Energy Requirements Research Articles

Thermally coupled distillation columns without vapor transfer – Current state and further needs

Reducing the energy requirements is one essential pillar in the effort to reduce the carbon footprint of the energy intensive chemical industry. Thermal coupling of distillation columns and the equipment-integrated implementation in dividing wall columns can be considered a mature and established technology to reduce the energy demand of distillation sequences. Despite the widespread investigations and applications, the vaporous transfer stream between thermally linked columns or vapor split in the dividing wall column is associated with certain limitations. Some of these can effectively be overcome by adding an additional column section with reboiler or condenser to the thermally linked column, converting the bidirectional transfer of liquid and vapor to a unidirectional liquid transfer, which mandates additional investment, but provides an additional degree of freedom and retains the energy saving potential of the thermally coupled sequence. Although these so-called Liquid-Only-Transfer (LOT) sequences have been introduced almost 25 years ago, the process concept is receiving an increasing interest in recent years, with specific focus on conceptual design and control studies. The current review provides a methodological overview on synthesis, design and control studies for LOT-sequences, considering zeotropic and azeotropic distillation processes. It analyzes the advantages and challenges of this interesting process concept and highlights research areas and questions that still require additional attention.

Applying Machine Learning to Design Delicate Amorphous Micro-Nano Materials for Rechargeable Batteries

As modern society evolves, the global importance of energy requirements has grown significantly. Thus, exploring new materials for renewable energy storage is urgently needed. Due to its intriguing characteristics, amorphous micro-nanomaterials demonstrate exceptional performance in energy storage. The long experimental periods and high costs associated with traditional methods make it challenging to meet the requirements of materials science. Currently, machine learning (ML) is emerging as a novel research paradigm with the potential to revolutionize the exploration of materials. This review provides an overview of the application of ML in studying amorphous micro-nanomaterials for rechargeable batteries. First, a comprehensive introduction to the fundamentals of amorphous materials and ML is summarized. Then, we highlight a series of representative works to elaborate the relationship between the ML for amorphous nanomaterials. Finally, an insightful perspective on utilization of amorphous materials to establish mature energy storage systems and future directions in ML for amorphous materials are presented. Through this review, we aim to unveil the underlying amorphous structure-function relationship and fuel further research in the design of amorphous materials with outstanding performance across diverse fields.

Lipoprotein (a) and diet: consuming sugar-sweetened beverages lowers lipoprotein (a) levels in obese and overweight adults

Lipoprotein (a) [Lp(a)] is a risk factor for cardiovascular disease. A size polymorphism in the apo(a) gene, determined by the number of Kringle (K) repeats, inversely regulates Lp(a) levels. Nongenetic factors including dietary saturated fat influence Lp(a) levels. However, less is known about the effects of carbohydrates including dietary sugars. In this double-blind, parallel-arm study among 32 overweight/obese adults, we investigated the effect of consuming glucose- or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks on Lp(a) level and assessed the role of the apo(a) size polymorphism. The mean (±SD) age of participants was 54 ± 8 years, 50% were women, and 75% were of European descent. At the end of the 10-week intervention, Lp(a) level was reduced by an average (±SEM) of −13.2% ± 4.3% in all participants (P = 0.005); by −15.3% ± 7.8% in the 15 participants who consumed glucose (P = 0.07); and by −11.3% ± 4.5% in the 17 participants who consumed fructose (P = 0.02), without any significant difference in the effect between the two sugar groups. The relative changes in Lp(a) levels were similar across subgroups of lower versus higher baseline Lp(a) level or carrier versus noncarrier of an atherogenic small (≤22K) apo(a) size. In contrast, LDL-C was increased. In conclusion, in older, overweight/obese adults, consuming sugar-sweetened beverages reduced Lp(a) levels by ∼13% independently of apo(a) size variability and the type of sugar consumed. The Lp(a) response was opposite to that of LDL-C and triglyceride concentrations. These findings suggest that metabolic pathways might impact Lp(a) levels.

