The missing link in H2 electrolysis on Pt surfaces: water networks

Sluggish kinetics of hydrogen evolution and oxidation reactions (HER/HOR) of platinum (Pt) in alkaline media limit the application of hydrogen electrocatalysis.Using x-ray absorption spectroscopy and infrared spectroscopy we probed the structures of interfacial water near Pt surfaces under reaction conditions in alkaline media.Spectroscopy collected at the Pt surfaces revealed that the adsorption/desorption behaviors of hydrogen, hydroxyl, and water molecules change dramatically with different pH and ion compositions.Infrared spectroscopy further showed that the ratio of liquid-like interfacial water molecules is critical for HER/HOR kinetics.Ab initio molecular dynamics proved that the cation can affect the water dissociation kinetics by altering the structures of the hydrogen bond network at the interface and at the bulk electrolyte, respectively.