Conversion Of Chemical Energy Research Articles

The controllable fabrication of a novel hierarchical nanosheet-assembled Bi2MoO6 hollow micronbox with ultra-high surface area for excellent solar to chemical energy conversion

In this study, we demonstrated that a novel controllable nano-sheet assembled Bi2MoO6 micronbox had higher activity for nitrogen fixation and dye degradation.

CFD ANALYSIS OF PULVERIZED COAL COMBUSTION IN A BLAST FURNACE TUYERE: COMPARISON BETWEEN WSGG AND GG MODELS FOR RADIATION MODELING

Combustion processes are being employed for many years, and remains a major source of energy for industrial operations through the conversion of chemical energy in thermal energy, besides being usually accompanied by formation of pollutants. This work presents a numerical investigation using the software Ansys CFX to model the process of combustion of pulverized coal injected into a blast furnace for production of pig iron making a comparison between WSGG and GG spectral models for gas radiation aim to verify the influence on the radiation heat transfer and the temperature field. Since global coal reserves are being constantly reduced, new techniques using coal are being studied. Among some effective techniques, there is the injection of pulverized coal through a tuyere installed at the bottom of the blast furnace. Thus, among the objectives of this work is to obtain information about the pulverized coal burning process injected. Firstly, it will be employed a North American coal as a base case in order to better understand the involved phenomena. Simulations were made using the actual operating conditions of a blast furnace, which uses atmospheric air enriched with oxygen for burning the coal. The same boundary conditions and operation of other investigations were considered in order to validate the model developed for this work, and so that it can be applied in similar situations, either in assessments or in projects of coal injection systems and combustion in blast furnaces. The results include temperature and velocity fields, oxygen concentration, and the formation of CO and CO2 and they are in agreement with data from literature. Comparing the results of this study with the results obtained in the work (Gu et al., 2010) It observed a qualitative similarity between them and also quantitative. Furthermore, it was found that, in this case, modeling the absorption spectrum of the combustion gases resulting in changes in flame form, but did not significantly alter the magnitude of temperatures, since the walls of the equipment are considered adiabatic.

A shadow detector for photosynthesis efficiency

Plants tolerate large variations in the intensity of the light environment by controlling the efficiency of solar to chemical energy conversion. To do this, plants have a mechanism to detect the intensity, duration, and change in light as they experience moving shadows, flickering light, and cloud cover. Sugars are the primary products of CO2 fixation, a metabolic pathway that is rate limited by this solar energy conversion. We propose that sugar is a signal encoding information about the intensity, duration and change in the light environment. We previously showed that the Arabidopsis heterotrimeric G protein complex including its receptor-like Regulator of G signaling protein, AtRGS1, detects both the concentration and the exposure time of sugars (Fu et al., 2014. Cell 156: 1084–1095). This unique property, designated dose-duration reciprocity, is a behavior that emerges from the system architecture / system motif. Here, we show that another property of the signaling system is to detect large changes in light while at the same time, filtering types of fluctuation in light that do not affect photosynthesis efficiency. When AtRGS1 is genetically ablated, photosynthesis efficiency is reduced in a changing- but not a constant-light environment. Mathematical modeling revealed that information about changes in the light environment is encoded in the amount of free AtRGS1 that becomes compartmentalized following stimulation. We propose that this property determines when to adjust photosynthetic efficiency in an environment where light intensity changes abruptly caused by moving shadows on top of a background of light changing gradually from sun rise to sun set and fluctuating light such as that caused by fluttering leaves.

Operation Evaluation Method for Marine Turbine Combustion Engines in Terms of Energetics

AbstractAn evaluation proposal (quantitative determination) of any combustion turbine engine operation has been presented, wherein the impact energy occurs at a given time due to Energy conversion. The fact has been taken into account that in this type of internal combustion engines the energy conversion occurs first in the combustion chambers and in the spaces between the blade of the turbine engine. It was assumed that in the combustion chambers occurs a conversion of chemical energy contained in the fuel-air mixture to the internal energy of the produced exhaust gases. This form of energy conversion has been called heat. It was also assumed that in the spaces between the blades of the rotor turbine, a replacement occurs of part of the internal energy of the exhaust gas, which is their thermal energy into kinetic energy conversion of its rotation. This form of energy conversion has been called the work. Operation of the combustion engine has been thus interpreted as a transmission of power receivers in a predetermined time when there the processing and transfer in the form (means) of work and heat occurs. Valuing the operation of this type of internal combustion engines, proposed by the authors of this article, is to determine their operation using physical size, which has a numerical value and a unit of measurement called joule-second [joule x second]. Operation of the combustion turbine engine resulting in the performance of the turbine rotor work has been presented, taking into account the fact that the impeller shaft is connected to the receiver, which may be a generator (in the case of one-shaft engine) or a propeller of the ship (in the case of two or three shaft engine).

