Low-energy Route Research Articles

All-Layer Electrodeposition of a CdTe/Hg0.1Cd0.9Te/CdTe Photodetector for Short- and Mid-Wavelength Infrared Detection

CdS, CdTe, Hg0.1Cd0.9Te, CdTe, and Ag films were progressively electrodeposited on ITO-coated soda–lime glass to manufacture a short- and mid-wavelength infrared photodetector. A distinctive feature of the applied electrodeposition method is the use of a non-aqueous solution containing ethylene glycol (EG) as the electrolyte in a traditional three-electrode configuration for every film deposition. Using EG as a supplementary electrolyte and using the same deposition conditions with a potential below 0.75 V for all film coatings reduces their environmental incompatibility and offers a low-cost and low-energy route for fabricating the reported photodetector. The produced photodetector has a sensitivity of up to ≈957 nm with a detectivity (D*) of 2.86 × 1012 cm Hz1/2 W−1 and a dark current density (Jdark) of 10−6 mA cm−2. Furthermore, the manufactured photodiode exhibits self-powered performance because Voc and Jsc are self-generated, unlike previously reported photodiodes. The presented all-layer electrodeposition assembly approach can easily be adapted to fabricate sensing devices for different applications.

Photocatalytic Hydrolysis-A Sustainable Option for the Chemical Upcycling of Polylactic Acid.

Plastic waste is a critical global issue, yet current strategies to avoid committing plastic waste to landfills include incineration, gasification, or pyrolysis high carbon emitting and energy consuming approaches. However, plastic waste can become a resource instead of a problem if high value products, such as fine chemicals and liquid fuel molecules, can be liberated from controlled its decomposition. This letter presents proof of concept on a low-cost, low energy approach to controlled decomposition of plastic, photocatalytic hydrolysis. This approach integrates photolysis and hydrolysis, both slow natural decomposition processes, with a photocatalytic process. The photocatalyst, α-Fe2O3, is embedded into a polylactic acid (PLA) plastic matrix. The photocatalyst/plastic composite is then immersed in water and subjected to low-energy (25 W) UV light for 90 h. The monomer lactide is produced as the major product. α-Fe2O3 (6.9 wt %) was found to accelerate the PLA degradation pathway, achieving 32% solid transformation into liquid phase products, in comparison to PLA on its own, which was found to not decompose, using the same conditions. This highlights a low energy route toward plastic waste upgrade and valorization that is less carbon intensive than pyrolysis and faster than natural degradation. By directly comparing a 25 W (0.025 kWh) UV bulb with a 13 kWh furnace, the photocatalytic reaction would directly consume 520× less energy than a conventional thermochemical pathway. Furthermore, this technology can be extended and applied to other plastics, and other photocatalysts can be used.

Secure Low-Energy Routing Protocol Based on Dynamic Trust Awareness and Load Balancing in Wireless Sensor Networks

Since wireless sensor networks (WSNs) have the requirements of high security and energy conservation, a distributed secure low-energy routing protocol (SLERP) based on dynamic trust awareness and load balancing is proposed. In order to reduce the adverse influence of malicious nodes in the network, the Chebyshev neural network is used to predict the dynamic trust degree of network nodes to accelerate the speed and accuracy of malicious node detection. Based on the comprehensive consideration of the average dynamic trust degree of cluster-head nodes, the load of the cluster-head node, network energy consumption, network lifetime, and accurate route evaluation model are established by the analytic hierarchy process (AHP). The search methods of secure low-energy routing and chromosome crossing and the mutation method are designed based on the genetic algorithm (GA), so as to quickly establish the optimal cluster-head node-set and the optimal routing path of each node. Simulation results show that SLERP can significantly improve the detection speed and detection success rate of malicious nodes, reduce the network energy consumption and load, and effectively extend the network lifetime.

A Robust and Low-Cost Sulfonated Hypercrosslinked Polymer for Atmospheric Water Harvesting.

