A Multiscale Morphological Insight into Graphene Based Coatings for Pool Boiling Applications

The application of graphene for pool boiling is an attractive option to facilitate compaction and promote efficient heat removal from high power density devices. In this context, chemical characterization of the depositions achieved through commonly employed coating techniques are an important topic of discussion. A detailed structure-property relationship between the morphologies obtained on the mono and multilayered graphene coatings and their corresponding pool boiling performance quantified by the experimental critical heat fluxes is presented. Three different types of graphene (G) and graphene oxide (GO) substrates are characterized: (i) nanoscale: mono and multilayer samples developed through chemical vapor deposition, (ii) Rochester Institute of Technology (RIT)-G/GO colloid generated through an oxygen embrittlement electrochemical process, and (iii) commercially available chemical vapor deposited (CVD)-G/GO colloid. The morphological features were characterized with scanning electron microscope while X-Ray Diffractometer analysis and Raman spectroscopy were used to examine the ordering and stacking of the sheets that result in the unique structural features. Fourier transform infrared and energy dispersive X-ray spectroscopy were employed to identify the overall compositional characteristics of the coated surfaces. The wettability changes and additional nucleation sites for nanoscale coatings, and multiscale roughness features and ridge microstructures for microscale coatings were identified as enhancement mechanisms.     

Co-pyrolysis and co-gasification of biomass and polyethylene: Thermal behaviors,volatile products and characteristics of their residues

Co-pyrolysis and co-gasification of biomass and plastics could be a promising method to alleviate environmental pollution and provide renewable energy. In this paper, co-pyrolysis and co-gasification of eucalyptus wood (EW) or rice straw (RS) with polyethylene (PE) were investigated by a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer (TG-FTIR) and a scanning electron microscope coupled with energy-dispersive spectroscopy (SEM/EDS). Results showed that the pyrolysis behaviors were characterized by two stages. The first stage was the decomposition of EW and RS, and the second stage primarily consisted of the degradation of PE. The gasification exhibited a third stage for the reaction of products with CO₂. A synergistic effect was presented in the pyrolysis and gasification of biomass with PE, and it could have a positive effect on the decomposition of biomass. Compared to individual pyrolysis and gasification, co-pyrolysis and co-gasification generated no new substances, but the yield of some products was changed in these processes. In co-pyrolysis, the decomposition of biomass was promoted. In co-gasification, the production of CH₄, CO and oxygenated compounds was inhibited, while the reaction to generate H₂O was promoted. Gasification and the addition of PE both increased the carbon content and reduced the oxygen content of volatile products. Additionally, more metal elements could be deposited in residues when PE was added.     

High hydrogen storage capacity of rice hull based porous carbon

A kind of porous carbon with high specific surface area (approximately 4000 m²/g) was prepared from rice hull through carbonization and sodium hydroxide activation. The effects of preparation parameters on the characteristics of the porous carbon were studied. The properties of these porous carbon samples were investigated by X-ray diffraction and scanning electron microscope (SEM) and Fourier transform infrared spectroscopy. The rice hull based porous carbon exhibits high hydrogen storage capacity of 7.7 wt% at 77 K and 1.2 MPa.     

Analysis of cycling performance failure of NMC811/SiO-C pouch cells with high specific energy

NMC811/SiO-C电池由于电极材料克容量高,工作平台电压高成为实现高比能量密度的一个重要途径,然而在实际应用中其循环寿命差的问题一直难以解决。本工作通过电化学阻抗谱（EIS）、X射线衍射光谱、傅里叶红外变换光谱（FTIR）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）等多种分析表征手段对循环前后电极材料进行了表征测试与分析,系统研究了NMC811/SiO-C电池长期循环失效的原因,结果表明：NMC811正极材料在循环过程中结构保持完整,金属溶出现象轻微;而SiO-C负极材料在循环过程中膨胀粉化,并且不断消耗电解液和形成更厚的SEI膜,最终导致负极克容量衰减严重,是全电池常温循环性能很差的主要原因。     

