Clean Energy Harvesting Research Articles

Phosphorene-based nanogenerator powered by cyclic molecular doping

In this work, we propose a novel nanogenerator (NG) powered by cyclically doping phosphorene with ambipolar organic molecules. In the device, we selected Benzyl viologen (BV) as n-type donor and tetracyanoquinodimethane (TCNQ) as p-type acceptor for phosphorene. Using the-art-of-state density functional theory, we systematically explore the electrical properties of the molecularly doped phosphorene. Remarkably, our calculations show that the phosphorene-based device is able to achieve an open-circuit voltage of ∼2.7V. Importantly, the output power of this device can be modulated by adjusting the concentration and cyclic frequency of molecular doping. The proposed design is simple and experimentally implementable, and thus promising for applications in clean energy harvesting and solid state lighting.

ChemInform Abstract: Organic Functionalized Carbon Nanostructures for Functional Polymer‐Based Nanocomposites

AbstractReview: [77 refs.

Organic Functionalized Carbon Nanostructures for Functional Polymer‐Based Nanocomposites

AbstractCarbon nanostructures (CNSs), which are made up of extended sp2‐hybridized carbon networks, are largely employed as nanofillers for polymer phases to obtain polymer‐based nanocomposites (PNCs). Following their inclusion, the polymer matrices are often improved in many ways, such as enhanced electrical and thermal conductivity, increased stability, and mechanical robustness. The chemical functionalization of the external CNS surfaces with organic substituents is often a key tool for their effective and homogeneous incorporation within a polymer phase, avoiding the formation of aggregates, which can lower the performance of the the final material. This microreview furnishes an overview of PNCs that contain substituted CNSs with organic functionalities. These CNS‐based PNCs can be used as organic functional materials in different applications that range from clean energy harvesting and storage to sensing and biomedicine.

Biomimetic smart nanochannels for power harvesting

With the increasing requirements of reliable and environmentally friendly energy resources, porous materials for sustainable energy conversion technologies have attracted intensive interest in the past decades. As an important block of porous materials, biomimetic smart nanochannels (BSN) have been developed rapidly into an attractive field for their well-tunable geometry and chemistry. With inspiration from nature, many works have been reported to utilize BSN to harvest clean energy. In this review, we summarize recent progress in the BSN for power harvesting from four parts of brief introduction of BSN, biological prototypes for power harvesting, BSN-based energy conversion, and conclusion and outlook. Overall, by learning from nature, exploiting new avenues and improving the performance of BSN, a number of exciting developments in the near future may be anticipated.

Layered crystalline ZnIn2S4 nanosheets: CVD synthesis and photo-electrochemical properties.

Two-dimensional semiconductors with layer thicknesses of a few nanometers to tens of nanometers have attracted tremendous research interest due to their fascinating electrical, optical, and optoelectronic properties and technologically important applications. In this work, two dimensional ternary ZnIn2S4 nanosheets which self-assemble into microflowers have been synthesized through a feasible chemical vapour deposition process. High-resolution transmission electron microscope (HRTEM) analysis reveals that the ZnIn2S4 nanostructure exhibits an extremely high phase purity and a single crystal nature free of dislocations, stacking faults or twins. UV-visible diffuse reflection measurements and room-temperature photoluminescence characterizations reveal that the ZnIn2S4 nanosheets have a strong visible absorption in the range of the energy band gap of 2.6 eV and a wide luminescence band covering the visible spectrum from the green to infrared regions. Photo-electrochemical tests using the ZnIn2S4 nanosheets as a photoanode suggest that ZnIn2S4 nanosheets have a sensitive photoresponse to irradiation with visible light and can thus be used for clean energy harvesting.

Multi-unit hydroelectric generator based on contact electrification and its service behavior

Water is one of the most abundant energy sources in our environment and hydroelectric power has been one of the main forms of macro-energy supply. However, for harvesting green micro-energy from water presented in our residential zone, industry or agricultural irrigation, traditional electromagnetic hydraulic turbine generator has limited applications due to its large size, complexity and high cost. Here we report a novel design of the multi-unit hydroelectric generator (HEG) for harvesting water-related energy based on contact electrification. The instantaneous output power density of the multi-unit HEG array is 0.07W/m2, which is 9 times of that from the individual HEG with the same dimension. Moreover, the rational design of the multi-unit HEG can increase the safety for its future service. By integrating with the multi-unit HEG, the household faucet can be a power source to supply clean energy continuously. Given the compelling features, such as, highly efficient, easily implemented, lightweight and extremely cost-effective, the multi-unit HEG renders a promising approach toward clean energy harvesting from ambient environment.

