Main-Group s-Block Element Lithium Atoms within Carbon Frameworks as High-Active Sites for Electrocatalytic Reduction Reactions

Inspired by the d-band center theory, previous studies mainly focus on transition metals as electrocatalytic active sites. The s-block metals in the periodic table, especially group Iota A metals with fewer valence electrons, are rarely reported as high-activity electrocatalysts for reduction reactions due to the difficulties associated with their electronic structure regulation. Herein, theoretical calculations demonstrate that group Iota A element lithium (Li) embedded in N, O-doped graphene is an effective electrocatalytic active center for carbon dioxide reduction reaction (CO2RR) and oxygen reduction reaction (ORR). This catalytic feasibility results from the s-p orbital hybridization between originally empty 2p orbital of Li and the orbitals of coordinated atoms. This vacant 2p orbital can serve as a site for additional p-p conjugation between Li and N, O-doped graphene. Theoretically, the zigzag-type Li-O-2 model shows remarkable CO2RR activity, while Li-pyridinic-N-1-C-1 exhibits high ORR activity. Furthermore, a carbon-based catalyst with well-anchored Li atoms coordinated to N, O substituents is experimentally demonstrated to exhibit exceptional CO2RR activity (FECO = 98.8% at -0.55 V) and ORR performance in acidic media (E-1/2 = 0.77 V). This is the first report on bifunctional high-performance electrocatalyst utilizing a group Iota A element with performance comparable to that of most previously reported transition-metal-based catalysts.

Automated summary

Theoretical calculations demonstrate that lithium embedded in N, O-doped graphene is an effective electrocatalytic active center for CO2 reduction and oxygen reduction reactions. This is due to the s-p orbital hybridization between the empty 2p orbital of lithium and the orbitals of coordinated atoms. Experimental results show that a carbon-based catalyst with well-anchored lithium atoms coordinated to N, O substituents exhibits exceptional performance in CO2 reduction and oxygen reduction reactions in acidic media.