Time profiles of energy balance in dairy cows in association with metabolic status, inflammatory status, and disease

The early lactation period in dairy cows is characterized by complex interactions among energy balance (EB), disease, and alterations in metabolic and inflammatory status. The objective of this study was to cluster cows based on EB time profiles in early lactation and investigate the association between EB clusters and inflammatory status, metabolic status, oxidative stress, and disease. Holstein-Friesian dairy cows (n = 153) were selected and monitored for disease treatments during wk 1 to 6 in lactation. Weekly EB was calculated based on energy intake and energy requirements for maintenance and milk yield in wk 1 to 6 in lactation. Weekly plasma samples were analyzed for metabolic variables in wk 1 to 6, and inflammatory and oxidative stress variables in wk 1, 2, and 4 in lactation. Liver activity index (LAI) was computed from plasma albumin, cholesterol, and retino-binding protein concentration. First, cows were clustered based on time profiles of EB, resulting in 4 clusters (SP: stable positive; MN: mild negative; IN: intermediate negative; SN: severe negative). Cows in the SN cluster had higher plasma nonesterified fatty acids and β-hydroxybutyrate concentrations, compared with cows in the SP cluster, with the MN and IN cluster being intermediate. Cows in the SN cluster had a higher milk yield, lower dry matter intake in wk 1, lower insulin concentration compared with cows in the SP cluster, and lower glucose and IGF-1 concentration compared with cows in the SP and MN clusters. Energy balance clusters were not related with plasma haptoglobin, cholesterol, albumin, paraoxonase, and liver activity index (LAI). Second, cows were grouped based on health status [IHP: cows with treatment for inflammatory health problem (endometritis, fever, clinical mastitis, vaginal discharge or retained placenta); OHP: cows with no IHP but treatment for other health problem (milk fever, cystic ovaries, claw, and leg problems, rumen and intestine problems or other diseases); NHP: cows with no treatments, in the first 6 weeks after calving]. Energy balance was not different among health status groups. The IHP cows had lower nonesterified fatty acids and greater insulin concentration in plasma compared with OHP. The IHP cows had lower plasma albumin concentration, lower LAI and higher haptoglobin concentration compared with OHP and NHP. Overall, EB time profiles were associated with the metabolic status of dairy cows in early lactation, but were only limitedly related with markers of inflammation and oxidative stress status. Inflammatory and metabolic status were related to disease events in early lactation and caused prolonged effects on liver metabolism.

Anti-Mainstream Culinary: The Influence of Post-Modernism on Gastronomy in Indonesian Restaurants

The culinary movement is currently undergoing interesting developments: initially, food was a basic requirement for energy and the food consumed was usually processed from nature. Consequently, processed food often characterized the identity of specific tribes, cultures, and regions. In the modern era, food has a long history (for example, the French Revolution), with ethics and rules. This shows that modern food culture is structured and even classifies social classes. Originally, food in the modern era had a concept adapted from the serving of food in palaces, with order and layout. However, this modern presentation of food was rejected by cooks who served food in different ways. For example, enjoying meals at a high altitude and serving food with unusual artistry. With this resistance to the European-style presentation of many luxury restaurants in Indonesia, this post-modernist restaurant can attract customers. This research uses a descriptive qualitative approach. Data collection technique is conducted through visual observation via social media. The findings reveal that the flow of post-modernism and post-structuralism has influenced the way food is served in several Indonesian restaurants. The full results and discussion are presented herein.

Anti-Mainstream Culinary: The Influence of Post-Modernism on Gastronomy in Indonesian Restaurants

The culinary movement is currently undergoing interesting developments: initially, food was a basic requirement for energy and the food consumed was usually processed from nature. Consequently, processed food often characterized the identity of specific tribes, cultures, and regions. In the modern era, food has a long history (for example, the French Revolution), with ethics and rules. This shows that modern food culture is structured and even classifies social classes. Originally, food in the modern era had a concept adapted from the serving of food in palaces, with order and layout. However, this modern presentation of food was rejected by cooks who served food in different ways. For example, enjoying meals at a high altitude and serving food with unusual artistry. With this resistance to the European-style presentation of many luxury restaurants in Indonesia, this post-modernist restaurant can attract customers. This research uses a descriptive qualitative approach. Data collection technique is conducted through visual observation via social media. The findings reveal that the flow of post-modernism and post-structuralism has influenced the way food is served in several Indonesian restaurants. The full results and discussion are presented herein.