The availability of freshwater is rapidly declining due to over-exploitation and climate change, with multiple parts of the globe already facing significant freshwater scarcity. Here, a sulfonated hypercrosslinked polymer able to repeatedly harvest significant amounts of water via direct air capture is reported. Water uptake from relative humidities as low as 10% is demonstrated, mimicking some of the harshest environments on Earth. A water harvesting device is used to show repeated uptake and harvesting without significant detriment to adsorbent performance. Desorption is triggered using simulated sunlight, presenting a low-energy route to water harvesting and adsorbent regeneration. The synthesis of sulfonated hypercrosslinked polymer requires only low-cost and readily available reagents, offering excellent potential for scale-up. Due to an almost limitless supply of water vapor from air in most regions around the globe, this approach can transform ourability to address water security concerns.

Applying an Improved Squirrel Search Algorithm (ISSA) for Clustering and Low-Energy Routing in Wireless Sensor Networks (WSNs)

Applying an Improved Squirrel Search Algorithm (ISSA) for Clustering and Low-Energy Routing in Wireless Sensor Networks (WSNs)

Role of Noncovalent Interactions in Inducing High Enantioselectivity in an Alcohol Reductive Deoxygenation Reaction Involving a Planar Carbocationic Intermediate

The involvement of planar carbocation intermediates is generally considered undesirable in asymmetric catalysis due to the difficulty in gaining facial control and their intrinsic stability issues. Recently, suitably designed chiral catalyst(s) have enabled a guided approach of nucleophiles to one of the prochiral faces of carbocations affording high enantiocontrol. Herein, we present the vital mechanistic insights from our comprehensive density functional theory (B3LYP-D3) study on a chiral Ir-phosphoramidite-catalyzed asymmetric reductive deoxygenation of racemic tertiary α-substituted allenylic alcohols. The catalytic transformation relies on the synergistic action of a phosphoramidite-modified Ir catalyst and Bi(OTf)3, first leading to the formation of an Ir-π-allenyl carbocation intermediate through a turn-over-determining SN1 ionization, followed by a face-selective hydride transfer from a Hantzsch ester analogue to yield an enantioenriched product. Bi(OTf)3 was found to promote a significant number of ionic interactions as well as noncovalent interactions (NCIs) with the catalyst and the substrates (allenylic alcohol and Hantzsch ester), thus providing access to a lower energy route as compared to the pathways devoid of Bi(OTf)3. In the nucleophilic addition, the chiral induction was found to depend on the number and efficacy of such key NCIs. The curious case of reversal of enantioselectivity, when the α-substituent of the allenyl alcohol is changed from methyl to cyclopropyl, was identified to originate from a change in mechanism from an enantioconvergent pathway (α-methyl) to a dynamic kinetic asymmetric transformation (α-cyclopropyl). These molecular insights could lead to newer strategies to tame tertiary carbocations in enantioselective reactions using suitable combinations of catalysts and additives.

Assembling covalent organic framework membranes via phase switching for ultrafast molecular transport

Fabrication of covalent organic framework (COF) membranes for molecular transport has excited highly pragmatic interest as a low energy and cost-effective route for molecular separations. However, currently, most COF membranes are assembled via a one-step procedure in liquid phase(s) by concurrent polymerization and crystallization, which are often accompanied by a loosely packed and less ordered structure. Herein, we propose a two-step procedure via a phase switching strategy, which decouples the polymerization process and the crystallization process to assemble compact and highly crystalline COF membranes. In the pre-assembly step, the mixed monomer solution is casted into a pristine membrane in the liquid phase, along with the completion of polymerization process. In the assembly step, the pristine membrane is transformed into a COF membrane in the vapour phase of solvent and catalyst, along with the completion of crystallization process. Owing to the compact and highly crystalline structure, the resultant COF membranes exhibit an unprecedented permeance (water ≈ 403 L m−2 bar−1 h−1 and acetonitrile ≈ 519 L m−2 bar−1 h−1). Our two-step procedure via phase switching strategy can open up a new avenue to the fabrication of advanced organic crystalline microporous membranes.