High electrochemical performance of PANI/CdO nanocomposite based on graphene oxide as a hybrid electrode materials for supercapacitor application

In the last decade, the production of clean and sustainable energy sources for energy storage purposes have grown dramatically due to the population growth and increasing demand for energy in the world. In this regard, supercapacitors have proved to be promising candidates in energy storage applications. Therefore, in this study, polyaniline/cadmium oxide/graphene oxide (PANI/CdO/GO) nanocomposite was prepared by co-precipitation method to evaluate the electrochemical performance. The structural and surface properties, morphology and particle size distribution were analyzed by XRD diffraction spectroscopy (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), N₂ adsorption-desorption, and Fourier transform infrared spectroscopy (FT-IR). Furthermore, the synthesized nanocomposite was applied as an active electrode material and its performance was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in terms of energy storage. The results of these tests confirmed that PANI/CdO/GO nanocomposite provides great electrochemical behavior, including specific capacity of 647 F g^?1, energy density of 116.6 W h kg^?1, power density of 388 W kg^?1 compared to the other electrode. According to the stability test, the initial capacity maintenance was about 82% after 500 charge-discharge cycles, which indicated relatively good electrochemical stability. Moreover, the impedance spectroscopy studies showed that the nanocomposite possessed much lower internal strength and charge transfer reaction resistance in comparison to the other synthesized materials. Based on these results, it was found that the prepared nanocomposite has a good performance in the field of energy storage.     

Copper oxide thin films prepared by chemical vapor deposition from copper dipivaloylmethanate

Polycrystalline copper oxide thin films are prepared at a reaction temperature above 280°C by an atmospheric-pressure chemical vapor deposition method. The source materials were copper dipivaloylmethanate and oxygen. It has been shown from the experiment that two kinds of films, i.e., Cu₂O and CuO are grown by controlling oxygen partial pressure. A series of characterizations on the film quality by scanning electron microscope, X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectrometer has been made, and the performance of solar thermal conversion are also identified on the produced films. Results show that the well-crystallized CuO film has lower infrared transmittances due to the scatterings of light through the optically anisotropic monoclinic structure.     

Fabrication and properties of hybrid membranes based on salts of heteropolyacid,zirconium phosphate and polyvinyl alcohol

The fabrication and properties of a hybrid membrane based on cesium salt of heteropoly acid, zirconium phosphate and polyvinyl alcohol are described. The fabricated membranes were characterized for their intra molecular interaction, thermal stability, surface morphology, water content and surface-charge properties using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water uptake and ion-exchange capacity measurements. These membranes showed reduced methanol crossover (for possible application in DMFC) relative to that of Nafion^® 115. At 50% of relative humidity, the protonic conductivity of the hybrid membranes was in the range of 10⁻³ to 10⁻² S cm⁻¹. The feasibility of these hybrid membranes as proton conducting electrolyte in direct methanol fuel cell (DMFC) was investigated and preliminary results are compared with that of Nafion^® 115. A maximum power density of 6 mW cm⁻² with PVA–ZrP–Cs₂STA hybrid membrane was obtained with the cell operated in passive mode at 373 K and atmospheric pressure. Open circuit voltage of the cell operated with hybrid membranes are high compared to that of Nafion^® 115 indicating reduced methanol crossover.     

Synthesizing graphene from waste mosquito repellent graphite rod by using electrochemical exfoliation for battery/supercapacitor applications

Two graphite rods from two empty mosquito repellent refills were employed for synthesis of few-layered graphene for material developments on batteries and supercapacitor applications. The graphene sheet is isolated from graphite rod via electrochemical exfoliation method. We exfoliate graphene by intercalating sodium dodecyl benzene sulfonate at a constant concentration with constant DC power supply. The purified graphene is characterized by scanning electron microscopy, Fourier transform infrared spectrometry, Raman spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. A newly promised approach in the production of energy source material by utilizing empty repellent rods has been explored.     

