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type:Journal Article, Hydrogen bond based visible-light-response heterojunction photocatalyst Melam/WO3 (MW) has been fabricated for the first time by facile planetary milling treatment. Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric (TG) analysis reveal the formation of hydrogen bonds (NH···O) between melam and WO3. As compared to WO3, the MW not only complete decomposes acetaldehyde, but also shows 10 times and 12 times higher photocatalytic activity for photo-degradation of 2-propanol and photo-generation of H2O2, respectively, under the visible-light irradiation. X-ray photoelectron spectroscopy suggests that the potential difference between N and O (N+H⋯O−) in the heterojunction provides the driving force for the charge transfer from WO3 to melam. Furthermore, hydrogen bonds offer an ultrafast electron pathway for heterojunction. This study demonstrates that hydrogen bond based heterojunction could be a promising approach for developing a new photocatalyst with efficient visible-light photocatalytic activity., source:https://doi.org/10.1016/j.apcatb.2016.12.069

type:Journal Article, In this study, yttrium-doped CeO2 was introduced into polymeric carbon nitride (PCN) through one-step hydrothermal reaction to form the Y-doped CeO2/PCN (YCC) nanocomposited photocatalysts. Morphology of products was observed by emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). The structure of the products was characterized by X-ray diffractometer (XRD), FT-IR and Raman analysis. Optical absorption and band energy properties were investigated by UV–vis, PL and VB-XPS spectra. The X-ray photoelectron spectroscopy (XPS) results further revealed that the surface active oxygen and Ce3+ concentration of nanocomposited photocatalyst were significantly increased compared with pure CeO2 and PCN counterparts. The YCC composites exhibited excellent photoredox performance under visible light irradiation, affording to 5.73- and 3.74-fold higher for RhB degradation and proton photoreduction to produce H2 than that of pure CeO2. The Y-doped nanocomposited means adopted in this study not only improve the optical utilization of visible light, but also effectively inhibit the recombination of photogenerated charge carriers, which are conducive to promote the photoredox performance synergistically.

type:Journal Article, Constructing heterojunction between two semiconductors is a cost-effective pathway to fabricate efficient photocatalysts for environmental remediation and energy-related applications, which is with profound significance and high desirability to contemporary era. In this work, we demonstrate an extremely facile approach to couple bismuth subcarbonate with polymeric carbon nitride (denoted as BIOC@PCN) by ion exchange between home-made rose-like Bi2O2(OH)(NO3) (denoted as BION) and PCN bulks at 433 K solvothermal condition. PCN bulks play multi-roles in this ingenious one-pot method. Firstly, PCN bulks guarantee the negatively charged surface to anchor plentiful bismuth precursor salts. More importantly, solvothermal treatment affords a weak basic and sufficient CO32− ions environment to promote the following ion exchange reaction. The evolution of morphology, components and structure from rose-like BION to BIOC@PCN were symmetrically characterized by means of SEM, HR-TEM, XRD, FTIR, TG, UV–vis, BET-BJH and XPS. The as-prepared nanohybrid photocatalyst (0.5BIOC@PCN) presents optimal photocatalytic performance for gaseous acetaldehyde removal, which is showing 10, 6.5 and 2 times higher than that of the PCN-Bulk, BION and mechanical mixed BIOC/PCN counterparts, respectively. Transient photocurrent response and EPR results further verify the validity of the established heterojunction of BIOC@PCN in facilitating the separation of charge carriers. The performance improvement gains from the efficient separation of charge carriers in BIOC@PCN heterojunction, manifested by PL spectra, transient photocurrent response and EPR results. In this study, a facile and cost-effective approach to build PCN-based nanohybrid photocatalysts for gaseous acetaldehyde efficient removal was established., source:https://doi.org/10.1016/j.cattod.2018.03.071

