Solar rechargeable battery combines the advantages of photoelectrochemical devices and batteries and has emerged as an attractive alternative to artificial photosynthesis for large-scale solar energy harvesting and storage. Due to the low photovoltages by the photoelectrodes, however, most previous demonstrations of unassisted photocharge have been realized on systems with low open circuit potentials (<0.8 V). In response to this critical challenge, here the present disclosure shows that the combined photovoltages exceeding 1.4 V can be obtained using a Ta.sub.3N.sub.5 nanotube photoanode and a GaN nanowire/Si photocathode with high photocurrents (>5 mA/cm.sup.2). The photoelectrode system makes it possible to operate a 1.2 V alkaline anthraquinone/ferrocyanide redox battery with a high ideal solar-to-chemical conversion efficiency of 3.0% without externally applied potentials. Importantly, the photocharged battery was successfully discharged with a high voltage output.

An energy conversion device for conversion of various energy forms into electricity. The energy forms may be chemical, photovoltaic or thermal gradients. The energy conversion device has a first and second electrode. A substrate is present that has a porous semiconductor or dielectric layer placed thereover. The substrate itself can be planar, two-dimensional, or three-dimensional, and possess internal and external surfaces. These substrates may be rigid, flexible and/or foldable. The porous semiconductor or dielectric layer can be a nano-engineered structure. A porous conductor material is placed on at least a portion of the porous semiconductor or dielectric layer such that at least some of the porous conductor material enters the nano-engineered structure of the porous semiconductor or dielectric layer, thereby forming an intertwining region.

An electrochemical direct heat to electricity converter includes a primary thermal energy source; a working fluid; an electrochemical cell comprising at least one membrane electrode assembly including a first porous electrode, a second porous electrode and at least one membrane, wherein the at least one membrane is sandwiched between the first and second porous electrodes and is a conductor of ions of the working fluid; an energy storage reservoir; and an external load. The electrochemical cell operates on heat to produce electricity. When thermal energy available from the primary thermal energy source is greater than necessary to meet demands of the external load, excess energy is stored in the energy storage reservoir, and when the thermal energy available from the primary thermal energy source is insufficient to meet the demands of the external load, at least a portion of the excess energy stored in the energy storage reservoir is used to supply power to the external load.

An electrochemical direct heat to electricity converter includes a primary thermal energy source; a working fluid; an electrochemical cell comprising at least one membrane electrode assembly including a first porous electrode, a second porous electrode and at least one membrane, wherein the at least one membrane is sandwiched between the first and second porous electrodes and is a conductor of ions of the working fluid; an energy storage reservoir; and an external load. The electrochemical cell operates on heat to produce electricity. When thermal energy available from the primary thermal energy source is greater than necessary to meet demands of the external load, excess energy is stored in the energy storage reservoir, and when the thermal energy available from the primary thermal energy source is insufficient to meet the demands of the external load, at least a portion of the excess energy stored in the energy storage reservoir is used to supply power to the external load.

An electrochemical direct heat to electricity converter includes a primary thermal energy source; a working fluid; an electrochemical cell comprising at least one membrane electrode assembly including a first porous electrode, a second porous electrode and at least one membrane, wherein the at least one membrane is sandwiched between the first and second porous electrodes and is a conductor of ions of the working fluid; an energy storage reservoir; and an external load. The electrochemical cell operates on heat to produce electricity. When thermal energy available from the primary thermal energy source is greater than necessary to meet demands of the external load, excess energy is stored in the energy storage reservoir, and when the thermal energy available from the primary thermal energy source is insufficient to meet the demands of the external load, at least a portion of the excess energy stored in the energy storage reservoir is used to supply power to the external load.

An energy conversion device for conversion of various energy forms into electricity. The energy forms may be chemical, photovoltaic or thermal gradients. The energy conversion device has a first and second electrode. A substrate is present that has a porous semiconductor or dielectric layer placed thereover. The substrate itself can be planar, two-dimensional, or three-dimensional, and possess internal and external surfaces. These substrates may be rigid, flexible and/or foldable. The porous semiconductor or dielectric layer can be a nano-engineered structure. A porous conductor material is placed on at least a portion of the porous semiconductor or dielectric layer such that at least some of the porous conductor material enters the nano-engineered structure of the porous semiconductor or dielectric layer, thereby forming an intertwining region.

The invention provides reversible bio sensitized photoelectric conversion and H.sub.2 to electricity conversion devices which use one or more of a proton pumping photoactive biological layers to generate a proton gradient that is harnessed to produce electrical energy. It is also provided a photoelectric conversion element that incorporates the device of the present invention

An intermediate structure unit for a secondary cell according to the present invention is the intermediate structure unit for a secondary cell having a secondary cell and a test structure unit on a common substrate. Each of the secondary cell and the test structure unit includes a first electrode layer and a second electrode layer. A plurality of layers are layered at the secondary cell between the first electrode layer and the second electrode layer. The plurality of layers include at least a metal oxide semiconductor layer and a charging layer. A party of the plurality of layers is formed at the test structure unit between the first electrode layer and the second electrode layer.

A method of preparing an electrode for use in a biophotovoltaic device, comprising the steps of: coating a self-assembled film on a substrate using Langmuir-Blodgett technique; and immersing the coated substrate into an microalgae culture, followed by incubating thereof to grow microalgae thereon hence obtaining a biofilm, characterised in that the self-assembled film is derived from graphene.

In one aspect, solar energy systems are described herein. In some embodiments, such a comprises an electrochemical cell comprising a photoelectrode, a counter electrode, and an ion transport membrane disposed between the photoelectrode and counter electrode. The cell further comprises a first electrolyte solution disposed in fluid communication with the photoelectrode and the membrane, and a second electrolyte solution disposed in fluid communication with the membrane and the counter electrode. The first and/or second electrolyte solution comprises a solvated redox pair. Additionally, the cell also comprises a storage electrode, a first external electrical connection between the photoelectrode and the counter electrode, and a second external electrical connection between the counter electrode and the storage electrode. Components of the system define a liquid junction photovoltaic cell under light conditions and a galvanic cell under dark conditions.