New borohydride fuel cell with multiwalled carbon nanotubes as anode: A step towards increasing the power output

A borohydride fuel cell has been constructed using a platinized multiwalled carbon nanotube (MWCNT) anode and an air cathode having an anionic exchange membrane separating the anode and cathode. The MWCNT was functionalized with carboxylic acid under nitric acid reflux. Platinum metal was subsequently incorporated into it by galvanostatic deposition. The platinized functionalized MWCNT was characterized by thermogravimetric analysis, Fourier transform infrared spectrum, scanning electron microscope and X-ray diffraction. The fuel cell produced a voltage of 0.95 V at low currents and a maximum power density of 44 mW cm⁻² at room temperature in 10% sodium borohydride in a 4 M sodium hydroxide medium. Another borohydride fuel cell under identical conditions using carbon as the anode produced a cell voltage of 0.90 V and power density of about 20 mW cm⁻². The improved performance of the MWCNT is attributed to the higher effective surface area and catalytic activity.     

Water hyacinth (Eichhornia crassipes) biochar as an alternative cathode electrocatalyst in an air-cathode single chamber microbial fuel cell

In the present work, Water Hyacinth Biochar (WHB) was produced by pyrolysis at 900 °C and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), EDX-SEM, Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area and particle size analyses. The results indicate that WHB has Oxygen Reduction Reaction (ORR) catalytic activity, with an average of 2.58 electrons per oxygen molecule transferred from WHB for ORR. The ORR catalytic activity of WHB is attributed to its physical and chemical surface properties. The maximum power density produced from an air cathode single chamber microbial fuel cell (ACSC-MFC) with WHB as the ORR catalyst versus the Pt/C catalyst were 24.7 and 12.3 mWm⁻², respectively. This study demonstrates that Water Hyacinth Biochar can be used as an inexpensive catalyst for the ORR in microbial fuel cells.     

Enhanced performance of carbon-based supercapacitors by constructing protonic and electric dual-channels in electrodes

Powdery carbonaceous materials have to use binder materials when they are integrated into electrodes for supercapacitors, which will results in high interfacial charge transfer resistances and reduced specific capacitance. To resolve the problem, protonic and electric dual-channels are constructed in electrodes by in situ synthesis of cesium hydrogen salt of phosphotungstic acid on the surface of carbonaceous materials. The cesium hydrogen salt particles are confirmed by a Fourier transform infrared spectroscopy, X-ray diffractometer and an energy dispersive X-ray spectroscopy. The electrochemical properties of as-fabricated electrodes are measured by cyclic voltammetry, galvanostatic charging-discharging, and impedance analysis with an electrochemical workstation. At a current density of 1 A g⁻¹, the electrode shows a specific capacitance of 152 F g⁻¹. Compared to the electrode without the cesium hydrogen salt, the value increases 25% at least. Furthermore, the specific capacitance retention of the electrode reaches 104% of its original capacitance after 5000 charge-discharge cycles, suggesting excellent cycling stability.     

Effect of electron beam irradiation on polydopamine and its application in polymer solar cells

Polydopamine (PDA) films were irradiated by an electron beam linear accelerator at different irradiation doses ranging from 10 to 150 kGy. The irradiated samples were characterized by Fourier transform infrared spectrometry, UV‐Vis, scanning electron microscopy, atomic force microscope, X‐ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, and thermogravimetric analysis. Changes in surface morphology, chemical structure, contact angle, frontier orbitals, and bandgap were analyzed. PDA films modified by electron beam irradiation were used in the interface design and control of polymer solar cells. Devices with the structures of ITO/ZnO/PTB7:PC₇₁BM/MoO₃/Al and ITO/PDA‐ZnO/PTB7:PC₇₁BM/MoO₃/Al were fabricated. The solar cells with a 100‐kGy electron beam‐irradiated PDA film‐modified ZnO electron transport layer had a significantly improved short circuit current density, and its efficiency reached a maximum value. The short circuit current density and power conversion efficiency reached 13.70 mA/cm² and 3.82%, respectively. Electron beam irradiation is an effective method to modify PDA, which can be used as an interface modifier in polymer solar cells.     