Improving Net Energy Efficiency of Dimethyl Ether Production Process by Methanol Dehydration

Dimethyl ether (DME) is a source of fuel that produces clean energy for the future. Methanol can be used as a raw material for the manufacture of DME as a natural gas that is treated for synthesis. This paper evaluates how to improve net energy efficiency in DME production and how to review the net energy efficiency calculations in DME production. Methods used for production of DME are methanol dehydration, thermodynamics examination, also improving the net energy efficiency of DME with the addition of the heat exchanger (E-100), the addition of a heater (E-104) before entering a column (T-102), and moved the mixer position before the heater (E-100). By modifying the addition of a heat exchanger (E-100), heater (E-104), and changing the position of the mixer in DME production, it has been proven that it can reduce energy requirements in the dimethyl ether synthesis process from methanol and increase net energy efficiency by up to 98.83%. The results of the case study indicate that the addition heat exchanger (E-100) able to reduce the heater load after the creation process and remove the cooler (E-101) that existed before creation, then the addition of the heater (E-104) serves to reduce the load of Qcond2 and Qreb2 on columns (T-102), also the position of the mixer for the methanol recycling flow is moved before the heater (E-100) is intended to remove the heaters (E-103). Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Teaching old laws new tricks: Specific energy requirements for breakage based on modern kernels and a population balance model

A general expression for specific energy requirements in particle breakage is derived from a population balance model. The model employs power-law rate kernels, self-similar fragment distributions and an energy dependence based on the Vogel-Peukert master curve. This model connects the empirical constants and exponents of size in older empirical energy laws to the parameters of the population balance model, the nature of the particles, and certain moments of the self-similar particle size distribution predicted by the model. The resulting model is used to extract values of the order of the power-law rate kernel from literature data. The extracted order values are consistent with known expressions for individual particle breakage. The model developed here may be coupled with experimental determination of the material parameter needed in the Vogel-Peukert master curve to enable extraction of energy utilization efficiency values from experimentally determined values of the size-independent portion of the selection function.

Carbon Dioxide Capture: Current Status and Future Prospects

The surge in greenhouse gas emissions, predominantly in the form of carbon dioxide (CO2) spurred by the Industrial Revolution, has surpassed the critical threshold of 400 ppm, fueling global warming, ocean acidification, and climate change. To mitigate the adverse effects of these emissions and limit the global temperature rise to below 2 °C, the ambitious target of achieving net zero emissions by 2050 was established in the Paris Agreement. Current state-of-the-art technologies, such as amine scrubbing, remain problematic owing to their high energy requirements, susceptibility to corrosion, and other operational challenges. Owing to the lack of suitable technologies coupled with escalating energy demand, there is still a significant amount of carbon dioxide being released into the atmosphere. Accordingly, there is an urgent need for the development of alternative technologies that offer high efficiency, low energy consumption, cost-effective installation, and operation. In this review, we delve into the emerging technologies poised to address these challenges, evaluating their maturity levels in comparison to existing commercially available solutions. Furthermore, we provide a brief overview of ongoing efforts aimed at commercializing these innovative technologies.

