The present study explored the effect of light intensity and spectral variation of the actinic light on the hydrophilic conversion of the surface of ZnO nanocoatings. The dependence on light intensity indicates that both formation and destruction of the surface hydrophilic states occurs in parallel. The proposed kinetic mechanism corresponds well with experimental dependences. The spectral dependence of the photoinduced hydrophilic conversion of the ZnO surface suggests the important role of electronic photoexcitation of the solid. Similarity between the spectral distributions of the efficiency of photoinduced hydrophilic conversion and the ratio between the surface concentrations of electrons and holes (estimated on the basis of the ratio between quantum yields of oxygen and methane photostimulated adsorption) infers that the reason for the hydrophilicity alteration is the surface charge redistribution caused by actinic light.

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