Electrooxidation of ethylene glycol using Ag-Pt nanotubes supported on silica: Correlating the unexpected O-vacancies creation with catalytic performance

Electrooxidation of small organic compounds is crucial in achieving clean and efficient energy production. In this context, ethylene glycol (EG) has attracted considerable interest due to its notable energy density, which is suitable for applications in direct alcohol fuel cells. In light of this, we prepared Ag-Pt nanotubes (Ag-PtNTs) supported on silica (SiO2) for the electrooxidation of this alcohol. However, our goal was not only to create an electrocatalyst that enhances electrooxidation efficiency but also to explore the interaction between the SiO2 and the nanotubes. Such an exploration aims to contest the prevailing perception of SiO2 as an inert and non-conductive material. Thus, comprehensive physicochemical characterization of the electrocatalyst was conducted, supported by density functional tight-binding (DFTB) calculations, to elucidate the correlation between composition, electronic effects, and catalytic performance, showing that Ag interacts more with the oxygen of SiO2 that Pt. The interaction between SiO2 and Ag-Pt NTs was explored through Mott-Schottky (M-S) analysis and electron paramagnetic resonance (EPR) spectroscopy, revealing the creation of oxygen vacancies (o-vacancies) and heterojunction formation, which enhance charge transfer and catalytic activity, both supported by theoretical calculations. In addition, mechanistic insights into the electrooxidation process were obtained through potential energy surface (PES) assessments, revealing a concerted pathway for glycolaldehyde formation with low barrier energy and favorable thermodynamics. Finally, the synthesized Ag-PtNTs/Si electrocatalyst exhibited an onset potential/current density of 0.45 V/0.09 mV mA cm−2 at 25 °C, demonstrating efficient electrooxidation capabilities. Therefore, this study provides valuable insights into designing efficient and stable electrocatalysts for alcohol electrooxidation, contributing to improving cleaner energy technologies. •Efficient ethylene glycol electrooxidation with Ag-Pt nanotubes onto SiO2.•Effective creation of oxygen vacancies and heterojunction formation.•DFTB calculation revealed the process of enhanced catalytic performance.•Concerted mechanism pathway for glycolaldehyde formation.