Method Of Converting Solar Energy Research Articles

A Review of Factors Affecting the Efficiency and Output of PV Systems Applied in the Tropical Climate of South-South Nigeria

The increasing adoption of renewable energy for electricity generation has led to a growing application of photovoltaic (PV) systems in residential and commercial settings across Nigeria. This study aims to provide a comprehensive review of the factors affecting the efficiency and output of PV systems applied in the tropical climate of South-South Nigeria. The environmental benefits of PV systems further enhance their appeal as a direct method of converting solar energy into electricity. For remote communities in South-South Nigeria, often disconnected from the national grid, PV systems offer a viable alternative electricity source. However, the efficiency and output of PV systems are significantly influenced by various environmental conditions prevalent in the tropical climate of South-South Nigeria. The methodology employed in this study includes an extensive literature review and analysis of PV system installations in the region. Data was collected from various sources, including journal articles, conference proceedings, and reports, to identify the key factors impacting PV system performance in South-South Nigeria. The findings highlight that high temperatures, humidity levels, frequent dust accumulation, and potential sea salt effects due to coastal proximity are among the critical environmental factors affecting PV system efficiency in this tropical zone. The study concludes that while the region's climate provides advantages for solar energy harvesting, it also presents unique challenges that need to be addressed when implementing PV systems in South-South Nigeria. The authors recommend strategies to mitigate the environmental challenges faced by PV systems in this tropical climate, contributing to the optimization of solar energy utilization in the region.

Highly efficient splitting of benzyl alcohol for the production of hydrogen and benzaldehyde using synergistic CuNi/CdS photocatalysts

The production of hydrogen and benzaldehyde (BAD) by splitting benzyl alcohol (BA) through photocatalysts is one of the common methods of converting solar energy to chemical energy. Herein, a photocatalyst to achieve high efficiency in hydrogen production was fabricated by loading Cu-Ni bi-metal on the CdS nanorods as a carrier. The 20% Cu1Ni1/CdS composite catalyst was used for simultaneous photocatalyze H2 production and BA oxidation to BAD under light with activities of 14.517 and 13.220 mmol g-1h−1, respectively, which is 8.7 times and 7.9 times higher than that of pure CdS. The high production efficiency can be mainly attributed to the synergistic effect of Cu-Ni bi-metal and the close contact between Cu-Ni and CdS interfaces. These microstructures enhance light absorption, effectively promote charge separation, and reduce the complexation of photogenerated electrons and holes. This work provides new ideas for the design of a cost-effective catalyst.

Interface engineering of 0D–1D Cu2NiSnS4/TiO2(B) p–n heterojunction nanowires for efficient photocatalytic hydrogen evolution

The photocatalytic hydrogen production is one of the clean and renewable methods of converting solar energy to chemical fuels. Herein, an 0D/1D Cu2NiSnS4/TiO2(B) p-n heterojunction photocatalyst was prepared by a hydrothermal route. The FE-SEM, and HR-TEM analysis revealed that the 1D nanowire morphology of TiO2(B) was coated uniformly with Cu2NiSnS4 (CNTS) nanoparticles. With an average particle size of 5 nm, CNTS nanoparticles improved the interfacial contact and formed an efficient p-n heterojunction with TiO2(B), which greatly improved the charge carrier separation, as evident from the transient photocurrent, photoluminescence, and impedance spectroscopies. The optimized Cu2NiSnS4/TiO2(B) sample produced an average of 7144 µmol/g of hydrogen in 4 h of reaction time under direct sunlight irradiation, which is nearly five times higher than bare TiO2(B). Based on the Mott-Schottky and UV–visDRS spectra, a Z-scheme p-n junction charge transfer mechanism has been proposed.