Low Temperature Nano Mechano-electrocatalytic CH4 Conversion.

Transforming natural resources to energy sources, such as converting CH4 to H2 and carbon, at high efficiency and low cost is crucial for many industries and environmental sustainability. The high temperature requirement of CH4 conversion regarding many of the current methods remains a critical bottleneck for their practical uptake. Here we report an approach based on gallium (Ga) liquid metal droplets, Ni(OH)2 cocatalysts, and mechanical energy input that offers low-temperature and scalable CH4 conversion into H2 and carbon. Mainly driven by the triboelectric voltage, originating from the joint contributions of the cocatalysts during agitation, CH4 is converted at the Ga and Ni(OH)2 interface through nanotribo-electrochemical reaction pathways. The efficiency of the system is enhanced when the reaction is performed at an increased pressure. The dehydrogenation of other nongaseous hydrocarbons using this approach is also demonstrated. This technology presents a possible low energy route for CH4 conversion without involving high temperature and harsh operating conditions.

Theoretical investigation of CH-bond activation by photocatalytic excited SO2 and the effects of C-, N-, S-, and Se-doped TiO2.

The photocatalytic sulfoxidation on TiO2 discovered by Parrino et al. represents a new, interesting and lower energy route for the synthesis of sulfonic acids. Sulfonic acids are important precursors for dyes, detergents and drugs. In the commonly known industrial process, SO2 and a specific hydrocarbon are converted into sulfonic acids using high-energy UV light. In this reaction, SO2 is excited into a metastable triplet state (3SO2), which has the potential to activate a CH-bond of hydrocarbons and start a radical reaction cycle. By introducing TiO2 as a photocatalyst, it has been shown that visible light can be used for the synthesis. This offers the potential to be a cost-effective reaction approach for industrial use. However, experimental studies indicate that the initial excitation mechanism of SO2 on TiO2 is significantly different from the catalyst-free mechanism. Parrino et al. were able to reveal first evidence for the existence of a charge-transfer process from SO2 to the TiO2 surface by means of electrochemical experiments. First theoretical investigations from first principles were able to further substantiate the existence of a charge-transfer. However, to fully understand this mechanism, more accurate methods such as Time Dependent Density Functional Theory (TD-DFT) or ab initio multireference methods such as the Complete Active Space Self Consistent Field (CASSCF) method are required. Furthermore, after understanding the charge-transfer mechanism, the introduction of dopants into TiO2 can be investigated in order to possibly redshift the excitation energy. This might open the route to using lower energy light for the sulfoxidation of hydrocarbons on TiO2 as a new potential industrial reaction for the synthesis of sulfonic acids. In this work, we will study the initial step of the photocatalytic sulfoxidation of hydrocarbons using the TD-DFT and CASSCF methods by using a combined approach consisting of calculations with periodic boundary conditions and a newly constructed embedded cluster model. Furthermore, we will explore the effects of doping by introducing four heteroatoms (C, N, S, and Se) into the TiO2 surfaces anatase[101] and rutile[110] to find a possible enhancement of the photocatalytic reactivity by lowering the electronic excitation energy.

Is mass-scale electrocatalysis of aqueous methanol an energetically and economically viable option for hydrogen production?

The use of primary alcohols (such as methanol) in the production of hydrogen (H2) has been spotlighted as one of the indispensable measures to pursue a greener economy. Here, we address some potential shortcomings concerning the production of H2 based on aqueous methanol electrolysis in reference to steam methane reforming (SMR) as a mature commercial technology. After all, is SMR an economic and low-energy route for H2 production? Is it feasible to use methanol to electrolytically generate H2? The liquid-phase methanol-based hydrogen evolution reaction (HER) at 335 K is an example of a potentially entropy driven reaction (exoergic, even though very endothermic) with a suitable catalyst using either ambient or waste heat. Further, would it be more efficient to use methane as a source of hydrogen via SMR or consume it directly as energy? The suitability of HER is assessed in the context of industrial energy analysis, thermodynamics, and sustainability.

