Proton shuttling flattens the energy landscape of nitrite catalytic reduction

Water molecules can enhance or inhibit hydrogenation reactions depending on the nature of reactive species and active sites. In metal-catalyzed nitrite (NO2–) reduction presence protons is essential to complete reaction in aqueous phase. By coupling rigorous kinetics studies Pd with kinetic isotope theoretical calculations we have shown that, contrary previously proposed mechanisms surface H-insertion NO*, environments proceeds via H-shuttling which move environment while electrons reach NO* through metal a concerted fashion. This unique mechanism flattens energy landscape, leads same apparent activation barrier (0.6 eV) for formation HNO* HNOH*. These results are consistent hydrogen orders, isotopic experiments, micro-kinetic modeling including co-limiting steps work provides new insights that will be key developing more efficient catalysts processes catalytic removal micro-pollutants, such as nitrate nitrite, drinking water broadly