(Digital Presentation) Plasmonic Enhanced CuBi2O4 Photocathode for Solar Driven Water Splitting

Hydrogen is a fuel for sustainable and renewable energy development that emits no carbon dioxide when compared to traditional fossil fuels. Photoelectrochemical (PEC) water splitting is a sustainable method of converting solar energy that falls on earth into useful chemical fuels. However, the sluggish surface reaction kinetics, high cost, and low natural abundance limit the use of photoelectrodes for practical application. It is critical to developing effective and resilient photoelectrodes that provide high efficiency with good stability. Copper based oxides like CuO, Cu2O, CuBi2O4, CuFeO2, and Cu3VO4 are some of the most well-known low-cost materials with apt band gap and band edges for proton reduction reaction. Among them, CuO is one of the most extensively researched photocathodic materials for PEC water splitting owing to its natural abundance and facile synthesis. However, the photocorrosion problem at CuO limits its use in practical application. The conduction band of CuO is contributed by Cu 3d bands which easily get reduced to Cu0 on photoexcited electron diffuse to conduction band. On the other hand, CuBi2O4 is ternary metal oxide which is more resistant and forbids photocorrosion owing to it conduction band contributed by Bi atom orbitals rather than Cu orbitals1.Metal sulfides like Sb2S3 is good photo-absorber material for solar cells consists of non-toxic and low-cost metal. It has favorable band gap and conduction band and valence band alignment for proton reduction reaction. The type II heterojunction between CuBi2O4 and Sb2S3 can present effective strategy of charge separation and enhanced photoconversion. The plasmon behavior of metal NPs is widely studied in PEC to further improve the photoelectrochemical performance of the photoelectrodes. Plasmonic metal nanoparticles (NPs) absorb light of a threshold wavelength and vibrate emitting out the hot electrons2. Adding Au plasmonic NPs to the photoelectrode might increase the charge carrier concentration, enhance the PEC efficiency, and boost hydrogen production.The objectives of this study are to investigate fabrication of CuBi2O4/Sb2S3 heterojunction and investigate the dual role of plasmonic Au NPs sandwiched between CuBi2O4/Sb2S3 heterojunction. This heterojunction is developed through three synthesis process: synthesis of CuBi2O4 microrods (MRs) through co-precipitation, Sb2S3 plates via a hybrid chemical bath deposition, and Au NPs via seed-assisted synthesis. XRD, SEM, TEM, and XPS are used to examine the CuBi2O4/Au/Sb2S3, CuBi2O4/Sb2S3, and CuBi2O4/Au heterostructures that were synthesized. At 0 VRHE, the photocurrent of CuBi2O4/Au/Sb2S3 (-3.12 mA.cm-2) was > 200 percent greater than that of pristine CuBi2O4 (-1.45 mA.cm-2), Sb2S3 (-1.02 mA.cm-2), and CuBi2O4/Sb2S3 (-2.15 mA.cm-2). Impedance spectroscopy revealed that CuBi2O4/Au/Sb2S3 has the lowest charge transfer resistance value when compared to the pristines. Stability tests revealed the superior stability of CuBi2O4/Au/Sb2S3 compared to their counterparts3. The increase in photoelectrode PEC activity can be attributed to: (i) effective heterojunction formation for facile charge transfer, (ii) increased light absorption, (iii) incorporation of plasmonic Au NPs increased charge carrier concentration, and (iv) Au NPs also served as a relay for charge transfer between CuBi2O4 and Sb2S3 due to their metallic properties, which increased photoelectrode conductivity. The synergistic effect of fabricated CuBi2O4/Sb2S3 heterojunction and dual role of Au NPs sandwiched resulted in improved PEC conversion and boosted hydrogen evolution. The findings of this study will pave the way for photoelectrodes to be sandwiched between plasmonic NPs through a heterojunction interface that boosts hydrogen production. References (1) Li, C.; He, J.; Xiao, Y.; Li, Y.; Delaunay, J. J. Earth-Abundant Cu-Based Metal Oxide Photocathodes for Photoelectrochemical Water Splitting. Energy Environ. Sci. 2020, 13 (10), 3269–3306. https://doi.org/10.1039/d0ee02397c.(2) Subramanyam, P.; Meena, B.; Biju, V.; Misawa, H.; Challapalli, S. Emerging Materials for Plasmon-Assisted Photoelectrochemical Water Splitting. J. Photochem. Photobiol. C Photochem. Rev. 2022, 51 (November 2021), 100472. https://doi.org/10.1016/j.jphotochemrev.2021.100472.(3) Kumar, M.; Ghosh, C. C.; Meena, B.; Ma, T.; Subrahmanyam, C. Plasmonic Au Nanoparticle Sandwiched CuBi2O4 /Sb2S3 Photocathode with Multi-Mediated Electron Transfer for Efficient Solar Water Splitting. Sustain. Energy Fuels 2022. https://doi.org/10.1039/D2SE00600F. Figure 1