Hydrogen Oxidation-Mediated Current Discharge in Mesoporous Pt/TiO2 Nanocomposite.

Here we report on direct evidence of a correlation between hydrogen-to-water oxidation on mesoporous Pt/TiO2 nanocomposites at room temperature and the conversion of surface-released chemical energy into a stationary electrical current. The Pt phase of this heterojunction device is an electrically continuous 15 nm thick mesh deposited onto a mesoporous TiO2 substrate fabricated with a plasma electrolytic oxidation process. The H2O turnover frequency approaches an asymptotic value associated with the saturation of the Pt/TiO2 interface as the concentration of hydrogen gas is increased. In situ measurements of the reaction-induced current concurrently with mass spectrometry measurements illuminate the polarity switch of the reaction current (from thermionic emission to a reverse steady-state flow) simultaneously with the production of water. Furthermore, a concentration-dependent value of 5 min is measured as the time constant for the adsorption of the initial addition of H2 and H2O formation and desorption.

Bandgap- and Local Field-Dependent Photoactivity of Ag/Black Phosphorus Nanohybrids

Black phosphorus (BP) is the most exciting post-graphene layered nanomaterial that serendipitously bridges the 2D materials gap between semimetallic graphene and large bandgap transition-metal dichalcogenides in terms of high charge-carrier mobility and tunable direct bandgap, yet research into BP-based solar to chemical energy conversion is still in its infancy. Herein, a novel hybrid photocatalyst with Ag nanoparticles supported on BP nanosheets is prepared using a chemical reduction approach. Spin-polarized density functional theory (DFT) calculations show that Ag nanoparticles are stabilized on BP by covalent bonds at the Ag/BP interface and Ag−Ag interactions. In the visible-light photocatalysis of rhodamine B by Ag/BP plasmonic nanohybrids, a significant rise in photoactivity compared with pristine BP nanosheets is observed either by decreasing BP layer thickness or increasing Ag particle size, with the greatest enhancement being up to ∼20-fold. By virtue of finite-difference time domain (FDTD) simu...

Microbial Fuel Cell for Conversion of Chemical Energy to Electrical Energy from Food Industry Wastewater

Microbial Fuel Cell for Conversion of Chemical Energy to Electrical Energy from Food Industry Wastewater

Efficient Photocatalytic Production of Hydrogen Peroxide from Water and Dioxygen with Bismuth Vanadate and a Cobalt(II) Chlorin Complex

Efficient photocatalytic production of H2O2 as a promising solar fuel from H2O and O2 in water has been achieved by the combination of bismuth vanadate (BiVO4) as a durable photocatalyst with a narrow band gap for the water oxidation and a cobalt chlorin complex (CoII(Ch)) as a selective electrocatalyst for the two-electron reduction of O2 in a two-compartment photoelectrochemical cell separated by a Nafion membrane under simulated solar light illumination. The concentration of H2O2 produced in the reaction solution of the cathode cell reached as high as 61 mM, when surface-modified BiVO4 with iron(III) oxide(hydroxide) (FeO(OH)) and CoII(Ch) were employed as a water oxidation catalyst in the photoanode and as an O2 reduction catalyst in the cathode, respectively. The highest solar energy conversion efficiency was determined to be 6.6% under simulated solar illumination adjusted to 0.05 sun after 1 h of photocatalytic reaction (0.89% under 1 sun illumination). The conversion of chemical energy into electr...

Ultrathin graphitic C3N4 nanosheet as a promising visible-light-activated support for boosting photoelectrocatalytic methanol oxidation

In this paper, ultrathin two dimensional (2D) g-C3N4 nanosheet worked as support for the deposition of ultrasmall Pt nanoclusters. The average size of Pt nanocluster is about 3.2nm. Firstly, the as-prepared Pt/g-C3N4 modified electrode exhibited enhanced electrocatalytic ability in methanol oxidation reaction (MOR) compared to bare Pt nanoparticles. Moreover, when this electrode was upon visible light irradiation, higher performance of MOR was clearly observed compared to the traditional ambient electrocatalytic oxidation. This is owing to the synergistic effects of photocatalytic and electrocatalytic MOR together with the efficient interfacial charger transfer in Pt/g-C3N4. These results show that 2D ultrathin g-C3N4 nanosheets can be used as promising photoactived support in the fields of solar and chemical energy conversion and also provide more insights into developing novel visible light photo-responsive electrode in direct methanol fuel cell.

