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.

Disclosed is a hybrid electrochemical cell with a first conductor having at least one portion that is both a first capacitor electrode and a first battery electrode. The hybrid electrochemical cell further includes a second conductor having at least one portion that is a second capacitor electrode and at least one other portion that is a second battery electrode. An electrolyte is in contact with both the first conductor and the second conductor. In some embodiments, the hybrid electrochemical cell further includes a separator between the first conductor and the second conductor to prevent physical contact between the first conductor and the second conductor, while facilitating ion transport between the first conductor and the second conductor.

Disclosed is a hybrid electrochemical cell with a first conductor having at least one portion that is both a first capacitor electrode and a first battery electrode. The hybrid electrochemical cell further includes a second conductor having at least one portion that is a second capacitor electrode and at least one other portion that is a second battery electrode. An electrolyte is in contact with both the first conductor and the second conductor. In some embodiments, the hybrid electrochemical cell further includes a separator between the first conductor and the second conductor to prevent physical contact between the first conductor and the second conductor, while facilitating ion transport between the first conductor and the second conductor.

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 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 air-water concentration cell is provided as follows. A cathode electrode is formed of a first material for catalyzing an oxygen reduction reaction (ORR). An anode electrode is formed of a second material for catalyzing an oxygen evolution reaction (OER). A proton conductive membrane is interposed between the cathode electrode and the anode electrode. A fuel reservoir is interposed between the proton conductive membrane and the anode electrode. The fuel reservoir contains water. The water of the fuel reservoir is in contact with the anode electrode and the proton conductive membrane.

An air-water concentration cell is provided as follows. A cathode electrode is formed of a first material for catalyzing an oxygen reduction reaction (ORR). An anode electrode is formed of a second material for catalyzing an oxygen evolution reaction (OER). A proton conductive membrane is interposed between the cathode electrode and the anode electrode. A fuel reservoir is interposed between the proton conductive membrane and the anode electrode. The fuel reservoir contains water. The water of the fuel reservoir is in contact with the anode electrode and the proton conductive membrane.

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.

The present disclosure provides engineered photosynthetic cells and organisms, methods for engineering photosynthetic cells and organisms with increased extracellular electron transport, photo-bioelectrochemical cells (PBECs), anodes for a PBECs and/or photosynthetic microbial fuel cells (PMFCs), methods of generating an electrical current with PBECs, and methods and systems for generating H.sub.2 fuel.

The present disclosure provides engineered photosynthetic cells and organisms, methods for engineering photosynthetic cells and organisms with increased extracellular electron transport, photo-bioelectrochemical cells (PBECs), anodes for a PBECs and/or photosynthetic microbial fuel cells (PMFCs), methods of generating an electrical current with PBECs, and methods and systems for generating H.sub.2 fuel.