Pyrolysis of kapok fibers over mesoporous molecular sieves of MCM-41, Zr-MCM-41 and Cr-MCM-41 (the mole ratio of Si:Zr or Si/Cr=50) was studied by using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Pure silicon MCM-41 showed weak acidity during pyrolysis with furfural as the main product. Zr-MCM-41 showed the dual-functionality of acid and base with both furfural and hydroxy acetone present in the products. Cr-MCM-41 was more acidic with more furfural produced. The optimal conditions for producing olefins were found to be 600°C and the ratio of kapok fiber to catalyst being 1:10 with the Zr-MCM-41 catalyst. The main products obtained via pyrolysis of kapok fiber were acetic acid, furfural, 2,4-di-tert-butylphenol, olefins, and alkanes. The excess of the catalyst and the high temperature of the reaction had certain effects on the pyrolysis of biomass to produce olefins, such as 1-decene, 1-dodecene, 1-undecene, 1-tridecene and heptadecane. Citation: Qiu, Q., Cai, Y., Ye, Q., and Lv, W. (2019). Catalytic Pyrolysis of Kapok Fiber for Production of Olefins. Trends in Renewable Energy, 5, 218-228. DOI: 10.17737/tre.2019.5.2.0097

type:Journal Article, The hydrothermal method is widely applied in nanomaterials synthesis, and most of the influencing factors have already been taken into account. However, the effect of atmosphere in solution on the performance of nanomaterials has been underestimated for a long time. In this article, reaction solvents were saturated with three classical gases (argon, oxygen, and carbon dioxide), and then heated at 180°C for 24 h to obtain the cerium dioxide (CeO2) nanoparticles. The properties of the three types of CeO2 are significantly different from that of the normal CeO2 (without gas saturation). The morphologies of the prepared CeO2 particles are different, even appear the hollow structure in CeO2−CO2 (synthesized in CO2 saturated condition). The more absorbing and meaningful thing is that the photocatalytic activity of CeO2−CO2 has been greatly improved. The concordance of the CO2 atmosphere (acid gas) and CeO2 (owning substantial content of basic sites) is the key point for the excellent photocatalytic performance., source:https://doi.org/10.1002/cctc.201800659

type:Journal Article, Active composite layers of bismuth triiodide (BiI3) and lead-free (CH3NH3)3Bi2I9 (MBI) perovskite were prepared using a simple chemical solution method under ambient conditions for thin-film solar cells. Results of X-ray diffraction and scanning electron microscopy indicated that the crystallization and surface morphologies of the composite films varied with perovskite contents. Multi-absorption was observed in the composite films due to the bandgap difference between BiI3 and MBI perovskite. Moreover, band bending at the BiI3-perovskite interfaces resulted in the realignment of energy levels in the composite films, and this phenomenon was beneficial to the efficient injection of excited electrons from the active layers into the TiO2 layers. Accordingly, due to the optimized crystallization and realigned energy level, when 20% of MBI perovskite was introduced into the active layers, the open-circuit voltage obviously increased from 0.44 V to 0.57 V in the (BiI3)0.8(MBI)0.2 composites solar cells, enhancing their power conversion efficiency by 67% compared with that in pure BiI3 solar cell. This study developed a new route for designing more efficient lead-free solar cells., source:https://doi.org/10.1016/j.jallcom.2017.01.169

Pyrolysis of kapok fibers over mesoporous molecular sieves of MCM-41, Zr-MCM-41 and Cr-MCM-41 (the mole ratio of Si:Zr or Si/Cr=50) was studied by using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Pure silicon MCM-41 showed weak acidity during pyrolysis with furfural as the main product. Zr-MCM-41 showed the dual-functionality of acid and base with both furfural and hydroxy acetone present in the products. Cr-MCM-41 was more acidic with more furfural produced. The optimal conditions for producing olefins were found to be 600°C and the ratio of kapok fiber to catalyst being 1:10 with the Zr-MCM-41 catalyst. The main products obtained via pyrolysis of kapok fiber were acetic acid, furfural, 2,4-di-tert-butylphenol, olefins, and alkanes. The excess of the catalyst and the high temperature of the reaction had certain effects on the pyrolysis of biomass to produce olefins, such as 1-decene, 1-dodecene, 1-undecene, 1-tridecene and heptadecane. Citation: Qiu, Q., Cai, Y., Ye, Q., and Lv, W. (2019). Catalytic Pyrolysis of Kapok Fiber for Production of Olefins. Trends in Renewable Energy, 5, 218-228. DOI: 10.17737/tre.2019.5.2.0097

