Vanadium pentaoxide-doped waste plastic-derived graphene nanocomposite for supercapacitors: a comparative electrochemical study of low and high metal oxide doping

We report the bulk phase synthesis of graphene sheets using waste plastic (WP) as a precursor following a modified pyrolysis approach. Furthermore, the low and high mass loading of vanadium pentaoxide was performed on graphene sheets in 1 : 10 and 1 : 1 ratios, respectively. Advanced characterization techniques such as Raman spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA) analysis, and SEM imaging were used to confirm the synthesis of graphene. FT-IR spectroscopy confirmed that the resonating structure affects the bond strength in the composite, which enables peak shifting in the FT-IR spectrum of the composite. Furthermore, bandgap analysis has been performed using UV-Vis spectroscopy, which confirmed the synthesis of the composites. The developed vanadium-doped graphene was used as the active material for the fabrication of supercapacitor electrodes. The electrochemical performance of these devices was evaluated in 1 M H₃PO₄ solution using cyclic voltammetry (CV), galvanic charge–discharge (GCD) analysis, and electrochemical impedance spectroscopy (EIS). Fabricated cells 1 and 2 showed exceptional specific capacitances of 139.7 F g⁻¹ and 51.2 F g⁻¹ at 5 mV s⁻¹ scan rate, respectively. Cell 1 showed a huge power density of 5312 W kg⁻¹ and an energy density of 19.7 W h kg⁻¹. Conversely, cell 2 showed a comparatively lower power density of 1941 W kg⁻¹ and an energy density of 7.2 W h kg⁻¹ at a 5 mV s⁻¹ scan rate. Moreover, we disclose some brief conclusions on the performance, mechanism, and required modifications that can improve the performance of such devices. This approach can surely help with universal WP problems as well as the development of high-performance supercapacitors.

We report the bulk phase synthesis of graphene sheets using waste plastic (WP) as a precursor following a modified pyrolysis approach.     

Investigation of the adsorption properties of gemcitabine anticancer drug with metal-doped boron nitride fullerenes as a drug-delivery carrier: a DFT study

Anticancer-drug delivery is now becoming a challenging approach for researchers as it allows controlled drug delivery near cancerous cells with minimized generic collection and the avoidance of secondary side effects. Hence in this work, the applications of nanostructures as anticancer drug-delivery carriers were widely investigated to target cancerous tissues. Based on DFT calculations, we investigated the transition metal-doped boron nitride nanostructure as a drug-delivery agent for the gemcitabine drug utilizing the B3LYP/6-31G (d, p) level of theory. In this research, the adsorption energy and electronic parameters of gemcitabine on the interaction with the metal-doped BN nanostructures were studied. It has been observed that metal doping significantly enhances the drug-delivery properties of BN nanostructures. Among the investigated nanostructures, Ni–BN has been found to be the most prominent nanostructure to transport gemcitabine with an elevated value of adsorption energy in both the gas phase (−45.79) and water media (−32.46). The interaction between gemcitabine and BN nanostructures was confirmed through frontier molecular orbitals and stabilization energy analysis. The fractional charge transfer, MEP, NCI, and NBO analyses exposed the charge transfer from drug molecule to the BN nanostructures. Transition density maps and UV-VIS spectra were also plotted to investigate the excited-state properties of the designed complexes. Thus, the present study provides an in-depth interaction mechanism of the gemcitabine drug with BN, which reveals that metal-doped BN nanostructures can be a favorable drug-delivery vehicle for the gemcitabine anticancer drug.

Anticancer-drug delivery is now becoming a challenging approach for researchers as it allows controlled drug delivery near cancerous cells with minimized generic collection and the avoidance of secondary side effects.     