Peridynamic Modelling of Propagation of Cracks in Photovoltaic Panels

Photovoltaics (PV) is a method of converting solar energy into direct current electricity using semiconducting materials that exhibit the photovoltaic effect. Cracking in PV panels can cause performance degradation in PV panels. In this study, a new computational methodology, peridynamics is utilised to investigate the cracking behaviour in PV panels. Peridynamics is based on integro-differential equations, and it is a very suitable technique to model crack initiation and propagation. Majority of PV panels are based on silicon solar cell technology. Therefore, polycrystalline material behaviour of silicon is explicitly considered in the model. The numerical framework can be used to support the design of high-performant, long-lasting and fracture-resistant PV panels. The results can also be used to produce practical guidelines aimed to facilitate the decision of PV module rejection due to cracking during production.

Solar charging power plant – a complex for laboratory and practical training

Problem . The development and implementation of green technologies is not only relevant, but also a very cost-effective scientific and engineering task. Therefore, training specialists in the latest green energy-saving and energy-efficient technologies is also an urgent task for the modern educational process. Goal. The aim is development of a conceptual solution for the complex for laboratory and practical classes based on a solar charging station. Methodology. The analytical methods of research on the development and application of methods and devices for transforming the energy of the sun into electricity were used. Methods of experimental research and mathematical methods of processing and modulation of the received results are used. Results. A review of decisions on the main methods of converting solar energy into electricity was made and the main kinds and types of solar power plants were studied. It is proposed to develop a complex for laboratory and practical classes with students based on a hybrid design of a solar power plant. The technical characteristics of the developed complex are given, its main components are indicated and the list of its equipment is presented. Because solar panels are the main element of the complex that converts the energy of solar radiation into electricity, the main dependences for calculating their parameters are given. The scheme for carrying out experimental research with solar panels of a complex is offered. Originality. A list of laboratory and practical classes that can be conducted on the developed complex for laboratory and practical classes is proposed. Practical value. Implementation of the proposed complex for laboratory and practical classes on the basis of a solar charging station will allow educational institutions not only to conduct a quality educational process on modern equipment, but also to generate a certain amount of green energy that can be used for their own needs. Key words: solar charging power station, green energy, green tariff, solar energy, solar power station, electric car, energy-efficient technologies, solar panels.

METHOD FOR USING SOLAR ENERGY TO GENERATE CLEAN ENERGY BASED ON VACUUM-ATMOSPHERIC POWER AMPLIFICATION TECHNOLOGY

New method of converting solar energy into useful work and generating clean energy based on the technology of vacuum-atmospheric power amplification has been developed. As an energy source this technology uses an external supply of potential energy of the atmosphere in the Earth's gravitational field, which exists everywhere and becomes useful when it is converted into the desired form for use.In this case, clean energy is generated in the same way as in hydroelectric power plants. The main advantage of the proposed method is that the devices in which it is used generate energy stably, regardless of the time of day, weather and location. Clean energy absorbed from the atmosphere is independently generated with any necessary design capacity for a specific consumer in the desired location without the use of organic fuel and main power grids. The article presents a theoretical justification of the method of generating clean energy based on the VAPA technology. Examples of using this method in various devices are given.

