Achieving reaction pathway separation for electrochemical nitrate fixation on triatomic catalysts: A new mechanism

As the continuous development of electrocatalytic technique, the degradation of toxic nitrate wastewater into green fuel ammonia has become the goal of researcher’s unremitting efforts by electrochemical method. Particularly, a high performance catalyst for electrochemical process is regarded as an indispensable tool for sustainable cycle. Although existing designed electrodes may effectively advance nitrate reduction reaction, they remain unsatisfactory due to elusive reaction processes. Here, a brand-new reaction mechanism has been proposed via density functional theory (DFT) and ab initio molecule dynamic (AIMD) methods, which breaks the bottleneck of linear scaling in atomic scale catalyst design. It is found that triple Mn atoms anchored on graphdiyne (Mn3-GDY) can drive nitrate adsorption and ammonia desorption on its surface with weak binding strength and strong activation by the spin polarization of active site. In addition, the powerful adsorption capacity of triatomic active site prevents the thermodynamic barrier from rising due to the transformation of the intermediates *NO3H and *NO2H into *NO2*OH and *NO*OH, respectively. More importantly, in accordance with the “weak-strong-weak” principle, Mn3-GDY has rapid response to ammonia desorption that is conducive to boost the turnover frequency. Anyway, this work may provide a new insight into atomic catalysts for improving reaction mechanisms.