The enhanced control of reactive selectivity is critical in the development of more high efficiency next generation catalysts in a variety of chemical applications. As part of a broad materials by design screening program, in this work we present the results of 1st principles calculations that characterize the selective production/inhibition of H2O2 (hydrogen peroxide) via transition metal catalysts. Our work probes the effects of catalyst composition as well as structure (ideal surface vs. stepped/defect surface). Finally, we examine the difference in selective reactive production of H2O2 as a function of electrochemical environment.