the decomposition of harmful emissions and recycling of CO2 into useful products. The work covered herein envelops synthesis, characterization, and evaluation of various nano catalysts such as TiO2, ZnO, Fe2O3, Au, Pt, Pd, and an Au-Pd nano alloy. These were synthesized by different preparation techniques, especially the sol-gel and hydrothermal methods, while their structural and surface properties were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and BET surface area analysis. The catalytic performances of the prepared nanomaterials were performed against the degradation of NOx, SOx, and VOCs and in the conversion of CO2 into methanol, ethanol, and hydrocarbons. The results obtained showed that nano catalysts did a tremendous job in controlling emissions through the decomposition of up to 95% of VOCs, while Pd-nano catalysts proved efficient enough in CO2 conversion, yielding up to 82% hydrocarbon products. Without doubt, the obtained results prove that nano catalysts bear huge potential to solve all environmental problems across the globe