Controllable synthesis of Au-TiO2 nanodumbbell photocatalysts with spatial redox region

Photocatalytic water splitting has increasingly attracted attention as one of the most useful methods of converting solar energy into chemical fuel. However, the undesirable reverse reaction significantly limits the enhancement of efficiency. Herein, we fabricated an Au nanorods/TiO2 nanodumbbells structure photocatalyst (Au NRs/TiO2 NDs) via a facile synthetic strategy, which has spatially separated oxidation and reduction reaction zones. Owing to the unique structure, the charge separation of these photocatalysts can be significantly improved and the reverse reaction can be efficiently inhibited. The photogenerated electrons were injected from the TiO2 to the Au NRs, and a positively charged TiO2 region and negatively charged Au region were formed under UV irradiation. An enhanced hydrogen production performance was obtained compared with that seen in normal Au-TiO2 heterostructure. Under optimized conditions, the H2-production rate can reach up to 60,264 μmol/g/h, about six times higher than previously reported Au/TiO2 photocatalysts. Besides this, our work also demonstrates the key factors of precise synthesis of the Au NRs/TiO2 NDs structure, which provides a new perspective and experience for the design of similar catalysts.

Seebeck-voltage-triggered self-biased photoelectrochemical water splitting using HfOx/SiOx bi-layer protected Si photocathodes

The use of a photoelectrochemical device is an efficient method of converting solar energy into hydrogen fuel via water splitting reactions. One of the best photoelectrode materials is Si, which absorbs a broad wavelength range of incident light and produces a high photocurrent level (~44 mA·cm−2). However, the maximum photovoltage that can be generated in single-junction Si devices (~0.75 V) is much lower than the voltage required for a water splitting reaction (>1.6 V). In addition, the Si surface is electrochemically oxidized or reduced when it comes into direct contact with the aqueous electrolyte. Here, we propose the hybridization of the photoelectrochemical device with a thermoelectric device, where the Seebeck voltage generated by the thermal energy triggers the self-biased water splitting reaction without compromising the photocurrent level at 42 mA cm−2. In this hybrid device p-Si, where the surface is protected by HfOx/SiOx bilayers, is used as a photocathode. The HfOx exhibits high corrosion resistance and protection ability, thereby ensuring stability. On applying the Seebeck voltage, the tunneling barrier of HfOx is placed at a negligible energy level in the electron transfer from Si to the electrolyte, showing charge transfer kinetics independent of the HfOx thickness. These findings serve as a proof-of-concept of the stable and high-efficiency production of hydrogen fuel by the photoelectrochemical-thermoelectric hybrid devices.

Harnessing Solar Energy Through Photovoltaic System in Chandigarh: A Step Towards Preparing for Climate Change

Climate is rapidly changing with disruptive impacts. Without decisive action, energy-related greenhouse gas (GHG) emissions would lead to climate degradation. All types of energy efficiency technologies will require widespread deployment, as global warming is likely to reach 1.5°C between 2030 and 2052, if it continues to increase at the current rate. Photovoltaic (PV) energy is one of the most promising emerging technologies in mitigating the impact of climate change. PV is the name of a method of converting solar energy into direct current electricity. Therefore, the objectives of this article are to study the initiatives taken by energy development agencies in India for promoting renewable sources of energy, to study the use of solar power as a renewable source of energy through PV system and to analyse the solar PV rooftop system in Chandigarh as a case study. The article is an empirical study based on primary data. For the purpose of collecting the primary data, a structured questionnaire was prepared for citizens and an interview schedule for officials. The results of the study show that the majority of the citizens were satisfied with the solar photovoltaic (SPV) installations in Chandigarh, while a very few of them were dissatisfied and their dissatisfaction revolved around getting clearances from different departments.

