Abstract: The invention discloses a tubular hydro-voltaic device configured to generate voltage and current. The device includes a tubular structure containing activated porous carbon of predetermined thickness and length. The tubular structure is placed in a reservoir of fluid whereby the contact between the tubular structure and fluid produces a capillary action of the fluid into the tubular structure forming an electric double layer at carbon particle-water interfaces of the activated porous carbon material leading to voltage and current generation. The voltage and current generated by the tubular hydro-voltaic device are a function of the thickness of the tubular structure, the length of the tubular structure, or a combination thereof. The device has potential to provide power at remote locations, as a device of size 50 mm length×10 mm diameter×1.5 mm thickness is capable of generating mA level currents at 0.85 V or more.

Abstract: The disclosure provides a solar evaporation substrate for recovering water from a solution. The substrate includes a porous support and an activated carbon-cement composite. The disclosure also provides a solar thermal evaporation apparatus based on a novel substrate. The apparatus includes an open tray, a solution, a solar evaporation substrate, an enclosure and a plurality of collectors. The disclosure further provides a method for preparing the substrate from activated carbon-cement composite coated porous support and that is used to heat the solution by harvesting solar energy. The apparatus and method is chemical free, cost effective and gives a high evaporation rate of 2.4 kg/m2 h under one-sun illumination with zero carbon footprint.