▎ 摘　　要

NOVELTY - A nano-composite selenide comprises cobalt selenide and tin selenide forming agglomerate hollow nanostructure with porous outer wall coated with graphene layer. USE - Nano-composite selenide used for electrocatalysis. ADVANTAGE - The nano-composite selenide achieves remarkable results in the field of electrocatalysis, and has high specific surface area, more reaction sites, and unique conductive network. The method has easy availability of raw materials, simple process, low cost, and high yield. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the nano-composite selenide comprising dissolving soluble cobalt salt, sodium citrate and soluble tin in graphene oxide dispersion liquid, adding sodium hydroxide solution, centrifuging, washing, separating solid product, dissolving in pure water, adding sodium hydroxide solution, centrifuging, washing, separating second solid product, and drying.