Enlarged Surface Area Research Articles

SiO2 mediated templating synthesis of γ-Fe2O3/MnO2 as peroxymonosulfate activator for enhanced phenol degradation dominated by singlet oxygen

Cost-effective and low-toxicity of MnO2 is regarded as a promising alternative to Co-based catalyst for peroxymonosulfate (PMS) activation to degrade recalcitrant organic pollutants. However, the sluggish Mn(IV)/Mn(III) redox cycling and limited specific surface area greatly hampered its wide application. To solve this challenge, a mesoporous γ-Fe2O3@MnO2 magnetic catalyst with SiO2 assistance (s-γ-Fe2O3@MnO2) was synthesized. Physicochemical characterization confirmed part MnO2 was coated on γ-Fe2O3 surface while the other existed independently. Furthermore, BET surface area of s-γ-Fe2O3@MnO2 was more than two times that of the counterpart without SiO2 assistance (ws-γ-Fe2O3@MnO2). s-γ-Fe2O3@MnO2 exhibited enhanced PMS activation capacity with 97.6% phenol removal efficiency within 80 min, superior to other samples. Various influencing parameters on phenol oxidation were optimized. Reactive oxygen species (ROS) scavenging experiment and electron paramagnetic resonance (EPR) validated co-existence of hydroxyl radicals (·OH) and sulfate radicals (SO4·−) as well as singlet oxygen (1O2) during PMS activation. However, phenol degradation was a non-radical oxidation process dominated by 1O2. A rational reaction mechanism was proposed. Fe(II) promoted Mn(IV)/Mn(III) redox cycling and the enlarged surface area derived from SiO2 mediated templating synthesis were responsible for the enhanced phenol degradation. This strategy can give a guidance for synthesis of highly efficient catalyst for sewage remediation.

Experimental study of a novel strategy to construct the battery thermal management module by using tubular phase change material units

For the thermal management of cylindrical power battery module, the classical cuboid-like phase change material (PCM) module still remains problematic, because the bulky structure remarkably decreases the energy density and secondary heat-dissipation capability of the battery module. Here a novel strategy to construct the PCM module was proposed by substituting the bulky cuboid PCM module with tubular PCM units. Compared to the classical cuboid module, the assembled tubular PCM module confers numerous naturally-formed channels for air flow, an enlarged outer surface area for secondary heat dissipation, and a greatly reduced module weight. As a result, the tubular PCM module demonstrates a superior heat-dissipation performance for cylindrical power batteries. For example, with forced air convection, the temperature and temperature difference can be controlled below 47.2 and 1.0 °C respectively under an extreme working environment, i.e., 10 charge and discharge cycles at a high environment temperature of 40 °C. More importantly, this novel strategy also benefits the flexible assembling and maintenance of the modules, and saves 54% of the PCM amount, thus increasing the energy density of the battery module from 75.5 to 94.4 Wh kg−1.

In Situ Reconstruction of V‐Doped Ni2P Pre‐Catalysts with Tunable Electronic Structures for Water Oxidation

AbstractNickel‐based electrocatalysts are promising candidates for oxygen evolution reaction (OER) but suffer from high activation overpotentials. Herein, in situ structural reconstruction of V‐doped Ni2P pre‐catalyst to form highly active NiV oxyhydroxides for OER is reported, during which the partial dissolution of V creates a disordered Ni structure with an enlarged electrochemical surface area. Operando electrochemical impedance spectroscopy reveals that the synergistic interaction between the Ni hosts and the remaining V dopants can regulate the electronic structure of NiV oxyhydroxides, which leads to enhanced kinetics for the adsorption of *OH and deprotonation of *OOH intermediates. Raman spectroscopy and X‐ray absorption spectroscopy further demonstrate that the increased content of active β‐NiOOH phase with the disordered Ni active sites contributes to OER activity enhancement. Density functional theory calculations verify that the V dopants facilitate the generation of *O intermediates during OER, which is the rate‐determining step for realizing efficient O2 evolution. Optimization of these properties endows the NiV oxyhydroxide electrode with a low overpotential of 221 mV to deliver a current density of 10 mA cm−2 and excellent stability in the alkaline electrolyte.

