Computational screening of a single transition metal atom supported on the C₂N monolayer for electrochemical ammonia synthesis

Abstract

The nitrogen reduction reaction (NRR) under ambient conditions using renewable energy is a green and sustainable strategy for the synthesis of NH3, which is one of the most important chemicals and carbon-free carriers. Thus, the search for low-cost, highly efficient, and stable NRR electrocatalysts is critical to achieve this goal. Herein, using comprehensive density functional theory (DFT) computations, we design a new class of NRR electrocatalysts based on a single transition metal (TM) atom supported on the experimentally feasible two-dimensional C2N monolayer (TM@C2N). Based on the computed free energies of each elementary pathway, Mo@C2N is predicted to exhibit the best catalytic activity among the TM@C2N, in which the proton-coupled electron transfer of the NH2* species to NH3(g) is the potential-determining step. Especially, the computed onset potential of the NRR on Mo@C2N is -0.17 V, which is even lower than that for the well-established stepped Ru(0001) surface (-0.43 V). Furthermore, the NRR catalytic performance of these TM@C2N can be well explained by their adsorption strength with N2H* species. Our findings open a new avenue for optimizing the TM catalytic performance for the NRR with the lowest number of metal atoms on porous low-dimensional materials.

Single vs double atom catalyst for N2 activation in nitrogen reduction reaction: A DFT perspective

“…The purple atom is in the armchair site, and the pink and purple circles are in the zig-zag and central site, respectively that the COF-like C 2 N monolayer and TM metal exhibited strong metal substrate interaction by forming TM 2 N 4 and TMN 2 , which keep the SSHC/SAC/DAC stable and uniformly dispersed, and prevent the TM atoms from agglomeration. The present study enriched the target elements reported the previous calculation, 33,40,41 and have stronger potential for practical application.…”

Electrochemical N2 Reduction to Ammonia Using Single Au/Fe Atoms Supported on Nitrogen-Doped Porous Carbon

“… 48 It is also reported that the dissociative adsorption of N 2 on similar systems is not thermodynamically favorable and furthermore has to overcome a high energy barrier. 49 Hence, in this study, only the associative mechanism is taken into account. The mechanism of the electrochemical reduction of N 2 to NH 3 catalyzed by similar materials has already been reported in the literature.…”

1 + 1′ > 2: Heteronuclear Biatom Catalyst Outperforms Its Homonuclear Counterparts for CO Oxidation

“…[32,33] Besides metal-oxides, a variety of porous graphene-like materials have been used as the substrates to anchor metal atoms/clusters for catalysis. For example, it has been experimentally demonstrated that single metal atoms (Pt, Pd, Ag, Ir, Au) embedded in g-C 3 N 4 are highly active for the semihydrogenation of 1-hexyne [34] and electrochemical synthesis of ammonia, [35] theoretical studies suggested that single transition metal atoms anchored on C 2 N could serve as low-cost but highly efficient catalysts for oxygen evolution reaction, [36] CO oxidation, [37] nitrogen reduction reaction, [38] HCOOH dehydrogenation, [39] and CO 2 electrochemical reduction, [40] and the noble metal atoms anchored on graphyne are very promising for low-temperature CO oxidation. [41] Beyond SACs, biatom catalysts, in which metal dimers are anchored on an appropriate substrate, have recently emerged as extended family members.…”