Platinum nanoparticle-graphene quantum dot nanocage as a promising Schottky heterojunction electrocatalyst for electrochemical detection of vanillin in baby milk powder

Facile synthesis of platinum nanocrystal and its improvement in catalytic activity still face great challenges. The paper reports one strategy for synthesis of platinum nanoparticle-serine-functionalized and boron-doped graphene quantum dot composite (Pt-Ser-B-GQD). The Ser-B-GQD was prepared by pyrolysis of serine, boric acid and citric acid at 180 °C for 3 h and then reacted with chloroplatinic acid to form platiunm nanocrystal. The resultant Pt-Ser-B-GQD offers a nanocage-like structure composing of tiny graphene sheets connecting many ultrasmall platinum nanocrystals with an average particle size of 8.2 ± 0.32 nm. The combination of Pt nanocrystal with Ser-B-GQD results in the formation of Schottky heterojunction at the interface. The unique structure achieves to an improved catalytic activity. Pt-Ser-B-GQD was further used as Schottky heterojunction electrocatalyst for the construction of electrochemical sensor for the detection of vanillin. Because of excellent electrochemical properties, the sensor based on Pt-Ser-B-GQD exhibits a high sensitivity for electrochemical detection of vanillin. Differential pulse voltammetric peak current will increase linearly with increasing vanillin concentration in the range of 1 × 10−9-1 × 10−4 M with the detection limit of 2.8 × 10−10 Μ (S/N = 3). The proposed analytical method provides advantage of sensitivity, selectivity and reproducibility and was successfully applied in the detection of vanillin in baby milk powder.