Periodic Micropillar-Patterned FTO/BiVO4 with Superior Light Absorption and Separation Efficiency for Efficient PEC Performance.

In this study, a high-performance photoanode based on 3D periodic, micropillar-structured fluorine-doped tin oxide (FTO-MP) deposited with BiVO4 is fabricated using the patterned FTO by direct printing and spray pyrolysis, followed by the deposition of BiVO4 by sputtering and V ion heat-treatment on the patterned FTO. The FTO-MP enables light scattering owing to its 3D periodic structure and increases the light absorption efficiency. In addition, the high electron mobility of FTO and enlarged surface area of FTO-MP enhance the separation efficiency. Due to the combination of these enhancing strategies, the photocurrent density of micropillar-patterned BiVO4 at 1.23 VRHE reached 2.97mA cm-2 , which is 67.8% higher than that of flat BiVO4 . The results suggest that the efficiency can increase significantly using the patterned FTO fabricated by an inexpensive and simple process (i.e., direct printing and spray pyrolysis), thereby indicating a new strategy for the enhancement of efficiency in various energy fields.

Rapid detection of cadmium ions in meat by a multi-walled carbon nanotubes enhanced metal-organic framework modified electrochemical sensor

This work presents an electrochemical device based on a composite modification of amine functionalized Zr(IV) metal–organic framework (UiO-66-NH2) and multi-walled carbon nanotubes (MWCNTs) for voltammetry determination of cadmium ions (Cd2+). The UiO-66-NH2@MWCNTs composites were prepared by one-pot hydrothermal reaction. The prepared sensor performs excellent performance, which was attributed to the synergism between UiO-66-NH2 with a special octahedral structure and enlarged surface area and MWCNTs with outstanding conductivity. Under optimal experiment condition, the fabricated sensor showed good linear relationship from 0.5 to 170 μg/L, with a detection limit of 0.2 μg/L. Finally, the sensor was successfully applied to detect Cd2+ in meat samples (N = 21) with relative standard deviation (RSD) lower than 4.5% and recovery of 95.1–107.5%, and the results were compared with certified method, there was no statistical significance difference between the developed sensor and certified method at a 95% confidence level.

Synthesis of Nitrogen-doped KTaTeO6 with Enhanced Visible Light Photocatalytic Degradation of Methylene Blue

Anion doping is one of the efficient ways to tailor the bandgap of photocatalysts for the treatment of polluted water. The present work describes the improved photocatalytic activity of defect pyrochlore, KTaTeO6 (KTTO), upon nitrogen doping, towards the degradation of methylene blue under visible light irradiation. The parent KTaTeO6 was synthesized by solid-state method. The N-doped KTaTeO6 (N-KTTO) was prepared by nitridation method using NH3. Techniques such as the XRD, N2 adsorption-desorption, FE-SEM/EDX/EDS elemental mapping, TEM-HRTEM, UV-Vis DRS, XPS, Raman, and PL were employed to characterize the physicochemical properties of photocatalysts. The N-doping in KTTO has resulted in enlarged surface area, narrowed the bandgap, and reduced the recombination of photogenerated electron-hole pairs, leading to enhanced photocatalytic activity compared to parent KTTO. The active species trapping experiments were conducted to elucidate the mechanism of photodegradation. The N-KTTO is chemically stable and can be used at least up to five cycles.

Functional Adaptations in the Forelimb of the Snow Leopard (Panthera uncia).

