Figure 1

The XRD patterns of diatomite substrate and the synthetic MgO/CaO NRs (A), the FT-IR spectra of diatomite substrate, diatomite loaded by MgO/CaO and the synthetic MgO/CaO NRs (B), the nitrogen adsorption/desorption isotherm curve of MgO/CaO NRs (C), the pore size distribution of MgO/CaO NRs (D), the UV–Vis spectra of CaO NRs and MgO/CaO NRs (E), and the estimated band gap energies of CaO NRs and MgO/CaO NRs (F)17.