One-pot mechanochemical exfoliation of graphite and in situ polymerization of aniline for the production of graphene/polyaniline composites for high-performance supercapacitors

Graphene/polyaniline composites have attracted considerable attention as high-performance supercapacitor electrode materials; however, there are still numerous challenges for their practical applications, such as the complex preparation process, high cost, and disequilibrium between energy density and power density. Herein, we report an efficient method to produce graphene/polyaniline composites via a one-pot ball-milling process, in which aniline molecules act as both the intercalator for the exfoliation of graphite and the monomer for mechanochemical polymerization into polyaniline clusters on the in situ exfoliated graphene sheets. The graphene/polyaniline composite electrode delivered a large specific capacitance of 886 F g⁻¹ at 5 mV s⁻¹ with a high retention of 73.4% at 100 mV s⁻¹. The high capacitance and rate capability of the graphene/polyaniline composite can contribute to the fast electron/ion transfer and dominantly capacitive contribution because of the synergistic effects between the conductive graphene and pseudocapacitive polyaniline. In addition, a high energy density of 40.9 W h kg⁻¹ was achieved by the graphene/polyaniline-based symmetric supercapacitor at a power density of 0.25 kW kg⁻¹, and the supercapacitor also maintained 89.1% of the initial capacitance over 10 000 cycles.

Efficient ball-milling production of graphene/polyaniline composites as supercapacitor electrodes with enhanced capacitive contribution, rate capability, and specific capacitance.     

Enhanced hydrogen storage performance of graphene nanoflakes doped with Cr atoms: a DFT study

The hydrogen storage performances of novel graphene nanoflakes doped with Cr atoms were systematically investigated using first-principles density functional theory. The calculated results showed that one Cr atom could be successfully doped into the graphene nanoflake with a binding energy of −4.402 eV. Different from the H₂ molecule moving away from the pristine graphene nanoflake surface, the built Cr-doped graphene nanoflake exhibited a high affinity to the H₂ molecule with a chemical adsorption energy of −0.574 eV. Moreover, the adsorptions of two to five H₂ molecules on the Cr-doped graphene nanoflake were studied as well. It was found that there were a maximum of three H₂ molecules stored on the graphene nanoflake doped with one Cr atom. Also, the further calculations showed that the numbers of the stored H₂ molecules were effectively improved to be six (or nine) when the graphene nanoflakes were doped with two (or three) Cr atoms. This research reveals that the graphene nanoflake doped with Cr atom could be a promising material to store H₂ molecules and its H₂ storage performance could be effectively enhanced through modifying the number of doped Cr atoms.

Our study reveals that the H₂ storage performance of a graphene nanoflake based material could be significantly enhanced through doping with Cr atoms.     

A facile strategy for the synthesis of graphene/V2O5 nanospheres and graphene/VN nanospheres derived from a single graphene oxide-wrapped VOx nanosphere precursor for hybrid supercapacitors

It remains a challenge to develop a facile approach to prepare positive and negative electrode materials with good electrochemical performance for application in hybrid supercapacitors. In this study, based on a facile strategy, a single graphene oxide-wrapped VO_x nanosphere precursor is transformed into both electrodes through different thermal treatments (i.e., graphene/VN nanospheres negative electrode materials and graphene/V₂O₅ nanospheres positive electrode materials) for hybrid supercapacitors. The conformally wrapped graphene has a significant influence on the electrochemical performance of VN and V₂O₅, deriving from the simultaneous improvements in electronic conductivity, structural stability, and electrolyte transport. Benefitting from these merits, the as-prepared graphene/VN nanospheres and graphene/V₂O₅ nanospheres exhibit excellent electrochemical performance for HSCs with high specific capacitance (83 F g⁻¹) and good long cycle life (90% specific capacitance retained after 7000 cycles). Furthermore, graphene/VN nanospheres//graphene/V₂O₅ nanosphere HSCs can deliver a high energy density of 35.2 W h kg⁻¹ at 0.4 kW kg⁻¹ and maintain about 70% high energy density even at a high power density of 8 kW kg⁻¹. Such impressive results of the hybrid supercapacitors show great potential in vanadium-based electrode materials for promising applications in high performance energy storage systems.

It remains a challenge to develop a facile approach to prepare positive and negative electrode materials with good electrochemical performance for application in hybrid supercapacitors.     

