Pb 10 V 6 O 25 : A new lead vanadate with apatite structure

Vanadate Crystals with an Enhanced Birefringence and a Broadened Transparency Spectrum through Controlled [VO3]∞ Chain Arrangements and Alkali Metal Cation Introduction

The vanadate (VO) polyhedron offers a compelling avenue for exploring birefringent materials within the infrared frequency range. Among many potential building blocks, the implementation of [VO3]∞ chains demonstrated great potential as effective birefringent functional units. In this article, we successfully synthesized the Li0.8Na0.2CsV2O6·H2O compound, which exhibits a remarkable birefringence of 0.134 at 546.1 nm, as confirmed by the experiment. Notably, the introduction of alkali metals in this compound led to a significantly shorter cutoff edge at 340 nm. Through a comprehensive investigation, Li0.8Na0.2CsV2O6·H2O has the shortest UV cutoff edge among all vanadates, whose birefringences are larger than 0.1, to the best of our best knowledge. This finding underscores the application potential of this novel material as a birefringent crystal.

Exploring the Synthesis, Band Edge Insights, and Photoelectrochemical Water Splitting Properties of Lead Vanadates

Exploring the ideal and stable semiconductor material for the efficient photoelectrochemical (PEC) overall water splitting reaction has remained a major challenge. Herein, we develop a facile hydrothermal method for the fabrication of monoclinic Pb₃[VO₄]₂ and orthorhombic PbV₂O₆ thin films for the efficient and stable PEC overall water splitting applications. Detailed characterization was performed to study the crystal structure and optical, electrical, and electrochemical properties. The band edge positions of Pb₃[VO₄]₂ and PbV₂O₆ are determined using spectroscopic data, revealing the conduction band edge positioned near the water reduction potential [∼0 V vs reversible hydrogen electrode (RHE)] and the valence band edge positioned well above the water oxidation potential, indicating the possible utilization of photogenerated electrons and holes for efficient water reduction and oxidation, respectively. With the optimized PbV₂O₆ thin films, a maximum photocurrent of 0.35 mA cm^-2 was obtained at 1.23 V versus RHE and the stable production of both O₂ and H₂ is observed with >90% Faradaic efficiency. Importantly, this work demonstrates the possibility of utilizing lead vanadate materials for PEC water splitting applications.