Review of nutrition and hydration in relation to physical exercise during pregnancy

Studies on nutritional recommendations for pregnant women who exercise are scarce. The objective of this article is not to focus on the diet of pregnant women as a whole, but to review those aspects of it that may be related to physical exercise. To this end, the nutritional and hydration recommendations contained in the main clinical practice guides on physical exercise during pregnancy are collected, including the first Spanish guides. Likewise, the energy requirements required by pregnant women who perform physical exercise during pregnancy for adequate gestational weight gain are addressed, aspects related to macronutrients in the aforementioned population group, and two specific topics, such as nutritional needs in the adolescent who practices physical exercise during pregnancy and eating disorders in pregnant athletes It is concluded by stating that pregnant women who exercise regularly should eat a varied and balanced diet, such as the Mediterranean diet, avoid long periods of fasting to avoid the appearance of hypoglycemia and maintain adequate fluid intake before, during and after physical exercise. Pregnant adolescents who engage in physical exercise require nutritional supervision to achieve adequate gestational weight gain. The pregnant athlete with an eating disorder has a higher risk of complications during pregnancy and childbirth, gynecological, fetal and neonatal, and, therefore, requires close monitoring by specialists in maternal-fetal medicine.

Low-energy electrochemical CO2-amine desorption driven by the proton-coupled electron transfer reaction (PCET)

The CO2 desorption in amine-based carbon capture processing is accompanied by significant energy consumption, accounting nearly 70% of energy requirements of the entire process. Electrochemical CO2 capture and release are promising technologies to reduce the energy consumption. The characteristics and CO2 desorption performance of QH2 (Tiron) in tertiary amine systems are investigated in this research. The reducing ability of Q (Oxidized QH2) was improved by modifying the electrode to achieve low-energy electrochemical desorption. The CO2 electrochemical desorption achieved low-energy CO2 desorption of 0.7 GJ ton−1 CO2 against over 2.4 GJ ton−1 in a conventional and mature MEA-based system.

Integrated CO2 Capture and Utilization by Combining Calcium Looping with CH4 Reforming Processes: A Thermodynamic and Exergetic Approach.

This study investigates a novel concept to coproduce high-purity H2 and syngas, which couples steam methane reforming with CaO carbonation to capture the generated CO2 and dry reforming of methane with CaCO3 calcination to directly utilize the captured CO2. The thermodynamic equilibrium of the reactive calcination stage was evaluated using Aspen Plus via a parametric analysis of various operating conditions, including the temperature, pressure, and CH4/CaCO3 molar ratio. Introducing a CH4 feed in the calcination stage promoted the driving force and completion of CaCO3 decomposition at lower temperatures (∼700 °C) compared to applying an inert flow, as a result of in situ CO2 conversion. A conceptual process design was investigated that employs a system of two moving bed reactors to produce nearly equivalent volumetric flows of pure H2 and a syngas stream with a H2/CO molar ratio close to 1. A solar reactor was examined for the reactive calcination step to cover the energy requirements of endothermic CaCO3 decomposition and dry reforming. The overall exergy efficiency of the process was found equal to ∼75.9%, a value ∼4.0 and ∼8.0% higher compared to sorption-enhanced reforming with oxy-fuel and solar calciner, respectively, without direct utilization of the captured CO2.

Design of a Solar Distillation Still Model with Backup Heat from Biomass

Water borne pathogens caused series of diseases, and millions died each year. Therefore, availability of safe drinking water and good water sanitation is of great global importance, while this can be done through solar still distillation. The distillation process is one of the technologies for water processing and purification, and solar energy is the main source of energy that used to energize the process. Therefore, in this paper, a solar distillation still with back-up heat from Biomass has been designed with basin area of 1.045 m2 (1290 mm x 810 mm). However, various design equation were utilized during the design process. The energy requirement for evaporating water is 226 0kJ/kg. This implies that much heat energy is required to produce 1 litre of pure. For this reason, a collector of 1.044m2 area was used. This will provide sufficient energy for distillation process. The solution obtained from the Polymath 5.0 software, shows that, the day is not as intrinsic as the solution for the night. This might be due to supply of heat as concentrated heat unlike for the day when the heating increased relatively gently. It is hereby recommended that more of the machine should be develop and made available in the market to enhance a safer and more sanitize drinking water for the society.

Simulation of the nutritional requirements and energy balance of adult cows in a northern temperate grassland.

