Biosynthesized metallic nanocatalysts in the removal and degradation of pollutants

•Biogenic synthesis of nanocatalysts is facile, up-scalable, inexpensive, and eco-friendly.•Biosynthesized metallic nanocatalysts (BMNs) are widely explored for environmental applications.•BMNs advantages: High catalytic activity, chemical reactivity, selectivity, and recyclability.•BMNs can efficiently convert industrial wastes into the high-value materials.•BMNs should be further optimized and analytically evaluated for large-scale production. Metallic nanocatalysts have been widely synthesized and deployed for assorted applications, including water splitting, degradation of pollutants, CO2 reduction, self-cleaning surfaces, hydrogen evolution, etc. Biosynthesis of such nanocatalysts encompasses crucial benefits of simplicity, up-scalability, inexpensiveness, and eco-friendliness, and has been widely explored for the removal and degradation of pollutants. Biosynthesized metallic nanocatalysts not only exhibit appropriate stability and reusability, but also offer excellent catalytic activity while using much lower resources and energy. Herein, the recent advancements related to the biosynthesis of metallic nanoparticles with respect to their catalytic applications for the removal/catalytic degradation of various pollutants are deliberated, focusing on important challenges and future perspectives, while most of the published research has predominantly focused on the synthesis approaches and its mechanism.