The snow leopard (Panthera uncia) is anatomically and physiologically adapted for life in the rocky terrain of alpine zones in Central and South Asia. Panthera uncia is scansorial, and typically hunts solitarily by using overhead ambush of prey, rather than the typical stalking pattern of other large pantherines. In this study, we conducted dissections, detailed documentation, and illustrated the forelimb anatomy of two adult P. uncia specimens (1M/1F). Qualitative and quantitative data revealed an intriguing combination of functional adaptations illustrating a balance between the diverse demands of head-first descent, pouncing, climbing across rocky terrain, restraint of large prey, rapid pursuit, and navigating deep snow. In many forelimb proportions, P. uncia is intermediate between the cursorial Acinonyx jubatus (cheetah) and the scansorial forest dwelling Panthera onca (jaguar). Enlarged scapular and pectoral musculature provide stability to the shoulder girdle during grappling with large prey, as well as support during jumping and climbing. A small, unarticulated bony clavicle may provide greater stability to the forelimb, while still allowing flexibility. In the brachium and antebrachium of P. uncia, there is a functional compromise between the powerful grip needed for grasping large prey and the stability necessary for rapid pursuit of prey over uneven, rocky terrain. A unique bifurcation in the tendon of m. biceps brachii may provide additional functional stability at the radiohumeral joint. Intrinsic muscles of the palmar manus are broad and fleshy, acting as an enlarged surface area to evenly distribute body weight while walking on soft snow. However, muscles that act to provide fine manual manipulation are reduced, as in other large prey specialists. Overall, P. uncia displays morphological adaptive parallels with scansorial, large prey specializing pantherines, such as P. onca, while also showing adaptations for running.

Harmine is an effective therapeutic small molecule for the treatment of cardiac hypertrophy.

Harmine is a β-carboline alkaloid isolated from Banisteria caapi and Peganum harmala L with various pharmacological activities, including antioxidant, anti-inflammatory, antitumor, anti-depressant, and anti-leishmanial capabilities. Nevertheless, the pharmacological effect of harmine on cardiomyocytes and heart muscle has not been reported. Here we found a protective effect of harmine on cardiac hypertrophy in spontaneously hypertensive rats in vivo. Further, harmine could inhibit the phenotypes of norepinephrine-induced hypertrophy in human embryonic stem cell-derived cardiomyocytes in vitro. It reduced the enlarged cell surface area, reversed the increased calcium handling and contractility, and downregulated expression of hypertrophy-related genes in norepinephrine-induced hypertrophy of human cardiomyocytes derived from embryonic stem cells. We further showed that one of the potential underlying mechanism by which harmine alleviates cardiac hypertrophy relied on inhibition of NF-κB phosphorylation and the stimulated inflammatory cytokines in pathological ventricular remodeling. Our data suggest that harmine is a promising therapeutic agent for cardiac hypertrophy independent of blood pressure modulation and could be a promising addition of current medications for cardiac hypertrophy.

Flower-like CoO@Cu2S nanocomposite for enhanced oxygen evolution reaction

Replacing precious metals with earth-abundant elements for electrochemical oxygen evolution reaction (OER) represents a judicious way to commercialization of large-scale water-splitting systems. However, the development of low-cost, efficient and durable OER catalysts remains a huge challenge. Herein, flower-like CoO@Cu2S nanocomposites were prepared with an etch-deposition approach by using cuprous oxide microcrystals as removable templates. Owing to the substantially enlarged surface area and interfacial charge transfer effects, the resulted product Cu2S@CoO was able to serve as highly efficient and durable OER electrocatalyst with a low overpotential (277 mV) at a current density of 10 mA·cm−2 in alkaline electrolyte. This work enriches the ways to prepare complicate bimetallic nanocomposites for long-life and high-performance OER electrocatalysts.

Substantial decrease in CO2 emissions from Chinese inland waters due to global change

Carbon dioxide (CO2) evasion from inland waters is an important component of the global carbon cycle. However, it remains unknown how global change affects CO2 emissions over longer time scales. Here, we present seasonal and annual fluxes of CO2 emissions from streams, rivers, lakes, and reservoirs throughout China and quantify their changes over the past three decades. We found that the CO2 emissions declined from 138 ± 31 Tg C yr−1 in the 1980s to 98 ± 19 Tg C yr−1 in the 2010s. Our results suggest that this unexpected decrease was driven by a combination of environmental alterations, including massive conversion of free-flowing rivers to reservoirs and widespread implementation of reforestation programs. Meanwhile, we found increasing CO2 emissions from the Tibetan Plateau inland waters, likely attributable to increased terrestrial deliveries of organic carbon and expanded surface area due to climate change. We suggest that the CO2 emissions from Chinese inland waters have greatly offset the terrestrial carbon sink and are therefore a key component of China’s carbon budget.