Algorithm for secure communication of wireless network based on node energy control

This paper analyzes the security algorithm and energy cost of wireless sensor networks in depth, and designs and implements a series of energy-optimized security solutions to ensure the secure establishment and operation of wireless sensor networks. This paper proposes an improved Ad hoc network routing protocol based on energy control. It introduces a low-energy balanced routing algorithm to reduce routing transmission energy consumption, balance network traffic, and improve the energy control performance of network routing protocols. The protocol uses a cross-layer design in this way, the route selection combines the information of the link the remaining energy. A joint function is formed by the transmit power level remaining energy. The joint function of all nodes on the path is used as the basis for route selection and applied to the route discovery stage. At the same time, the protocol introduces edge degree parameters in the establishment process, the idea of minimum energy consumption path and the introduction of energy consumption ratio parameters in the cluster skull backbone network generation process are adopted to realize the energy optimization of the path establishment process. At the same time, the protocol uses the message interaction mechanism in the path establishment process to implement a node security authentication scheme based on secret shared information without adding any routing communication messages, which effectively prevents the passive and active attacks of the attacker on the network. The results of simulation experiments prove that the secure routing protocol achieves the network’s balanced energy consumption while ensuring the secure communication of the network, and solves the energy problem.

Single-Step Fiber Pretreatment with Monocomponent Endoglucanase: Defibrillation Energy and Cellulose Nanofibril Quality

The combination of enzymatic pretreatment of cellulose fibers followed by mechanical defibrillation has become a green and low-energy route to obtain cellulose nanofibrils (CNF). However, the variability in the properties of the as-produced CNF remains a major challenge that needs to be addressed for any application to be realized. Herein, we study the effect of monocomponent endoglucanase (EG) on the energy consumed in defibrillation as well as the physical properties of the obtained CNF. This single-step enzymatic pretreatment (0.5–25 EGU/g cellulose fibers for 1–3 h) reduces the defibrillation energy (by up to 50%) at nearly 100% yield to obtain CNF of a similar morphology, size, and crystallinity compared to CNF obtained in the absence of pretreatment. Under mild conditions (5.6 EGU/g for 1 h), aiming to minimize energy consumption while preserving rheological properties, EG pretreatment increased the water retention value, reduced the molecular weight, and promoted structural surface modification (amorphogenesis), without significant cellulose solubilization. In addition, the carbohydrate binding module of the EG was found to improve the interaction of the catalytic core with the substrate. The combination of the factors considered here boosts the effect of the enzyme even if used at low loadings, facilitating high-yield, more sustainable production of CNF.

Arylation of gem-difluoroalkenes using a Pd/Cu Co-catalytic system that avoids β-fluoride elimination.

PdII/CuI co-catalyze an arylation reaction of gem-difluoroalkenes using arylsulfonyl chlorides to deliver α,α-difluorobenzyl products. The reaction proceeds through a β,β-difluoroalkyl–Pd intermediate that typically undergoes unimolecular β-F elimination to deliver monofluorinated alkene products in a net C–F functionalization reaction. However to avoid β-F elimination, we offer the β,β-difluoroalkyl–Pd intermediate an alternate low-energy route involving β-H elimination to ultimately deliver difluorinated products in a net arylation/isomerization sequence. Overall, this reaction enables exploration of new reactivities of unstable fluorinated alkyl–metal species, while also providing new opportunities for transforming readily available fluorinated alkenes into more elaborate substructures.