A three-dimensional mathematical model for the anode of a direct ethanol fuel cell

In this paper, we develop a mathematical model to analyze a direct ethanol fuel cell (DEFC). The three-dimensional model is able to predict the flow on all layers of the fuel cell and allow a better analysis of physical and chemical phenomena that occur inside it. In addition, the calculation of mole fraction of species allows one to observe that the diffusion layer has great influence on mass transfer of fuel between the input channel and the catalyst layer. Numerical simulation of reactive flow was made based on the central finite difference method. The equations were integrated in time using the simplified Runge-Kutta multistage scheme. The results obtained are in agreement with the experimental data found in the literature, for different feed concentrations of ethanol and for different operating temperatures of the cell. In this way, the paper contributes to the development of a model for direct ethanol fuel cells, taking into account all losses overpotentials at the anode and the cathode, providing a better understanding of the physical and chemical behavior inside the cell, and on the conversion of chemical energy into electrical energy.

A highly efficient immobilized ZnO/Zn photoanode for degradation of azo dye Reactive Green 19 in a photocatalytic fuel cell

Photocatalytic fuel cell (PFC) is a potential wastewater treatment technology that can generate electricity from the conversion of chemical energy of organic pollutants. An immobilized ZnO/Zn fabricated by sonication and heat attachment method was applied as the photoanode and Pt/C plate was used as the cathode of the PFC in this study. Factors that affect the decolorization efficiency and electricity generation of the PFC such as different initial dye concentrations and pH were investigated. Results revealed that the degradation of Reactive Green 19 (RG19) was enhanced in a closed circuit PFC compared with that of a opened circuit PFC. Almost 100% decolorization could be achieved in 8 h when 250 mL of 30 mg L−1 of RG19 was treated in a PFC without any supporting electrolyte. The highest short circuit current of 0.0427 mA cm−2 and maximum power density of 0.0102 mW cm−2 was obtained by PFC using 30 mg L−1 of RG19. The correlation between dye degradation, conductivity and voltage output were also investigated and discussed.

(Keynote) Electrochemical and Molecular Approaches for Artificial Photosynthesis

The ultimate goal of artificial photosynthesis research is to develop methods to produce carbon-based gaseous and liquid fuels such as carbon monoxide, methane, and methanol from carbon dioxide and water using solar energy as the energy source. In particular for the methods to be commercially viable the overall costs for the production processes should be low enough so that the processes can compete with the current fossil fuel based processes. The fastest and the most feasible approach would be to combine solar cells and electrochemistry. In other words to electrochemically reduce CO2 to CO, CH4, C2H4, and alcohols such as methanol, ethanol, propanol, and others using the electricity produced by solar cells. For this, to be economically feasible, two electrode systems should be used, the electrochemical reaction should be stable for months, and the electrical energy to chemical energy conversion efficiency (ECCE) should be over high (>70%). Our recent results arising from our efforts to address the above issues will be presented. Another simplest strategy to commercialize artificial photosynthesis is to develop artificial molecular enzymes which can carry out artificial photosynthesis by merely dissolving them into the water pool placed under the sunlight. To make this strategy to be feasible the effective molecular water oxidation catalysts and CO2 reduction catalysts should be developed and the molecular system consisting of a water oxidation catalyst, a photopump (photosensitizer), and a CO2 reduction catalyst should be developed. Our recent efforts to address this issue will also be presented.

Fuel Cell Modeling Strategic Roadmap: A Systematic Approach

Polymer electrolyte fuel cells (PEFCs) are promising electrochemical devices for the direct conversion of chemical energy of a fuel into useful electrical work with vast applications in automotive, stationary, and autonomous power. It is widely recognized that progress in PEFC technology is a multi-disciplinary challenge and hinges on Research and Development (RD Services; Products; High Level Targets; Technology; Science; and Enablers and Resources. This study contributes to a much needed foundation for further planning of potential R&D and demonstration projects of fuel cells for automotive and other emerging sectors.

Amino-modification and successive electrochemical reduction of graphene oxide for highly sensitive electrochemical detection of trace Pb2+

Both synthesis method and heteroatom doping could tailor graphene properties and promise its practical application. Here, a facile electrolytic route was developed to prepare amino-functionalized graphene, which could be directly used to build chemical sensor electrode. In this method, graphene oxide (GO) was electrolyzed in ethylenediamine aqueous solution to induce ammonization and electrochemical reduction successively. The unique chemical structure of ammoniated reduced GO (AErGO) strongly increased the chelation between electrode surface and Pb2+, and provided plenty active sites for electrochemical redox. Therefore, AErGO exhibits good electrical conductivity and high electrocatalytic activities, which ensures high selectivity, low detection limit (0.0924 μg L−1 at S/N = 3) and ultra wide linear range (0.5–350 μg L−1) during the Pb2+ detection. This simple and effective route can also be extended in the preparation of S-doping or S, N-dual doping graphene materials with potential applications in chemical sensor, electrochemical catalysis, and energy conversion or storage.

