NOVELTY - A nanoparticle system comprises a copper oxide nanoparticle containing a core comprising crystalline cuprous oxide (Cu2O); and a shell of amorphous cupric oxide (CuO) present on at least a portion of the surface of the core; and a spacer, in which the copper oxide nanoparticle is dispersed or supported upon its surface.    USE - As catalyst for catalyzing a chemical reaction including oxidizing carbon monoxide to carbon dioxide; reducing nitrogen dioxide, nitric oxide or sulfur dioxide; oxidizing hydrocarbon; and coupling two aryl halides using Ullmann coupling (claimed), in the process to produce hydrogen as an energy source for use in fuel cells.    ADVANTAGE - The copper oxide nanoparticles can have a narrow size distribution. The nanocrystal size can be controlled by the temperature, time allowed for growth, and/or the subsequent addition of ligands. The method produces copper oxide nanoparticles identical in crystal structure and almost identical in size, which can be dispersed in solvents and transferred to other media relatively easily with minimal agglomeration on surfaces. The method of synthesizing copper oxide nanoparticles prior to impregnation allows one to create copper oxide nanoparticles of a specific and relatively uniform diameter, and then add them to the support material. The monodispersity of the copper oxide nanoparticles contributes to the preparation of a highly uniform and active catalyst over the support. The system employs the copper oxide nanoparticles, as a catalyst toward carbon monoxide oxidation at relatively low temperatures. The catalyst can convert monoxide oxidation contained within a gas stream that also contains oxygen. The presence of the support material extends the lifetime of the nanoparticles, by minimizing or diminishing the occurrence of sintering, which decreases the effective surface area. The nanoparticle system oxidizes CO to CO2 for over 144 hours with relatively little or no dependence on O2 concentration. The catalyst is a cost effective, highly efficient alternative to current CO oxidation systems, thus opening the doorway to several applications requiring cheap one-time use or short timeframe catalysts for oxidizing CO to CO2. Thus, the system provides a relatively inexpensive and effective method of using copper oxide nanoparticles, loaded onto a support material, as an exceptional catalyst toward CO oxidation at relatively low temperatures. Over sustained periods of time, conversions of 99.5% of CO to CO2 are routinely observed and the catalyst structure is retained during the reaction. Additionally, the catalysts possess relatively long lifetimes (up to 220 hours). The catalysts can work at a very high flow rate, averaging greater than 99.5% CO conversion at 80000 per hour and greater than 90% CO conversion at 150000 per hour over 120 hours. The catalysts oxidize over 70% of CO in a 65% hydrogen stream, leaving over 70% of the hydrogen alone.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a catalyst (C1) comprising a copper oxide nanoparticle containing a core having copper-cuprous oxide (Cu-Cu2O), and cupric oxide present on at least a portion of the surface of the core; optionally a surfactant present on at least a portion of the surface of the copper oxide nanoparticle; and a spacer in which the copper oxide nanoparticle is dispersed or supported upon its surface;    (2) a method (M1) for catalyzing a chemical reaction, involving contacting starting material of the chemical reaction with the catalyst (C1); and    (3) manufacturing (M2) catalyst involving contacting a spacer with a nanoparticle comprising a copper oxide nanoparticle containing a core having crystalline cuprous oxide and a shell of amorphous cupric oxide present on at least a portion of the surface of the core, and a ligand which coats the copper oxide nanoparticle to form a catalyst precursor; and drying the catalyst precursor to provide a dried catalyst precursor.    Claims 21-46 are missing from the parent specification. Abstract is based on available information.