The enhanced performance of Cr(VI) photoreduction and antibiotic removal on 2D/3D TiO2/ZnIn2S4 nanostructures

In this study, 2D/3D TiO2/ZnIn2S4 nanostructures with TiO2 sheet cluster embedded into ZnIn2S4 micro flowers were fabricated via hydrothermal method. The matched band structure, the enlarged surface area and the efficient photo-induced charge transfer offered by effective heterostructures formed between the two components endowed the TiO2/ZnIn2S4 nanoarchitecture with excellent photocatalytic Cr(VI) reduction and tetracycline hydrochloride (TC) degradation performance. Especially, the Cr(VI) photoreduction efficiency of 50% TiO2/ZnIn2S4 was 8.8 times higher compared to pure ZnIn2S4. The enhanced separation efficiency of photo-excited charge carriers was induced by the matched band structure, the enlarged surface area and the strong interaction between TiO2 and ZnIn2S4. The key roles of ·O2− was confirmed via trapping experiments. Otherwise, the pathway of TC degradation was investigated. The proposed mechanism during photocatalysis process was also discussed according to the photocatalytic and characterization results.

Engineered biochars for recovering phosphate and ammonium from wastewater: A review.

Biochar has gained great scientific attention as a promising agent for agricultural and environmental applications. A variety of biochars with excellent properties such as high porosity, surface area and functional groups have been developed for nutrients recovery from wastewater. Compared to pristine biochar, engineered biochar with enlarged surface area and abundant functional groups has been prepared which shows a new type of carbon-based material with enhanced adsorption potential for nutrients in wastewater. To date, a few reviews have been specifically focused on several important aspects of engineered biochar, such as its application to recover phosphate and ammonium from wastewater and subsequent use as a slow-release fertilizer. In this work, novel modification/treatment methods including activation with acid/alkali, functionalization with amides, thiols and oxidizing agents, metal salt impregnation, loading with various minerals and carbon-based materials are reviewed for preparing engineered biochar with improved adsorption capacity. Various sources of biomass for producing biochars were estimated, and the intrinsic characteristics and potential of biochar products for simultaneous recovery/removal of phosphate and ammonium from wastewater were evaluated. Relevant interaction mechanisms of phosphate and ammonium adsorption on engineered biochars have been discussed in details. Finally, important future prospects as well as industrial/commercial-scale application of engineered biochars for phosphate and ammonium recovery from wastewater have been emphasized. We believe that this review will provide broad scientific opportunities for thorough understanding of applying engineered biochar as a low-cost and environmentally sustainable material for nutrients recovery from wastewater.

ZnAl-LDH and B-impregnated polymeric semiconductor (g-C3N4) for solar light-driven photocatalysis to treat phenolic effluent

The structural transformation of graphitic carbon nitride (g-C3N4) has been done by means of Zinc Aluminium layered double hydroxide (ZnAl-LDH), and a non-metal, i.e. boron impregnation to enhance its visible light absorption. Optical and morphological study intimates that an altered band assembly formed due to the impregnation, resulting in a shorten bandgap in conjunction with the development of an irregular hexagonally interrelated morphology. In addition, the impregnated g-C3N4 (40% B-g-C3N4 and 30%ZnAl-LDH/g-C3N4) owns an expanded surface area of 14.3137, and 26.292 m2/g, which demonstrate 90.25, 86.31% degradation in phenol at 270 min illumination, with 700 mg/L of chemical oxidant concentration, and 5 L/h of flowrate, whereas under same conditions g-C3N4 impart 62.38% degradation. We hope this study will open a new dimensions for the sustainable use of solar energy for environmental applications.

Simple and scalable synthesis of urchin-like ZnO nanoparticles via a microwave-assisted drying process

The urchin-like nanoparticles of semiconducting oxides have been attracting considerable attention as they can significantly improve reactivity owing to their enlarged surface areas. Herein, we report a simple and scalable synthesis method of ZnO nanomaterials via a microwave-assisted drying process. Commercial ZnO powders (~300 nm) and expanded graphite were used as starting materials to prepare urchin-like ZnO nanoparticles with nanoscale legs (diameter ~20 nm) by triggering the rapid phase transformation, which was induced by a repeated microwave irradiation in an alumina crucible for a few minutes. The possible mechanisms to trigger this morphological and dimensional change are described in detail. The high-yield production and superior reproducibility completed in shortened processing times enable this synthetic route to be widely applicable for the massive production of nanostructured oxide particles.

