Novel starch-mediated synthesis of Au/ZnO nanocrystals and their photocatalytic properties

Abstract

A novel solution-solid synthesis method for preparation of ZnO and Au/ZnO composite nanocrystals using starch matrix has been developed and optimized. The process is characterized by simplicity, environmental compatibility and good performance. Nanocomposite samples with different gold content have been synthesized and studied with respect to their structure, size and shape of nanocrystals, thermal behavior, surface characteristics and optical properties, as well as their photocatalytic activity. We have found that modification of nanocrystalline ZnO with gold nanocrystals strongly influences the porosity of nanocomposites -less micro-and mesopores are formed, which results in a reduced specific surface area. The synthesized ZnO and Au/ZnO nanocrystals are active photocatalysts for the photocatalytic degradation of methylene blue (MB), as a model pollutant dye, in the UV region. There is a decrease in photocatalytic activity with an increase of the gold content in the nanocomposite photocatalyst. The degree of MB degradation obtained with a pure ZnO sample is comparable to that with the Au/ ZnO photocatalyst with the lowest gold content 0.05 at. %. New and interesting result has been obtained relating to maximum specific (intrinsic) photocatalytic activity of 0.05 at. % Au/ZnO nanocrystals.

Evaluation of Au nanosphere content on ZnO nanoparticle surfaces as reusable and durable plasmonic nanocatalysts

“…Nevertheless, to date, only a few works evaluate stability, an important property for feasible applications. In order to identify the reach of our contributions, Table 2 shows the photocatalytic activity from recent works employing Au/ZnO and other nanocomposites based on ZnO as potential catalysts for wastewater remediation testing MB under UV light 24,40,41,49‐58 . As shown in the table, most of the excitation sources used by other researchers have higher power than the lamp used in this work; higher power lamps can accelerate photocatalytic mechanisms.…”

“…In order to identify the reach of our contributions, Table 2 shows the photocatalytic activity from recent works employing Au/ZnO and other nanocomposites based on ZnO as potential catalysts for wastewater remediation testing MB under UV light. 24,40,41,[49][50][51][52][53][54][55][56][57][58] As shown in the table, most of the excitation sources used by other researchers have higher power than the lamp used in this work; higher power lamps can accelerate photocatalytic mechanisms. Moreover, some works did not evaluate the photolysis (Np) that directly affects the % deg or K app reported.…”

“…This means that this MB solution is stable under UV irradiation, unlike those in other works that reported a considerable effect of UV light on MB (% deg > 5); 4,[36][37][38] these results could be due to the highpower lamps used during research. Other studies do not report photolysis effects in their MB degradation results; 12,19,25,[39][40][41][42] even when photolysis is measured, their reported degradation percentages are not reliable and comparison with other catalysts is not possible. On the other hand, the adsorption of MB onto ZnO and Au/ZnO surfaces was carried out as expected.…”

Polysaccharides and Metal Nanoparticles for Functional Textiles: A Review

“…In addition to its application in the production of traditional textiles, starch also has potential for the development of functional textiles, namely in functionalization with MNPs. In the green synthesis of MNPs, starch can act as a surface-capping agent; as a complexing agent to stabilize NPs, preventing their agglomeration; or as an assistant in heterogeneous nucleation [ 102 ]. Tahereh et al used starch as a capping agent in the in situ synthesis of ZnONPs on cotton fabrics.…”

A Study on Doping and Compound of Zinc Oxide Photocatalysts

“…Boyan Peychev et al [ 51 ] used a novel starch-based solid solution method to prepare zinc oxide and gold-doped zinc oxide and synthesized nano-composite samples with different gold content. It was found that the nano-zinc oxide modified with gold nanocrystals had a great effect on the porosity of the nanocomposites, and the nanocomposites formed fewer micropores and mesoporous pores as shown in Figure 6 , thus reducing the specific surface area, the photocatalytic activity decreases with the increase of gold content, and the photocatalytic activity was comparable to that of pure zinc oxide when the gold content is 0.05%.…”