Probe‐Molecule‐Assisted NMR Spectroscopy: A Comparison with Photoluminescence and Electron Paramagnetic Resonance Spectroscopy as a Characterization Tool in Facet‐Specific Photocatalysis

Photoluminescence (PL) and EPR spectroscopy are the two most commonly used techniques to evaluate surface oxygen vacancies (V O surface ) on photoactive transition metal oxides. However, these techniques have shortcomings in the characterization of facet‐dependent catalysis. Here, we used the chemical adsorption of a 31 P‐containing probe molecule to obtain the distribution/concentration of V O surface as well as other surface features (hydroxyl groups) of ZnO by using 31 P magic‐angle spinning NMR spectroscopy. This facet‐specific technique not only makes cross‐literature comparison feasible but also provides more comprehensive information to lead to a further understanding of the photocatalytic mechanism.