Switchable molecular electrocatalysis
Shifali Dutt, Alagar Raja Kottaichamy, Neethu Christudas Dargily, Sanchayita Mukhopadhyay, Bhojkumar Nayak, Mruthyunjayachari Chattanhali Devendrachari, Chatakudhath Prabakaran Vinod, Harish Makri Nimbegondi Kotresh, Musthafa Ottakam Thotiyl
Abstract
We demonstrate a switchable electrocatalysis mechanism modulated by hydrogen bonding interactions in ligand geometries. By manipulating these geometries, specific electrochemical processes at a single catalytic site can be selectively and precisely activated or deactivated. The α geometry enhances dioxygen electroreduction (ORR) while inhibiting protium redox processes, with the opposite effect seen in the β geometry. Intramolecular hydrogen bonding in the α geometry boosts electron density at the catalytic center, facilitating a shift of ORR to a 4-electron pathway. Conversely, the β geometry promotes a 2-electron ORR and facilitates electrocatalytic hydrogen evolution through an extensive proton charge assembly; offering a paradigm shift to conventional electrocatalytic principles. The expectations that ligand geometry induced electron density modulations in the catalytic metal centre would have a comparable impact on both ORR and HER has been questioned due to the contrasting reactivity exhibited by α-geometry and β-geometry molecules. This further emphasizes the complex and intriguing nature of the roles played by ligands in molecular electrocatalysis.