Broadening the sunlight response region with carbon dot sensitized TiO2 as a support for a Pt catalyst in the methanol oxidation reaction

Abstract

TiO₂ is a celebrated photo-catalyst for methanol oxidation reaction (MOR). However, its modification is necessitated by a narrow light response region and swift recombination of electrons and holes. Incorporating carbon dots (CDs) with TiO₂ can broaden the light response range, while a composite of TiO₂ with Pt can significantly enhance the catalytic performance and also suppress the electron–hole recombination process. Herein, we report the structural, optical and electrochemical evaluation of a new photo-electrocatalyst – platinized TiO₂ sensitized by CDs – through a series of systematic studies. Reasonably, by combining both photo-catalytic and electro-catalytic mechanisms, the ternary composite catalyst (Pt/CD/TiO₂) under irradiation shows better performance in the MOR in terms of the forward peak current density value of 2.5 mA cm⁻², which exceeds that obtained without illumination by 24%. The performance enhancement can be attributed to the unique upconversion properties of CDs that allow the utilization of the visible solar range, which is otherwise restricted in case only TiO₂ is present.