The forage-livestock balance is an important component of natural grassland management, and realizing a balance between the nutrient energy demand of domestic animals and the energy supply of grasslands is the core challenge in forage-livestock management. This study was performed at the Xieertala Ranch in Hulunbuir City, Inner Mongolia. Using the GRAZPLAN and GrazFeed models, we examined the forage-livestock energy balance during different grazing periods and physiological stages of livestock growth under natural grazing conditions. Data on pasture conditions, climatic factors, supplemental feeding, and livestock characteristics, were used to analyze the metabolizable energy (ME), metabolizable energy for maintenance (MEm), and total metabolizable energy intake (MEItotal) of grazing livestock. The results showed that the energy balance between forage and animals differed for adult cows at different physiological stages. In the early lactation period, although the MEItotal was greater than MEm, it did not meet the requirement for ME. MEItotal was greater than ME during mid-lactation, but there was still an energy imbalance in the early and late lactation periods. In the late lactation period, MEItotal could meet ME requirements from April-September. Adult gestational lactating cows with or without calves were unable to meet their ME requirement, especially in the dry period, even though MEItotal was greater than MEm. Adult cows at different physiological stages exhibited differences in daily forage intake and rumen microbial crude protein (MCP) metabolism, and the forage intake by nonpregnant cows decreased as follows: early lactation > mid-lactation > late lactation, pregnant cows' lactation > dry period. For the degradation, digestion and synthesis of rumen MCP, early-lactation cows were similar to those in the mid-lactation group, but both were higher than those in the late-lactation group, while pregnant cows had greater degradation, digestion, and synthesis of MCP in the lactation period relative to the dry period. For lactating cows, especially those with calves, grazing energy requirements, methane emission metabolism and heat production were highest in August, with increased energy expenditure in winter. Overall, grazing energy, methane emissions and heat production by dry cows were low. In the context of global climate change and grassland degradation, managers must adopt different strategies according to the physiological stages of livestock to ensure a forage-livestock balance and the sustainable utilization and development of grasslands.

Flow Properties of Coarse Powders Used in Food Extrusion as a Function of Moisture Content

The extrusion processing of food powder relies heavily on its moisture content to aid in flow and proper cooking, shaping, and/or puffing. This study focused on the impact of the moisture content on the dynamic flow and shear properties of coarse food powders (corn meal, wheat farina, and granulated sugar). The dynamic flow properties explored were the specific basic flowability energy (SBFE), specific energy, stability index, and flow rate index. The shear properties were the angle of internal friction, unconfined yield strength, major principal stress, wall friction angle, flow factor (FF), and compressibility. Corn meal exhibited an increase in SBFE as the moisture content increased (6.70 mJ/g at 13.13% to 9.14 mJ/g at 19.61%) but no change in FF (4.94 to 5.11); wheat farina also showed an increase in energy requirement as the moisture increased (5.81 mJ/g at 13.73% to 9.47 mJ/g 19.57%) but a marked decrease in FF ratings (18.47 to 6.1); granulated sugar showed a decrease in energy requirements as the moisture increased (51.73 mJ/g at 0.06% moisture content to 13.58 mJ/g at 0.78% moisture content) and a decrease in FF ratings (8.53 to 3.47). Overall, upon the addition of moisture, corn meal became cohesive yet free-flowing; wheat farina became less compressible and more cohesive; and granulated sugar became more cohesive and compressible and less free-flowing.

Design and Construction of an Anaerobic Digester for the Ingestion of Waste from the Cocoa Industry in Nigeria

