H 2 O 2 rejuvenation-mediated synthesis of stable mixed-morphology Ag 3 PO 4 photocatalysts

Abstract

Ag3PO4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag3PO4 photo-corrodes if electron accepter such as AgNO3 is not used as scavenger. Synthesis of efficient Ag3PO4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag3PO4, whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB), Methyl orange (MO) and Rhodamine B (RhB) organic dyes for degradation tests. Approximately, 19 % of Ag3PO4 is converted to Ag0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag3PO4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H2O2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag3PO4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA). Surprisingly, the as- regenerated Ag3PO4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO2, and some of TiO2 composites tested in this work.

Peroxide route to the synthesis of ultrafine CeO2-Fe2O3 nanocomposite via successive ionic layer deposition

“…Since the results of a simultaneous thermal analysis demonstrate the presence of an effect associated with the decomposition of cerium hydroxo-peroxide at 397 °C [37, 38] according to Eq. (4), it may be supposed that the compound remains in the sample after synthesis, and that the process of its decomposition in solution III occurs predominantly on the surface of the particles due to diffusion limitations preventing its occurrence in the nanoparticles bulk, as was shown, for example, in [39]. Besides, based on the mass losses in the processes of am-CeO(OOH)2 and am-CeO(OH)2 decomposition (Fig.…”

Synthesis of nanostructured cupric oxide for visible light assisted degradation of organic wastewater pollutants

“…As noted earlier, exposing the dyes to the photocatalytic system leads to their degradation by the action of ROS and in particular, hydroxyl radicals (•OH − ). However, while CuO nanoparticles exhibited excellent degradation, it does not mean complete mineralization of dyes into inorganic CO 2 and H 2 O occurred (Agbe et al, 2018). The percentage of the residual dye was determined using Equation 9 taking into account the fact that the change in the amount of dye (concentration) with time is directly proportional to the change in absorbance as appeared in Equation 10.…”

“…Nanostructured semiconducting materials have over the years inspired intensive research activities for several applications because of their unique characteristics such as their high surface-tovolume ratio, and quantum confinement effects at the nanometre scale. As industrialization rapidly evolves, substantial quantity of waste keeps being discharged into the environment which tends to negatively affect the quality of water for everyday use (Agbe et al, 2018;Dodoo-Arhin et al, 2018;Omaish et al, 2015). Organic dyes (Azo and Xanthene) have a wide variety of applications in numerous industries such as the paper and pulp, edible confectionaries, and leather tanning industries.…”

“…With the textile industry having about 60-70% usage of all available commercial dye products (Saggioro et al, 2011), the dye pollutants from these industries tend to contaminate the environment especially water bodies; when they are indecorously disposed-of (Habib et al, 2013;Rahman et al, 2014;Rezig & Hadjel, 2014). Furthermore, recent advances in environmental remediation strategies such as photocatalysis and flocculation have been researched as an alternative technique for purification of dye-polluted water (Agbe et al, 2018;Diko et al, 2020). Photocatalysis using porous nanostructured semiconducting transition metal oxide photocatalysts such as TiO 2 , SnO (Byberg et al, 2013), ZnO and Cu 2 O (Agbe et al, 2019) seem to be the most suitable approach due to the fact that these photocatalysts are energetically sustainable, and can be easily used in combination with other catalysts.…”

Ag3PO4-Red Banyan Fruit Extract (Ficus benjamina. L) Nanocomposite for Degradation of Detergent Waste

“…With a deteriorating environment and a growing energy crisis worldwide, semiconductor photocatalysts have attracted widespread attention for potential applications such as degradation of organic pollutants, decomposition of H 2 O to H 2 , and CO 2 photoreduction (Li, 2017). Photocatalysis is a promising technology that can be used as an important toolkit for overcoming the global energy crisis and overcoming many environmental problems (Agbe, 2018). Photocatalyst material has long been used in various fields both in daily life or industry today.…”