Carbon-doped porous hollow alpha-Fe2O3 microtubules controlled by absorbent cotton bio-template to detect acetic acid vapor

To overcome the scarcity and costliness of noble metal dopants, carbon (C) doping, as a low-cost alternative, was achieved by absorbent cotton when the alpha (α)-Fe₂O₃ microtubules were synthesized with a facile hydrothermal method and necessary calcination. The absorbent cotton not only provided carbon source but controlled the microtubular morphology of α-Fe₂O₃. Meanwhile, for comparison, a pure α-Fe₂O₃ nanoparticles sample was also prepared without using absorbent cotton. Numerous techniques were employed to characterize the element composition and microstructures. The consequences demonstrated that carbon had been successfully incorporated into the porous hollow α-Fe₂O₃ microtubules composed of many nanoparticles. Compared with the α-Fe₂O₃ nanoparticles, the carbon-doped α-Fe₂O₃ microtubules possessed the unique morphology, large specific surface area and pore size, and abundant oxygen vacancies (O_V). To reveal the function of the carbon-doped α-Fe₂O₃ microtubules and α-Fe₂O₃ nanoparticles, two chemical gas sensors were manufactured and researched systematically. Forasmuch as those advantages mentioned above, the sensor based on the carbon-doped α-Fe₂O₃ microtubules exhibited better gas sensing properties to acetic acid vapor at a lower optimal operating temperature of 260 °C, such as higher response value, shorter response and recovery time, good repeatability, and stability. And thence the carbon-doped α-Fe₂O₃ microtubules product could be considered as an excellent acetic acid vapor sensor in the future. In addition, the possible grown mechanism and gas sensing mechanism of the carbon-doped α-Fe₂O₃ microtubules were discussed in detail. The work provides a new strategy to improve the gas sensing performance of α-Fe₂O₃ material.     

Microwave assisted synthesis of biomorphic hydroxyapatite

Hydroxyapatite has been synthesized using eggshell membrane as bio-template along with the assistance of microwave heating. Eggshell membrane is infiltrated with calcium and phosphorous precursors before heating it in a domestic microwave oven. Hydroxyapatite formed retained the interwoven hierarchical structure of the eggshell membrane. Structural analysis was performed using X-ray diffraction, and the microstructural features are characterized by scanning electron microscopy. Distinct morphological features were present in microwave processed hydroxyapatite when compared to the conventionally processed one. Transmission electron microscopic investigations and BET surface area analysis were also carried out.     

以鸡蛋壳内膜为模板制备碳酸钙及吸附性能

利用鸡蛋壳内膜为生物模板剂,氯化钙为钙源制备碳酸钙。通过单因素实验考察反应物初始浓度、生物模板用量及反应时间等因素对碳酸钙制备的影响。结果显示其较佳制备条件是:反应物初始浓度为1.5mol/L,生物模板用量为0.02g,反应时间为30min。利用较佳条件下制备的碳酸钙处理10mg/L的铁离子溶液时,在碳酸钙用量为0.2g时,吸附反应10min后的铁离子去除率为91.39%。     

Solvothermal preparation and gas sensing properties of hierarchical pore structure SnO2 produced using grapefruit peel as a bio-template

Hierarchical pore structure nano-sized SnO₂ was synthesized using a solvothermal method with SnCl₄ as the raw material and grapefruit peel as the bio-template. The products were characterized by powder X-ray diffraction, high resolution scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. The results show that the SnO₂ prepared from the grapefruit peel bio-template consists of many large size (5–20 µm) interconnected pores with a honeycomb structure and nanosized pores (9.46 nm) on the walls of the large pores. The as-prepared SnO₂ presented a high specific surface area of 42.98 m²/g and the average crystallite size was about 10±0.5 nm. The gas sensing performance of the prepared material toward several volatile organic compounds was investigated. The results show that the hierarchical pore structure nano-sized SnO₂ was highly sensitive and selective to n-butanol, indicating that this material may be a promising candidate for future development as a n-butanol gas sensor.     