污泥基生物炭的制备及其作为污泥调理剂的可行性探究

基于污泥资源化利用需求,选用市政污泥制备污泥基生物炭,通过冷场扫描电镜（SEM）、傅里叶变换红外光谱（FTIR）及氮吸附比表面积分析仪对其进行物化性质表征。结果显示：当污泥和浓硫酸按照1∶2比例活化时制备得到的生物炭比表面积最大,但弱酸或强碱弱酸盐有利于提高活化后污泥基生物炭官能团种类。此外,将污泥基生物炭作为活性污泥调节剂,对其可行性进行了探究,采用沉降性能、过滤性能和脱水性能作为调理后活性污泥脱水性能评价指标。结果表明：在CO₂氛围下制备的污泥基生物炭调理后,活性污泥脱水性能最好,泥饼含水率仅为50%,满足单独焚烧用泥质和卫生填埋对泥饼含水率的要求,显示出污泥基生物炭用作污泥调理剂具有良好的可行性。     

Polyaniline/fullerene derivative nanocomposite for highly efficient supercapacitor electrode

The effect of intercalation of fullerene derivative Phenyl-C60-butyric acid methyl ester (PCBM) into polyaniline (PANI) matrix with different ratio is reported. The PANI/PCBMx (where x = 0, 2.5, 5 and 10) nanocomposites are characterized by UV-VIS spectroscopy, Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction spectroscopy (XRD). The results confirm that the PANI/PCBM nanocomposites are synthesized successfully. The prepared nanocomposites are cast onto Nickel foam as a current collector and tested as a supercapacitor electrode in 2 M KOH electrolyte using cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD). The effect of different current collector substrates including stainless steel, nickel metal and graphite sheet on the supercapacitor performance is compared. The electrochemical measurements show an improvement by more than two times in the specific capacitance of PANI/PCBM5 electrode compared to pure PANI electrode. It is found that, the specific capacitance is 2201 F/g at a current density of 2 A/g with a good rate capability of about 73% at 10 A/g. The energy and power densities of PANI/PCBM5 electrode are 61.9 W h/Kg and 2250 W/Kg, respectively. Furthermore, the PANI/PCBM5 electrode shows an excellent cycling stability with 96% of the capacity retention after 1000 cycles.     

Effect of MnO2:rGO ratio on the performance of a microbial fuel cell: An experimental optimization study

Oxygen reduction reaction plays an important role in improving the performance of microbial fuel cell (MFC). MnO₂:rGO with different ratios (100:0), (85:15), (75:25), and (60:40) were used as cathode electro-catalyst, and performance analysis was done to find the optimum ratio. The isolated bacteria with new strain, Bacillus subtilis subspecies spizizenii strain No NBRC 101239 (ACCESSION no NR_112686) was used for the first time as a biocatalyst. MnO₂ and MnO₂:rGO were synthesized by reflux method and were characterized by X-ray diffractometer, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and laser Raman spectroscopy. It was found that the MFC with ratio (75:25) showed higher performance with maximum power density 32.5 mW/m² compared to 6.76 mW/m² (85:15), 3.79 mW/m² (100:0), and 3 mW/m² (60:40).     

CO_2对CaS氧化反应的影响

煤气化钙剂脱硫产物CaS是一种不稳定的化学物质,氧化是使其稳定的有效方法.在加压热重分析仪上进行了CaS的氧化试验,重点考察了CO2摩尔分数对CaS反应产物的影响,并利用傅里叶变换红外光谱(FTTR)法对反应固体产物进行了定量分析.研究发现,COO2气体的存在对于CaS的氧化反应有显著影响.CO2能直接与CaS发生反应,一定程度上提高了CaS的转化率.CO2分压对CaS的氧化反应影响较大.相对于低CO2分压,高CO2分压下反应产物中CaCO3的摩尔分数较高,而CaS的转化率较低.原因在于CaCO3和CaCO3分解生成的CaO摩尔体积的不同,导致了反应气体在颗粒内的扩散特性有所差异.     

