Bismuth Oxide Faceted Structures as a Photocatalyst Produced Using an Atmospheric Pressure Plasma Jet

Abstract

The photocatalyst bismuth oxide, which is active under visual light, was deposited using an atmospheric pressure plasma jet (APPJ). Sixteen different samples were generated under different parameters of the APPJ to investigate their catalytic activity. The prepared samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), laser scanning microscopy (LSM), and UV–vis diffuse reflectance absorption spectroscopy. The measured data, such as average sample thickness, coverage ratio, phase fraction, chemical composition, band gap, and photocatalytic performance were used for comparing the samples. The XRD analysis showed that the deposition process produced a mixed phase of monocline Bi2O3 and tetragonal Bi2O2.33. Using the Rietveld refinement method, phase fractions could be determined and compared with the XPS data. The non-stoichiometric phases were influenced by the introduction of nitrogen to the surface as a result of the deposition process. The band gap calculated from the diffuse absorption spectroscopy shows that Bi2O2.33 with 2.78 eV had a higher band gap compared to the phases with a high proportion of Bi2O3 (2.64 eV). Furthermore, it was shown that the band gap was dependent on the thickness of the sample and oxygen vacancies or loss of oxygen in the surface. All coatings had degraded methyl orange (MO) under irradiation by xenon lamps.

Gallium‐Based Liquid Metal Reaction Media for Interfacial Precipitation of Bismuth Nanomaterials with Controlled Phases and Morphologies

“…[ 20 ] The deconvolution of the O1s XPS region (Figure 4g) results in two peaks at 529.8 and 531.3 eV, respectively corresponding to the lattice oxygen and its shifted component due to an oxygen deficiency in the bismuth oxide. [ 20–21 ] In Figure 4h,i, the X‐ray diffraction (XRD) pattern and Raman spectrum of the expelled product reveals an alpha‐phase bismuth oxide (α‐Bi 2 O 3 ). The full indexed XRD pattern is available in Figure S4 (Supporting Information).…”

“…The former peak, corresponding to the lattice oxygen, exhibits a significant shift due to the increasing loss of oxygen (i.e., oxygen deficiency) in the bismuth oxide structure. [ 20–21 ] The peak at 532.2 eV corresponds to the physisorbed water or OH − species in the sample. [ 27 ] The Raman spectrum of the product from the expulsion process in 1.0 m KCl–0.10 m NaOH is presented in Figure 6f.…”

“…The XPS analysis of the sample, Figure 7d, shows two spin‐orbit components of Bi4f 7/2 (at 159.3 eV) and Bi4f 5/2 (164.6 eV) corresponding to Bi 3+ . [ 20–21 ] Another two small spin‐orbit components of Bi4f 7/2 (at 157 eV) and Bi4f 5/2 (162.3 eV) corresponding to bismuth metal are also observed. [ 31 ] The analysis of the O1s XPS spectrum, Figure 7e, shows two deconvoluted peaks at 530.9 and 532.2 eV.…”

“…The former peak, corresponding to the lattice oxygen, exhibits a significant shift due to the increasing loss of oxygen (i.e., oxygen deficiency) in the oxidized bismuth. [ 20–21 ] The peak at 532.2 eV corresponds to the physisorbed water or OH − species in the sample. [ 27 ] Since the XRD pattern in Figure 7f suggests a product of bismuth metal (rhombohedral lattice, space group R3m No.…”

Wood Protection through Plasma Powder Deposition—An Alternative Coating Process

“…To ensure that the metal oxide was present on the surface of the CSs, the CSs were manufactured in two stages-at first, a polyester layer was sprayed onto the wood samples, afterwards the metal or metal oxide was applied. The parameters used for the coating process refer to the layers described in Köhler et al [7,27] and are shown in Table 1. Before the coating process, the wood samples were conditioned at 20 • C/65% relative humidity (RH) until constant mass was reached, and the densities of European beech and pine sapwood were measured with a balance (Kern KB 360-3N, KERN & Sohn GmbH, Balingen, Germany)-the density is 690.1 kg/m 3 and 514.8 kg/m 3 , respectively.…”