance. In this research, watermelon rinds were used as a source of carbon production, and melamine phosphate (FR-MP) was employed as a modifying agent. The FR-MP modified porous biomass-derived activated carbon (PWAC) was created by subjecting it to physical milling, carbonization, and activation. This approach not only utilized a waste biomass effectively but also reduced the overall carbon footprint of the production process. An examination of the effects of FR-MP dosage on the pore structure, surface chemical properties, and VOCs adsorption abilities of PWAC revealed that a higher FR-MP dosage resulted in a wider range of pore sizes within PWAC. The incorporation of FR-MP intensified the development of internal porosity and pore expansion in PWAC. Specifically, the optimized PWAC-0.3 exhibited a significant increase in specific surface area (3149 m²/g) and pore volume (1.76 cm³/g), enhancing adsorption capacities for acetone and n-hexane up to 1046 mg/g and 760 mg/g, respectively. Furthermore, the PWAC demonstrated exceptional recyclability, maintaining 97% of its original adsorption capacity after five cycles, underscoring its sustainable and economic viability. The highly advanced hierarchical ultra-meso-macroporous structure of PWAC significantly reduced the diffusion resistance of VOCs, guaranteeing swift mass transfer and desorption of VOCs. Consequently, the developed PWAC represents a novel, cost-effective, and environmentally-friendly approach for VOCs adsorption, aligning with the principles of green chemistry and low-energy consumption. This research not only provides a promising solution for VOCs mitigation but also highlights the potential of waste biomass in producing high-performance carbon materials.

Defective UiO-66-NH2 (Zr) for Simultaneous Adsorption of Phosphate and Pb2+ for Hydrogen Peroxide Purification.

Removal of hetero ions from the hydrogen peroxide solution is a crucial step in purifying electronic-grade H2O2. Conventional adsorption materials are challenged to meet the need for the simultaneous adsorption of both anions and cations in solvents. UiO-66 (Zr) modified by acetic acid and amino group for simultaneous adsorption of phosphate and Pb2+ in H2O2 purification was fabricated in this work. The as-prepared defective UiO-66-NH2 (Zr) demonstrated a significant increase in specific surface area and porosity, along with more exposed sites for phosphate and Pb2+ adsorption. The adsorption capacity of De-UiO-66-NH2 for phosphate and Pb2+ in H2O2 solution was 52.28 mg g-1 and 35.4 mg g-1, which is 1.19 times and 1.88 times that of unmodified UiO-66 (Zr), respectively. The trace simultaneous adsorption with both 100 ppb phosphate and Pb2+ showed removal rates of 94.0% and 88.7%, respectively, confirming the practicality of MOF materials in the purification of electronic chemicals. This work highlights the potential of Zr-based MOFs as anionic and cationic simultaneous adsorbents for highly efficient purification of electronic-grade solvents.

Effects of different wall-breaking methods on the nutrient release of Ganoderma lucidum spore powder during in vitro digestion.

The hard double-walled structure of Ganoderma lucidum spore powder (GLSP) is difficult for the human body to digest, so it is very important to break the wall of GLSP. In this study, the wall of GLSP was broken by mechanical milling at room temperature (MM-R) and ultra-fine grinding at low temperature (UFG-L), respectively. Compared with MM-R, UFG-L could better retain the sporangium powder's morphological and structural integrity. During in vitro digestion, compared with unbroken GLSP, the released amounts of polysaccharides and triterpenes from broken GLSP were significantly increased, and they increased with the increase of specific surface area. The bioaccessibility of polysaccharide and triterpene from unbroken GLSP after the intestinal stage were 29.52% and 5.37%, respectively. The bioaccessibility of polysaccharides and triterpene from broken GLSP by MM-R after the intestinal phase were 39.73-72.45% and 16.44-24.97%, while those by UFG-L were 44.53-104.18% and 12.96-32.90%, respectively. The active ingredients of broken GLSP showed better digestion and absorption abilities than unbroken GLSP. Moreover, the specific surface area of GLSP by UFG-L was lower than that by MM-R, and the bioaccessibility of GLSP by UFG-L was higher than that by MM-R. © 2024 Society of Chemical Industry.

