The Polymerization Effect on Synthesis and Visible-Light Photocatalytic Properties of Low-Temperature β-BiNbO4 Using Nb-Citrate Precursor

Abstract

Low-temperature β-BiNbO4 powders (denoted as Low-β) were prepared by citrate and Pechini methods using homemade water-soluble niobium precursors. The addition of ethylene glycol and the resultant polymerization effect on the synthesis and visible-light photocatalytic performance of β-BiNbO4 powders were fully investigated. The polymerization effect is beneficial to lower the phase formation temperature and obtain smaller particle catalysts. Both methods can synthesize catalysts with excellent performance of visible-light degradation of methyl violet (MV). The Low-β BiNbO4 powder prepared by citrate method shows better degradation rate of about 1 h to decompose 80 % of MV and also displays good photocatalytic stability. The photodegradation of MV under the visible-light irradiation followed the pseudo-first-order kinetics according to the Langmuir-Hinshelwood model, and the obtained first-order rate constant and half-time are 2.85 × 10−2 min−1 and 24.3 min, respectively. The better photocatalytic performance of BiNbO4 powders prepared by citrate method can be attributed to its smaller band gap and better crystallinity.

Combined experimental and DFT approach to BiNbO4polymorphs

“…The estimated parameters for α-BNO (β-BNO) are a = 5.683 Å, b = 11.717 Å and c = 4.986 Å ( a = 7.619 Å, b = 5.540 Å and c = 7.933 Å) are in excellent agreement with that of standard values to be found in ref. 26 , 28 and 89 and confirms the phase purity of the as-synthesized samples. In the case of α-BNO, the Nb–O bond lengths d Nb–O in the corner sharing distorted NbO 6 octahedra vary from 1.879 to 2.206 Å, whereas the Bi–O bond lengths d Bi–O in the four-pyramidal structure reside within the range of 2.164 to 2.295 Å.…”

“…1. 13–15,17,23,27–29,38,40,48,80,85–89 Similarly, the XRD peaks at diffraction angles 23.94, 27.93, 28.24, 28.70, 29.62, 32.35, 36.98, 48.83 and 51.02° originating from (020), (102̄), (12̄0), (112̄), (120), (200), (022), (22̄2̄) and (14̄0) as per the JCPDS no. 71-1518 conform with the triclinic structure of β-BNO with the space group P 1̄(2).…”

Preparation and Photocatalytic Performance of Hollow Structure LiNb3O8 Photocatalysts

“…Niobates, mainly including three groups: alkali niobates, columbite niobates, and rare-earths orthoniobates, have been widely studied in many applications such as optical devices, solid electrolytic capacitors, dye-sensitized solar cells, and catalysis due to their interesting physical and chemical properties [ 2 – 4 ]. For the applications of clean energy and environmental remediation, some niobates, such as BiNbO 4 [ 5 , 6 ], LiNbO 3 [ 7 ], (Na, K)NbO 3 [ 8 ], and LiNb 3 O 8 [ 9 – 15 ], have been investigated due to their unique distorted [NbO6] octahedral structures which provide active sites for photocatalysis. Among these materials, LiNb 3 O 8 is considered as a novel lithium-ion battery (LIB) anode material with a large theoretical capacity of 389 mAh/g assuming two-electron transfers (Nb 5+ →Nb 3+ ) [ 10 , 11 ].…”

The Effects of Li/Nb Ratio on the Preparation and Photocatalytic Performance of Li-Nb-O Compounds

“…For environmental remediation and clean energy applications, niobates, such as (Na, K)NbO 3 [8], BiNbO 4 [9], LiNbO 3 [10], and LiNb 3 O 8 [11], have been deeply investigated, owing to their special distorted [NbO 6 ] octahedral structures which favor a possible delocalization of charge carriers [12]. Secondly, the conduction bands consisting of Nb4d orbitals located at a more negative state of redox potential of H+/H 2 promote the separation and transfer of photo-induced charge carriers and result in high photocatalytic activities [13].…”