Insight into the Reactivity of Carbon Structures for Nitrogen Reduction Reaction

Abstract

Graphene-based structures have been widely reported as promising metal-free catalysts for nitrogen reduction reaction. To explain the reactivity origin, various structures have been proposed and debated, including defects, functional groups, and doped heteroatoms. This computational work demonstrates that these structures may evolve from one to another under electrochemical conditions, generating weakly coordinated carbons, which have been identified as the active sites for N 2 adsorption and activation.

Amorphous Boron Carbide on Titanium Dioxide Nanobelt Arrays for High‐Efficiency Electrocatalytic NO Reduction to NH3

“…play the essential role to fix/activate NO via electron injection, which mechanism associated with lowly coordinated non-metals has also been extensively observed in N 2 reduction. [50,51] In summary, a-B 2.6 C@TiO 2 /Ti was verified as a 3D catalyst with high activity and durability to activate NO via an eNORR process for achieving selective NH 3 synthesis. Under mild conditions, it exhibits both lower E onset and higher j than those of TiO 2 /Ti and a-B 2.6 C/Ti and achieves a large NH 3 yield of 3678.6 μg h À 1 cm À 2 with a high FE of up to 87.6 % that superiors to TiO 2 /Ti (563.5 μg h À 1 cm À 2 , 42.6 %) and a-B 2.6 C/Ti (2499.2 μg h À 1 cm À 2 , 85.6 %) counterparts.…”

“…Given water product forms stable hydrogen bonding with solution, energy costs associated with OH* reduction should be reduced [13] . Overall, B 3c and C 3c play the essential role to fix/activate NO via electron injection, which mechanism associated with lowly coordinated non‐metals has also been extensively observed in N 2 reduction [50, 51] …”

Progress of Experimental and Computational Catalyst Design for Electrochemical Nitrogen Fixation

“…In contrast, on the graphene with vacancy and dislocation sites, the N 2 molecule can form effective adsorption with very negative free energy, followed by the hydrogenation into NH 3 with acceptable U L (−0.49 and −1.05 V, respectively) and high selectivity. Also, Li et al performed theoretical simulations to gain insight into the reactivity of carbon structures for eNRR 474 and proposed that carbon atoms with low coordination generated by the functional group evolution are active for N 2 adsorption and reduction. In this case, alkali metal ions with stabilizing ability were considered to achieve long-term stability.…”

Nitrogenase-Inspired Atomically Dispersed Fe–S–C Linkages for Improved Electrochemical Reduction of Dinitrogen to Ammonia

“…Single-atom catalysts (SACs) have been extensively studied for different electrocatalytic applications due to their full atom utilization, the anomalous quantum size effect, and a tunable coordination environment. − Incorporation of metal centers in heteroatom-doped carbon at the atomic scale results in modified electronic structures of the active center that facilitate the adsorption of reactants and intermediates. , Several SACs have been explored for electrochemical NRR where the main aim was to develop M–N and M–O linkages to stabilize the metallic center. − Among these, M–N-based catalysts are superior in the NRR performance that can be attributed to the optimized charge distribution between the metal center and N atom in the carbon matrix. These localized charge density sites improve N 2 adsorption (the first step in the NRR mechanism) with a decrease in the free energy required for this process by sharing electronic density between metal and N 2 .…”