**Abstract**

Engineering the plasmonic nanohybrid structures to provide the advancement in their optical and photocatalytic profiles is one of the important aspects for the development of several environmental and energy applications. Plasmonic nanohybrids, integration of semiconductors and noble nanoparticles provide efficient charge separation due to Schottky junction and plasmon nanoparticle induced electromagnetic field. Effective charge separation and electromagnetic features make plasmonic nanohybrids a promising candidate for SERS-based detection environmental detoxification and energy harvesting applications. In the present chapter, we will summarize and elaborate the different strategies and modification techniques to enhance photocatalytic-driven environmental and energy applications. Moreover, the current chapter also includes the detection of various harmful pollutant molecules and their decomposition under sunlight using several plasmonic nanohybrids. This chapter also reveals the origins of morphological, optical, and plasmonic variations on TiO2 nanostructures for enhanced photocatalytic efficiency. We have also highlighted the probable mechanism due to the plasmonic nanoparticles' aspects over TiO2 nanostructures and their future perspectives of advanced photocatalysis. This chapter provides the fundamental synthesis aspects of plasmonic nanohybrid and their possible usage in energy and environmental applications significantly. This chapter will provide a basic understanding for the readers to develop several plasmonic nanostructures for environmental applications.

**Keywords:** TiO2, plasmonic nanohybrids, photocatalysis, energy, pollutants in water
