Realizing a Not-Strong-Not-Weak Polarization Electric Field in Single-Atom Catalysts Sandwiched by Boron Nitride and Graphene Sheets for Efficient Nitrogen Fixation

Abstract

Developing efficient single-atom catalysts (SACs) for nitrogen fixation is of great importance while remaining a great challenge. The lack of an effective strategy to control the polarization electric field of SACs limits their activity and selectivity. Here, using first-principles calculations, we report that a single transition metal (TM) atom sandwiched between hexagonal boron nitride (h-BN) and graphene sheets (namely, BN/TM/G) acts as an efficient SAC for the electrochemical nitrogen reduction reaction (NRR). These sandwich structures realize stable and tunable interfacial polarization fields that enable the TM atom to donate electrons to a neighboring B atom as the active site. As a result, the partially occupied p z orbital of a B atom can form B-to-N π-back bonding with the antibonding state of N 2 , thus weakening the NN bond. The not-strong-not-weak electric field on the h-BN surface further promotes N 2 adsorption and activation. The NRR catalytic activity of the BN/TM/G system is highly correlated with the degree of positively polarized charges on the TM atom. In particular, BN/Ti/G and BN/V/G are identified as promising NRR catalysts with high stability, offering excellent energy efficiency and suppression of the competing hydrogen evolution reaction.

Molecular Crowding Effect in Aqueous Electrolytes to Suppress Hydrogen Reduction Reaction and Enhance Electrochemical Nitrogen Reduction

“…Therefore, suppressing the HER kinetics and widening the potential gap between NRR and HER, especially in acidic electrolytes, are critical to addressing the challenge of NH 3 selectivity and achieving a high NH 3 FE. [ 10–13 ]…”

Confining Chainmail‐Bearing Ni Nanoparticles in N‐doped Carbon Nanotubes for Robust and Efficient Electroreduction of CO2

“…Recently, a dual‐protection strategy has been proposed to further improve the structure and performance stability by introducing a second chainmail (carbon layer or network) [50–52] . Theoretical calculations also proved that single atoms sandwiched by graphene and boron nitride or carbon nitride chainmail could significantly enhance the catalyst stability [53,54] . Although high stability and activity can be achieved, the selectivity of chainmail catalysts remains unsatisfying.…”

Can NOx reduction by CO react over carbon‐based single‐atom catalysts at low temperatures? A theoretical study

“…For the description of the barrier of the CO oxidation, we also try to conduct a charge density difference analysis (Figure S26). It can be found, to a certain extent, the greater the amount of electrons transfer from the dopant atom to O*, the easier it is for O* to oxidize CO. On the other hand, due to the weak adsorption of N 2 O and the low‐energy barrier in the reaction process, there are no obvious trends of change, the descriptor φ N2O cannot fit the N 2 O reduction well (Figure 8C): In addition to the adsorption energy and electronegativity, the charge distribution of a SAC can be used to simply predict its adsorption performance for key species 54 . As shown in Figure 9, the relationships between the Bader charges of active site of SADGr catalysts and the adsorption free energies of key species (NO, CO, NO 2 , O) are derived.…”