▎ 摘　　要

NOVELTY - Method for preparing nitrogen-doped carbon quantum dots, involves (a) drying vinegar residue, carbonizing dried vinegar residue in muffle furnace, and grinding carbonized product to carbonized vinegar residue powder, (b) uniformly mixing carbonized vinegar residue powder, nitrogen source and water to form mixture, placing obtained mixture in reaction kettle for hydrothermal reaction to obtain hydrothermal reaction product, and (c) filtering hydrothermal reaction product using filter paper with aperture of 100-500 nm to obtain nitrogen-doped carbon quantum dot solution, where the nitrogen-doped carbon quantum dot is in nitrogen-doped carbon quantum dot solution. USE - Method for preparing nitrogen-doped carbon quantum dots used in reduced graphene oxide used as catalyst for hydrogen evolution of electrolyzed water (all claimed). ADVANTAGE - The quantum dot has excellent catalytic performance and electrical conductivity, which reduces the over-potential in process of hydrogen production by electrolysis of water, catalyzes and accelerates the process of electrolysis of water, and improves the utilization rate of waste, and the reduced graphene oxide replaces the precious metal catalyst, reduces the preparation cost of catalyst, and realizes the large-scale production of hydrogen produced by electrolysis of water. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a nitrogen-doped carbon quantum dots prepared using above-mentioned method, where the particle size of nitrogen-doped carbon quantum dots is less than or equal to 10 nm; (2) a reduced graphene oxide loaded with above-mentioned nitrogen-doped carbon quantum dots; and (3) a method for preparing reduced graphene oxide, involving (i) uniformly mixing nitrogen-doped carbon quantum dot solution, graphene oxide and water, and ultrasonically treating to obtain mixed solution, (ii) freeze-drying mixed solution in cold dryer to obtain solid nitrogen-doped carbon quantum dot loaded graphene oxide, (iii) placing solid nitrogen-doped carbon quantum dot loaded graphene oxide in tubular furnace for high-temperature calcination to obtain reduced graphene oxide, where the reduced graphene oxide is loaded with nitrogen-doped carbon quantum dots.