Abstract
Electrocatalytic nitrogen reduction reaction (NRR) is a promising and sustainable approach for ammonia production. Since boron as an active center possesses electronic structure similar to that of transition metals withd-orbitals (J. Am. Chem. Soc., 2019, 141 (7), 2884), it is supposed to be able to effectively activate the triple bond in N2. MXenes can be applied as substrates due to the large specific surface area, high conductivity, and tunable surface composition. In this work, the catalytic performance of a series of MXenes-supported single boron atom systems (labeled as B@MXenes) has been systematically studied by using density functional theory (DFT). B@Nb4C3O2, B@Ti4N3O2, and B@Ti3N2O2were screened out owing to outstanding catalytic activity with limiting potentials of −0.26, −0.15, and −0.10 V, respectively. Further analysis shows that the unique property of boron that can intensely accept lone pair and back-donate the anti-bond of nitrogen contributes to the activation of inert triple bond. This work provides a new idea for the rational design of NRR catalyst and is of great significance for the future development of nitrogen reduction catalysts.
Highlights
NH3 is one of the most important basic chemicals used in the downstream manufacturing of various products in the agricultural industry, synthetic fiber, and fine chemicals (Giddey et al, 2013; Zhan and Zhang, 2021)
All density functional theory (DFT) computations were performed by using the Vienna ab initio simulation package (VASP) with the projector augmented wave (PAW) (Blöchl, 1994; Kresse and Furthmüller, 1996; Kresse and Joubert, 1999; Grimme, 2006)
The weaker hydrogen adsorption than nitrogen adsorption in the end-on configuration indicates a high selectivity of the nitrogen reduction reaction (NRR) over the hydrogen evolution reaction (HER) on all the considered B@MXenes
Summary
NH3 is one of the most important basic chemicals used in the downstream manufacturing of various products in the agricultural industry, synthetic fiber, and fine chemicals (Giddey et al, 2013; Zhan and Zhang, 2021). The atmosphere consists of more than 70% of nitrogen and the reduction of nitrogen to produce NH3 is an exothermic reaction under standard conditions, the nitrogen fixation from N2 to NH3 is still tough because of the inherent nature of the N≡N bond with extremely high bond energy (Gambarotta and Scott, 2004). Industrial production of NH3 relies on the high energy-intensive Haber–Bosch process, which results in a huge amount of energy consumption and carbon emissions around the world (Cui et al, 2018). Inspired by the biological N2 fixation in bacteria (Singh et al, 2021), the electrochemical nitrogen reduction reaction (NRR) provides a green and sustainable alternative to produce NH3 at relatively mild conditions (Liu et al, 2021a).
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