Operando Attenuated Total Reflection Fourier-transform Infrared (ATR-FTIR) Spectroscopy for Water Splitting

Operando attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy is discussed in this paper for water splitting application. The first part of the paper focuses on the discussion of the opportunities and challenges of this method for the characterization of the solid-liquid interface in water splitting. The second part of the paper focuses on recent results and future perspectives: We present stable and robust operando ATR-FTIR measurements using low temperature processing of hematite and a set-up where the functional thin film is integrated on the ATR crystal. We find increased absorbance as a function of applied potential at wavenumbers of 1000 cm-1 to 900 cm-1 and relate this to changes in the surface species during water oxidation. We argue that this approach has the potential to be developed to a routine characterization method for the characterization of interfaces in water splitting. Such ATR-FTIR data is of crucial importance for the validation of models in microkinetic modeling. We show some recent results of microkinetic modeling of the hematite-electrolyte interface and explain how a combination of operando ATR-FTIR measurements and microkinetic modeling enables the identification of the reaction mechanism in water splitting. We discuss how this combined approach will enable designing of tailored catalysts and accelerating their development in the future.