Assemble an Actinide-uranium single atom catalyst on defective MXenes for efficient NO electroreduction

Abstract

The research on actinide-uranium single atom catalyst is particularly crucial in small pollutant molecule reduction due to its unique f orbital with adjustable oxidation states. This work screens a series of an actinide-uranium single atom catalyst embedded MXenes monolayer with oxygen vacancy (UO2@MXene, MXene = Ti2CO2, V2CO2, Cr2CO2, Zr2CO2, Nb2CO2 and Mo2CO2) for product selectivity in electric catalytic NO reduction (ENOR) by well defined ab initio calculations. Our results indicate that the change from higher oxidation state U(VI) to sparingly soluble low valent U species anchored O-defective MXenes surfaces when the model of uranyl adsorbate approached O vacancy of MXenes, which can solve limitation of catalytic performance of actinide metal centers. Furthermore, their efficiency for electrochemical NO reduction reaction to NH3 were evaluated. Among all actinide-uranium single atom catalyst, UO2@Nb2CO2 exhibits the best activity and selectivity in NO reduction to NH3, characterized by the lowest theoretical limiting potential of −0.14 V. Additionally, the constant-potential method (CPM) was performed to explore pH-dependent catalytic activity of UO2@Nb2CO2. The findings indicate that the onset potential is −0.228 V vs RHE at pH = 1, which is lower than 0.305 V vs RHE at pH = 13, which suggest the acid environment is relatively facilitated to ENOR on UO2@Nb2CO2. This work leverages environmental remediation and electro-catalytic reaction in actinide-uranium complex, offering a novel approach to establish a theoretical framework for the most effective strategies of NH3 synthesis.