Noble metal-based nanocrystals have played important roles in heterogeneous catalysts due to their high activity and chemical stability. The high cost of noble metals, however, created roadblocks for the large volume production of noble metal catalysts for many applications. Improving the catalytic activity or the efficiency of noble metal usage, and prolong the life-time of a noble metal based catalysts are solutions to these challenges. On a nanocatalyst, the composition, atomic coordination, and strains of the top surface layers eventually determine its performance in catalytic reactions. Slight changes in the surface structure of catalytic materials for example, such as increase in the number of accessible surface adsorption sites or generating uniform surfaces with abundant specific defects, can have large impacts on the catalytic stability and activity. In this presentation I will share our recent efforts on tuning the surface compositions and structures of noble metal catalysts to improve both catalytic activity and stability.