NOVELTY - Particle, comprises a core containing a first electrically conducting or semiconducting material, and a shell containing a second dielectric or semiconducting material, where composition of second material is different from composition of first material. The core has a size of 100 nm to 100 mu m (preferably larger than 150 nm, more preferably larger than 1000 nm, especially smaller than 25 mu m, particularly smaller than 3 mu m). The shell has a thickness of 10-200 (preferably more than 30, especially more than 50) nm.    USE - As a photocatalyst, an anti-fogging material and a chemical agent capable of decomposing water, organic material such as acetaldehyde, soil, organic solvents, surfactants, agrochemicals, environmental pollutants and odors, and reducing compounds such as benzoic acid, carbon dioxide and nitrogen oxide (NOx). Also useful in a device such as a solar cell, in coating or thin film, security coating, and in a system for producing hydrogen; and for killing microbes (all claimed) in a wastewater apparatus, an air cleaning apparatus, and a sanitation device.    ADVANTAGE - The particles comprising the core and shell with different chemical compositions provide different physical and/or chemical characteristics, such as different electrical characteristics, different chemical activity or different stability; are easy to use, and have high effectiveness, high activities in various fields, relative non-toxicity, environmental friendliness, and stability in time and in various environments; show a strong activity in daylight, thus many applications are available in situations and places where daylight, without a need for some other source of radiation such as UV-light is available, that makes the operation extremely at low cost, as no or limited further energy is needed for such operations; exhibit good photoactivity, chemical activity, cleaning activity, and/or anti-microbiological activity; exhibit good coating physical unclonable functions, depends on the design of the electrode used in the application and distance between electrodes in the packaging; increase the lateral variety of effective dielectric constant over circuits, which gives a different effective dielectric constant depending on composition of core-shell and thickness of core and shell, respectively; and enhance the absorption rate and the absorption spectra such that a dye is applied on the surface of the particles. The method by using the particles provides solar cell that is cheaper and simpler than standard P-N junction type solar cells, and more efficient than colloidal photocatalyst and silicone solar cell; provides possibility to integrate several layered semiconductive materials to widen absorption spectra, by using less energy to produce the solar cell than a silicone solar cell (environmentally friendlier); and helps to purify water and/or air, where both pollutants are effectively removed and bacteria are killed.