Synthesis and properties of Schiff base Fe(II) complex

In our current study, Fe (II) complex with 4-4?-methylene bis (2,6-diethyl)aniline-3,5-di-tert-butylsalisilaldimine (HL1) ligand was synthesized by chemical method and the synthesized Fe (II) complex with HL1 ligand was named as Fe(L₁)₂ complex. Structural, morphological, electronic absorption and photovoltaic properties of Fe(L₁)₂ complex were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, electronic absorption, and current density (J)–voltage (V) measurements, respectively. The obtained result from the J-V measurement shows that Fe(L₁)₂ complex synthesized by the chemical method can be used as a promising sensitizer for a dye-sensitized solar cell.     

Study on properties of polypyrrole-coated sulfur-based composite prepared by drop addition method

采用简单的溶液滴加法将颗粒状聚吡咯（PPy）包覆在单质硫（S）表面,制备了S和PPy质量比分别为6∶4、7∶3、8∶2的S/PPy复合材料,探究S/PPy材料最佳合成条件。利用X射线衍射（XRD）、傅里叶红外变换（FTIR）、场发射扫描电镜（FESEM）、透射电镜（TEM）表征手段和电化学性能测试对这3种不同硫含量的S/PPy复合材料的结构和电化学性能进行研究。形貌观察结果表明,当S和PPy质量比为7∶3时（S/PPy-30）,PPy颗粒分散均匀,对单质硫包覆效果最佳,同时S/PPy-30也表现出最优的电化学性能,在200 mA/g电流密度下,首圈放电比容量为1151 mA·h/g,循环120圈后,容量剩余623 mA·h/g,相比其他两个比例的S/PPy材料,S/PPy-30的倍率性能也表现出明显的优势。     

A metal–organic-framework/carbon composite with enhanced bifunctional electrocatalytic activities towards oxygen reduction/evolution reactions

A Co-OBA/C (OBA = 4,4′-Oxybis (benzoic acid)) composite catalyst was synthesized by integrating MOF (Co-OBA) with black carbon through a hydrothermal process. The catalyst was characterized using X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The catalytic activities toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were evaluated by linear-sweep voltammetry (LSV) in an alkaline electrolyte. The ligand mode of the carboxylate binding is chelating coordination and the ligand mode of imidazole is monodentate ligand in the Co-OBA/C catalyst. The Co-OBA/C catalyst shows much better ORR, OER and bifunctional activities than the Co-OBA + C catalyst due to the synergistic effect between Co-OBA and carbon black in the Co-OBA/C catalyst.     

Methanol-blocking Nafion composite membranes fabricated by layer-by-layer self-assembly for direct methanol fuel cells

In this paper, a series of Nafion composite membranes with improved methanol barrier properties were fabricated from chitosan (CS) and silicotungstic acid (SiWA) by Layer-by-layer (LbL) self-assembly technique. The Fourier transform infrared attenuated total reflection (FTIR-ATR) spectra and scanning electron microscope (SEM) were employed to prove the successful deposition of CS/SiWA layers. The effect of the methanol-blocking layer on proton conductivity, methanol permeability and direct methanol fuel cell (DMFC) performance was studied. Both proton conductivity and methanol permeability of Nafion composite membranes decreased with the increase of CS/SiWA bi-layer number. The Nafion composite membrane with a reduced proton conductivity of 22% showed a reduced methanol permeability of 47%. Approximate 18% improvement of the selectivity was achieved as compared with plain Nafion membrane. But it did not result in better DMFC performance than that of plain Nafion membrane.