Band gap engineering of tungsten oxide-based nanomaterials

Abstract

A band gap energy, a fundamental property of semiconductors, governs both their electrical and optical behaviors. When aiming to utilize semiconductors with tailored physical properties for specific applications, such as optoelectronic or photovoltaic devices, or as photoelectrodes in photoelectrochemical cells, there is often a need to adjust the energy band gap of the semiconductor. In this review, we have provided a comprehensive overview of various techniques employed for band gap determination. Noteworthy methods include UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) using the Tauc method, photoelectrochemical spectroscopy with external quantum efficiency measurements, spectroscopic ellipsometry (SE), photoluminescence (PL) spectroscopy, and photoacoustic (PA) spectroscopy. This article also offers an overview of extensive investigations undertaken to develop and characterize WO₃-based nanomaterials with enhanced photoactive properties. Our exploration specifically delved into WO₃ nanomaterials doped with various elements, encompassing alkali metals, nonmetals, transition metals, noble metals, and lanthanides. The scrutiny involved a meticulous analysis of these nanomaterials, considering their morphology and properties, while taking into account the intricacies of the applied synthesis methods. Additionally, our focus extended to the determination of band gap values and the exploration of practical applications of these WO₃-based nanomaterials, aiming to provide a comprehensive understanding of how these materials can be employed in diverse technological domains, from photovoltaics to catalysis and beyond. The multifaceted nature of WO₃-based nanomaterials positions them as promising candidates for advanced applications, and our exploration seeks to contribute valuable insights into their potential functionalities and performance across various fields.