Hydrothermal modification of zinc oxide and titanium dioxide for photocatalytic degradation of Rhodamine B

Wai, Kok Poh; Pang, Yean Ling; Lim, Steven; Koo, Chai Hoon; Chong, Woon Chan

doi:10.1063/1.5126541

Cited by 2 publications

(1 citation statement)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Among the MOXs investigated as heterogeneous photocatalysts, zinc oxide (ZnO) has exhibited favorable optical, electronic and surface properties, appearing as a promising candidate in the photocatalysis area due to its green and sustainable technology [14,[18][19][20][21][22][23]. Because of its unique characteristics, such as direct and wide band gap in the near-UV spectral region (E g = 3.2 eV, at 300 K), strong oxidation ability and a large free-exciton binding energy, ZnO has been considered a compelling choice for environmental waste management systems [19,[24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

The role of counter-ions in crystal morphology, surface structure and photocatalytic activity of ZnO crystals grown onto a substrate

Catto

Ferrer

Lopes

et al. 2020

Applied Surface Science

View full text Add to dashboard Cite

In this contribution, we present an experimental and theoretical investigation of the role of counter-ions in the crystal morphology, surface structure, and photocatalytic activity of hierarchical ZnO nanostructures. The effect of zinc precursor (nitrate, acetate and, sulfate) along the synthesis of ZnO nanostructures grown directly onto a substrate by means of a simple hydrothermal method was analyzed in detail. Scanning electron microscopy images showed a preferential growth of ZnO nanostructures along the caxis, with a slight reduction in the orientation depending on the choice of the Zn source. 2 Theoretical calculations based on Wulff theory allowed us a better understanding of the morphological changes and to directly relate the photocatalytic performance at the different exposed surfaces of the as-observed crystal shapes. Our results showed that photocatalytic activities in the discoloration of organic dyes became superior for hierarchical ZnO nanostructures obtained from zinc nitrate. This finding was explained by X-ray photoelectron and photoluminescence spectroscopies, which revealed that the presence of surface defects, as well as the attached counter-ions and the abundance of carboxylate groups and organic residuals on ZnO surfaces are determinant for enhanced photocatalytic performance.

show abstract