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Interest in acquiring green energy from sunlight is driving research into the incorporation of biological photosynthetic materials into biohybrid devices. A potential way to enhance solar energy conversion by photosynthetic proteins is to couple them to plasmonic nanomaterials to enhance absorption of incident radiation. In this work, a variety of plasmonic nanoparticles were used to boost the photocurrent output of a Protein Electricity Generator (PEG). Mixing gold nanoparticles (NPs) of five different architectures into the photoprotein/electrolyte contents of the cell was found to increase device performance, the most effective being ∼120 nm diameter star-shaped clusters that caused a ∼six-fold increase in photocurrent at the optimum dopant level. In addition, high-resolution electrohydrodynamic printing was used to create parallel line and square lattice patterns of silver nanoparticle ink on the tungsten rear electrode of the cells. Patterns with a 700 nm spacing between lines boosted photocurrents by up to three-fold and the effects of the gold and silver nanoparticles were additive, such that the ideal combination produced a ∼19-fold increase in photocurrent and device efficiency. We attribute the elevated performance to plasmonic enhancement of absorbance and scattering effects that increase the path length for photons in the device. Use of rear electrodes with silver nanoparticle lines and grids at 1100 nm spacing did not increase photocurrents, highlighting the importance of precision printing of nanostructures for the enhancement of device performance.

The salt fouling issue, which has become the major bottleneck hindering a sustainable solar desalination process in practice. Herein, a fluidic photothermal structure that is able to completely pre...

As an excellent candidate for lightweight structural materials and nonmetal electrical conductors, carbon nanotube reinforced carbon matrix (CNT/C) composites have potential use in technologies employed in aerospace, military, and defense endeavors, where the combinations of light weight, high strength, and excellent conductivity are required. Both polymer infiltration pyrolysis (PIP) and chemical vapor infiltration (CVI) methods have been widely studied for CNT/C composite fabrications with diverse focuses and various modifications. Progress has been reported to optimize the performance of CNT/C composites from broad aspects, including matrix densification, CNT alignment, microstructure control, and interface engineering, etc. Recent approaches, such as using resistance heating for PIP or CVI, contribute to the development of CNT/C composites. To deliver a timely and up-to-date overview of CNT/C composites, we have reviewed the most recent trends in fabrication processes, summarized the mechanical reinforcement mechanism, and discussed the electrical and thermal properties, as well as relevant case studies for high-temperature applications. Conclusions and perspectives addressing future routes for performance optimization are also presented. Hence, this review serves as a rundown of recent advances in CNT/C composites and will be a valuable resource to aid future developments in this field.

Shadows are everywhere. Not much engineering use has been found for shadows, and this ubiquitous effect is strenuously avoided in optoelectronic applications. In this work, we present a shadow-effect energy generator (SEG) that scavenges the illumination contrast that arises on the device from shadow castings, and generates a direct current, simply by placing a part of the generator in shadow. The shadow-effect mechanism is experimentally validated by Kelvin Probe Force Microscopy (KPFM). The SEG is capable of harvesting energy from illumination contrasts arising under weak ambient light. Without any optimization, our generator has a power density of 0.14 μW cm−2 under indoor conditions 0.001 sun, where shadows are persistent. Our SEG performs 200% better than that of commercial silicon solar cells under the effects of shadows. The harvested energy from our generator in the presence of shadows arising at a very low intensity (0.0025 sun) can drive an electronic watch (1.2 V). In addition, the SEG can serve as a self-powered sensor for monitoring moving objects by tracking the movement of shadows. With its cost-efficiency, simplicity and stability, our SEG offers a promising architecture to generate green energy from ambient conditions to power electronics, and as a part of a smart sensor systems, especially in buildings.

Summary Direct utilization of abundantly available solar energy is a promising way to create a sustainable society. Here, we report a ferroelectric-semiconductor (BaTiO3@BiVO4) hybrid that uses an effective strategy to enhance charge separation and transfer during water oxidation. The tetragonal BaTiO3 can induce an outward vector of built-in electric field after positive polarization, which aids in increasing the photovoltage and accelerating holes’ transfer to BiVO4’s surface. A super-hygroscopic metal hydrogel serves as an atmospheric humidity harvester for continuous water supply to the hybrid, where water oxidation takes place. As the hydrogel absorbs moisture from ambient humid air, it functions as a dehumidifying agent and carries water to the photoanode for power generation, being connected in series with a solar cell, further boosting the carrier’s mobility. This photoanode-hydrogel and solar-cell intelligent assembly can generate a photocurrent of 0.4 mA/cm2 with a relative humidity reduction of 12.0% under an illumination of 10 mW/cm2.

