Boosting Electrocatalytic N₂ Reduction to NH₃ over Two-Dimensional Gallium Selenide by Defect-Size Engineering

Abstract

Using density functional theory calculations, we propose that the exposed Ga atom in a two-dimensional defective gallium selenide monolayer (V-GaSe) can display a good dinitrogen fixation capacity and an excellent nitrogen reduction reaction (NRR) performance. Our results show that N 2 can be captured by three sp 3 -hybridized Ga atoms due to the pulling effect. With the enlargement in vacancy size through applying tensile strain, the adsorption of N 2 is strengthened and the electrochemical NRR performance is enhanced. On 8% strained V-GaSe, the estimated onset potential is as low as 0.30 V. Inspired by the concept of "defect-sizedependent" NRR performance, we further design a Janus V-GaInSe 2 structure in which the natural size of the cavity is enlarged and the electron density of the active Ga atoms is enriched. It is found that N 2 adsorption is demonstrably enhanced with respect to V-GaSe. On 4% strained V-GaInSe 2 , the onset potential is calculated to be 0.31 V, which is the same as the 8% strained V-GaSe. Moreover, the produced NH 3 can be removed rapidly with a free-energy change of less than 0.52 eV, which is much lower than those of most reported catalysts with low overpotentials. Meanwhile, the side hydrogen evolution reaction is successively suppressed as the strain increases. Our work offers a feasible method that utilizes the size of a defect to tune the NRR performance, adding a new understanding of N 2 fixation and sustainable NH 3 production.

Mutual modulationviacharge transfer and unpaired electrons of catalytic sites for the superior intrinsic activity of N2reduction: from high-throughput computation assisted with a machine learning perspective

“…The thermodynamic stability of superior SACs was carried out by ab initio molecular dynamics (AIMD) simulations within the NVT ensemble at 400 K up to 10 ps with a time step of 2 fs. In our previous work, the solvent effect which was performed by implicit model VASPsol 49,50 was proved to play a minor role in NRR within 0.2 eV, which was also supported by other experimental and theoretical results 10,[51][52][53][54][55][56][57] . Thus, the solvent effect was not taken into account in this work.…”

“…In our previous work, the solvent effect, which was performed by the implicit model VASPsol 49,50 was proved to play a minor role in NRR within 0.2 eV, which was also supported by other experimental and theoretical results. 10,[51][52][53][54][55][56][57] Thus, the solvent effect was not taken into account in this work.…”

“…In particular, 1Bs-Os@MoS 2 has the best performance with DG max of 0.25 eV, showing better performance than other studies. 37,51,52 The reaction processes with the most energy favorable pathway are shown in Fig. 4c-f.…”

Graphene Derivatives and Graphene Composite Electrocatalysts for N2 Reduction Reaction

“…Compared with metal‐based NRR electrocatalysts, these PDS potentials are relatively low, such as Ru‐based electrocatalysts (>1 eV), Nb 2 O 5 (1.15 eV), MoO (1.88 eV), Bi nanosheet (2.15 eV), and SeO (>2 eV). [ 1,12,18,80,81 ]…”

“…Compared with metal-based NRR electrocatalysts, these PDS potentials are relatively low, such as Ru-based electrocatalysts (>1 eV), Nb 2 O 5 (1.15 eV), MoO (1.88 eV), Bi nanosheet (2.15 eV), and SeO (>2 eV). [1,12,18,80,81] potentials. e) DFT calculated Gibbs free energy profiles for the NRR reaction on F-graphene, and corresponding Mulliken charges analysis and CDD analysis.…”