Closed Circuit PRO Series No 5: clean energy generation from seawater and its concentrates by CC-PRO without need of energy recovery

This study explores the prospects for clean energy generation in coastal regions from salinity gradient made of seawater (SW) and its concentrates (SWC) by the CC-PRO technology of near absolute energy efficiency without energy recovery device and semi-permeable membranes such as HTI-TFC (A = 2.49 lmh/bar, B = 0.39 lmh, and S = 564 μm) of 48.3 bar maximum applied pressure and alike. This power generation process is fueled by SW as low salinity feed and SWC as high salinity feed (HSF) and the regeneration of HSF from the produced high salinity diluted feed achieved through evaporation ponds of the types extensively used by the sea salt manufacturing industry. Large-scale harvesting of clean energy from the sea could be found particularly attractive along coastlines of arid zones where climate conditions (e.g. solar radiation, temperature, wind, humidity, etc.) favor effective evaporation from reservoirs of SWC. The simulated CC-PRO process of the SW (4.2%)–SWC (25%) salinity gradient with the HTI-TFC membrane revealed maximum membrane power density of 55.6 W/m2 and net electric power density after accounting for the auxiliary pumps of 39.3 W/m2 at the hydraulic pressure difference of 48.3 bar under draw/permeation flow ratio of 5.0 and membrane actual/ideal flux ratio of 0.2 estimated from available forward osmosis data of the same membrane in the 1.0–3.0 NaCl salinity gradients range. HTI-TFC membrane surface area of 1,000 m2 should provide 943 kWh electric energy per day enough to desalinate 377 m3/d of SW (4.2%) with 50% recovery by means of the closed circuit desalination (CCD) technology (RO: 2.5 kWh/m3). The results of this study reveal that the CC-PRO technology opens the door for large-scale commercial clean power generation from SW–SWC salinity gradients already with existing PRO membranes and improved economic feasibility when PRO membrane of higher actual/ideal flux ratio and burst pressure shall become available in the near future.

Role of membranes in bioelectrochemical systems

This paper provides an overview of the role of membranes in bioelectrochemical systems (BESs). Bioelectrochemical systems harvest clean energy from waste organic sources by employing indigenous exoelectrogenic bacteria. This energy is extracted in the form of bioelectricity or valuable biofuels such as ethanol, methane, hydrogen, and hydrogen peroxide. Various types of membranes were applied in these systems, the most common membrane being the cation exchange membrane. In this paper, we discuss three major bioelectrochemical technology research areas namely microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial desalination cells (MDCs). The operation principles of these BESs, role of membranes in these systems and various factors that affect their performance and economics are discussed in detail. Among the three technologies, the MFCs may be functional with or without membranes as separators while the MECs and MDCs require membrane separators. The preliminary economic analysis shows that the capital and operational costs for BESs will significantly decrease in the future due mainly to differences in membrane costs. Currently, MECs appear to be cost-competitive and energy-yielding technology followed by MFCs. Future research endeavors should focus on maximizing the process benefits while simultaneously minimizing the membrane costs related to fouling, maintenance and replacement.

The future Clean Energy Harvesting by Wind Power Generation

The electricity generation today is the major issue toward development of human mankind. The current electricity generation depends almost completely on the fissile fuels like coal, petroleum products etc. we are using it in very large scale resulting in pollution and high cost of electricity. The non-conventional methods like solar & wind is being developed on the scale where its use is affordable and pollution free, without any side effects. In this paper we have discussed the basics of wind power generation and the technologies involved in the process. The overall energy harvesting by wind power plants and transmitting it into usable form can solve the electricity problems, In country like India where electricity demand is estimated to increase at least 30% in next 5 to 10 years. This process involves the complex engineering and out of which some of the basics aspects like capacity , stricter of turbines, Synchronous generators are discussed briefly along with the basic components of the Wind Power Generation.

Multi-energy conversion of Gd5 (Si2Ge2)-poly (vinylidene fluoride), a hybrid material

A class of multiphase composites is reported here. These composites consist of magnetocaloric Gd5Si2Ge2 (GSG) particles embedded in a polyvinylidene fluoride (PVDF) matrix. Under an external magnetic field, those materials were found to generate an electrical voltage up to 0.11 V, equivalent to the power density of 14.3 mW/cm3 Oe when the concentration of Gd5Si2Ge2 was at 4 wt. %. This was due to the magnet-induced strain in Gd5Si2Ge2 leading to the voltage generation in the piezoelectric polymer. The power density of the hybrid system has proven to be significantly higher than each single phase alone. When tested individually PVDF has a power density of 3.25 mW/cm3 Oe and Gd5Si2Ge2 has 0 power output. The coupling of magnetic and piezoelectric effects enables multi-energy conversion that is unique for device design and clean energy harvesting.

Three-dimensional ZnO/Si broom-like nanowire heterostructures as photoelectrochemical anodes for solar energy conversion

We report a low-cost solution fabrication of three-dimensional (3D) ZnO/Si broom-like nanowire (NW, “nanobroom”) heterostructures, consisting of Si NW “backbones” and ZnO NW “stalls”, and their application as photoelectrochemical anodes for solar water splitting and energy conversion. The nanobroom morphology and atomic structure are characterized using the scanning, transmission, and scanning transmission electron microscopies. Both Si NW backbones and ZnO NW stalls are defect-free, single-crystalline, and their surfaces are smooth. The optical absorption and photocurrents from nanobroom array electrodes with different Si and ZnO NW dimensions are studied. The longer Si NW backbones and smaller ZnO NW stalls lead to better light absorption and larger photoanodic current. The ZnO/Si nanobrooms show much higher photoanodic current than the bare Si NWs due to the effective Si/ZnO junction and increased surface area. The nanobroom electrode stability is also investigated and using a thin TiO2 coating layer protecting the NWs against dissolution, long-term stability is obtained without any change in shape and morphology of nanobrooms. Finally, the effect of catalyst to improve the oxygen evolution reaction (OER) at the electrode surface is studied resulting in large enhancement in photoanodic current and significant reduction in anodic turn-on potential. This study reveals the promise of the use of simply fabricated and low-cost 3D heterostructured NW photoelectrodes for clean solar energy harvesting and conversion.

