Understanding the role of ZnO nanosheet surface in photocatalytic dye degradation: The key to effective wastewater treatment

Abstract

The current study proposes an introduction of interfering ions to the reaction medium as a simple way for obtaining efficient visible-light driven photocatalysts with active surface based on ZnO nanosheets. 9 samples with different morphological and structural parameters were obtained via simple and inexpensive precipitation and hydrothermal methods. XRD, SEM, FTIR, SSA, XPS, Raman, absorption spectra and DLS methods were used for ZnO nanosheet characterisation. An original approach was used to determine the amount of defects by processing Raman spectra via software specially designed for this purpose. XPS was used to estimate an overall amount of oxygen vacancies in the samples, and the DFT method was employed to model oxygen vacancies in the crystal structure. The latter were verified via absorption spectra. The most effective sample showed a dye degradation efficiency of 94 % after 60 min of irradiating by a common LED lamp available in a local store. The kinetic studies showed that the rate of adsorption and photodegradation depends on the DFT-calculated “surface-dye” interaction energy. Consequently, by regulating the ratio of ZnO nanosheet surface parameters, adsorption and photodegradation efficiency against a particular dye can be improved.