**Abstract**

Perovskites possess an interesting crystal structure and its structural properties allow us to achieve various applications. Beside its ferroelectric, piezoelectric, magnetic, multiferroic, etc., properties, these branches of materials are also useful to develop materials for various environmental applications. As the population is increasing nowadays, different type of environmental pollution is one of the growing worries for society. The effort of researchers and scientists focuses on developing new materials to get rid of these individual issues. With modern advances in synthesis methods, including the preparation of perovskite nanocomposites, there is a growing interest in perovskite-type materials for environmental application. Basically, this chapter concludes with a few of the major issues in the recent environment: green energy (solar cell), fuel cell, sensors (gas and for biomedical), and remediation of heavy metals from industrial wastewater.

**Keywords:** perovskite, nanocomposite, fuel cell, sensors, solar cell, heavy metals, wastewater treatment

#### **1. Introduction**

Perovskites possess a very interesting crystal structure; are basically a combination of three basic crystal structures (simple cubic structure, body center cubic structure, and face-centered cubic structure). The extraordinary range of structure and properties interplay of perovskites makes them an exceptional research field for different branches like materials science, physics and solid-state chemistry. A wide range of unique functional materials and device ideas can be predicted through a basic understanding of the correlation between structural and chemical compatibility.

The perovskite structure is shown to be the single most adaptable ceramic host. Inorganic perovskite-type oxides are attractive compounds for varied applications due to its large number of compounds, they exhibit both physical and biochemical characteristics and their nano-formulation have been utilized as catalysts in many reactions due to their sensitivity, unique long-term stability, and anti-interference ability. Some perovskite materials are very hopeful applicants for the improvement of effective anodic catalysts performance. Depending on perovskite-phase metal oxides' distinct variety of properties they became useful for various applications they are newly used in electrochemical sensing of alcohols, glucose, hydrogenperoxide, gases, and neurotransmitters. Perovskite organometallic halide showed efficient essential properties for photovoltaic solar cells.
