Developing stable and efficient catalysts for the electroreduction of nitrogen remains a huge challenge and single atom catalysts (SACs) are expected to achieve relatively high ammonia selectivity at low applied potential. Based on density functional theory calculations, the potential application of 27 single transition metal (TM = Sc–Zn, Y–Ag, Hf–Au) atoms supported by N(O)-dual-doped graphene (TM-O₂N₂/G) for the electroreduction of nitrogen is intensively investigated. At low nitrogen coverage, W(Mo, Nb, Ta)-O₂N₂/G are predicted to yield low ammonia selectivity (< 13%) at limiting-potential of −0.58, −0.53, −0.56, and −0.76 V starting from adsorbed nitrogen with side-on mode, respectively. With the increasing N₂ coverage, the TM-O₂N₂/G is reconstructed as TM-(N₂)₂N₂/graphene. The electroreduction of nitrogen proceeds from end-on adsorbed nitrogen molecule with high ammonia selectivity, and the limiting-potentials are theoretically predicted as −0.20, −0.40, −0.29, and −0.21 V on W(Mo, Nb, Ta)-(N₂)₂N₂/G, respectively. It is suggested that utilizing the reorganization of local coordination environments of SACs by high coverage of reactant molecules under reaction condition can not only enhance the activity at lower limiting-potential but also improve the ammonia selectivity.

Organic-inorganic layered perovskites are two-dimensional quantum well layers in which the layers of lead halide octahedra are stacked between the organic cation layers. The packing geometry of the soft organic molecules and the stiff ionic crystals induce structural deformation of the inorganic octahedra, generating complex lattice dynamics. Especially, the dielectric confinement and ionic sublattice lead to strong coupling between the photogenerated excitons and the phonons from the polar lattice which intensively affects the properties for device applications. The anharmonicity and dynamic disorder from the organic cations participate in the relaxation dynamics coupled with excitations. However, a detailed understanding of this underlying mechanism remains obscure. This work investigates the electron–optical phonon coupling dynamics by employing ultrafast pump-probe transient absorption spectroscopy. The activated different optical phonon modes are observed via systematic studies of (PEA)₂PbBr₄ perovskite films on the ultrafast lattice vibrational dynamics. The experimental results indicate that solvent engineering has a significant influence on lattice vibrational modes and coherent phonon dynamics. This work provides fresh insights into electron-optical phonon coupling for emergent optoelectronics development based on layered perovskites.