Fabrication of a direct Z-scheme heterojunction between MoS2 and B/Eu-g-C3N4 for an enhanced photocatalytic performance toward tetracycline degradation

A sulfur vacancy (SV)- and nitrogen vacancy (NV)-mediated Z-scheme MoS2/Eu/B-g-C3N4 (MS/BEuCN) photocatalyst was synthesized via thermal polymerization and ultrasonic dispersion methods. Based on the results of various characterizations, a direct Z-scheme heterojunction was successfully constructed between MS and BEuCN, which efficiently promoted photoinduced carrier charge separation and prevented the occurrence of photocorrosion. Meanwhile, the MS/BEuCN composites displayed an enlarged BET specific surface area, widened the visible-light absorption range and accelerated the photoinduced electron-hole pair separation, which significantly promoted photodegradation toward tetracycline (TC). The existence of NVs and SVs had a synergistic effect, providing more active sites, enhancing the visible-light absorbance capacity and promoting the separation of photoinduced carriers charge. The optimized photocatalytic degradation rate of MS/BEuCN could be improved to 99.0%, nearly 1.6, 2.1 and 1.2 times that of MS, CN and BEuCN, respectively. The significant contribution of ·O2− and ·OH in the MS/BEuCN/Vis system was proven via radical quenching experiments and electron spin response measurements (ESR). This work provided a novel combination mode for the construction of high-efficiency heterostructure photocatalysts, which could be applied in environmental restoration.

Photocatalytic oxidation of atrazine using BaTiO3 -MWCNT nanocomposites under visible light

Despite the importance of Atrazine (AT) as herbicide, it represents crucial danger for the different living things. Therefore, many studies have been completed to treat the polluted systems from such herbicide. In this research, sol-gel method was applied simply to synthesize BaTiO3 nanoparticles (NPs) that were furtherly incorporated with Multi-walled carbon nanotube (MWCNT) to prepare BaTiO3@MWCNT photocatalyst. The physicochemical, photoelectronic, photocatalytic and textural properties of BaTiO3 have been improved as a result of the incorporation with MWCNT. Evidently, inclusion of the optimized percentage of MWCNT (3.0 wt %) with BaTiO3 is acknowledged as a successful way to enhance the capability of BaTiO3 to absorb visible light such that BaTiO3@MWCNT-3 wt.% photocatalyst exhibited declined bandgap (2.64 eV) that allows improved absorbance in visible region. Furthermore, 2.0 gL–1 of the optimized nanocomposite accomplished efficiently the photocatalytic oxidation of AT when illuminated by visible light for 40 min. The recycled BaTiO3@MWCNT nanocomposite was able to achieve the photocatalytic oxidation of AT up to five times without any loss of the photocatalytic performance affirming its great stability and durability as well as its appropriateness for the industrial applications. The enhanced characteristics possessed by the synthesized nanocomposites could be correlated to different factors such as the enlarged surface area, the hindered recombination between the photoinduced charges as well as the reduced bandgap energy. This study proposes an eco-friendly regime to remove some hazardous herbicides from the aquatic systems.

Enhanced photocatalytic degradation of methyl orange by coconut shell-derived biochar composites under visible LED light irradiation.

The conversion of carbon-rich biomass into valuable material is an environmental-friendly approach for its reutilization. In this study, coconut shell-derived biochar, graphitic carbon nitride (g-C3N4), g-C3N4/biochar, titanium dioxide (TiO2)/biochar, zinc oxide (ZnO)/biochar, and ferric oxide (Fe2O3)/biochar were synthesized and characterized by using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), surface area analysis, UV-Vis diffuse reflectance spectroscopy (DRS), and zeta potential analysis. The g-C3N4 or metal oxide particles were found to be well-distributed on the coconut shell-derived biochar with the improvement in thermal stability and enlargement of specific surface area. A great reduction in band gap energy was observed in the composite materials after incorporating with the biochar. Among different biochar composites, g-C3N4/biochar was found to have the highest photocatalytic activity. The interactive effect of parameters such as catalyst dosage, peroxymonosulfate (PMS) oxidant dosage, and solution pH on the photocatalytic degradation of methyl orange was investigated using the response surface methodology (RSM). The highest photocatalytic degradation efficiency (96.63%) was achieved at catalyst dosage of 0.75g/L, oxidant dosage of 0.6mM, and solution pH 3 after 30min.

