Isobaric Vapor–Liquid Equilibria of Binary Systems Containing Oxygenated Biofuel Compounds (Ethanol + Cyclopentanone, Propyl Butanoate + 4‑Methylphenol, Cyclopentanone + Propane-1,2-diol) at Atmospheric Pressure

The isobaric phase equilibrium data for the binary systems of ethanol + cyclopentanone, propyl butanoate + 4-methylphenol, and cyclopentanone + propane-1,2-diol at atmospheric pressure were measured using a modified distillation apparatus. The Herington and Van Ness tests were employed to confirm the thermodynamic consistency of the experimental data. In addition, the Wilson, NRTL, and UNIQUAC models were used to correlate experimental vapor–liquid equilibrium data. The corresponding binary interaction parameters (BIPs) for the three models, which are useful for the modeling and designing separation processes involving biofuel, were obtained using a maximum likelihood objective function. It has been confirmed that when appropriate BIPs are used in each model, the outputs are consistent with each other and with experimental data

High-Performance TiO₂ Photoanode with an Efficient Electron Transport Network for Dye-Sensitized Solar Cells

A titanium organic sol was synthesized for the modification of conventional porous TiO2 photoanodes for dye-sensitized solar cells (DSSCs). As a result, a compact thin TiO2 film was superimposed on the porous TiO2 structure as an efficient electron transport network, covering bare conducting substrate surface (FTO) and bridging gaps between TiO2 nanoparticles, which was confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Dark current measurement suggested that the sol modified photoanode had a remarkably slower recombination rate of the photoelectrons due to the reduced bare FTO surface in comparison with the porous photoanode. The network facilitates the electron transfer in the DSSC process by removing the dead ends of electron pathways, connecting gaps along the electron pathways, and physically enlarging electron pathways, which can be demonstrated by the performance improvement of photocurrent and open-circuit potential. Consequently, the overall energy conversion efficiency of the DSSC was significantly enhanced by 28% after this simple and low-cost organic sol modification. The significant performance improvements observed from the organic sol modified DSSCs suggest that the proposed modification method is a promising alternative to the traditional TiCl4 modification method

Correlation and Prediction of Isobaric Vapor–Liquid Equilibria of Binary and Ternary Systems Containing Oxygenated Biofuel Compounds (Butan-2-one + 2‑Methylpropan-1-ol + Cyclopentanone) at Atmospheric Pressure

Process modeling and feasibility studies for biofuel production require accurate phase equilibria data. Binary mixtures of common biofuel compounds butan-2-one + 2-methylpropan-1-ol, butan-2-one + cyclopentanone, 2-methylpropan-1-ol + cyclopentanone, and a ternary system of all three components were studied to obtain vapor–liquid equilibrium data at atmospheric pressure. The experimental data were validated and verified thermodynamically by employing the modified McDermott–Ellis, Van Ness, and Herington methods. The binary vapor–liquid equilibrium (VLE) data were successfully correlated with the Wilson, NRTL, and UNIQUAC activity coefficient models and predicted with the PSRK model. Further, the PSRK model and NRTL with the obtained binary interaction parameter (BIP) model were applied to forecast VLE data for the ternary system of butan-2-one + 2-methylpropan-1-ol + cyclopentanone. Both PSRK and NRTL models showed good accuracy in predicting the equilibrium temperature. At the same time, the PSRK model outperformed the NRTL model in predicting the composition of the vapor phase. The PSRK model was quite accurate for predicting the VLE of these biofuel components, even without any experimental data

Electrochemically Exfoliated Graphene for Electrode Films: Effect of Graphene Flake Thickness on the Sheet Resistance and Capacitive Properties

We present an electrochemical exfoliation method to produce controlled thickness graphene flakes by ultrasound assistance. Bilayer graphene flakes are dominant in the final product by using sonication during the electrochemical exfoliation process, while without sonication the product contains a larger percentage of four-layer graphene flakes. Graphene sheets prepared by using the two procedures are processed into films to measure their respective sheet resistance and optical transmittance. Solid-state electrolyte supercapacitors are made using the two types of graphene films. Our study reveals that films with a higher content of multilayer graphene flakes are more conductive, and their resistance is more easily reduced by thermal annealing, making them suitable as transparent conducting films. The film with higher content of bilayer graphene flakes shows instead higher capacitance when used as electrode in a supercapacitor

Nanoconfined Synthesis of Nitrogen-Rich Metal-Free Mesoporous Carbon Nitride Electrocatalyst for the Oxygen Evolution Reaction

Synthesizing metal-free, low-cost, and durable electrocatalysts that are active for the oxygen evolution reaction (OER) is essential for the development of commercial alkaline water electrolyzers. Herein, we develop a nanoconfined synthesis approach for the fabrication of a metal-free graphitic mesoporous carbon nitride (gMesoCN) electrocatalyst with a high surface area of 406 m2/g and high nitrogen content of 48%. This is achieved by a nanohard-templating approach through simple polymerization of guanidine hydrochloride (GndCl) as a single carbon–nitrogen source inside the organized mesopore channels of a mesoporous SBA15 silica nanotemplate. The produced material is characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM), which confirmed the formation of a well-ordered mesoporous carbon nitride, while analysis of the pore size distribution indicated the formation of uniformly sized pore channels of 4.56 nm. X-ray photoelectron spectroscopy (XPS) indicated that gMesoCN consisted of C and N. The metal-free gMesoCN material showed good electrocatalytic performance for the OER in alkaline medium, where a Tafel slope of 52.4 mV/dec indicated favorable OER kinetics. Significantly, the gMesoCN material demonstrates long-term durability with 98.4% retention of current density after 24 h. The reported gMesoCN material is inexpensive, environmentally friendly, and easy-to-synthesize with the potential for applicability in the field of electrocatalysis

Additional file 1 of Boosting capacitive performance of manganese oxide nanorods by decorating with three-dimensional crushed graphene

Additional file 1: Figure S1. TEM images of (a) MnOx/S-rGO and (b) MnOx/C-rGO and HRTEM images of (c) MnOx/S-rGO and (d) MnOx/C-rGO. Figure S2. High-resolution O1s XPS spectra of (a) MnOx/S-rGO and (b) MnOx/C-rGO. Figure S3. High resolution C 1 s XPS spectra of (a) MnOx/S-rGO and (b) MnOx/C-rGO. Figure S4. High resolution Mn 2p XPS spectra of (a) MnOx/S-rGO and (b) MnOx/C-rGO. Figure S5. (a) CV curves at different scan rates and (b) GCD curves at different current densities of MnOx in 0.5 M Na2SO4 electrolyte in the potential range of − 0.1 to 0.8 V. Figure S6. Electrochemical study in 0.5 M Na2SO4 electrolyte with a three-electrode system: (a) CV curves at different scan rates and (b) GCD curves at different current densities of MnOx/S-rGO in the potential range of − 0.1 to 0.8 V. Figure S7. (a) CV curves at different scan rates and (b) GCD at different current densities of MnOx/C-rGO in 0.5 M Na2SO4 electrolyte in the potential range of − 0.1 to 0.8 V. Figure S8. Electrochemical study in 1 M Na2SO4 electrolyte with a two-electrode system. CV curves of the symmetric devices prepared with (a) MnOx/S-rGO and (b) MnOx/C-rGO at different scan rates. GCD curves of the symmetric devices prepared with (c) MnOx/S-rGO and (d) MnOx/C-rGO at different current densities in the voltage range of 0 to 1.5 V. Figure S9. Equivalent fitting circuit. Table. S1 The obtained values of RS, Rct, Cdl, Zw, Cp, from EIS fitting