Polyaniline-Grafted RuO2-TiO2 Heterostructure for the Catalysed Degradation of Methyl Orange in Darkness

Abstract

Massive industrial and agricultural developments have led to adverse effects of environmental pollution resisting conventional treatment processes. The issue can be addressed via heterogeneous photocatalysis as witnessed recently. Herein, we have developed novel metal/semi-conductor/polymer nanocomposite for the catalyzed degradation and mineralization of model organic dye pollutants in darkness. RuO2-TiO2 mixed oxide nanoparticles (NPs) were modified with diphenyl amino (DPA) groups from the 4-diphenylamine diazonium salt precursor. The latter was reduced with ascorbic acid to provide radicals that modified the NPs and further served for in situ synthesis of polyaniline (PANI) that resulted in RuO2/TiO2-DPA-PANI nanocomposite catalyst. Excellent adhesion of PANI to RuO2/TiO2-DPA was noted but not in the case of the bare mixed oxide. This stresses the central role of diazonium compounds to tether PANI to the underlying mixed oxide. RuO2-TiO2/DPA/PANI nanocomposite revealed superior catalytic properties in the degradation of Methyl Orange (MO) compared to RuO2-TiO2/PANI and RuO2-TiO2. Interestingly, it is active even in the darkness due to high PANI mass loading. In addition, PANI constitutes a protective layer of RuO2-TiO2 NPs that permitted us to reuse the RuO2-TiO2/DPA/PANI nanocomposite nine times, whereas RuO2-TiO2/PANI and RuO2-TiO2 were reused seven and five times only, respectively. The electronic displacements at the interface of the heterojunction metal/semi-conductor under visible light and the synergistic effects between PANI and RuO2 result in the separation of electron-hole pairs and a reduction of its recombination rate as well as a significant catalytic activity of RuO2-TiO2/DPA/PANI under simulated sunlight and in the dark, respectively.

Preparation, characterization, and morphology insight of ZnO nanodisk–TiO2‐coated SWCNT thin film composites for catalytic sensor application

“…The photocatalytic efficiency mainly depends on quick recombination rate of photo‐generated charge carrier in the hybrid‐modified TiO 2 composites 7–9 . The foreign component can capture the photo‐induced charge carriers and consequently enhances the interfacial charge‐transfer processes 7,10,11 . The pristine ZnO, TiO 2 , and ZnO/TiO 2 nanocomposite have been shown as improved visible light‐driven photocatalysis for phenolic, chlorophenol derivative compounds, 12–15 and salicylic‐acid degradation 16 .…”

“…[7][8][9] The foreign component can capture the photo-induced charge carriers and consequently enhances the interfacial charge-transfer processes. 7,10,11 The pristine ZnO, TiO 2 , and ZnO/TiO 2 nanocomposite have been shown as improved visible lightdriven photocatalysis for phenolic, chlorophenol derivative compounds, [12][13][14][15] and salicylic-acid degradation. 16 However, the above reports mainly considered the coupled ZnO/TiO 2 with a simple core-shell structure (coated surface) or randomly adhered particles (sandwich type).…”

Diazonium Modification of Inorganic and Organic Fillers for the Design of Robust Composites: A Review

“…The use of a large substituent affects the formation of a monolayer. [75,76] Covalent [77] Poly(styrene-co-acrylonitrile) Non-covalent [78] Poly(vinyl alcohol) Non-covalent [79] Poly(vinylidene fluoride) Non-covalent [80] Silica Phenol-formaldehyde resin Covalent [81,82] Ruthenium oxide / Titanium oxide Polyaniline Covalent [83] Titanium dioxide Polyaniline Covalent [84] Zeolite Phenol-formaldehyde resin Covalent [85,86] Methacrylic resin Covalent [87] 3 Diazonium Modified Fillers that Form Covalent Bonds with the Polymer…”

“…Composite was prepared by in situ oxidative polymerization of aniline on diazonium-modified ruthenium oxide/titanium oxide heterostructure [83]. Mixed oxide nanoparticles were modified with a 4-diphenylamine diazonium salt.…”

Visible light photodegradation of methyl orange and Escherichia coli O157:H7 in wastewater

“…7 Recent developments in nanotechnology have led to the use of carbon-based and metal oxide nanocomposites to remove organic compounds. 8,9 However, these techniques have high capital and maintenance costs, and produce secondary pollutants through the generation of sludge, while oxidation processes may produce metabolic products that pose public health risks. 10 Greener and more cost-effective methods such as dye solubilisation using natural surfactants or biosurfactants have been recently proposed.…”