One-pot synthesis of amine-functionalized graphene oxide by microwave-assisted reactions: an outstanding alternative for supporting materials in supercapacitors

A simple and straightforward method using microwave-assisted reactions is presented for the functionalization of graphene oxide with aromatic and non-aromatic amines, notedly dibenzylamine (DBA), p-phenylenediamine (PPD), diisopropylamine (DPA) and piperidine (PA). The as-synthesized amine-functionalized graphene oxide materials (amine-GO) were characterized using spectroscopic techniques including XRD, FTIR, ¹³C NMR, XPS, TEM for imaging and thermogravimetric analysis (TGA). The characterization confirmed the functionalization for all amines, reaching relatively high surface nitrogen atomic concentrations of up to 8.8%. The investigations of electrochemical behavior for the amine-GOs show the significant improvement in GO''s electrochemical properties through amine functionalization, exhibiting long life cycle stability and reaching specific capacitance values of up to 290 F g⁻¹ and 260 F g⁻¹ for GO-PA and GO-DPA samples, respectively, confirming their potential application as alternative supporting materials in supercapacitors.

A simple and straightforward method using microwave-assisted reactions is presented for the functionalization of graphene oxide with aromatic and non-aromatic amines.     

Nitrogen self-doped activated carbons via the direct activation of Samanea saman leaves for high energy density supercapacitors

In this study, nitrogen self-doped activated carbons (ACs) obtained via the direct activation of Samanea saman green leaves (SSLs) for high energy density supercapacitors were investigated. The SSL-derived direct-activated carbons (hereinafter referred to SD-ACs) were synthesized by impregnating sodium hydroxide as an activating agent and heating up to 720 °C without a hydrothermal carbonization or pyrolysis step. The optimum condition was investigated by varying the weight ratio of raw SSLs to NaOH. Surpassing the ACs derived from the two-step convention method, SD-ACs showed superior properties, including a higher surface area (2930 m² g⁻¹), total pore volume (1.37 cm³ g⁻¹) and nitrogen content (4.6 at%). Moreover, SD-ACs exhibited enhanced electrochemical properties with specific gravimetric and volumetric capacitances of 179 F g⁻¹ and 88 F cm⁻³ in an organic electrolyte, respectively, a high capacitance retention of approximately 87% at a current density of 0.5 A g⁻¹ and excellent cycling stability of 97.5% after 3000 cycles at a current density of 5 A g⁻¹. Moreover, the potential window of the supercapacitor cell was extended to 3.5 V with a significantly enhanced energy density of up to 79 W h kg⁻¹. These results demonstrate that the direct activation of nitrogen-enriched SSLs offers advantages in terms of simplicity, low-cost and sustainable synthetic route to achieve nitrogen self-doped ACs for high energy density supercapacitors, which exhibit superior properties to that of ACs prepared via the conventional method.

Nitrogen self-doped activated carbons with high surface area obtained via the direct activation of Samanea saman leaves for high energy density supercapacitors.     

Rapid microwave activation of waste palm into hierarchical porous carbons for supercapacitors using biochars from different carbonization temperatures as catalysts

A rapid, simple and cost-effective approach to prepare hierarchical porous carbons (PCs) for supercapacitors is reported by microwave activation of abundant and low-cost waste palm, biochar (BC) and KOH. BCs from waste palm at different carbonization temperatures (300–700 °C), as catalysts and microwave receptors, were used here for the first time to facilitate the conversion of waste palm into hierarchical PCs. As a result, the high-graphitization PC obtained at a BC carbonization temperature of 300 °C (PC-300) possessed a high surface area (1755 m² g⁻¹), a high pore volume (0.942 cm³ g⁻¹) and a moderate mesoporosity (37.79%). Besides their high-graphitization and hierarchical porous structure, the oxygen doping in PC-300 can also promote the rapid transport of electrolyte ions. The symmetric supercapacitor based on the PC-300 even in PVA/LiCl gel electrolyte exhibited a high specific capacitance of 164.8 F g⁻¹ at a current density of 0.5 A g⁻¹ and retained a specific capacitance of 121.3 F g⁻¹ at 10 A g⁻¹, demonstrating a superior rate capacity of 73.6%. Additionally, the PC-300 supercapacitor delivered a high energy density of 14.6 W h kg⁻¹ at a power density of 398.9 W kg⁻¹ and maintained an energy density of 10.8 W h kg⁻¹ at a high power density of 8016.5 W kg⁻¹, as well as an excellent cycling stability after 2000 cycles with a capacitance retention of 92.06%.

A rapid, simple and cost-effective approach to prepare hierarchical porous carbons (PCs) for supercapacitors is reported by microwave activation of abundant and low-cost waste palm, biochar (BC) and KOH.     

