S = 1/2 Chain in BiVO₃F: Spin Dimers versus Photoanodic Properties

Abstract

BiVO3F was prepared, characterized and identified as the unique example of bismuth vanadyl oxyhalide with paramagnetic V 4+ centres. Its crystal structure shows 1D magnetic units with rare alternation of edge sharing O-O and F-F µ2 bridges along the octahedral chains. Structural pairing across the O2 edges induces antiferromagnetic spin dimers(S=0) with J/Kb300K, ⁓15 times greater than the exchange across the F2 bridges, within a non-ordered magnetic ground state. Despite multiple compositional, structural, and electronic analogies with the BiVO4 scheelite compound, one of the most promising photo-anode for solar water splitting, the photo activity of BiVO3F is relatively modest, partially due to this electronic pairing playing for fast electron-hole recombination. Similar to monoclinic-VO2, the V 4+ spin dimerization plays against the singlet → triplet electronic photo-excitation, but brings potential carrier lifetime benefits. The reduction of the bandgap from Eg 2.4 eV to 1.7 eV after incorporation of d 1 cations in BiVO4 makes BiVO3F an inspiring compound for local modifications toward an enhanced photo-active material. The direct d → d transition provides a significant enhancement of the visible light capture section, and opens a prospective route for the chemical design of performant photoanodes with a mixed anionic sublattice.

Photocatalytic and Photocurrent Responses to Visible Light of the Lone-Pair-Based Oxysulfide Sr6Cd2Sb6S10O7

“…The cell used allows standardized illumination over 1 cm 2 of the rear face of the working electrode. The working electrode was made using the drop-casting technique . For this, the photocatalyst was dispersed in polyvinylidene fluoride (PVDF) binder (with a 2:1 ratio) and then deposited evenly on a ITO/glass substrate (Delta Technologies, Ltd).…”

“…The working electrode was made using the drop-casting technique. 37 For this, the photocatalyst was dispersed in polyvinylidene fluoride (PVDF) binder (with a 2:1 ratio) and then deposited evenly on a ITO/glass substrate (Delta Technologies, Ltd). The electrolyte employed is an aqueous 0.1 M Na 2 SO 4 solution.…”

Two-dimensional ultra-thin nanosheets optimize the surface reaction dynamics and photo/pyro-generated carrier transfer of NaNbO3 for an efficient pyro-photo-electric catalytic system

“…Therefore, the research and development of semiconductor materials has become a research hotspot. At present, researchers have developed many semiconductor materials, such as α-Fe 2 O 3 , 15,16 BiVO 4 , 17–20 WO 3 , 21,22 ZnO, 23 and CdS, 24,25 to achieve efficient hydrogen production. However, wide band gap semiconductors can only capture about 4% of ultraviolet light because of their narrow optical response range.…”

Synthesis of Fluoride-Substituted Layered Perovskites ZnMoO4 with an Enhanced Photocatalytic Activity

“…2.4 and 3.0 eV, respectively) and therefore shown visible light-driven photocatalytic activities. , This is due to the short Pb–O bond leading a strong interaction between Pb-6s and O-2p orbitals, which results in high VBM in the compounds. These works have greatly expanded the applications of fluoride-doped compounds, but the synthesis challenge still remains …”

“…These works have greatly expanded the applications of fluoride-doped compounds, but the synthesis challenge still remains. 14 The experimental conditions in the synthesis of oxyfluoride generally require high-temperature and/or high-pressure conditions. 15 Tsujimoto et al have synthesized Sr 2 NiO 3 F under the conditions of 6 GPa and 1500 °C using SrF 2 as a fluorine source.…”