Magnetic Fe3O4/attapulgite hybrids for Cd(II) adsorption: Performance, mechanism and recovery

Herein, a Fe3O4 decorated attapulgite adsorbent (FA) is fabricated for the removal of Cd(II) from wastewater, and subsequently a feasible strategy for converting the saturated waste adsorbent to CdS/FA photocatalyst is reported. Owing to the in situ growth of Fe3O4 on the attapulgite (ATP), the FA adsorbents exhibit enlarged surface area and increased adsorption sites. More importantly, the strong interaction between Fe3O4 and ATP leads to changes of coordination environment around the O‒Fe‒O bond with the ATP. Based on the results of density functional theory calculations, the electrons are more readily transferred from Fe to O, and the hanging O atoms with more electronegativity act as the efficient adsorption sites for Cd(II), efficiently improving the adsorption performance of the Fe3O4 phases. Furthermore, the waste FA adsorbent could be conveniently separated from the treated water by magnets and converted to CdS/FA photocatalyst, which exhibits satisfying degradation efficiency for tetracycline with low concentration. This work provides a potential strategy to optimize the ATP-based materials for heavy ions adsorption and reutilize the waste adsorbents.

Facile synthesis of high-performance indium nanocrystals for selective CO2-to-formate electroreduction

Selective electrocatalytic reduction of CO2 to formate has received increasing interest for CO2 conversion and utilization. Yet, the CO2 reduction process still faces major challenges, partly due to the lack of cost-effective, highly active, selective and stable electrocatalysts. Here, we report a mesoporous indium (mp-In) electrocatalyst composed of nanobelts synthesized via a simple solution-based approach for selective CO2 reduction to formate. The mp-In nanocrystals provide enlarged surface areas, abundant surface active sites and edge/low-coordinated sites. Such advantages afford the mp-In with an outstanding electrocatalytic performance for the CO2-to-formate conversion. A high formate selectivity, with a Faradaic efficiency (FE) of >90% was achieved over a potential of −0.95 V to −1.1 V (vs VRHE). The mp-In catalyst showed excellent durability, reflected by the stable formate selectivity and current density over a 24 h reaction period. Density functional theory (DFT) calculations reveal that the stabilization of the intermediate OCHO* on the In-plane surfaces is energetically feasible, further elucidating the origin of its enhanced CO2-to-formate activity and selectivity. This work may offer valuable insights for the facile fabrication of porous hierarchical nanostructures for electrocatalytic and selective reduction of CO2.

A facile method for preparing porous g–C3N4 nanosheets with efficient photocatalytic activity under visible light

g–C3N4 nanosheets with porous structures (labelled PGN) were prepared by an extremely facile one-step, template-free method. The method used to prepare porous g–C3N4 nanosheets in this research was thermal polycondensation of urea pre-treated with ethanol. These nanosheets were compared with g–C3N4 agglomerates (labelled BG) prepared with raw urea. The pre-treatment process did not change the crystal structure of urea but changed the thermal polymerization process of urea to form g–C3N4. The change in the thermal polymerization process resulted in the formation of porous g–C3N4 nanosheets. The as-prepared PGN photocatalyst has an enlarged surface area of 66.0 m2 g−1 and a pore volume of 0.357 cm3 g−1, leading to enhanced visible light photocatalytic efficiency. The photocatalytic activity of g–C3N4 was evaluated by the photodegradation experiments with methylene blue (MB). The results indicated that PGN exhibited high and stable photocatalytic activity. The effective separation and transmission of photogenerated electron–hole pairs caused by precursor (urea) pre-treatment as well as the large BET surface area are associated with the enhanced photocatalytic activity of PGN.