Disclosed is a semiconductor-liquid junction based photoelectrochemical (PEC) cell for the unassisted solar splitting of water into hydrogen and oxygen gas, the solar-driven reduction of CO.sub.2 to higher-order hydrocarbons, and the solar-driven synthesis of NH.sub.3. The disclosed system can employ a photocathode based upon wurtzite hexagonal semiconductors that can be tailored with proper band alignment for the redox potentials for water, CO.sub.2 reduction, and NH.sub.3 production, and with bandgap energy for maximum solar absorption. The design maximizes the carrier collection efficiency by leveraging spontaneous and piezoelectric polarization in these materials systems to generate hot electrons within the photocathode. These electrons have sufficient excess energy, preserved at a designed energy capture region, to overcome the kinetic overpotential (surface chemistry limitation) required for the reactions to occur at a high rate.

The present disclosure relates to a composition that includes, in order: a first layer that includes MA.sub.w; a second layer that includes MO.sub.yA.sub.z; and a third layer that includes MO.sub.x, where M includes a transition metal, A includes at least one of sulfur, selenium, and/or tellurium, w is between greater than zero and less than or equal to five, x is between greater than zero and less than or equal to five, y is between greater than zero and less than or equal to five, and z is between greater than zero and less than or equal to five. In some embodiments of the present disclosure, the transition metal may include at least one of molybdenum and/or tungsten. In some embodiments of the present disclosure, A may be sulfur.

An aspect of the present disclosure is a photoelectrochemical device that includes a first cell that includes a first semiconductor alloy, a capping layer that includes a second semiconductor alloy, and a passivating layer that includes a third semiconductor alloy, where the passivating layer is positioned between the first cell and the capping layer, and at least a portion of the capping layer is configured to be in direct contact with an electrolyte.

An electronic device includes a substrate and at least two electrodes spaced by a nanogap, wherein the at least two electrodes are bridged by at least one nanoparticle and wherein the at least one nanoparticle has an overlap area with the at least two electrodes higher than 2% of the area of the at least one nanoparticle. A method of manufacturing the electronic device and the use of the electronic device in photodetector, transistor, phototransistor, optical modulator, electrical diode, photovoltaic cell or electroluminescent component are also described.

A photosynthesis apparatus includes a groove part formed in a semiconductor substrate; a first conductive type area formed on one side surface of the groove part; a second conductive type area formed on another side surface of the groove part; an oxidation electrode formed in contact with the first conductive type area on the one side surface; a reduction electrode formed in contact with the second conductive type area on the other side surface; and a proton diaphragm formed at a center part of the groove part. Water including carbon dioxide is supplied to the groove part, and light is radiated to the oxidation electrode or the reduction electrode to generate oxygen and a hydrogen ion from the water at the oxidation electrode, and the generated hydrogen ion penetrates the proton diaphragm and reacts with the carbon dioxide to generate formic acid at the reduction electrode.

A method for fabricating a film on a substrate and a method for controlling the heating rate of a plurality of nanoparticles to transform the plurality of nanoparticles into a plurality of nanorods and nano-cone structures includes the steps of providing a sol precursor, providing a substrate, depositing the sol precursor onto the substrate via a sol-gel technique, annealing the sol precursor under ambient pressure at a controlled heating rate, and cooling down the sol precursor to form a film.