Flexible and Robust Polyaniline Composites for Highly Efficient and Durable Solar Desalination

Due to the intermittent nature of sunlight, practical solar energy utilization systems demand both efficient solar energy conversion and inexpensive large scale energy storage. We will first discuss the rational design and demonstration of efficient photoelectrochemical hydrogen generation systems using efficient semiconductors and earth-abundant catalyst materials. We have further developed novel hybrid solar-charged storage devices that integrate regenerative photoelectrochemical solar cells and redox flow batteries (RFBs) that share the same pair of redox couples. In these integrated solar flow batteries (SFBs), solar energy is absorbed by semiconductor electrodes and photoexcited caries are collected at the semiconductor-liquid electrolyte interface and used to convert the redox couples in the RFB to fully charge up the battery. When electricity is needed, the charged up redox couples will be discharged on carbon electrodes to generate the electricity as in a RFB. We have demonstrated that such SFB devices can be charged under solar light without external electric bias and deliver a high discharge capacity comparable with state-of-the-art RFBs over many cycles. After developing silicon solar cells and high performance solar cells, carefully matching them with various organic or inorganic redox couples, and optimizing several generations of SFB device designs, we have recently achieved integrated SFB device with an overall direct solar-to-output electricity efficiency (SOEE) of 14%. These high performance SFBs can serve as distributed and standalone solar energy conversion and storage systems in remote locations and enable practical off-gird electrification.

Di-functional nanocomposite films for efficient conversion and storage of solar energy

In this work, the collection of solar energy by a broad-band nanospiral antenna is investigated in order to solve the low efficiency of the solar rectenna based on conventional nanoantennas. The antenna impedance, radiation, polarization and effective area are all considered in the efficiency calculation using the finite integral technique. The wavelength range investigated is 300-3000 nm, which corresponds to more than 98% of the solar radiation energy. It's found that the nanospiral has stronger field enhancement in the gap than a nanodipole counterpart. And a maximum harvesting efficiency about 80% is possible in principle for the nanospiral coupled to a rectifier resistance of 200 Ω, while about 10% for the nanodipole under the same conditions. Moreover, the nanospiral could be coupled to a rectifier diode of high resistance more easily than the nanodipole. These results indicate that the efficient full-spectrum utilization, reception and conversion of solar energy can be achieved by the nanospiral antenna, which is expected to promote the solar rectenna to be a promising technology in the clean, renewable energy application.

Low-dimensional semiconductors provide a rich tapestry of tunable optical and electrical properties for a wide variety of applications. Semiconducting single-walled carbon nanotubes (s-SWCNTs) have shown tremendous potential in applications ranging from digital logic, biological imaging, quantum information processing, photovoltaics, and thermoelectric energy harvesting. Energy harvesting applications rely critically upon the creation of tailored interfaces that enable the movement of energetic species (excitons, electrons, holes) in specified directions. While organic energy harvesting devices often employ interfaces between distinct organic species such as polymers, fullerenes, and carbon nanotubes, hybrid interfaces between organic and inorganic semiconductors have unique properties that are relatively unexplored. In this talk, I will discuss our recent efforts at constructing novel hybrid interfaces between s-SWCNTs and low-dimensional inorganic semiconductors. I will highlight time-resolved spectroscopy results that illustrate exceptionally long-lived photoinduced charge separation across such interfaces. These studies provide insight into some of the remarkable properties of these interfaces that can enable efficient solar energy harvesting and conversion to fuels.

Efficiency of solar energy utilizatiion (Eu, %), efficiency of solar energy conversion (Ec, %) and conversion efficiency were determined for two-rowed barley (cv. Nishinochikara) plant grown in warm regions in Japan. Absorbed solar radiation during the stage from internode elongation to heading was about 56% of the total supplied solar radiation, and that in the ripening stage was about 70%. Absorbed solar radiation (SRα) in the growing period was 865.02 MJ m-2, equivalent to about 40% of the total solar radiation. Ec at the internode elongation to heading stage was 3.94%. Eu and Ec were 1.47% and 2.13% in the ripening period, both of which accounted for 1.09% and 2.71% in the whole growing period, respectively. These values were equal to those of rice grown in the same regions in Japan. Top dry weight was variable in proportion to SRα, and Cs (Conversion efficiency) was 2.32g MJ-1, The value of Cs determined in the early and middle ripening stages were 1.79g MJ-1 and 1.17g MJ-1, respectively.

