Abstract: Photoelectrolysis of water by solar radiation to produce hydrogen is achieved using semiconducting thin film electrodes. The cell comprises (a) an electrode comprising at least one thin film semiconducting layer disposed on a substrate, each layer having a bandgap which ranges from about 1.3 to 4.0 eV; (b) a counter-electrode; (c) an electrolyte disposed between the thin film semiconducting electrode and the counter-electrode; (d) external bias means between the electrode for biasing the electrode with from 0 to about 1 V; and (e) means for collecting hydrogen produced.

Abstract: Cadmium stannate has been found to be useful as a window for solar heat absorbing systems in which advantage is taken of the unique optical properties of cadmium stannate. When cadmium stannate is in an electrically conductive state, having a conductivity of greater than 10.sup.3 ohm.sup..sup.-1 cm.sup..sup.-1, it becomes transparent to solar radiation and reflective of thermal infrared radiation. This enables the cadmium stannate to function as a window which allows passage of solar radiation through it and incident onto a black body, and at the same time serve as a reflector of thermal infrared radiation emitted from said body. This results in more efficient solar heat transfer to the solar heat collector provided with such a window.

Abstract: Cadmium stannate has been found to be useful as a window for solar heat absorbing systems in which advantage is taken of the unique optical properties of cadmium stannate. When cadmium stannate is in an electrically conductive state, having a conductivity of greater than 10.sup.3 ohm.sup.-.sup.1 cm.sup.-.sup.1, it becomes transparent to solar radiation and reflective of thermal infrared radiation. This enables the cadmium stannate to function as a window which allows passage of solar radiation through it and incident onto a black body, and at the same time serve as a reflector of thermal infrared radiation emitted from said body. This results in more efficient solar heat transfer to the solar heat collector provided with such a window.

Abstract: Cadmium stannate has been found to be useful as a window for solar heat absorbing systems in which advantage is taken of the unique optical properties of cadmium stannate. When cadmium stannate is in an electrically conductive state, having a conductivity of greater than 10.sup.3 ohm.sup..sup.-1 cm.sup..sup.-1 , it becomes transparent to solar radiation and reflective of thermal infrared radiation. This enables the cadmium stannate to function as a window which allows passage of solar radiation through it and incident onto a black body, and at the same time serve as a reflector of thermal infrared radiation emitted from said body. This results in more efficient solar heat transfer to the solar heat collector provided with such a window.