Highlights of the characterization techniques on inorganic, organic (COF) and hybrid (MOF) photocatalytic semiconductors

Harnessing the energy of photons by photocatalytic semiconducting materials is a topic of paramount interest in the present era because of its sustainable eco-friendly impact. The harnessed energy by photocatalyst is intricately employed for a plethora of photocatalytic applications, such as pollutant remediation, energy conversion, organic transformations and many more. Hence, the global research community has focused their interest on the design and development of cost-effective and actively efficient photocatalytic semiconductors crafted to the needs of a desired photocatalytic process. In this regard, the stimulation of a broad range of characterization techniques becomes an imperative necessity to reveal various physico-chemical properties of the semiconductor photocatalyst. This review aims to summarize the sophisticated characterisation techniques that are used to analyse various organic, inorganic and hybrid type photocatalysts by qualitative and quantitative methods. In detail, this review is centred on the techniques utilised to contemplate, as well as correlate the physical structure, topography, chemical state, elemental composition, electrochemical properties and band structures of a wide range of photocatalysts. The discussion of each characterization method consists of a concise fundamental explanation, followed by proper exemplification intended to disseminate to materials chemists, predominantly individuals who are near the beginning of their careers focused on the development of competent photocatalysts. This review is dedicated to the brave COVID warriors fighting against the COVID-2019 pandemic.