Synthesis and characterization of ZnZr composites for the photocatalytic degradation of phenolic molecules: addition effect of ZrO₂ over hydrozincite Zn₅(OH)₆(CO₃)₂

Abstract

BACKGROUND: The composite materials ZrO 2 /Zn 5 (OH) 6 (CO 3 ) 2 were prepared in only one step by chemical co-precipitation and thermal hydrolysis of urea. ZrO 2 was added at 5, 8 and 10 mol%. The samples were dried at 80 ∘ C and characterized by adsorption-desorption of N 2 isotherms, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, and diffuse reflectance (DRS), UV-visible, Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies. The materials were assessed in the photodegradation of phenol and polychlorinated phenolic molecules under UV-light irradiation. The possible mechanism was discussed from studies that corroborated or discarded the formation of the species •OH, •O 2 − and h + .RESULTS: The addition of ZrO 2 to Zn 5 (OH) 6 (CO 3 ) 2 resulted in a composite material with high photoactivity. The material containing 8 mol% of ZrO 2 (ZnZr-8.0%) was the sample with the best percentages of photodegradation and mineralization. The photodegradation enhancement was achieved partly by an increment in the specific surface area and principally due to localized states originating in the composite interphase which improved charge transfer. XPS study revealed that the ZrO 2 addition increases the oxygen vacancies which enhanced the organic molecule photodegradation via direct hole attack. CONCLUSION: The ZnZr composite system constitutes an excellent alternative for the photodegradation of persistent organic pollutants due to the low cost, high stability and null toxicity of the support Zn 5 (OH) 6 (CO 3 ) 2 .

Visible-Light-Responsive Photocatalytic Activity Significantly Enhanced by Active [VZn+VO+] Defects in Self-Assembled ZnO Nanoparticles

“…108 However, the component situated at a relatively lower binding energy of 531.6 eV is attributed to the oxygen-deficient regions (oxygen vacancies) within the ZnO nanoparticle surface, which resulted from the loss of the C−OH into CO groups. 109 Finally, the intensity of the relevant carbonate component was entirely suppressed by the Zn 2p 3/2 spectrum (Figure 4f). The lone peak slightly shifted to higher binding energy (1022.8 eV) is related to the Zn 2+ in the wurtzite ZnO structure.…”

“…In addition, the component at 530.6 eV defines the oxygen atoms as being in a fully oxidized stoichiometric neighborhood in the ZnO crystal lattice forming the Zn–O bonds . However, the component situated at a relatively lower binding energy of 531.6 eV is attributed to the oxygen-deficient regions (oxygen vacancies) within the ZnO nanoparticle surface, which resulted from the loss of the C–OH into CO groups . Finally, the intensity of the relevant carbonate component was entirely suppressed by the Zn 2p 3/2 spectrum (Figure f).…”

In focus: materials and the environment symposium (XXVII IMRC México)

“…In this In Focus edition of the Materials and the Environment Symposium , 11 articles were selected for publication among all the amazing work that was presented during this event. This In Focus includes articles on the production of photocatalysts for the degradation of pollutants such as herbicides, as well as the use of sugar cane bagasse and coal fly ash for the production of adsorbent materials, and the production of materials with enhanced water adsorption for agricultural applications.…”

Efecto de la adición de carbonato de bismuto en óxido de zirconio en el proceso de producción de hidrógeno vía fotocatalítica

“…También se puede observar que la adición de Bi2O2(CO3) aumenta la cantidad de vacancias de oxígeno presentes en el soporte de ZrO2. Por tanto, las vacancias de oxígeno podrían estar desempeñando un papel importante en la formación de estados localizados y como sitios de adsorción para moléculas donantes de electrones [53]. Además, Chang et al…”