Human-machine interfaces in emerging smart-skin technologies tend to be focussed towards high-sensitivity tactile sensing primarily with visual/numerical feedback, and research on e-skin technologies for the visually impaired is sparse. Here we demonstrate a proof-of-concept six-pixel tactile sensor that converts touch stimuli based on Braille codes into an auditory output, and which could potentially be miniaturized as an ‘energy-autonomous on-skin e-Braille reader’ for the visually impaired. By applying the concepts of electric double layer capacitance and bio-photo capacitance, a self-powered sensor is constructed that generates electrical signals as large as 2 V by modulating a bio-electrochemical liquid bridge between electrodes of opposite wetting characteristics. The liquid bridge, composed of photosynthetic pigment-proteins with a redox electrolyte, both augments the sensory response and serves as a standalone solar-capacitor that can generate a photocurrent as high as 140 µA cm-2, and which displays a long discharge time of ~20 mins with just ~3 mins of photo charging.

Band structure engineering offers a perfect route to tune the transport properties of electrons and holes independently, especially in semiconductors for water splitting. Here, we explore the possibility of achieving a bias-free single-step solar to chemical energy conversion using gas-phase moisture as the reactant while generating hydrogen as the reaction product. A metal-based superhygroscopic hydrogel scavenges moisture from the ambient environment and serves as the water source. The FeOOH/BiVO4 heterojunction works as the photoanode wherein the interface allows the transport of electrons to the outer layer, resulting in an upward band bending. Concomitantly, the negative charges will accumulate on the Cu2O surface in the FeOOH/Cu2O photocathode, inducing a downward band bending. With the use of the hydrogel, photoanode, and photocathode, a device for directly splitting the moisture absorbed from the ambient air is realized, generating a photocurrent of 0.75 mA cm-2 under the one-sun intensity of cool daylight without any additional bias. The solar-cell-assisted device can split 6 mg of moisture in 10 h, and the hydrogel can absorb more than 30 mg of moisture in the same period.

Many exciting developments have unfolded on the recently emerged research topic of solar-driven interfacial evaporation, which is a promising technology for water purification. However, the sole heat source, i.e., solar energy, has put a limit on the maximum achievable evaporation rate. Therefore, to boost the evaporation beyond the limit, we here in this work have put forth a new photothermal system with a trilayered structure (TLS) that is capable of simultaneously harvesting hybrid energy in addition to solar energy for enhanced evaporation. A carbon-based material with broad-band light absorption that can be facilely synthesized through dehydration effect is also reported. Demonstrations of TLS evaporator by recovering the free thermal energy from sources like ground surficial heat and waste heat from laboratory facility and building walls together with solar radiation have been carried out. A remarkable synergic evaporation rate exceeding 2.4 kg m-2 h-1 is achieved, and moreover, the hybrid heating makes evaporation independent of solar intermittency. Besides, a TLS integrated hybrid water-purification bottle with outstanding portability is further demonstrated, which is expected to be of great significance to the development of mobile water purification and safe water security in the future.

Low intensity indoor lightings are often wasted and unutilized, when they could be harvested to produce electrical energy. Unfortunately there is currently no solar cells which could harvest low light intensity efficiently. Therefore, this work reports the synthesis of energy transfer redox couples (ETRCs) that aid in the harvesting of low light intensity for photoelectrochemical cells. Such ETRCs are excellent choices as electrolytes in solid-state photoelectrochemical cells owing to their multifunctional attributes like faster dye regeneration, more efficient light absorption and faster energy transfer kinetics. Electrochemical characterizations reveal that Forster Resonance Energy Transfer (FRET) is occurring between ERTC electrolyte (donor) and the N719 dye (acceptor). Photovoltaic efficiency of the reported device is 28% higher than the conventional silicon solar cells, tested under low light intensity. Additionally, the idiosyncratic design of this device makes it versatile to be used in indoor conditions or can be mounted at a wide range of incidence angle with an ability to retain a high efficiency of 21.08%. Superior ionic-conductivity imparted by the single-component electrolyte provides a platform for future directions in energy harvesting and storage.

