Two-dimensional transition metal phthalocyanine sheet as a promising electrocatalyst for nitric oxide reduction: a first principle study.

Electrochemical reduction is a promising technology to treat polluted water contaminated by nitrate and nitrite ions under mild conditions. NO is an important intermediate species and determines selectivity toward different product and rate of whole reaction. However, the most studied NOER electrocatalysts are noble pure metal, which face problems of low utilization and high cost. Herein, by means of density functional theory computations, catalytic performance of 2D TM-Pc sheets (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ru) as NOER catalysts were systematically evaluated. Among all the studied 2D TM-Pc sheets, our results revealed 2D Co-Pc sheet was identified as the best NOER catalyst, for a proper NO absorption energy and its relatively low limiting potential. The final reduction product of NOER is either NH3 at low coverages with energy input of 0.58 eV or N2O at high coverages with no energy barrier. Moreover, 2D Co-Pc sheet can efficiently suppress the competing HER. This study could not only provide a new approach for electrochemical denitrification to resolve environmental pollution but also be useful for valuable ammonia production.