A study on the preparation of polycation gel polymer electrolyte for supercapacitors

The polycation gel polymer electrolyte (PGPE) is a promising electrolyte material for supercapacitors due to its high ionic conductivity and great flexibility. Herein, we report a novel flexible PGPE film, which is prepared by thermal copolymerization. The superiority of PGPE is attributed to the existence of charged groups in the polymer skeleton. Consequently, the crystallinity of the polymer is effectively reduced, and the migration of the lithium ion is evidently promoted. Moreover, the liquid retention capacity of the film is improved, which enhances its ionic conductivity as well. The reported PGPE exhibits a high ionic conductivity of 57.6 mS cm⁻¹ at 25 °C and a potential window of 0–1.2 V. The symmetrical PGPE supercapacitor (AC/AC) shows 95.21% mass-specific capacitance retention after 5000 cycles at 2 A g⁻¹ with a maximum energy density of 12.8 W h kg⁻¹ and a maximum power density of 5.475 kW kg⁻¹. This study confirms the exciting potential of PGPE for high performance supercapacitors.

The polycation gel polymer electrolyte (PGPE) is a promising electrolyte material for supercapacitors due to its high ionic conductivity and great flexibility.     

Exploration of a high-efficiency and low-cost technique for maximizing the glucoamylase production from food waste

This study was aimed at the exploration of high-efficiency and low-cost technique for glucoamylase (GA) production from food waste; moreover, the produced GA could be directly used in the hydrolysis of food waste. A mixture of food waste, rice waste and cake waste as a sole feedstock was investigated for the production of GA via solid-state fermentation. The highest GA activity of 458.3 U g⁻¹ was obtained from the rice waste after 9 days of incubation. The cake waste also demonstrated a high GA production, achieving 406.5 U g⁻¹ dry substrate. However, the most practical substrate for GA production that could be integrated in the food waste treatment was the mixed food waste, which could effectively produce GA without any additives or adjustments using the technique developed in this study. The optimum conditions for GA production from the mixed food waste were determined through a response surface methodology: the temperature of 31.16 °C, the inoculum amount of 1.54 mL, and the time of fermentation of 7.81 days. The maximum GA activity of 180.59 U g⁻¹ could be achieved under these optimum conditions, which was actually much higher than those reported in the literature. This study showed that the mixed food waste could be an ideal feedstock for the on-site production of high-activity GA, and the produced GA could be directly applied in food waste hydrolysis, which significantly reduced the process cost.

Remarkably high glucoamylase production from food waste was achieved by optimizing the fermentation conditions using the response surface methodology.     

Modulating and opposite actions of two aqueous extracts prepared from Cinnamomum cassia L. bark and Quercus ilex L. on the gastrointestinal tract in rats

Cinnamon bark and evergreen oak acorns, natural sources of functional ingredients, are effective for those suffering from diarrhea, constipation and irritable bowel syndrome. This study aimed to evaluate the dissimilar phytochemical composition and the opposite potential actions of Cinnamomum cassia bark (ACCE) and Quercus ilex aqueous extracts (GIAE) on gastrointestinal (GI)-physiological activities and disruptions. An HPLC-PDA/ESI-MS assay was used to identify the distinctive qualitative and quantitative profiles of phenolic compounds. The GI-physiological action of both extracts on gastric emptying (GE) and gastrointestinal transit time (GIT) were evaluated using the phenol-red colorimetric method and a test meal containing charcoal/gum arabic in water. Loperamide (LOP)-induced colonic constipation and delayed emptying of the stomach were used to explore the reverse effects of ACCE/GIAE on GI disorders. HPLC-PDA/ESI-MS showed that the main phenolic compounds detected in ACCE are trans-cinnamic acid, quinic acid, protocatechuic acid and rosmarinic acid, while gallic acid, quinic acid and protocatechuic acid are the major chemical constituents found in GIAE. GIAE at two doses (150 and 300 mg kg⁻¹) exerted a reduction of GE (66.40% and 60.87%, respectively) compared to a control group (70.25%). However, ACCE at the same concentrations induced contradictory actions on GE/GIT in comparison to GIAE and antagonistic synthetic pharmacological drugs in rats. The protective effect of CCAE against constipation induced by LOP in rats was accompanied by a strong antioxidant property related to moderation of intracellular-mediator disorders. An absence of toxic actions was revealed in the case of the hematological profile and biochemical parameters. Hence, in-depth investigations of these nutrients of both extracts may help future researchers to derive the underlying mechanisms and potential molecular targets for the development of physiologically functional foods and future therapies.

