A comprehensive review of zinc vanadate materials: from synthesis to multifunctional devices

Abstract

Zinc vanadates have recently attracted attention as highly tunable metal oxides where optical, electronic, magnetic, and electrochemical functionalities can be combined into one system. Although much literature can be found on various zinc vanadate phases and their properties in various applications, there is a lack of comprehensive knowledge connecting synthesis parameters, structural features, defect generation, and functional properties. In this work, a systematic survey of zinc vanadate phases orthorhombic, monoclinic, tetragonal, and spinel is carried out, and the role of synthetic methods, namely solid-state, combustion, sol-gel, coprecipitation, and hydrothermal approaches, in controlling phase purity, morphology development, and defect formation is discussed in detail. Particular focus is made on oxygen defects, zinc defects, mixed valence V4+/V5+ ions, and surface defects. Mechanisms through which these defects affect charge transfer, ion migration, light harvesting, catalytic rates, and surface polarizability are considered. Structure-defect-functionality aspects are assessed in terms of potential application areas for zinc vanadates such as supercapacitors, lithium and zinc-ion batteries, photocatalysis, triboelectric nanogenerators, phosphor-based white LEDs, and optoelectronics. Perspectives regarding current limitations and future advances in the field, especially regarding large-scale synthesis, defect control, and interface engineering, are highlighted.