A trick before the split
With the aim of finding the elusive oxygen evolution reaction (OER), Geiger’s team used an iron-rich mineral known as hematite as an electrode. Geiger’s lab fabricated a water-PR-SHG technique that let them observe the water molecules’ dynamics over the electrode’s surface.
There is a cost to achieving the oxygen flips. The energy expenditure required for the rearrangement of water molecules was calculated, and it turned out to be almost equal to the energy-binding water as a liquid.
“These electrodes are negatively charged, so the water molecule wants to put its positively charged hydrogen atoms toward the electrode’s surface,” Geiger said. “In that position, electron transfer — from water’s oxygen atoms to the electrode’s active site — is blocked.”