Preparation and properties study of high performance Eu2Sn2O7–SnO2 composites humidity sensor

In the work, a high-performance Eu2Sn2O7–SnO2 (ES-2) humidity sensors were prepared through a one-step hydrothermal method. Eu2Sn2O7 is a bimetallic material can increase the adsorption capacity to water molecules and promote electron transfer, thus improving the sensitivity of the sensor. The introduction of Eu2Sn2O7 promotes the increase of the content of oxygen vacancies in the ES-2 composite material, which promotes the accelerated decomposition of water molecules, and facilitates the formation of the chemisorbed layer to improve the sensitivity of the sensor and the response time. The increase in specific surface area of ES-2 provided more adsorption sites for H2O and also provided a good transport channel for water molecules to diffuse into the interior of the material. ES-2 humidity sensor exhibits high sensitivity (22,405 ± 363), small humidity hysteresis (1 ± 0.3 %), short response/recovery time (7/6 ± 0.5 s), good repeatability and stability (11%–95 % RH). This study not only promotes the development of SnO2-based humidity sensors, but provides new ideas for the preparation of high-performance humidity sensors.

Removal of COD from petroleum refinery wastewater by adsorption using activated carbon derived from avocado plant

In the present work, removing of COD from wastewater generated via Al-Diwanya petroleum refinery plant located in Iraq by adsorption with activated carbon (AC) derived from avocado seeds was successfully performed via a two-step approach. In the first step, AC was prepared from avocado seeds via impregnating with H3PO4 at 400 °C where effects of H3PO4 concentration and calcination time on the specific surface area of AC were studied. Additionally, properties of the prepared AC were examined by XRD, SEM, and FTIR to knowledge the features of the internal structure of AC. Results showed that the prepared AC has mesopores structure with pore diameters in the range between 30.07 and 50.8 µm. Increasing the weight percent of H3PO4 led to an increase in the specific surface area of AC to reach a maximum value beyond which a decrease in the specific surface area was happened with further increasing in H3PO4 percent. Increasing the time resulted in an increase in the AC specific surface area to reach a maximum value beyond which a decrease in specific surface area was happened. The best value of AC specific surface area was 436.6 m2/g which obtained at 70 %H3PO4 and 4 h. At the second step, the performance of the prepared AC in removing of COD by adsorption process was evaluated via studying the effects of three operating parameters, namely adsorbent dosage (1–5 g/L), pH (3–9), and shaking speed (100–400 rpm) on the removal of COD(RE%) using a response surface methodology (RSM). Increasing AC dosage led to an increase in RE% while increasing each of pH and shaking speed resulted in lowering RE%. The optimum conditions for higher RE% were AC dosage of 5 g/L, pH of 3, and shaking speed of 100 rpm in which a removal efficiency of 94.54 % was obtained. The degradation of COD with time was found to obey a second order kinetic confirming the chemisorption is the rate limiting step in the adsorption process.

Construction of BiOClxI1-x solid solutions and novel 2D/2D Z-scheme g-C3N4/BiOCl0.7I0.3 heterojunctions for visible-light driven photocatalytic removal of ammonium dinitramide

The eco-friendly and cost-effective visible-light driven photocatalytic technology is a promising strategy for achieving sustainable remediation of explosive wastewater pollution. Ammonium dinitramide (ADN), as a high-energy oxidant in explosives, few studies on its photocatalytic removal have been reported. Thus, this study focuses on photocatalytic remediation of ADN from water over two-dimensional (2D) BiOClxI1-x solid solutions and 2D/2D Z-scheme g-C3N4/BiOCl0.7I0.3 (CN/BCI) heterojunctions. First, BiOClxI1-x solid solutions were constructed through a hydrothermal process. Because of the formation of thinner 2D nanosheets and the increase of specific surface area, the degradation rate of ADN over BiOCl0.7I0.3 is higher than those over other monomers after visible-light illumination for 60 min. In order to further enhance the photocatalytic performance, 2D/2D CN/BCI composite nanosheets were further synthesized by an in-situ hydrothermal method. It suggests that the degradation rate can reach 99.9 % with CN mass ratio of 30 %, due to the formation of a large number of tight contact interfaces in Z-scheme 30CN/BCI heterojunction, which not only further increases the specific surface area, but also promotes the transfer of charge carriers at the interfaces. In addition, the capture experiments indicate that ∙O2−, e− and h+ are the key active species. This study is expected to provide a new perspective for efficient photocatalytic remediation of ADN-based explosive wastewater.

