Catalysts are of vital importance for many chemical processes. Crystal facets have been known to exert a significant influence on the catalytic activity and selectivity. To tailor the surface morphology and select the optimal shape, traditional methods introduce additives and crystal modifiers during the materials synthesis process. In this work, we propose a novel strategy for rapid catalyst screening by having the chemical reaction select its own catalyst. The resulting modified metal crystals thus possess a unique arrangement of crystal facets, which selectively binds the reaction intermediates, exhibiting superior catalytic performances, which is demonstrated by lead and copper used in electrochemical CO2 reduction reaction. Therefore, we anticipate this proposed screening approach searching for a proper catalyst will be applicable to a wide range of chemical processes in addition to CO2 reduction, holding great potential for the future catalyst discovery and improvement.