The Anaerobic Digester designed and constructed for waste ingestion from the Nigerian cocoa industry aims to harness abundant renewable energy from crop residues like cocoa rinds and groundnuts. This study evaluates the biogas potential of these sources in contributing to the country's overall energy needs, emphasizing the imperative for environmental sustainability. Focusing on reducing fossil energy consumption, greenhouse gas emissions, and minimizing environmental impact, the project advocates for a shift towards biogas for day-to-day energy requirements, presenting direct cost savings. The utilization of fossil fuel-derived energy is known to contribute to temperature increase, greenhouse gas emissions, noise pollution, and ground-level air pollution, all of which can be mitigated through biogas utilization. This initiative involves the design and construction of a 0.24m<sup>3</sup> pilot plastic fossil plant for biogas generation, aiming to "green" various applications, including domestic and industrial usage as well as transportation. The digester, constructed from high-density polyethylene (HDPE) plastic, demonstrates leak-free operation, further supporting its potential for long-term sustainability. Results from a 28-day retention period show a cumulative biogas yield, with a daily assessment indicating a gas yield of 0.0496 m<sup>3</sup> on the 12th day. The study highlights the positive and negative influences of temperature inequality gradients ≥34°C≤38°C on biogas production. This comprehensive research contributes valuable insights for the sustainable management of waste and the utilization of biogas as a viable alternative energy source.

Catalytic behavior of aluminum-modified SAPO-34 catalysts for reducing the energy penalty of CO2-rich amine solutions regeneration

The goal of this research is to develop a potential strategy to significantly decrease the heat duty for the amine-based CO2 capture process. Here, a variety of Al2O3-modified SAPO-34 composite catalysts with varying Al2O3 contents are synthesized and utilized to catalytically facilitate the CO2 desorption process. The catalytic CO2 desorption characteristics of various catalysts, Al-SAPO-34, SAPO-34, and γ-Al2O3 are investigated in a CO2-loaded 5 M monoethanolamine (MEA) solution. The results indicate that all catalysts accelerate CO2 desorption, while the Al-SAPO-34 catalysts work better than the parent Al2O3 and SAPO-34 catalysts. Especially, the 15 % Al-SAPO-34 increases the CO2 desorption rate by 78.4 % and reduces the relative energy requirement by 37 % at a desorption time of 1440 s. The catalysts are characterized by different methods and their structure–activity relationship is analyzed. The increased acid sites and mesoporous surface area of the Al-SAPO-34 catalyst may be responsible for its greater catalytic activity. The intermediates of the catalytic CO2 desorption process are identified by FT-IR and NMR, and then a possible catalytic regeneration mechanism is put forward. Additionally, the cyclic stability of the Al-SAPO-34 catalyst for cyclic CO2 absorption–desorption is evaluated. This work demonstrates that the Al-SAPO-34 exhibits greater catalytic CO2 desorption performance, and outstanding stability, and has the opportunity to become an attractive industrial catalyst for the amine-based CO2 capture process.

A numerical approach to exergy-based sustainability and environmental assessments of solar energy-powered district cooling systems using actual operational data

The demand for cooling in buildings has been increasing at a higher rate than heating, and more energy is expected to meet this demand. Solar energy can be vital in fulfilling this energy requirement based on its unique renewable energy features. The solar thermal powered absorption cooling (STAC) and solar electrical assisted vapor compression cooling (SEVC) systems are assessed in this study by conducting the conventional and advanced exergy analyses and environmental assessment. Determining the unavoidable part of exergy destruction, as in this study, provides a unique convenience in design problems where the thermodynamic performances of distinct systems are compared. Under current technological conditions, removing the thermodynamically optimized parameters of the designed systems from the minima-maxima dichotomy and rationally evaluating the avoidable part of exergy destruction will protect the researcher from the arbitrariness of the design. The obtained results based on conventional exergy analysis in a component manner showed that priority should be given to solar technologies due to their lowest exergy efficiencies (0.16 for a photovoltaic (PV) and 0.19 for a collector) and sustainability indices (1.20 for the PV and 1.24 for the collector). Advanced exergy analysis results revealed that the exergy destruction significantly originated from the unavoidable part of the total exergy destruction of the components for the solar technologies (93.02 % for the collector and 96.41 % for the PV), cooling (92.12 % for the absorption and 98.42 % for the vapor compression), and overall system (99.92 % for the SEVC and 99.99 % for the STAC). The initial estimated carbon dioxide emissions from the STAC were 0.28 kg CO2-eq, attributed to pump power consumption. However, these emissions varied dynamically for the SEVC, ranging from 0 (when the solar PV field meets the total power) to 5.58 kg CO2-eq (when radiation is not available), depending on the power-consuming components (compressor and pumps).