Visible-light-driven 2D π-conjugated polyimide/ZnO efficiently removes tetracycline

Heterojunction organic-inorganic composites are promising for wastewater treatment due to their excellent physical and chemical properties. ZnO was immobilized on the PI surface using the hydrothermal technique to prepare PI/ZnO n-n heterojunctions with outstanding visible photocatalytic properties. The photocatalytic performance of different ratios of PI/ZnO composites was significantly improved in comparison to pure PI and ZnO, among which 40% PI/ZnO showed the most outstanding results. The 40% PI/ZnO can adsorption remove around 40% of tetracycline (TC) in 20 min in entirely shaded conditions and can attain up to 90% of the TC removal efficiency in 40 min under visible light exposure. The formation of a PI/ZnO heterojunction enhances the efficiency of charge separation and reduces the recombination of photogenerated electron-hole pairs, resulting in improved photocatalytic performance. Meanwhile, the 40% PI/ZnO composites showed a substantial increase in specific surface area (205.22 m2/g) compared to pure PI and ZnO, which was 103 and 25 times that of PI and ZnO, respectively. The increase in surface area provided a larger number of adsorption sites, thereby increasing the contact area between the pollutants and the photocatalysts, which led to a significant improvement of the PI/ZnO composites in the adsorption and photocatalytic properties. In this study, the heterojunction was formed by the composite of conjugated polymer and metal oxide, so that the composites could remove the organic matter more efficiently by adsorption and then photocatalysis, which will provide some ideas for the development of more efficient conjugated polymer materials.

Microwave assisted biomass derived carbon aerogel for highly efficient oxytetracycline hydrochloride degradation: Singlet oxygen mechanism and C vacancies accelerated electron transfer

With plant biomass α-cellulose and sodium lignosulfonate as starting materials, biochar aerogel catalysts were prepared with facile microwave assisted pyrolysis in 5 min; and the as-prepared biochars were utilized for efficient peroxymonosulfate (PMS) activation and oxytetracycline hydrochloride (OTC) degradation under transition metal free conditions. It was found that microwave treatment and sodium lignosulfonate were beneficial for thiophene S introduction, C = O groups and C vacancies enrichment, as well as specific surface area increase. The optimal α-cellulose and sodium lignosulfonate derived metal free biochar aerogel catalyst C3S2 displayed excellent ability to promote PMS activation for 99.9 % OTC degradation during 15 min with rate constant up to 0.818 min−1. Through correlation analysis, quenching tests as well as EPR characterization, C = O groups and thiophene S were considered as main sites for PMS activation to produce nonradicals singlet oxygen (1O2) in OTC degradation. Meanwhile, C vacancies enrichment further improved the pollutants degradation by means of electron transfer acceleration. This research demonstrated new insight in metal-free biochar catalyst design for highly efficient contaminants degradation with 1O2 pathway.

Modification of tetrahedrite Cu12Sb4S13 thermoelectric performance via the combined treatment of mechanochemistry and composite formation

Tetrahedrite Cu12Sb4S13 with its low thermal conductivity represents a flagship in sulphide thermoelectrics. However, to achieve a reasonable figure-of-merit ZT (measure of thermoelectric efficiency), adequate doping or special sample processing is needed. In this work, a different approach (without doping) is illustrated for the two tetrahedrite-containing systems. In the first approach binary composite tetrahedrite Cu12Sb4S13/chalcopyrite CuFeS2 was prepared by mechanochemical leaching with the aim to obtain partly decomposed tetrahedrite. In this approach, the alkaline leaching medium (Na2S + NaOH) was applied to extract Sb from tetrahedrite thus changing its composition. The obtained composite (formed from its own phases in an intrinsic mode) shows low values of ZT = 0.0022@673 K in comparison with the non-treated tetrahedrite where ZT was 0.0090@673 K. In this case the extremely high electric resistivity (6–20 mΩ cm−1) was documented. In the second approach binary composite tetrahedrite Cu12Sb4S13/muscovite KAl2(AlSi3O10)(OH)2 (formed from its own and foreign phases in an extrinsic mode) was prepared by two-step mechanical activation in which combined treatment of industrial vibratory milling and subsequent laboratory planetary milling was applied. The addition of a foreign phase, muscovite, did not give extraordinary thermoelectric performance results. However, the two-step milling process (without the addition of foreign phase) gives the value of ZT = 0.752@673 K which belongs to the highest in the tetrahedrite thermoelectric community. In this case, the two-times increase in specific surface area and the increased amount of tetrahedrite in comparison to famatinite are suspectable for this effect. Both applied non-traditional approaches to synthesize tetrahedrite composites form a platform for potential modification of its thermoelectric performance.