Metal on metal oxide nanowire Co-catalyzed Si photocathode for solar water splitting

We report a systematic study of Si|ZnO and Si|ZnO| metal photocathodes for effective photoelectrochemical cells and hydrogen generation. Both ZnO nanocrystalline thin films and vertical nanowire arrays were studied. Si|ZnO electrodes showed increased cathodic photocurrents due to improved charge separation by the formation of a p/n junction, and Si|ZnO:Al (n+-ZnO) and Si|ZnO(N2) (thin films prepared in N2/Ar gas) lead to a further increase in cathodic photocurrents. Si|ZnONW (nanowire array) photocathodes dramatically increased the photocurrents and thus photoelectrochemical conversion efficiency due to the enhanced light absorption and enlarged surface area. The ZnO film thickness and ZnO nanowire length were important to the enhancements. A thin metal coating on ZnO showed increased photocurrent due to a catalyzed hydrogen evolution reaction and Ni metal showed comparable catalytic activities to those of Pt and Pd. Moreover, photoelectrochemical instability of Si|ZnO electrodes was minimized by metal co-catalysts. Our results indicate that the metal and ZnO on p-type Si serve as co-catalysts for photoelectrochemical water splitting, which can provide a possible low-cost and scalable method to fabricate high efficiency photocathodes for practical applications in clean solar energy harvesting.

Fabrication and properties of thermoelectric oxide thick films deposited with aerosol deposition method

Thermoelectric materials can directly convert thermal energy to electric energy via Seebeck effect and have attracted attention for clean energy harvesting material. Ca3Co4O9+δ (Co349) oxide shows a high thermoelectric performance. Since the Co349 is a misfit-layered oxide, the c-axis oriented structure should be required to achieve high thermoelectric performance. In this study, the Co349 thick film was deposited with aerosol deposition (AD) method. The effect of process parameters on the microstructure and thermoelectric properties were investigated. The thermal strain caused by the difference in thermal expansion coefficient should be less than 0.2%. The deposition rate of 2 μm/min could be attained by controlling particle size distribution. The c-axis oriented Co349 film was obtained after the annealing at the temperature higher than 700°C. Seebeck coefficient of 170 (μV/°C) and electrical conductivity of 110 (S/cm) were achieved at 700 °C in the film annealed at 900 °C for 1 hour. The thermoelectric performance could be kept up to the thick film of 55μm. These values were as high as those of the usual bulk samples. This suggests that the AD process is effective to fabricate thick film type thermoelectric module.

Vertical Silicon Nanowire Platform for Low Power Electronics and Clean Energy Applications

This paper reviews the progress of the vertical top-down nanowire technology platform developed to explore novel device architectures and integration schemes for green electronics and clean energy applications. Under electronics domain, besides having ultimate scaling potential, the vertical wire offers (1) CMOS circuits with much smaller foot print as compared to planar transistor at the same technology node, (2) a natural platform for tunneling FETs, and (3) a route to fabricate stacked nonvolatile memory cells. Under clean energy harvesting area, vertical wires could provide (1) cost reduction in photovoltaic energy conversion through enhanced light trapping and (2) a fully CMOS compatible thermoelectric engine converting waste-heat into electricity. In addition to progress review, we discuss the challenges and future prospects with vertical nanowires platform.

Energy harvesting with bio-inspired synthetic nanochannels

With more than four billion years evolution and selection, natural creatures inherit almost perfect functional structures to harvesting clean energy from their living environments. Particularly, biological ion channels and pumps on cell membrane play a crucial role in many bioelectrogenesis processes. Learning from Nature, such as the electric eels, the synthesis of ATP molecules, the Bacteriorhodopsin on retina, etc, provides new approaches for the construction of novel energy conversion systems. In this review article, we briefly summarize the three most intensively studied topics on the clean energy conversion system with bio-inspired nanochannels and nanopores, which are the nanofluidic electrokinetic conversion systems, the nanofluidic reverse electrodialysis systems, and these newly arisen advanced energy conversion system with smart synthetic ion channels. In a predictable future, the performance of these bio-inspired energy conversion system will surly exceed the present achievements of the conventional man-made systems. The bio-mimetic and bio-inspired strategies provide new insights into future energy conversion techniques.

Caterpillar drive harvests power from the sea

It started as a secret spin-off from the cold war. Now this revolutionary submarine drive could end up harvesting clean energy from tidal currents