Hybrid energy-harvesting systems that capture both wave and solar energy from the oceans using triboelectric nanogenerators and photovoltaic cells are promising renewable energy solutions. However, ubiquitous shadows cast from moving objects in these systems are undesirable as they degrade the performance of the photovoltaic cells. Here we report a shadow-tribo-effect nanogenerator that hybrids tribo-effect and shadow-effect together to overcome this issue. Several fiber-supercapacitors are integrated with the shadow-tribo-effect nanogenerator to form a self-charging power system. To capture and store wave/solar energy from oceans, an energy ball based on the self-charging power system is demonstrated. By harnessing the shadow-effect, i.e. the shadow of the moving object in the energy ball, the charging time shortens to 253.3 s to charge the fiber-supercapacitors to the same voltage (0.3 V) as using pure tribo-effect. This cost-effective method to harvest and store the wave/solar energy from the oceans in this work is expected to inspire next-generation large-scale blue energy harvesting., Ubiquitous shadows cast from moving objects in hybrid energy-harvesting systems are undesirable as they degrade the performance of the photovoltaic cells. Here the authors report the shadow of the moving object in a hybrid energy-harvesting system shortens charging time to charge a self-charging power system.

Photosynthetic proteins carry out photochemical charge separation with a near-unity quantum efficiency and provide interesting materials for sustainable solar energy conversion in man-made photoelectrochemical devices. The three-dimensional architectures of natural photosynthesisers on both macroscopic and microscopic length scales contrast strikingly with the essentially two-dimensional architectures of commercial photovoltaic devices. In this work we fabricated flexible and semi-transparent bio-photoelectrochemical cells (BPEC) that showed excellent flexibility and durability in response to repeated mechanical deformation. A three-dimensional stack of five such BPECs connected in parallel produced a peak photocurrent of 2900 nA under simulated sunlight in the laboratory and 2400 nA when tested outdoors. Placement of the BPEC stack within either a regular solid reflective well or a Johnson solid reflective well further boosted these photocurrents, computational analysis indicating that the strongest boost that more than doubled output was the consequence of multiple reflections within the Johnson solid that increased the light intensity incident on the BPEC stack. These design features, inspired by natural structures for absorbing and reflecting sunlight, improved the relative performance of the BPECs under non-peak insolation, such that the photocurrent output under natural sunlight was relatively uniform between 10 a.m. and 5 p.m. We discuss how the flexibility, durability and partial transparency of the individual BPECs enable the fabrication of cell arrays with a range of three-dimensional architectures.

Tridentate, bis-phenolate N-heterocyclic carbenes (NHCs) are among the ligands giving the most selective and active group 4-based catalysts for the copolymerization of cyclohexene oxide (CHO) with CO2. In particular, ligands based on imidazolidin-2-ylidene (saturated NHC) moieties have given catalysts which exclusively form polycarbonate in moderate-to-high yields even under low CO2 pressure and at low copolymerization temperatures. Here, to evaluate the influence of the NHC moiety on the molecular structure of the catalyst and its performance in copolymerization, we extend this chemistry by synthesizing and characterizing titanium complexes bearing tridentate bis-phenolate imidazol-2-ylidene (unsaturated NHC) and benzimidazol-2-ylidene (benzannulated NHC) ligands. The electronic properties of the ligands and the nature of their bonds to titanium are studied using density functional theory (DFT) and natural bond orbital (NBO) analysis. The metal&ndash, NHC bond distances and bond strengths are governed by ligand-to-metal &sigma, and &pi, donation, whereas back-donation directly from the metal to the NHC ligand seems to be less important. The NHC &pi, acceptor orbitals are still involved in bonding, as they interact with THF and isopropoxide oxygen lone-pair donor orbitals. The new complexes are, when combined with [PPN]Cl co-catalyst, selective in polycarbonate formation. The highest activity, albeit lower than that of the previously reported Ti catalysts based on saturated NHC, was obtained with the benzannulated NHC-Ti catalyst. Attempts to synthesize unsaturated and benzannulated NHC analogues based on Hf invariably led, as in earlier work with Zr, to a mixture of products that include zwitterionic and homoleptic complexes. However, the benzannulated NHC-Hf complexes were obtained as the major products, allowing for isolation. Although these complexes selectively form polycarbonate, their catalytic performance is inferior to that of analogues based on saturated NHC.

