Monitoring oxygen production on mass-selected iridium–tantalum oxide electrocatalysts
Mass-selected IrTaOx nanoparticles below 2 nm deliver 2× higher mass activity and 4× higher turnover frequency than IrO₂ at 320 mV overpotential. EC-MS with isotope labelling quantifies active sites under dynamic conditions, while DFT points to special Ir coordination environments as the origin of the enhanced OER performance.