Effect of coordination interaction between water and zinc on photochemistry property of Zn3(PO4)2·2H2O

Although widely existing in nature, crystal water compounds are still ignored by photochemistry scientists so far. In this work, we mainly investigated the influence of structure water on light absorption, charge transfer and photochemical property of Zn3(PO4)2·2H2O. The X-ray diffraction (XRD) results confirm the formation of phase-pure Zn3(PO4)2 and Zn3(PO4)2·2H2O, respectively; the ultraviolet–visible light diffuse reflectance spectra (UV-DRS) results show that although as a weak electron donor, the coordination of H2O with zinc(II) increases the electron density of zinc(II), and a ligand-to-metal charge transfer (LMCT) occurs from H2O to zinc(II), obviously increasing light absorption of Zn3(PO4)2·2H2O; the theory calculation demonstrates that structure water obviously contributes to the energy bands and electronic states; the electrochemical impedance spectroscopy (EIS) results illustrate that Zn3(PO4)2.2H2O has a higher electron transfer ability. This work suggests that crystal water chemicals could become a new category of photochemical materials, which may greatly enrich the photochemical science.