An Efficient Multipath Routing Protocol for Decentralized Wireless Sensor Networks for Mission and Safety-Critical Systems

Background: Wireless Sensor Network (WSN) is a useful integral part of mission and safety-critical systems, whose failure may result in injury, loss of life, serious environmental damage and/or may result in the failure of some goal-directed activities. Its major challenges are reliability, and security related issues during data delivery. To mitigate these, the development of secure routing protocols, which are capable of optimum utilization of WSNs’ nodes resources for effective data delivery, has been one of the major research interests. However, most of the existing single path routing protocols for WSNs are not able to meet with up with the performance requirements of the mission and safety-critical systems. Meanwhile, a few that are multipath require high computational power, energy and their multiple paths are not ranked, this makes them unsuitable as routing protocol for WSNs in mission and safety-critical systems. Objective: In this work, we propose a secure multipath routing protocol based on sectorisation and best neighbouring nodes selection models to meet up with the performance requirements of WSNs in the mission and safety-critical systems. The protocol is capable of providing optimal multiple ranked route paths for reliable data delivery. Methods: A route management technique, using direct approach, is developed for selecting different optimal data paths for reliable data routing. Also, simple but efficient lightweight privacy preserving authentication scheme is proposed for the protocol to ensure security and privacy during data routing. Computational and security analysis were performed to ascertain its efficiency in terms of computational cost, energy consumption and security. Results: The results showed that SMRP achieved better performance compared to the two stateof- the-art solutions in terms of end-to-end delay, energy consumption and data routing reliability. Conclusion: The proposed protocol is suitable for wireless sensor network due to its low delay, low energy consumption and routing reliability metrics.

Synthesis of methyl acetate by nano-photocatalyst based on titania: Temperature dependence studies

Design of low energy processes for synthesis of industrially important esters is imperative expanse of research. Sulphonated Titania based nano-catalysts have been prepared by wet impregnation route has been utilizated for low energy photo-catalytic synthesis of methyl acetate at ambient temperature conditions and optimized the parameters for maximum conversion. In the present paper we have carried out the kinetic study of the reaction at optimized conditions of catalyst loading and molar ratio varying the thermal conditions to observe the effect of temperature on the reaction conversion and equilibrium time. Morphology of the catalysts was analysed using Scanning electron microscopy which suggest a stable and oval particle morphology of the catalyst particles. Sulphonation characteristics of the catalyst was characterized by FT-IR analysis in bare as well as activated state. The kinetic data has been modelled according to second order kinetic model to calculate forward rate constant at various temperatures and maximum reaction rate of 6.77 E-05 L 2 g − 1 mol -1 min −1 was observed at 333.15 K. Further activation energy of the reaction has been calculated by Arrhenius equation and Activation energy for the overall process was 22.26 kJ/mol. The reaction enthalpy calculated from Vant Hoff equation was found to be 47.66 kJ/mol and entropy was found to be 142.03 J/mol/K. Therefore this photocatlytic material can efficiently catalyze the esterification reaction of acetic acid and methanol at low energy conditions. This finding has broaden and deepen fundamental understanding of CH 3 C O O H on TiO 2 surface and demonstrate a low energy route for esterification reactions.

Facile and low-temperature strategy to prepare hollow ZIF-8/CNT polyhedrons as high-performance lithium-sulfur cathodes

Great efforts have been devoted to developing novel cathodes to alleviate the shuttle effect of lithium polysulfides (LiPSs). The limited intrinsic conductivity of metal–organic frameworks (MOFs) compels their utilization as the templates to prepare carbonaceous Li-S battery cathodes after high-temperature treatments. The facile and low-temperature fabrication methods of MOF-derived cathodes are largely unexplored. Herein, the hybrid of hollow zeolitic imidazolate framework-8 (ZIF-8) polyhedron functionalized with carbon nanotube (HZIF/CNT) cathode is fabricated via facile tannic acid (TA) etching and low-temperature treatment. The conductive HZIF/CNT structure with ordered hollow ZIF-8 morphology, rich heteroatoms functionalities, and hydrophilic surface endow strong adsorption of LiPSs, boosted LiPSs conversion kinetics, and regulated Li2S deposition. As a result, S@HZIF/CNT cathode delivers a superior initial capacity of 1371 mAh g−1 at 0.1C and excellent rate retention at 3.0C (696 mAh g−1). The remarkable cycling stability is evaluated for 500cycles at 0.5C with a 0.073% capacity decay per cycle. Moreover, the cathode with a high sulfur loading of 3.41 mg cm−2 delivers an initial capacity of 696.4 mAh g−1 at 1.0C and stable cycling performance over 200cycles. This work opens a facile and low-energy route to design advanced sulfur cathodes for high-performance Li-S batteries.

