Photocatalysis method for environmental applications has been using for a long time. This review article traces back the origin of catalysis, its classification and journey of development to heterogeneous photocatalysis and the article’s novelty is in the simplicity, and easily understandable language, designed for the beginners. These heterogeneous photocatalysts are grouped into eleven different categories. As the paper is focused on photocatalysis, an insight on fundamental principles and mechanisms of photocatalysis are explained systematically with schematic illustrations and reactions that take place during redox- oxidation and reduction reactions in photocatalysis. With an approach towards utilizing green energy and expanding the photocatalyst’ absorption wavelength range towards the visible regime, bandgap engineering techniques by adopting doping and hetero-structures are explained with examples of different materials. In addition, dominating factors of photocatalysis reaction viz. composition of a heterogeneous photocatalyst, doping, hetero-structures, pH, surface defects on photocatalysis reaction are explored, focussing on variable charge transfer mechanisms. The main influencing factor in generating reactive oxygen species is pH of the photocatalysis reaction and are studied indetail. The effect of alkalinity or acidity in catalyst surfaces and molecular interaction depending upon the point zero charges of the photocatalyst are discussed. For the better study of catalyst properties, careful analysis and study is a much-needed field as a scope for further improvement. Hence, this article will guide a beginner to understand the photocatalysis topic with ease.

用于环境应用的光催化方法已经使用了很长时间。这篇评论文章追溯了催化的起源、分类和发展历程到多相光催化，文章的新颖之处在于简单易懂的语言，专为初学者设计。这些多相光催化剂分为十一个不同的类别。由于本文专注于光催化，因此系统地解释了光催化的基本原理和机制，并通过示意图和光催化中氧化还原-氧化和还原反应期间发生的反应进行了系统解释。通过利用绿色能源并将光催化剂的吸收波长范围扩大到可见光范围的方法，通过不同材料的例子解释了采用掺杂和异质结构的带隙工程技术。此外，光催化反应的主导因素即。研究了多相光催化剂的组成、掺杂、异质结构、pH、光催化反应的表面缺陷，重点关注可变电荷转移机制。产生活性氧的主要影响因素是光催化反应的 pH 值，并对其进行了详细研究。讨论了取决于光催化剂零点电荷的催化剂表面的碱度或酸度和分子相互作用的影响。为了更好地研究催化剂的性能，仔细分析研究是一个亟待进一步改进的领域。因此，