Pyrolysis of kapok fibers over mesoporous molecular sieves of MCM-41, Zr-MCM-41 and Cr-MCM-41 (the mole ratio of Si:Zr or Si/Cr=50) was studied by using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Pure silicon MCM-41 showed weak acidity during pyrolysis with furfural as the main product. Zr-MCM-41 showed the dual-functionality of acid and base with both furfural and hydroxy acetone present in the products. Cr-MCM-41 was more acidic with more furfural produced. The optimal conditions for producing olefins were found to be 600°C and the ratio of kapok fiber to catalyst being 1:10 with the Zr-MCM-41 catalyst. The main products obtained via pyrolysis of kapok fiber were acetic acid, furfural, 2,4-di-tert-butylphenol, olefins, and alkanes. The excess of the catalyst and the high temperature of the reaction had certain effects on the pyrolysis of biomass to produce olefins, such as 1-decene, 1-dodecene, 1-undecene, 1-tridecene and heptadecane. Citation: Qiu, Q., Cai, Y., Ye, Q., and Lv, W. (2019). Catalytic Pyrolysis of Kapok Fiber for Production of Olefins. Trends in Renewable Energy, 5, 218-228. DOI: 10.17737/tre.2019.5.2.0097

Background The further application of conventional ultrasound (US) image-guided microwave (MW) ablation of liver cancer is often limited by two-dimensional (2D) imaging, inaccurate needle placement and the resulting skill requirement. The three-dimensional (3D) image-guided robotic-assisted system provides an appealing alternative option, enabling the physician to perform consistent, accurate therapy with improved treatment effectiveness. Methods Our robotic system is constructed by integrating an imaging module, a needle-driven robot, a MW thermal field simulation module, and surgical navigation software in a practical and user-friendly manner. The robot executes precise needle placement based on the 3D model reconstructed from freehand-tracked 2D B-scans. A qualitative slice guidance method for fine registration is introduced to reduce the placement error caused by target motion. By incorporating the 3D MW specific absorption rate (SAR) model into the heat transfer equation, the MW thermal field simulation module determines the MW power level and the coagulation time for improved ablation therapy. Two types of wrists are developed for the robot: a ???remote centre of motion??? (RCM) wrist and a non-RCM wrist, which is preferred in real applications. Results The needle placement accuracies were < 3 mm for both wrists in the mechanical phantom experiment. The target accuracy for the robot with the RCM wrist was improved to 1.6 ?? 1.0 mm when real-time 2D US feedback was used in the artificial-tissue phantom experiment. By using the slice guidance method, the robot with the non-RCM wrist achieved accuracy of 1.8 ?? 0.9 mm in the ex vivo experiment; even target motion was introduced. In the thermal field experiment, a 5.6% relative mean error was observed between the experimental coagulated neurosis volume and the simulation result. Conclusion The proposed robotic system holds promise to enhance the clinical performance of percutaneous MW ablation of malignant liver t

Prediction of machine tool failure has been very important in modern metal cutting operations in order to meet the growing demand for product quality and cost reduction. This paper presents the study of building a neural network model for predicting the behavior of a boring process during its full life cycle. This prediction is achieved by the fusion of the predictions of three principal components extracted as features from the joint time???frequency distributions of energy of the spindle loads observed during the boring process. Furthermore, prediction uncertainty is assessed using nonlinear regression in order to quantify the errors associated with the prediction. The results show that the implemented Elman recurrent neural network is a viable method for the prediction of the feature behavior of the boring process, and that the constructed confidence bounds provide information crucial for subsequent maintenance decision making based on the predicted cutting tool degradation.