In this paper, an efficient method for Content Based Image Retrieval (CBIR) to retrieve the images of diabetic retinopathy (DR) is proposed. The methodology involves inter-plane relationship between pixel intensities and feature reduction. Key pixels are selected from an edgy image and are used for computing the intensities in inter-plane relationship. By using the selected point as a center pixel the Local Binary Patterns (LBPs) are computed. Our approach enhanced the results by compressing the size of the resultant metrics. Feature reduction is performed by using the Random Bin Selection method. The experiments conducted on the STARE dataset indicates an increment of 42.04% in the average precision rate compared to the existing method.

Summary Dual attributes of UV-photo-responsive organic-ionic conductors are exploited in bio-photoelectrochemical cells based on photosynthetic RC-LH1 proteins from Rhodobacter sphaeroides. These UV enhancer molecules (UVEM) can generate small photocurrents in the absence of protein and are also effective electrolytes for photocurrent generation by RC-LH1 complexes in response to near-infrared excitation. Mixing RC-LH1 and UVEM components strongly enhanced UV photocurrents relative to those obtained with protein or UVEM alone, an effect that is attributed to energy transfer from the hetero-anthracene chromophore of the UVEM to the carotenoids of the RC-LH1 complex. RC-LH1/UVEM bio-photoelectrochemical cells were superior to conventional RC-LH1 cells in terms of UV external quantum efficiency, photo-response sensitivity, and photocurrent rise-decay times. These bio-photodetectors could detect weak UV radiation with intensities as low as 2 μW/cm2. This combination of photosynthetic proteins with dual-function electrolytes is the first attempt to construct fully functional bio-photoelectrochemical UV photodetector based on natural components.

The development of new technologies that use sunlight as an energy source is adding to pressure on finite natural resources and the challenges of recycling and disposal. Looking to nature for material assistance, we describe a proof-of-concept flexible and biodegradable photoelectrochemical cell based almost entirely on pigments, proteins, polysaccharides, and graphene platelets. In addition to being largely environmentally benign, such devices present opportunities for the recovery of valuable components such as, in the present case, the geologically scarce metal indium and the precious metal gold. Recovery is achieved through dissolution in ethanol followed by physical separation of the heavy element, leaving a residue made up from common elements that can be recycled through natural biodegradation. Potential applications for flexible, biomolecule-based photoelectrochemical cells are considered.

Oxo- and imido-vanadium(V) metal complexes supported by bis(phenolate)-functionalized N-heterocyclic carbene (NHC) ligands were synthesized and structurally identified. In the presence of [(Ph3P=)2N]Cl ([PPN]Cl), saturated NHC oxo-vanadium complexes showed activity in the coupling of CO2 and cyclohexene oxide (CHO) into cis-cyclohexene carbonate (cis-CHC). More importantly, the oxo-vanadium complex bearing the less electron-donating benzannulated NHC ligand was found to be more active in CHO conversion to poly(cyclohexene carbonate) (PCHC) in addition to the cis-CHC, highlighting the beneficial effect of the weak electron-donating ability of the latter vs. saturated NHC ligands within such vanadium catalysts. Evaluation of the saturated NHC imido-vanadium catalyst performance led to the same activity and selectivity as the analogous oxo-vanadium catalysts owing to its reactivity with CO2 via a [2+2] cycloaddition reaction forming an oxo-vanadium species. publishedVersion