Cinnamon bark and evergreen oak acorns, natural sources of functional ingredients, are effective for those suffering from diarrhea, constipation and irritable bowel syndrome.     

The risky business of production agriculture: health and safety for farm workers.

The lifestyles of employees affect their work and their health. Occupational health nurses need to know as much as possible about employees to render the best care possible. Production agriculture is a risky business performed by many employees. By understanding the risks involved, occupational health nurses can optimize the health of workers in the off farm and on farm contexts of their lives. Managers and supervisors need to realize that investment in farm health and safety can yield financial benefits in terms of decreasing lost workdays caused by injury and illness and increased morale through public recognition of the importance of agricultural production.     

Catalytic pyrolysis of plastic waste for the production of liquid fuels for engines

Catalytic pyrolysis of waste plastics using low cost binder-free pelletized bentonite clay has been investigated to yield pyrolysis oils as drop-in replacements for commercial liquid fuels such as diesel and gasohol 91. Pyrolysis of four waste plastics, polystyrene, polypropylene, low density polyethylene and high density polyethylene, was achieved at a bench scale (1 kg per batch) to produce useful fuel products. Importantly, the addition of binder-free bentonite clay pellets successfully yielded liquid based fuels with increased calorific values and lower viscosity for all plastic wastes. This larger scale pyrolysis study demonstrated that use of a catalyst in powder form can lead to significant pressure drops in the catalyst column, thus slowing the process (more than 1 hour). Importantly, the use of catalyst pellets eliminated the pressure drop and reduced pyrolysis processing time to only 10 minutes for 1 kg of plastic waste. The pyrolysis oil composition from polystyrene consists of 95% aromatic hydrocarbons, while in contrast, those from polypropylene, low density polyethylene and high density polyethylene, were dominated by aliphatic hydrocarbons, as confirmed by GC-MS. FTIR analysis demonstrated that low density polyethylene and high density polyethylene oils had functional groups that were consistent with those of commercial diesel (96% similarity match). In contrast, pyrolysis-oils from polystyrene demonstrated chemical and physical properties similar to those of gasohol 91. In both cases no wax formation was observed when using the bentonite clay pellets as a catalyst in the pyrolysis process, which was attributed to the high acidity of the bentonite catalyst (low SiO₂ : Al₂O₃ ratio), thus making it more active in cracking waxes compared to the less acidic heterogeneous catalysts reported in the literature. Pyrolysis-oil from the catalytic treatment of polystyrene resulted in greater engine power, comparable engine temperature, and lower carbon monoxide (CO) and carbon dioxide (CO₂) emissions, as compared to those of uncatalysed oils and commercial fuel in a gasoline engine. Pyrolysis-oils from all other polymers demonstrated comparable performance to diesel in engine power tests. The application of inexpensive and widely available bentonite clay in pyrolysis could significantly aid in repurposing plastic wastes.

Catalytic pyrolysis of waste plastics using low cost binder-free pelletized bentonite clay has been investigated to yield pyrolysis oils as drop-in replacements for commercial liquid fuels such as diesel and gasohol 91.     

Synthesis of bifunctional nanocatalyst from waste palm kernel shell and its application for biodiesel production

The potential of bifunctional nanocatalysts obtained from waste palm kernel shell (PKS) was investigated for one-step transesterification–esterification under mild conditions. State-of-the-art characterization illustrated that the synthesized catalyst has high stability through the thermal test, high BET surface area of 438.08 m² g⁻¹, pore volume of 0.367 cm³ g⁻¹ and pore width of 3.8 nm. The high amount of basicity (8.866 mmol g⁻¹) and acidity (27.016 mmol g⁻¹) promoted the successfulness of simultaneous transesterification–esterification. The investigation revealed that the combination of potassium and copper on activated carbon surface showed good catalytic activity by giving 95.0% FAME yield and 97.3% FFA conversion at a relatively mild condition of 5 wt% catalyst loading, 12 : 1 methanol to oil molar ratio at 80 °C for 4 hours with FAME yield > 80% after 5 reaction cycles. Characterization of the spent catalyst showed that the amount of basicity was reduced to 3.106 mmol g⁻¹, which validated the reduction of the catalytic performance. The usage of waste material was successfully discovered in producing an effective bifunctional catalyst for biodiesel production from waste cooking oil (WCO) and has high potential for commercialization in the future.