Comparative analysis of non-invasive and invasive alternating electric fields therapy for malignant gliomas: a simulation study

Alternating electric fields (AEFs) at intermediate frequencies (100–300 kHz) and low intensities (1–3 V/cm) have shown promise as an effective approach for inhibiting cancer cell proliferation. However, a noticeable research gap exists in comparing the biophysical properties of invasive and non-invasive AEFs methods, and AEFs delivery strategies require further improvement. In this study, we constructed a realistic head model to simulate the effects of non-invasive and invasive AEFs on malignant gliomas. Additionally, a novel method was proposed involving the placement of a return electrode under the scalp. We simulated the electric field and temperature distributions in the brain tissue for each method. Our results underscore the advantages of invasive AEFs, showcasing their superior tumor-targeting abilities and reduced energy requirements. The analysis of brain tissue temperature changes reveals that non-invasive AEFs primarily generate heat at the scalp level, whereas invasive methods localize heat production within the tumor itself, thereby preserving surrounding healthy brain tissue. Our proposed invasive AEFs method also shows potential for selective electric field intervention. In conclusion, invasive AEFs demonstrate potential for precise and effective tumor treatment. Its enhanced targeting capabilities and limited impact on healthy tissue make it a promising avenue for further research in the realm of cancer treatment.

Unveiling the potential of TPA-based molecules to tune the optoelectronic properties and enhance the efficiency of dye-sensitized solar cells.

The world's energy and environmental requirements are changing due to rapid population growth and industrial growth, and solar cells can be used to meet these demands. Dye-sensitized solar cells (DSSCs) are solar cells in which energy conversion occurs via a process similar to photosynthesis in plants. DSSC development is still in its infancy. DSSCs can operate under cloudy conditions and indirect sunlight and have attracted considerable attention due to their low cost and high efficiency. We designed two metal-free TPA-based dyes (Dye2 and Dye3) based on the reference dye Mg207 (Dye1) by increasing the donor strength of the molecule, as such dyes have shown enhanced efficiency in DSSCs. Moreover, the triphenylamine (TPA) moiety has been demonstrated to be a good donor that prevents charge recombination. Intramolecular charge transfer (ICT) from the donor to acceptor moiety was found in the sensitizers, and electrons were promoted to the conduction band (CB) of the TiO2 semiconductor. The negative binding energy of the dye@TiO2 clusters indicated that dye adsorption on the semiconductor surface was stable. The double donor increased the electron injection and electronic coupling constants in Dye2 and Dye3, indicating that these newly designed dyes have superior charge injection capacity. Accordingly, the efficiencies of DSSCs with Dye2 and Dye3 were 9.77% and 9.62%, respectively, and substitution with the TPA unit at the -R1 and -R2 positions in Dye1 resulted in better power conversion compared to the parent compound (9.09%). Increased donor strength improved photovoltaic performance by increasing current density and light-harvesting efficiency. This is a good molecular design approach for preparing targeted donor- -acceptor (D- -A) organic dyes with high DSSC efficiency. To predict the charge transport and optoelectronic characteristics of the TPA dyes, quantum chemical calculations were carried out using Gaussian16. The ground-state (S0) optimized geometries of the sensitizers were computed by utilizing DFT at the B3LYP/6-31G** level. The absorption spectra ( max) were computed by employing TD-DFT with various functionals (B3LYP, PBE1PBE, CAM-B3LYP, and BHandHLYP) in the gas and solvent (DCM) phases. Among the studied functionals, BHandHLYP was found to be best at successfully reproducing the experimental data. Thus, the absorption spectra of the newly designed dyes and dye@TiO2 were calculated at the BHandHLYP/6-31G** level. The dye@TiO2 cluster optimizations were carried out at the B3LYP/6-31G**(LANL2DZ) level.