Selected applications of operando Raman spectroscopy in electrocatalysis research

Knowledge-guided improvement of electrocatalytic materials is facilitated by insight in determinants of activity, selectivity, and stability. Catalyst re-construction, surface adsorbates and reaction intermediates, and the mechanistic role of the electrolyte can be addressed by operando (= in situ) Raman spectroscopy, where Raman scattering is detected during electrochemical operation. After outlining the basic experimental technology and addressing the light-damage problem, selected applications in electrocatalysis research are reviewed: (1) Redox-state changes of the catalyst material induced by electrode potentials are traced by operando Raman spectroscopy. (2) Surface-bound (adsorbed) educt, products and reaction intermediates are detected using surface-enhanced Raman spectroscopy (SERS). (3) Local-pH values are determined at the catalyst-electrolyte interface, with spatial resolution at the visible-light diffraction limit.