Recent advances in visible light-driven water oxidation and reduction in suspension systems

Abstract In order to solve the shortage of sustainable energy and the related concern about combustion of fossil fuels, converting the most abundant solar energy into chemical fuels becomes one of the most promising choices to provide the everlasting and environmentally friendly energy vector along with the minimum impact on environment. Among the methods of converting solar energy into chemical fuels, there is a significant interest in the renewable hydrogen production by photocatalysts from abundant water under visible light irradiation. Therefore, the development of efficient photocatalysts for water reduction and oxidation in a suspension system is the footstone for the development of solar energy conversion. In this review, the fundamental theory of photocatalysis and key factors affecting photocatalysis will be introduced first. Then the new materials development covering inorganic materials (oxides, nitrides and sulfides), carbon-based photocatalysts, and semiconductor-coordination compound photocatalysts developed over the past 10 years will be addressed with discussion about dominating factors in the photochemical process. This review would provide a comprehensive reference to exploring the efficient and novel materials working for the solar energy conversion to affordable and sustainable fuels. Finally, the perspective of the technology is also discussed.

Selected methods of converting solar energy into electricity - comparative analysis

This article presents selected methods of converting solar energy into electricity: photovoltaic cells (PV), converters which use photon-enhanced thermionic emission (PETE), and near-field enhanced thermionic energy conversion systems (NETEC). PETE and NETEC systems are innovative solutions that use the thermionic emission phenomenon and can replace photovoltaic generation of electricity. We did a comparative analysis of such issues as: structure, principle of operation, working temperature and with particular emphasis - efficiency. A comparison of these parameters is shown in the graphs and summarized in the table. Based on the analysis, we have drawn conclusions about previous achievements and development perspectives in the field of converting methods.

Investigation into SrO/SrCO3 for high temperature thermochemical energy storage

Global energy needs are continuously increasing while fossil fuels remain an uncertain resource. With a growing population and increasing demand for energy, alternative energy is being pursued to power the future. Concentrated solar power (CSP) is a promising method of converting solar energy into electricity and works in conjunction with thermal energy storage (TES) to allow for power generation beyond on-sun hours. One method of TES is thermochemical energy storage (TCES), which is based on storing chemical energy via reversible reactions. An SrO/SrCO3 carbonation cycle offers high temperature heat (ca. 1200 °C), leading to higher efficiencies. The carbonation reaction was further investigated to determine the effects of particle size, temperature, partial pressure of CO2, and heat treatment temperature. Unfortunately, high temperatures cause materials to sinter, resulting in a decrease in reactivity over multiple cycles. The use of an inert diluent may help to inhibit sintering by acting as a physical barrier between the particles. Stored energy density of SrO/SrCO3 systems supported by CaSO4 and Sr3(PO4)2 was investigated for multiple cycles of 1150 °C exothermic carbonation followed by 1235 °C decomposition. At 25 and 50 wt%, Sr3(PO4), stable energy densities of roughly 500 ± 0.05 kJ/kg are achieved. In addition, it was found that the initial moisture content of the material affects performance of the material over several cycles due to a change in particle size. This behavior was thoroughly investigated and is useful for future work in TCES involving carbonation cycles.

Advances in Perovskite-Based Solar Cells

The increase in energy demand due to increase in population and reduction of fossil fuels has led to the search of alternative energy sources. Solar energy, which is an alternative source of energy, has been in the fore front of this research. Various methods of converting solar energy into electricity has been attained by silicon solar cells, thin film solar cells, dye sensitized solar cells and perovskite solar cells. Unlike dye sensitized solar cells, perovskite solar cells based on lead halide perovskite or organic-inorganic halide perovskite have had a significant impact on photovoltaic devices. A power conversion efficiency of approximately 20.1% has been attained by perovskite solar cells compared to organic solar cells. Also, several fabrication techniques, hole and electron transport materials have been developed for high performance. Although, some issues need to be addressed before commercialization is possible. Issues like stability of the cells under moisture and temperature. In this review, fundamental aspects of the perovskite device and recent breakthroughs are illustrated.

