Organic Compounds Improving the HER/HOR Kinetics of Pt in Alkaline By Reorienting Interfacial Water
Abstract
Hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) are fundamentally and practically important in electrochemistry. However, the sluggish kinetics of HER/HOR in alkaline solution remains ambiguous and has been under extensive debate1. Most recently, Snyder’s and Tang’s groups2 reported that caffeine can significantly enhance both the HER and HOR kinetics of all Pt surfaces in alkaline solutions. However, the underlying mechanism for the caffeine-induced HER/HOR improvement of Pt in alkaline remains unexplained. In this work, we tend to resolve this puzzle by modulating the HER/HOR kinetics of Pt in alkaline by adding a variety of organic compounds in alkaline solutions, and probing how these organic compounds react with the Pt surface and tune the interfacial environment via advanced electrochemical characterizations and in situ spectroscopic techniques. We found that the organic compounds are non-specifically adsorbed on the Pt surface during the HER/HOR, and thus their induced HER/HOR improvement of Pt in alkaline cannot be accounted for by the hydrogen binding energy theory and bifunctional mechanism. We alternatively argue that the organic compounds improve the HER/HOR kinetics of Pt in alkaline by reorienting the interfacial water to facilitate the Volmer step, which refines our previous argument that interfacial water improves the HER/HOR kinetics of Pt via shuffling the reaction intermediates such as Had and OHad throughout the interface3.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 30, 2021
- Source ID
- 10.1149/ma2021-01461862mtgabs
Entities
People
- Qiang Sun
- Qingying Jia
- Sanjeev Mukerjee