“Physical Chemistry of Solar Fuels Catalysis” — An Event for Early Career Researchers at the Max-Planck-Institute for Chemical Energy Conversion

“Physical Chemistry of Solar Fuels Catalysis” — An Event for Early Career Researchers at the Max-Planck-Institute for Chemical Energy Conversion

ChemInform Abstract: Functional Arrays for Light Energy Capture and Charge Separation

AbstractReview: [typical procedures for the effective design and optimization of functional multicomponent structures for light to chemical energy conversion for a variety of examples based on corroles and terpyridyl metal complexes; 64 refs.

A study of laser induced ignition of methane–air mixtures inside a Rapid Compression Machine

Presented herein is a fundamental study of laser ignition of methane/air mixtures at temperatures and pressures representative of an internal combustion engine. An Nd:YAG laser operating at λ=1064nm was used to ignite methane/air mixtures at equivalence ratios of 0.4 ≤ Φ ≤ 1 in a Rapid Compression Machine (RCM). Experiments were conducted to study the lean limit, minimum spark energy (MSE), and minimum ignition energy (MIE). The results show that laser ignition exhibits a stochastic behavior which must be interpreted statistically. A 90% probability of occurrence was used to evaluate the MSE and MIE, which resulted in MSE90 =2.3mJ and MIE90 =7.2mJ at an equivalence ratio Φ=0.4 at compressed pressure and temperature of Pcomp=29bar and Tcomp=750K, respectively. The lean limit was characterized based on the fraction of chemical energy converted into thermal energy, which was determined by calculating the apparent rate of heat release as derived from RCM high speed pressure data. A lean limit for 90% chemical energy conversion was found to correspond to an equivalence ratio of 0.47 (Tcomp=782K). Schlieren photography was employed as a diagnostics tool to visualize the flame initiation and propagation inside the RCM.

Electricity from Wood: A Wood Quality and Energy Efficiency Approach to Small Scale Pyro-gasification

The global demand for renewable energy in the last years is facing innovations like the co-generation of electricity and heat from wooden industrial residues and biomass. Wood gasification is a very promising technique for conversion of wood chemical energy into thermal energy and into electricity. A new generation of small scale, moderately priced and easy to install pyro-gasification plants became available on the market, being an opportunity for the SMEs. These systems are also characterized by a remarkable operational easiness and great versatility in the type of used biomass, which can range from industrial residues (sawdust, wood chips...) to biomass of forestry and non-forestry origin. This study performed an extensive testing of a small size pyro-gasification plant capable of producing 30kW of electricity and 30kW of thermal energy, both net to enter in the network of GSE (Energy Services Manager) via the feed-in tariff and in a small district heating network or other uses. The process of pyro-gasification is analyzed in its entirety by a characterization of input biomass, pyro-gasification process monitoring, analysis of the quality of the produced syngas, characterization of residues due to the process (washing water smoke, charcoal...) and verification of the total efficiency. The electric efficiency of the system, from hardwood to syngas to electricity is quantified in being 12%.

Operando and Time-Resolved X-Ray Absorption Spectroscopy for the Study of Photoelectrode Architectures

Photoelectrocatalytic processes (e.g. water splitting) are particularly interesting as a method of solar to chemical energy conversion. The catalytic process is driven by transient changes in the semiconductor material’s properties, such as the metal oxidation state, the local reconstruction of catalytic sites or charge recombination processes. Here, we report a novel experimental technique for performing pump and probe time-resolved hard X-ray absorption spectroscopy in electrochemical conditions under UV–vis irradiation: pump and probe XAS enables the study of processes occurring in pico- to microseconds time scale by probing the local electronic properties of a selected atom. The described technique was developed using α-Fe2O3/IrOx as a model photoelectrode.

Visible-light driven biofuel cell based on hierarchically branched titanium dioxide nanorods photoanode for tumor marker detection

In this work, a novel sensing platform based on visible light driven biofuel cell (BFC) has been facilely designed for sensitive detection of prostate-specific antigen (PSA) with the photo-response bioanode, realizing the dual route energy conversion of light energy and chemical energy to electricity. The hierarchical branched TiO2 nanorods (B-TiO2 NRs) decorated with CdS quantum dots (QDs) act as the substrate to confine glucose dehydrogenase (GDH) for the visible light driven glucose oxidation at the bioanode. Three dimensional flowers like hierarchical carbon/gold nanoparticles/bilirubin oxidase (3D FCM/AuNPs/BOD) bioconjugate served as biocatalyst for O2 reduction at the biocathode. With an increase in the concentration of PSA, the amount of BOD labels on biocathode increases, thus leading to the higher current output of the as-proposed visible light driven BFC. Based on this, this sensing platform provide great performance in sensitivity and specificity, increasing linear detection range from 0.3pgmL−1 to 7μgmL−1 with a detection limit of 0.1pgmL−1. Most importantly, our new sensing strategy provided a simple and inexpensive sensing platform for tumor markers detection, suggesting its wide potential applications for clinical diagnostics.