High-efficient synthesis of bright yellow carbon quantum dots catalyzed by SnO2 NPs

Highlights: • Bright yellow carbon quantum dots were synthesized by one-step solvothermal method. • The synthesis time was reduced much in 2 h at 180 °C by using SnO₂ NPs as a catalyst. • The absolute quantum yield for yellow carbon quantum dots reached 38%. Green-yellow carbon quantum dots (CDs-2) were synthesized using 2, 4, 6-trihydroxybenzoic acid as carbon source with SnO₂ nanoparticles (NPs) as a catalyst in one-step solvothermal method. The color of CDs-2 was tuned to be yellow (CDs-4) using m-phenylenediamine as both nitrogen source and a base. The pyrolysis of 2, 4, 6-trihydroxybenzoic acid and m-phenylenediamine was greatly catalyzed by SnO₂ NPs which were formed by hydrolysis of pentahydrate SnCl₄ with n-butylamine or m-phenylenediamine as a base in the one-step solvothermal reaction. The absolute fluorescence quantum yields for CDs-2 and CDs-4 were reached 15.2% and 38.0% respectively at 180 °C for 2 h. The emission intensity of CDs-4 was not observed to decline over 35 days in ethanol dilute solutions. The catalysis of SnO₂ NPs was further investigated and discussed.