▎ 摘　　要

NOVELTY - Copper oxide nanoparticle comprises a hollow cube copper oxide nanocrystal, and a small cube copper oxide nanocrystal is wrapped in a hollow structure of the hollow cube copper oxide nanocrystal. USE - The copper oxide nanoparticles are used as carbon dioxide electroreduction catalysts (claimed) for electro-catalytic reduction of carbon dioxide as catalyst, carbon monoxide, methane, ethylene and formic acid. ADVANTAGE - The copper oxide nanoparticle of the structure greatly increases the specific surface area, so that it is especially suitable for electro-catalytic reduction of carbon dioxide, with excellent electro catalytic activity and ethylene selectivity. The method uses wet synthesis with convenient operation, the synthesis method is simple, the reaction condition is mild, and raw material is easy to obtain. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: a method for preparing copper oxide nanoparticle comprising synthesizing copper citrate as a precursor, further reducing, and leaving it in the air for 7-9 days to obtain the copper oxide nanoparticles; and a copper oxide electroreduction method comprising using the copper oxide nanoparticles prepared by the above-mentioned method as a catalyst to perform electroreduction of carbon dioxide.