Natural photosynthetic proteins can convert solar energy into electrical energy with close to 100% quantum efficiency, and there is increasing interest in their use for sustainable photoelectrochemical devices. The primary processes of photosynthesis remain operational and efficient down to extremely low temperatures, and natural photosystems exhibit a variety of self-healing mechanisms. Herein we demonstrate the use of an amphiphilic triblock copolymer, Pluronic F127, to fabricate a self-healing photosynthetic protein photoelectrochemical cell that operates optimally at sub-zero temperatures. A concentration of 30% (w/w) Pluronic F127 depressed the freezing point of an electrolyte comprising 50 mM ubiquinone-0 in aqueous buffer such that optimal device solar energy conversion was seen at -12 °C rather than at room temperature. Fabrication of the protein photoelectrochemical cells with flexible electrodes enabled the demonstration of self-healing of damage caused by repeated mechanical deformation. Multiple bending cycles caused a marked deterioration of the photocurrent response to around a third of initial levels due to damage to the gel phase of the electrolyte, but this could be restored to ~95% by simply cooling and rewarming the device. This self-recoverability of the electrolyte extended the operational life of the protein cell through a process that increased its photoelectrochemical output during the repair. Utility of the cells as components of a touch sensor operational across a wide temperature range, including freezing conditions, is demonstrated.

The advent of foldable mobiles and electronic devices has persuaded the need for the development of safe, robust and durable flexible energy storage devices. With global temperatures plunging well below 0 °C in most parts of the globe during winters, it is vital to enhance the low temperature performance of these energy storage devices. Aqueous electrolytes for supercapacitors and batteries offer the most sustainable solution when compared to electrolytes made of organic solvents or ionic liquids. Here, we report an inverse-melting pluronic polymer gel electrolyte (PPGE) consisting of an amphiphilic pluronic polymer/water mixture that acts as a cryoprotectant thereby rendering flexible supercapacitors operational down to −30 °C. Organic ionic conductors (OIC) were introduced into the PPGE to boost ionic conductivity. The fabricated supercapacitors exhibit a specific capacitance of 436 Fg-1 and 441 Fg-1 at 25 °C with PiHI and PiBr as OIC, respectively (at 1 Ag-1 current density). The same devices have a significantly higher capacitance of 140 Fg-1 and 339 Fg-1 at −30 °C. A maximum energy density of 16.8 Wh/kg and 11.77 Wh/kg were obtained at 25 °C and −30 °C, respectively. Additionally, the device with PiBr exhibits high capacitance retention of 70% at −30 °C. Furthrmore, the fabricated devices exhibit cooling performance recovery.

With rising global concerns over the alarming levels of particulate pollution, a sustainable air quality management is the need of the hour. Air filtration research has gained momentum in recent years. However, the research perspective is still blinkered toward formulating new fiber systems for the energy-intensive electrospinning process to fabricate high quality factor air filters. A holistic approach on sustainable air filtration models is still lacking. The air filter model presented in this work uses a simple process involving water-induced self-organization and self-regeneration of nanofibers, and an easy recycling route after the filter life that not only facilitates reuse of the microfibrous scaffold holding the nanofibers but also allows renewal of nanofibers. Three generations of air filters are fabricated and tested, all having high particulate matter (PM)-adsorbing tendency, high filtration efficiency (>95%), and high Young's modulus (≈5 GPa). The renewable air filters offer a sustainable alternative to the present cost-intensive electrospun air filters.

A high power density IPMSM is proposed in this paper with a rated output power of 150kW and a maximum torque of 300N-m. The power density of this machine is calculated to be 29.18kW/L (26kW/kg). The proposed design is realized for a drive system driven by inverter with 355V DC input. The current and voltage characteristics of the machine are studied and the number of series-parallel paths are chosen to be driven by the inverter voltage.

Introduction: Stress is an important factor of depression that causes the changes in various body systems. The forced swim test is a commonly used stressor test where rats are forced to swim in specially constructed tanks for a particular period where there is behavioral activation characterized by vigorous swimming and diving to search for alternate routes of escape. Animal health including human has been shown to be affected by the stressful events of life inducing situation which alters cognition, learning memory and emotional responses, causing mental disorders like depression and anxiety and stress in rats. Methods: The experiment was carried out with 12 healthy albino Wistar female rats weighing about 150-180gms. The animals were randomly divided into two groups of six animals each. Group – I (control), Group – II (Stressed Group). Group –II rats are placed in plastic tanks for 45minutes for15 days. Temperature of water was maintained at 20˚C. During stress phase, the animals will be trained for forced swim test, behavioral changes observed by open field apparatus for emotions, and eight arm maze for memory & leaning, elevated plus maze for anxiety. Results: Forced swim stress causes to a significant change (p