Artificial spinning of natural silk threads

Silk producing arthropods spin solid fibres from an aqueous protein feedstock apparently relying on the complex structure of the silk protein and its controlled aggregation by shear forces, alongside biochemical changes. This flow-induced phase-transition of the stored native silk molecules is irreversible, environmentally sound and remarkably energy efficient. The process seemingly relies on a self-assembling, fibrillation process. Here we test this hypothesis by biomimetically spinning a native-based silk feedstock, extracted by custom processes, into silk fibres that equal their natural models’ mechanical properties. Importantly, these filaments, which featured cross-section morphologies ranged from large crescent-like to small ribbon-like shapes, also had the slender cross-sectional areas of native fibres and their hierarchical nanofibrillar structures. The modulation of the post-draw conditions directly affected mechanical properties, correlated with the extent of fibre crystallinity, i.e. degree of molecular order. We believe our study contributes significantly to the understanding and development of artificial silks by demonstrating successful biomimetic spinning relies on appropriately designed feedstock properties. In addition, our study provides inspiration for low-energy routes to novel synthetic polymers.

A Low Energy Routing Algorithm for the IoT Environment

A Low Energy Routing Algorithm for the IoT Environment

Low Temperature Fabrication for High Performance Flexible CsPbI2Br Perovskite Solar Cells.

All‐inorganic CsPbX3‐based perovskites, such as CsPbI2Br, show much better thermal and illumination stability than their organic–inorganic hybrid counterparts. However, fabrication of high‐quality CsPbI2Br perovskite film normally requires annealing at a high temperature (>250 °C) that is not compatible with the plastic substrate. In this work, a Lewis base adduct‐promoted growth process that makes it possible to fabricate high quality CsPbI2Br perovskite films at low temperature is promoted. The mechanism is attributed to synthesized dimethyl sulfoxide (DMSO) adducts which allow a low activation energy route to form CsPbI2Br perovskite films during the thermal annealing treatment. A power conversion efficiency (PCE) of 13.54% is achieved. As far as it is known, this is the highest efficiency for the CsPbI2Br solar cells fabricated at low temperature (120 °C). In addition, the method enables fabrication of flexible CsPbI2Br PSCs with PCE as high as 11.73%. Surprisingly, the bare devices without any encapsulation maintain 70% of their original PCEs after being stored in ambient air for 700 h. This work provides an approach for preparing other high performance CsPbX3‐based perovskite solar cells (PSCs) at low temperature, particularly for flexible ones.

The role of 1πσ∗ states in the formation of adenine radical-cations in DNA duplexes

Photoinduced damage of DNA is a well-known but still far from fully understood phenomenon. Electronic structure methods are here employed to investigate potential roles of πσ∗ states in initiating photodamage, and ways in which πσ∗-state driven photochemistry might evolve with increasing molecular complexity. The study starts with the bare 9H-adenine molecule and progresses through to a model double-helix DNA duplex in aqueous solution. Relative to the gas phase, aqueous solvation is predicted to stabilize the 1πσ∗ states of these systems when exciting at the respective ground state equilibrium geometries, but to have relatively little effect on the asymptotic NH bond strengths. But the study also re-emphasises the potential importance of rival σ∗ ← π excitations, wherein a solute π electron is promoted to a σ∗ orbital localized on an OH bond of a complexing H2O molecule, as a route to forming parent radical cations – as have recently been observed following near UV photoexcitation of double-helix adenine-thymine duplexes in water (Banyasz et al., 2018). The subsequent deprotonation of such radical cations offers a rival low energy route to NH bond fission and radical formation in such duplexes.