(Photo)catalyst characterization techniques: Adsorption isotherms and BET, SEM, FTIR, UV-Vis, photoluminescence, and electrochemical characterizations

This chapter reports on some characterization techniques that are commonly used for catalysts and photocatalysts. Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), UV-visible (UV-Vis), photoluminescence (PL), and electrochemical characterization techniques are presented with experimental details and actual case studies from literature are discussed. The chapter starts with adsorption phenomena on (photo)catalysis and adsorption isotherms are presented. Then BET analysis technique and its applications in (photo)catalysis are explained. Morphological properties (SEM), functional groups, and the interaction of substrate (and intermediates) with the catalyst under dark or under irradiation are discussed using the FTIR technique. The discussion moves on with estimation of band-gap energies and oxidation states of loaded or metal-doped catalysts (through UV-Vis), and to the identification of impurity/defects levels and the investigation of recombination mechanisms by PL. Finally, as electrochemical characterizations, linear sweep and cyclic voltammetry, chronoamperometry (photocurrent), electrochemical impedance spectroscopy, and Fermi level estimation are presented. Special attention is given to comparative assessment between catalysts and photocatalysts, for both powder and supported samples.