The potential of bifunctional nanocatalysts obtained from waste palm kernel shell (PKS) was investigated for one-step transesterification–esterification under mild conditions.     

Isolation and characterization of a novel bacterium Pseudomonas aeruginosa for biofertilizer production from kitchen waste oil

Kitchen waste oil is composed of long chain triglycerides (LCTs) that has high energy density. However, it is hard to be degraded by microbes, thereby leading to increasing levels of environmental pollution due to landfill disposition. In this study, we isolated and characterized a novel bacterium Pseudomonas aeruginosa PA-3 that could convert kitchen waste oil into biofertilizer. PA-3 could survive on trilaurin or kitchen waste oil as the sole carbon source, and 10 g L⁻¹ trilaurin or kitchen waste oil was completely consumed within 7 days. Interestingly, the degradation products of kitchen waste oil can be used as biofertilizer in promoting cabbage growth. The plant height, leaf area and stem diameter of cabbage plants were all increased with the addition of kitchen waste oil cultivation products into the soil. Kitchen waste oil degradation products were analyzed by gas chromatography mass spectrometry (GC-MS), and short chain alcohols or fatty acids were observed to be the main products. To unravel the mechanism underlying the accelerated cabbage growth, bacterial diversity of the soil was investigated after using this biofertilizer. Results showed that agricultural probiotics accumulated with the addition of kitchen waste oil cultivation products. Finally, the whole genome of PA-3 was sequenced and analyzed, which showed the existence of a complete β-oxidation pathway in the genome of PA-3. To our knowledge, this is the first study on kitchen waste oil degradation and re-utilization by bacteria, which provides a new method for waste source re-utilization.

Kitchen waste oil is composed of long chain triglycerides (LCTs) that has high energy density.     

Understanding the role of Cu+/Cu0 sites at Cu2O based catalysts in ethanol production from CO2 electroreduction -A DFT study

Cu₂O based electrocatalysts generally exhibit better selectivity for C₂ products (ethylene or ethanol) in electrochemical carbon dioxide reduction. The surface characteristic of the mixed Cu⁺ and Cu⁰ chemical state is believed to play an essential role that is still unclear. In the present study, density functional theory (DFT) calculations have been performed to understand the role of copper chemical states in selective ethanol formation using a partially reduced Cu₂O surface model consisting of adjacent Cu⁺/Cu⁰ sites. We mapped out the free energy diagram of the reaction pathway from CO intermediate to ethanol and discussed the relation between the formation of critical reduction intermediates and the configuration of Cu⁺/Cu⁰ sites. The results showed that Cu⁺ sites facilitate the adsorption and stabilization of *CO, as well as its further hydrogenation to *CHO. More importantly, as compared to the high reaction energy (1.23 eV) of the dimerization of two *CO on Cu⁺/Cu⁰ sites, the preferable formation of *CHO on the Cu⁺ site makes the C–C coupling reaction with *CO on the Cu⁰ site happen under a relatively lower energy barrier of 0.58 eV. Furthermore, the post C–C coupling steps leading to the formation of the key intermediate *OCHCH₂ to C₂ compound are all thermodynamically favoured. Noteworthily, it is found that *OCHCH₂ inclines to the ethanol formation because the coordinatively unsaturated Cu⁺ site could maintain the C–O bond of *OCHCH₂, and the weak binding between *O and Cu⁺/Cu⁰ sites helps inhibit the pathway toward ethylene. These findings may provide guidelines for the design of CO and CO₂ reduction active sites with enhanced ethanol selectivity.

Cu⁺ site facilitates the adsorption and stabilization of *CO. The preferable formation of *CHO on Cu⁺ makes C–C coupling reaction happen with *CO on the adjacent Cu⁰ under a lower energy barrier. The Cu⁺/Cu⁰ sites favor the pathway toward ethanol.     