Realization of 2 Axes Solar Tracking System

In this Paper, method of converting solar energy into direct current electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon commonly studied in physics, photochemistry and electrochemistry. A photovoltaic system employs solar panels composed of a number of solar cells to supply usable solar power. Hence it is the challenge for the present generation to generate maximum electricity by using solar power although many developments were made to collect the solar energy. Hence solar tracking system has been implemented that plays a vital role in collecting the solar energy. The present invention consists of a 2 axes solar servo control tracking device that performs the remote servo control and remote monitoring of solar module assemblies without manual interference according to the solar azimuth that generates maximum electric power with single power transmission that improves the tracking accuracy, with minimum cost and can check the malfunctions to track the solar luminance. The efficiency of photo voltaic power generation can be improved by 15% to 18%.

(Invited) Investigation of the Si/TiO2/Electrolyte Interface Using Operando Tender X-ray Photoelectron Spectroscopy

Photoelectrochemical (PEC) cells based on semiconductor-liquid interfaces provide a method of converting solar energy to electricity or fuels 1-3. Recently, we have demonstrated operational systems that involved stabilized semiconductor-liquid junctions 4,5. We have employed operando ambient-pressure X-Ray photoelectron spectroscopy (AP-XPS) on these highly stable semiconductor-liquids junctions to directly characterize the semiconductor-liquid junction at room temperature under real-time electrochemical control 6,7. The escape depth of photoelectrons that originate from tender X-ray synchrotron radiation — 2.3 to 5.2 keV — allows for sampling of the sample simultaneously near the sample surface but through an electrolyte layer as the inelastic mean free path of such photoelectrons is on the order of 5 to 10 nanometers. Accordingly, tender X-ray AP-XPS has enabled simultaneous monitoring of the semiconductor surface, the semiconductor-electrolyte interface, and the bulk electrolyte of a PEC cell as a function of the applied potential, E. Accumulation, depletion and Fermi level pinning were observed. The observed shifts in the core level emission binding energies with respect to the applied potential directly revealed ohmic and rectifying junction behavior on metallized and semiconducting samples, respectively. 1. H. J. Lewerenz et al., Energ. Environ. Sci., 3, 748–760 (2010). 2. H. J. Lewerenz, in Photoelectrochemical Materials and Energy Conversion Processes, R. C. Alkire, D. M. Kolb, J. Lipkowski, and P. N. Ross, Editors, vol. 12, p. 61–181, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany (2010). 3. Z. Huang, C. Xiang, H. J. Lewerenz, and N. S. Lewis, Energ. Environ. Sci., 7, 1207–1211 (2014). 4. S. Hu et al., Science, 344, 1005–1009 (2014). 5. M. F. Lichterman et al., Energy Environ. Sci., 7, 3334–3337 (2014). 6. S. Axnanda et al., Meet. Abstr., MA2013-02, 921–921 (2013). 7. S. Axnanda et al., (2014), submitted.

Enhanced Charge Collection for Splitting of Water Enabled by an Engineered Three-Dimensional Nanospike Array

Photoelectrochemical (PEC) water splitting is a promising method of converting solar energy to hydrogen fuel from water using photocatalysts. Despite much effort in preparing mesoporous thin films on planar substrates, relatively little attention has been paid to their deposition on three-dimensional (3D) substrates, which could improve electron collection and enhance light-trapping. Here, we report the first synthesis of hierarchically branched anatase TiO2 nanotetrapods, achieved by dissolution and nucleation processes on a ZnO nanotetrapods template. When used as a photoanode for efficient PEC water splitting, the unique branched anatase TiO2 nanotetrapods yielded a photocurrent density of 0.54 mA cm–2 at applied potential of 0.35 V vs RHE, much higher than that of commercial TiO2 nanoparticles under otherwise identical conditions. Moreover, when the nanotetrapods were deposited on an ordered, purposely engineered 3D F-doped tin oxide (FTO) nanospike array, the photocurrent density was upgraded to 0.72 mA cm–2. This large photocurrent enhancement can be attributed to the ultrahigh contact surface area with the electrolyte, which is bequeathed by the hierarchically branched TiO2 nanotetrapods with a skin layer of vertically aligned ultrathin nanospines, as well as the short charge transport distance and enhanced light-trapping due to the peculiar 3D FTO nanospike array we have engineered by design.

