Self-Doped ZnO Microrods—High Temperature Stable Oxygen Deficient Platforms for Solar Photocatalysis

Abstract

Dopant free, solar active ZnO photocatalysts with oxygen vacancy richness were achieved by a solution processing strategy followed by calcination at various temperatures 300, 500, 700, 800, and 900 °C. All the ZnO nanocrystals possessed defective structures with copious surface oxygen vacancies directed toward notable visible light absorption around λ = 480 nm (band gap = 3.05−3.09 eV). The photocatalytic efficiencies of all ZnO samples were systematically examined under sunlight and UV illumination using methylene blue (MB) as a model system. ZnO calcined at 500 and 700 °C demonstrated microrod morphology with band gap energies of 3.08 and 3.09 eV respectively have shown the highest solar photocatalytic activity revealed the synergistic effect between oxygen vacancy and the rod morphology. ZnO calcined at 500 °C, having maximum surface oxygen vacancy sites degraded MB within 10 min whereas the commercial photocatalyst Degussa-P25 has taken 20 min under solar illumination.

Photocatalytic Water Oxidation on ZnO: A Review

“…The amount of oxygen vacancies was also influenced by the structure of the ZnO crystal, e.g., a greater amount of oxygen vacancies were observed at the surfaces of rod-structured ZnO [66]. Accordingly, the concentration and type of oxygen defects vary according to the synthesis technique and reaction parameters, e.g., choice of solvent [67], synthesis temperature [66], and pressure.…”

Construction of 2D‐ZnS@ZnO Z‐Scheme Heterostructured Nanosheets with a Highly Ordered ZnO Core and Disordered ZnS Shell for Enhancing Photocatalytic Hydrogen Evolution

“…However the photocatalytic efficiency of TiO 2 is low due to its low quantum efficiency. ZnO is a promising candidate to TiO 2 with similar physical and chemical properties, and ZnO exhibits a higher quantum efficiency compared to TiO 2 . However, the direct band gap ZnO with a large band gap of 3.2 eV and the conduction position of −0.31 eV at pH=7, compared with that of standard hydrogen electrode (SHE, −0.41 eV), hinder the production of photocatalytic H 2 .…”

“…ZnO is a promising candidate to TiO 2 with similar physical and chemical properties, [4][5]6] and ZnO exhibits a higher quantum efficiency compared to TiO 2 . [7,8] However, the direct band gap ZnO with a large band gap of 3.2 eV and the conduction position of À 0.31 eV at pH = 7, compared with that of standard hydrogen electrode (SHE, À 0.41 eV), hinder the production of photocatalytic H 2 . Besides, the ZnO exhibits poor stability in acidic or basic environments, which limits its applications.…”

Enhanced Thermocatalytic Activity of Porous Yellow ZnO Nanoflakes: Defect‐ and Morphology‐Induced Perspectives

“…However,v ery few chemical methods have been developed to produce stable oxygen-vacant ZnO systems. [19][20][21][22][23][24][25] The most popular method to achieves table yellow ZnO with adequate oxygen vacancy sites is the calcination of zinc peroxide( ZnO 2 ). [19][20][21] Later,X ue tal.…”