Efficient tuning of zinc phthalocyanine-based dyes for dye-sensitized solar cells: a detailed DFT study

The growing energy demand speed up the designing of competent photovoltaic materials. Herein, five zinc phthalocyanine-based donor materials T1–T5 are designed by substituting various groups (isopropoxy, cyano, fluoro, methoxycarbonyl, and dicyanomethyl) around zinc phthalocyanine. B3LYP/6-31G (d,p) level density functional theory (DFT) was used to investigate the optoelectronic properties of five zinc phthalocyanine-based dyes T1–T5 for dye-sensitized solar cells. The designed molecule T1 shows maximum absorption wavelength (λ_max) in the absorption spectrum at 708.89 and 751.88 nm both in gaseous state and in THF (tetrahydrofuran) solvent. The E_g value of T1 (1.86 eV) is less than reference R, indicating a greater charge transfer rate for T1 among the molecules. The values of open-circuit voltages achieved with acceptor polymer PC₇₁BM are higher than R except for T1 and are 0.69 V, 1.95 V, 1.20 V, 1.44 V, and 1.84 V for T1, T2, T3, T4, and T5, respectively. The lower the reorganization energy, the higher the charge transfer for T1 due to its lower hole mobility (0.06297 eV) than R. Thus, the designed T1–T5 molecules are expected to exhibit superior performance in dye-sensitized solar cells.

We used a quantum chemical approach to investigate the optoelectronic properties of dyes T1–T5 for dye-sensitized solar cells using DFT and TD-DFT computation. The newly designed molecules exhibited outstanding photovoltaic and optoelectronic properties.     

Tunable ductility of a nano-network from few-layered graphene bonded with benzene: a molecular dynamics study

Developing novel graphene-based materials with unique mechanical properties is of significance to meet the requirements in new applications. The pristine graphene shows a brittle fracture when the stretching strain on it exceeds the critical value. Further, it fails to bear the external load. Herein, to enhance the ductility of the pristine graphene, we proposed a corrugated sandwich carbon network based on few-layered graphene, in which the two surface layers are bonded with several corrugated core layers via benzene molecules. The effects of factors such as the geometry, temperature, and strain rate on the ductility of the carbon network were evaluated using the uniaxial tension tests by molecular dynamics simulations. Results show that the new carbon material has more than one peak fracture strain in stretching. The second peak fracture strain is proportional to the length difference between the surface layers and core layers. Hence, the carbon network has a tunable ductility, which suggests a flexible design of such novel materials in a nanostructure/nanodevice with large deformation.

The ductility of the corrugated sandwich carbon nano-network is tunable and higher than that of the pristine graphene.     

2-Bromoanthraquinone as a highly efficient photocatalyst for the oxidation of sec-aromatic alcohols: experimental and DFT study

Anthraquinones are recognized as high efficiency photocatalysts which can perform various redox reactions in aqueous or organic phases. We have experimentally proven that 2-BrAQ can undergo hydrogen transfer with an alpha-aromatic alcohol under light conditions, thereby efficiently oxidizing the aromatic alcohol to the corresponding product. The yield of 1-phenethanol to acetophenone can reach more than 96%. In subsequent catalyst screening experiments, it was found that the electronegativity of the substituent at the 2 position of the anthraquinone ring and the acidity of the solvent affect the photocatalytic activity of anthraquinones. After using various aromatic alcohol substrates, 2-BrAQ showed good conversion and selectivity for most aromatic alcohols, but showed C–C bond cleavage and low selectivity with non-α-position aromatic alcohols. In order to explore the mechanism of the redox reaction of 2-BrAQ in acetonitrile solution, the corresponding free radical reaction pathway was proposed and verified by density functional theory (DFT). Focusing on calculations for 2-BrAQ during the reaction and the first-step hydrogen transfer reaction between the 2-BrAQ triplet molecule and the 1-phenylethanol molecule, we recognized the changes that occurred during the reaction and thus have a deeper understanding of the redox reaction of anthraquinone compounds in organic systems.

Anthraquinones are recognized as high efficiency photocatalysts which can perform various redox reactions in aqueous or organic phases.