Single molybdenum atom anchored on 2D Ti2NO2 MXene as a promising electrocatalyst for N2 fixation. Issue 39 (25th September 2019)

• Record Type: Journal Article
• Authors: Cheng, Yuwen; Dai, Jianhong; Song, Yan; Zhang, Yumin
• Is Part Of: Nanoscale. Volume 11:Issue 39(2019)
• Page Start: 18132
• Page End: 18141
• Publication Date: 2019-09-25
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c9nr05402b
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Mo anchored on Ti2 NO2 (Mo/Ti2 NO2 ) surface possesses superior NRR performance, with an overpotential η NRR of 0.16 V via enzymatic mechanism. Abstract : The electrocatalytic synthesis of ammonia (NH3 ) at ambient temperature is an attractive and challenging subject in the chemical industry. The synthesis of NH3 under ambient conditions requires efficient and stable electrocatalysts with ultralow overpotential to ensure low energy consumption and high NH3 yield. Herein, electrocatalysts consisting of a single transition metal (TM) atom (TM = Mo, Mn, Fe, Co, Ni, or Cu) anchored on 2D M2 NO2 MXene (M = Ti, V, and Cr), designated as TM/M2 NO2, are designed for N2 reduction reaction (NRR) by density functional theory calculations. The results show that the bonding strength between Mo and Ti2 NO2 is strong. The overpotential ( η NRR ) of Mo/Ti2 NO2 surface-catalyzed NRR is estimated to be as low as 0.16 V via an enzymatic mechanism, which is lower than those reported to date. For Mo/V2 NO2 and Mo/Cr2 NO2 catalysts, the NRR occurs through the consecutive mechanism and enzymatic mechanism, with corresponding η NRR values of 0.38 V and 0.22 V, respectively. In addition, the reaction Gibbs free energy of NH3 desorption from the Mo/Ti2 NO2 surface is only 0.12 eV. Electronic structure analysis indicates that Mo/Ti2 NO2 shows metallic characteristics, which ensures the efficient transfer of electrons between Mo and Ti2 NO2 . Ab initio molecular dynamics simulations indicate that the Mo atom can be stably immobilized on the Ti2 NO2 substrate to prevent its aggregation into Mo clusters. Further analysis illustrates that hydrogen adsorption is not favored on the Mo/Ti2 NO2 surface. Mixing the N2 source with extra gases, such as NO2, NO, SO2, SO, and O2, should be avoided for NRR on Mo/Ti2 NO2 surface. These predictions offer a new opportunity for the electrocatalytic synthesis of NH3 by N2 reduction in the future.