Composition Tailoring via N & S Co-doping and Structure Tuning by Constructing Hierarchical Pores Enable Metal-free Catalysts for High-Performance Electrochemical Reduction of CO2.

We report a facile route to scalable production of N and S co-doped, hierarchically porous carbon nanofiber (NSHCF) mem-branes (i.e., ~400 cm2 membrane in a single process). As-synthesized NSHCF membranes are flexible and free-standing, rendering their direct use as cathodes for efficient electrochemical CO2 reduction reaction (CO2RR). Notably, CO with 94% Faradaic efficiency and -103 mA cm-2 current density are readily achieved with only ~1.2 mg catalyst loading, which are among the best results ever obtained by metal-free CO2RR catalysts. On the basis of control experiments and DFT calculations, such outstanding CO Faradaic efficiency can be attributed to the co-doped pyridinic N and carbon-bonded S atoms, which effectively decrease the Gibbs free energy of key *COOH intermediate. Furthermore, hierarchically porous structures of NSHCF membranes impart a much higher density of accessible active sites for CO2RR, leading to the ultra-high current density.
PMID: 30284359 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - October 3, 2018 Category: Chemistry Authors: Yang H, Wu Y, Lin Q, Fan L, Chai X, Zhang Q, Liu J, He C, Lin Z Tags: Angew Chem Int Ed Engl Source Type: research