Solar energy induced catalytic reactions allow solar energy to be used directly in sunlight-to-chemical energy conversions. Many scientific progress have been made in solar energy utilization and conversions, whereas, scientists from all over the world claimed that there are still many problems need to be further addressed including how to further enhance the solar energy utilization & conversion efficiency etc. The detail micro-interface process, redox mechanism, charge-carrier transfer behavior and active species actions need to be further studied. Following all of these concerns, series of multifunctional complex oxides with hetero-junctions have been well designed in our group towards solar energy utilization and conversion process via photo-induced chemical process, and different transient physical techniques including in situ EPR, in situ SPV and transient laser flash photolysis etc. have also been used to elucidate the interfacial photo-induced redox process and charge-carrier behaviors. We found that hierarchical nanostructured assemblies can be engineered to tailor the properties of external fields modulated and/or light harvesting assemblies. The crystal-, micro- and surface-interface structure could be tailored by utilizing various synthesis strategies, which would incur the nanomaterials with novel PEC/PC properties. Furthermore, combined in - situ spectroscopic characterization could provide more detail structural information and redox process over micro-interface, which would be beneficial for design efficient solar and energy conversion based materials at molecular utilization and/or atomic level. The tailored hierarchical nanomaterials may find novel applications in multidisciplinary fields.

Electrochemistry of 2D-materials for the remediation of environmental pollutants and alternative energy storage/conversion materials and devices, a comprehensive review

In this chapter we introduce the physical models at the basis of photosynthetic light harvesting and energy conversion (charge separation). We discuss experiments that demonstrate the processes of light harvesting in the major plant light-harvesting complex (LHCII) and charge separation in the photosystem II reaction center (PSII RC) and how these processes can be modeled at a quantitative level. This is only possible by taking into account the exciton structure of the chromophores in the pigment–protein complexes, static (conformational) disorder, and coupling of electronic excitations and charge-transfer (CT) states to fast nuclear motions. We give examples of simultaneous fitting of linear and nonlinear (time-dependent) spectral responses based on modified Redfield theory that resulted in a consistent physical picture of the energy- and electron-transfer reactions. This picture, which includes the time scales and pathways of energy and charge transfer, allows for a visualization of the excitation dynamics, thus leading to a deeper understanding of how photosynthetic pigment-proteins perform their function in the harvesting and efficient conversion of solar energy. We show that LHCII has the intrinsic capacity to switch between different light-harvesting and energy-dissipating (quenched) states. We introduce the conformational “switching” model for the LHCII protein to explain its role both in light harvesting and in photoprotection. This model explains how the local environment of the protein controls its intrinsic conformational disorder to serve a functional role. Finally, we demonstrate that the PSII RC performs charge separation via two competing pathways of which the selection depends on the conformational disorder induced by slow protein motions. Therefore, we show that the pigment–protein interactions play a decisive role in controlling the functionality of the pigment–protein complexes at work in photosynthesis.

Largely enhanced thermal conductivity of poly (ethylene glycol)/boron nitride composite phase change materials for solar-thermal-electric energy conversion and storage with very low content of graphene nanoplatelets

Bi/Bi2O3/TiO2 heterojunction photocathode for high-efficiency visible-light-driven lithium-sulfur batteries: Advancing light harvesting and polysulfide conversion

A Hybrid Electric and Thermal Solar Receiver

Solar cells hold promise as energy conversion devices but intermittent sunlight limits their continuous applications. The self‐powering integrated solar cells and electrical energy storage devices can be an alternative to resolve this problem. This study demonstrates the integration of solar cell with supercapacitor (SC) device and evaluates its performance for energy conversion and storage for practical validity. SC carbon is derived from agar‐agar as low‐cost carbon precursor and a high‐performance SC electrode is utilized for the first time. The fabricated SC shows an excellent specific capacitance of 170 F g−1 and retains 85% of its original value up to 15 000 charge/discharge cycles at 1 A g−1, and it holds a maximum energy density of 17.7 Wh kg−1. The integration of SCs (three cells in series with 5.4 V) with a commercial solar lantern for a self‐sustaining power pack is demonstrated. The SC is charged by solar cells in a few seconds and powers a solar lantern with 40 light‐emitting diodes without sunlight, demonstrates its potential for efficient conversion of solar energy into electrical energy storage. This result highlights that solar SC can be considered as an ultrafast next‐generation energy‐storage device that can mitigate the energy demand in the near future.

Programmable photocatalysts for hydrogen evolution have been fabricated based on multi-segmented CdS-Au nanorod arrays, which exhibited high-efficiency and programmability in hydrogen evolution as the photoanodes in the photoelectrochemical cell. Multiple different components each possess unique physical and chemical properties that provide these cascade nanostructures with multiformity, programmability, and adaptability. These advantages allow these nanostructures as promising candidates for high efficient harvesting and conversion of solar energy.

Solar selective absorber coatings (SSACs), with the characteristics of efficient harvesting and conversion of solar energy into the heat work fluid, are considered to be one of the key components f...

Energy was generated by using methanol as a solvent to extract dye from Aspilia africana Flowers. The maximum absorption of the extracted dye was observed at different wavelengths (350-1000nm). TiO2 was annealed at different temperatures and phytochemical screening was done. We observed insignificant presence of anthocyanin compared to flavonoids in the flowers. The solar energy conversion efficiency changes from 0.21% to 0.52%, due to the sintering of the TiO2 at different temperatures. The increase in solar energy conversion efficiency can be attributed to the changes in the morphology, crystalline quality, and the optical properties caused by the sintering effect.