ZnO hierarchical structures with tunable oxygen vacancies for high performance in photocatalytic degradation of phenol

ZnO hierarchical structures were synthesized in a simple and low-cost way and displayed excellent photocatalytic performance. Different ZnO hierarchical structures with tunable oxygen vacancies (OVs) were hydrothermally synthesized with the assistance of sodium carboxymethyl cellulose (CMC) and their photocatalytic performance for phenol degradation under UV-visible light irradiation was investigated. OV-rich hollow ZnO hierarchical structures displayed excellent phenol degradation efficiency of 99.8%. The recycling test exhibited that the hollow ZnO had high photocatalytic sustainability (phenol degradation efficiency of 94.4% after 6 cycles). The high photocatalytic performance was attributed to the efficient separation and transfer of photoproduced electron-hole pairs that were realized by the synergistic effect of the abundant oxygen vacancy defects, favorable light absorption and scattering ability of the ZnO hollow structure. The photocatalytic mechanism was proposed that •OH is the dominant active radical, then h+ and •O2− are active radicals in the photocatalytic process of phenol degradation.