Crystalline metallic Au nanoparticle-loaded α-Bi2O3 microrods for improved photocatalysis

Abstract

Crystalline metallic Au nanoparticles were loaded on α-Bi(2)O(3) microrods (Au/α-Bi(2)O(3)) using an Au deposition-precipitation method. The prepared samples were characterized by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Upon visible light irradiation, the Au/α-Bi(2)O(3) exhibits much higher photocatalytic activities than the pure α-Bi(2)O(3) for the degradation of Rhodamine B and 2,4-dichlorophenol in aqueous solution. The role of the Au and the paths of electron transport in the photocatalysis of the Au/α-Bi(2)O(3) were investigated and discussed in detail based on the analysis of the photo-generated hydroxyl radicals (˙OH) and hydrogen peroxide (H(2)O(2)) in the visible light irradiated suspension of pure α-Bi(2)O(3) and Au/α-Bi(2)O(3). The result reveals that the Au loaded on α-Bi(2)O(3) plays a critical role in the separation of the electron and hole pairs by accumulating the electrons from the excited α-Bi(2)O(3), which is responsible for the enhanced photocatalytic activity.

Preparation of Au-Bi2O3Nanocomposite by Anodic Electrodeposition Combined with Galvanic Replacement

“…This trend is attributable to enhanced light absorption through the surface plasmon resonance of Au although no special surface plasmon peak was noticed. 5,7,17 The energy band gaps (E g ) of the Bi 2 O 3 and AuBi 2 O 3 samples can be obtained from the diffuse reflectance data after Kubelka-Munk transformation and using a Tauc plot. 18 For this, the reflectance was converted to F(R) according to the Kubelka-Munk equation:…”

“…In one such study Bi 2 O 3 microrods were prepared by hydrolysis and Au was loaded by a deposition-precipitation technique. 7 This study revealed that Au loaded on Bi 2 O 3 (Au-Bi 2 O 3 ) plays a critical role in the separation of photoinduced charge carriers, and for the enhanced photocatalytic activity. 7 In another study, Au-Bi 2 O 3 was prepared by a precipitation-microwave irradiation technique followed by Au loading using aqueous HAuCl 4 solution at 80…”

Sunlight induced formation of surface Bi2O4−–Bi2O3 nanocomposite during the photocatalytic mineralization of 2-chloro and 2-nitrophenol

“…It has been emphasized that depending upon the polymorph and the preparation methodology, the band gap of Bi 2 O 3 may vary from about 2.0 to 3.96 eV [23]. ␣-Bi 2 O 3 is an efficient photocatalyst due to its relatively smaller band gap, higher oxidation power of the valence band holes and non-toxic properties [24]. The intrinsic polarizability induced by the Bi 3+ 6s 2 lone pair of electrons favors the separation of photogenerated electron-hole pairs.…”

Photocatalytic activity of enlarged microrods of α-Bi2O3 produced using ethylenediamine-solvent

“…Their lengths (L) can reach 3-5 mm and the diameters (D) varied between 0.8 and 1 mm. This morphology-shape is typically obtained when the Bi 2 O 3 is precipitated with NaOH [8,13,16], where different NO 3 À /OH À molar ratio induce the growth of the α-Bi 2 O 3 as needle-like, plate-like, or in polyhedral shape [14]. On the other hand, replacing the OH À ions by EN-solvent, the α-Bi 2 O 3 materials prepared at low EN-solvent content (20 vol%) exhibited heterogeneous morphology of diverse shape and particle size, observing sheets, needles and rods-like morphology in nanosized and microsized regimes (Fig.…”

“…Different nanostructures (nanoparticles, nanorods or nanowires) of α-Bi 2 O 3 have been prepared by different methods like: femtosecond pulsed laser ablation in liquids [7], simple one pot sol-gel method [4], free sonochemical process [8], via a catalysts-driven vapor transport method [9], by using g-C 3 N 4 as a template [10] and so on. Specifically, α-Bi 2 O 3 microrods, sometimes mistakenly called as nanorods, have been obtained by a microwave method [11,12] and by a simple chemical precipitation method using inorganic precipitating agents (NaOH, KOH, NH 4 OH) [13][14][15][16][17][18][19], but in most of these cases, the microrods are thermally treated at temperatures about 450-550°C. Using this chemical precipitation method, different molar ratios of HNO 3 /precipitating-agent lead to variations in the pH solution influencing the crystalline structure, the phase composition, the crystal growth Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ceramint and the morphology; needle, plate-like or polyhedral shape of the final Bi 2 O 3 can be obtained [12][13][14].…”