Assessing the role of sulfite in photoelectrocatalytic oxidation of glucose on Pt/TiO2 for hydrogen production

Abstract

• Highly dispersed electro-generated Pt-O bonds are activated by TiO 2 . • Electrochemical oxidation of Sulf-Glc occurs in approximately neutral media. • Sulf-Glc oxidation can be improved by electro-generated Pt-O bond sites. • Glc can be oxidized by photoelectro-generated highly oxidative intermediates. • Hydrogen production is remarkably promoted by enhanced Sulf-Glc oxidation. Sluggish oxygen evolution reactions always hinder water splitting for sustainable hydrogen production. Herein, the photoelectrocatalytic oxidation of sulfite (Sulf) and glucose (Glc) is used to promote the hydrogen generation by substituting the oxygen evolution reaction in approximately neutral media. The introduction of TiO 2 weakens the interaction between Pt particles, making the highly dispersed Pt particles (ca. 3 nm) assembled onto the TiO 2 surface. The as-prepared Pt/TiO 2 electrode exhibits more oxygen-active centers, leading to a negative shift of 0.11 V or 0.31 V in the half-peak oxidation potential of Sulf-Glc compared with that of Pt or TiO 2 alone, representing the Pt-O activation effect by Sulf. The electrochemical oxidation of Glc can be largely improved by Sulf and Pt/TiO 2 , showing a linear relationship of the oxidation peak current of Glc with the logarithm of concentration. The electro-generated intermediate species can be used to promote the oxidation of Glc in the three potential regions, including Pt-O sites, and SO 3 •− and SO 4 •− /•OH radicals. The photoelectrocatalytic oxidation of Sulf-Glc on Pt/TiO 2 causes a 518-fold increase in the hydrogen production rate controlled potentiostatically at 1.2 V ( vs . SCE) under approximately neutral conditions.