SCIENTIFIC APPROACH TO RENEWABLE ENERGY THROUGH SOLAR CELLS

Renewable energy is increasingly viewed as critically important globally. Solar cells convert the energy of the sun into electricity. The method of converting solar energy to electricity is pollution free, and appears a good practical solution to the global energy problems. Energy policies have pushed for different technologies to decrease pollutant emissions and reduce global climate change. Photovoltaic technology, which utilizes sunlight to generate energy, is an attractive alternate energy source because it is renewable, harmless and domestically secure. Transparent conducting metal oxides, being n-type were used extensively in the production of heterojunction cells using p-type Cu 2 O . The long held consensus is that the best approach to improve cell efficiency in Cu 2 O -based photovoltaic devices is to achieve both p- and n-type Cu 2 O and thus p-n homojunction of Cu 2 O solar cells. Silicon, which, next to oxygen, is the most represented element in the earth's crust, is used for the production of monocrystalline silicon solar cells. Silicon is easily obtained and processed and it is not toxic and does not form compounds that would be environmentally harmful. In contemporary electronic industry silicon is the main semiconducting element. Thin-film cadmium telluride (CdTe) solar cells are the basis of a significant technology with major commercial impact on solar energy production. Polycrystalline thin-film solar cells such as CuInSe 2 (CIS), Cu (In, Ga) Se 2 (CIGS) and CdTe compound semiconductors are important for terrestrial applications because of their high efficiency, long-term stable performance and potential for low-cost production. Highest record efficiencies of 19.2% for CIGS and 16.5% for CdTe have been achieved.

Cobalt-dithiolene complexes for the photocatalytic and electrocatalytic reduction of protons in aqueous solutions

Artificial photosynthesis (AP) is a promising method of converting solar energy into fuel (H(2)). Harnessing solar energy to generate H(2) from H(+) is a crucial process in systems for artificial photosynthesis. Widespread application of a device for AP would rely on the use of platinum-free catalysts due to the scarcity of noble metals. Here we report a series of cobalt dithiolene complexes that are exceptionally active for the catalytic reduction of protons in aqueous solvent mixtures. All catalysts perform visible-light-driven reduction of protons from water when paired with Ru(bpy)(3)(2+) as the photosensitizer and ascorbic acid as the sacrificial donor. Photocatalysts with electron withdrawing groups exhibit the highest activity with turnovers up to 9,000 with respect to catalyst. The same complexes are also active electrocatalysts in 11 acetonitrile/water. The electrocatalytic mechanism is proposed to be ECEC, where the Co dithiolene catalysts undergo rapid protonation once they are reduced to CoL(2)(2-). Subsequent reduction and reaction with H(+) lead to H(2) formation. Cobalt dithiolene complexes thus represent a new group of active catalysts for the reduction of protons.

Organic ionic plastic crystal electrolytes; a new class of electrolyte for high efficiency solid state dye-sensitized solar cells

Dye-sensitized solar cells are an increasingly promising alternative to conventional silicon solar cells as a method of converting solar energy to electricity and thus providing an effectively inexhaustible energy source. However, the most efficient of these devices currently utilize liquid electrolytes, which suffer from the associated problems of leakage and evaporation. Hence, significant research is currently focused on the development of solid state alternatives. Here we report a new class of solid state electrolyte for these devices, organic ionic plastic crystal electrolytes, that allow relatively rapid diffusion of the redox couple through the matrix, which is critical to the cell performance. A range of different organic ionic plastic crystal materials, utilizing different cation and anion structures, have been investigated and the conductivities, diffusion rates and photovoltaic performance of the electrolytes are reported. The best material, utilizing the dicyanamide anion, achieves efficiencies of more than 5%.