Eggplant as an appreciable bio-template for green synthesis of NiO nanoparticles: Study of physical and photocatalytic properties

In this study, we described a green, sustainable, and feasible method for synthesizing 5 nm NiO nanoparticles. Eggplant skin was chosen as an appropriate bio-template with a high potential to induce its structure into the desired metal oxide. Two approaches were used and compared to synthesize NiO bio-template: hydrothermal and sol-gel. The morphology and physical properties of the obtained NiO nanoparticles were evaluated using FESEM, TEM, XRD, BET, FT-IR, TGA, and UV–Vis analyses. All these methods confirm that the hydrothermal method is a better approach for synthesizing NiO bio-template nanoparticles than the sol-gel method. UV–Vis analysis revealed that the NiO nanoparticles produced by the hydrothermal method have a low bandgap of 2.88 eV, which is a key factor for photocatalytic applications.     

Enhancement of visible light photocatalytic hydrogen evolution by bio-mimetic C-doped graphitic carbon nitride

Bio-mimetic C-doped graphitic carbon nitride (g-C₃N₄) with mesoporous microtubular structure has been prepared by a simple chemical wet bio-template impregnation approach (direct impregnation and hydrothermal impregnation) using urea as a precursor and kapok fibre as bio-template and in-situ carbon dopant. Our finding indicated that the hydrothermal impregnation had induced more in-situ C-doping in g-C₃N₄ as compared to the direct impregnation approach. The introduction of in-situ C doping in the g-C₃N₄ and the mesoporous microtubular structure remarkably enhanced light-harvesting capability up to near infrared regions. The photocurrent measurement and electrochemical impedance spectroscopy (EIS) analysis suggested that the bio-template C-doped g-C₃N₄ exhibits a superior photoinduced electron-hole pairs separation efficiency due to C doping and mesoporous microtubular structure significantly promotes excellent conductivity and electron redistribution in the sample. C-doped graphitic carbon nitride sample prepared by the hydrothermal (HB/g-C₃N₄) approach exhibits excellent photocatalytic hydrogen production with an H₂ production rate of 216.8 μmol h⁻¹ g⁻¹ which was a 1.3 and 2.9 improvement over C-doped graphitic carbon nitride prepared by direct impregnation (DB/g-C₃N₄) and pristine g-C₃N_4, respectively. This study provides new insights into the development of low-cost and sustainable photocatalysts for photocatalytic hydrogen production.     

Preparation of meso-porous SnO2 fibers with enhanced sensitivity for n-butanol

Meso-porous SnO₂ fibers were synthesized using a solvothermal method with metaplexis fruit as the bio-template. The products were characterized by powder X-ray diffraction, high resolution scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Results show that SnO₂ fibers present a high specific surface area of 73.665 m²/g and a meso-porous structure with the pore size of 7.821 nm, and the crystal size of SnO₂ is about 6.5 ± 0.5 nm. The gas sensing performance of the prepared SnO₂ fibers toward several volatile organic compounds was investigated. The results show that the meso-porous SnO₂ fibers were highly sensitive and selective to n-butanol.     

生物模板法制备MnO/C复合材料及其储锂性能研究

以天然的柚子皮为生物模板,高锰酸钾为锰源,通过化学浴(CBD)方法和后续煅烧处理制备MnO/碳(MnO/C)复合材料。采用X射线衍射(XRD),热重-差热分析法(TG-DTA),拉曼(Raman),扫描电子显微镜(SEM)和透射电子显微镜(TEM)对材料的物相组成、形貌和微结构进行表征。结果表明,柚子皮模板原位转变为碳基体,同时MnO颗粒均匀负载于碳基体形成MnO/C复合材料,其中碳含量约为30%。电化学测试表明该复合材料具有优异的储锂性能,在0.2 A/g电流密度下循环100次后可逆容量依旧保持在664 mAh/g,在3 A/g大电流密度下,可逆容量仍有441 mAh/g。     

Bio-template fabrication of nanoporous Ni@Al2O3: Durable catalyst for biogas reforming reaction

Following green chemistry principles and the significant role of catalysts in chemical transformations, in this study, for the first time, Ni@Al₂O₃ nanoparticles were prepared via a green, a sustainable, and practical approach using the waste management concept. To achieve this goal, the eggplant skin was employed as an abundant and green bio-template to synthesize desired materials, applying for biogas reforming (CH₄/CO₂ = 1:1) at four temperatures (600–750 °C). Synthesized materials were fully characterized and according to the findings, the bio-template was able to induce its structure on prepared materials and had a considerable effect on the activity of nickel-based alumina catalysts thanks to the high dispersion of Ni nanoparticles on the prepared materials. This catalyst could tolerate the reaction conditions even after 30 h of the catalytic run at 650 °C, along with a remarkable coke resistance (less than 4% carbon deposition).