Title : Gold digital video disc platform modified with graphitic carbon nitride decorated Au–Pt nanoparticles for electrochemical oxidation of methanol
Abstract:
Herein, for the first time, a novel disposable anodic catalyst based on a bilayer nanocomposite consisting of graphitic carbon nitride (g-C3N4) nanosheets and gold-platinum binary alloy nanoparticles (AuPtNPs) at the surface of a gold electrode derived from gold digital video disc (GDVD) was introduced for electrochemical oxidation of methanol. Graphitic carbon nitride nanosheets were synthesized through pyrolysis method, and they were employed as a substrate for the co-electrodeposition of Au–PtNPs. The morphology and structure of the synthesized g-C3N4 were characterized using scanning electron microscope and X-ray diffraction, and corresponding results showed the successful synthesis of g-C3N4. G-C3N4 nanosheets not only served as the signal amplifier but also, they provided a high electrical conductivity and large surface area for electrodeposition of Au-PtNPs. The change in the electrochemical behavior of the surface was investigated using cyclic voltammetry and chronoamperometry techniques. Moreover, SEM images illustrated the changes of the FTO surface in each modification step. The electrocatalytic activity of Au–Pt/g-C3N4/GDVD for methanol oxidation was evaluated, and an anodic peak current density of about 12.5 mA cm-2 was obtained at 0.7 V. The cyclic voltammetric measurements indicated that the Au–Pt/g-C3N4/GDVD has a higher electrocatalytic activity for the oxidation of methanol under the optimized experimental conditions in comparison with Pt/GDVD and Pt/g-C3N4/GDVD catalysts. In addition, the chronoamperometry studies showed that Au–Pt/g-C3N4/GDVD retains about 92% of its initial value after 50 consecutive scans which confirms the improved stability of Au–Pt/g-C3N4/GDVD compared to the other studied catalysts. The values of the exchange current density (J0) calculated using Tafel equation were found to be: 1.19 × 10-6, 2.8 × 10-6 and 4.01 × 10-6 mA cm-2 for the Pt/GDVD, Pt/g-C3N4/GDVD and Au–Pt/g-C3N4/GDVD catalysts, respectively. These values revealed that the methanol oxidation reaction is less limited kinetically in the presence of Au–Pt/g-C3N4/GDVD. The better electrocatalytic activity of Au–Pt/g-C3N4/GDVD can be attributed to the uniform deposition of Au and Pt nanoparticles at the surface of g-C3N4 nanosheets, and the synergistic effects between these components.
