TY - JOUR
T1 - Chemistry of Multitudinous Active Sites for Oxygen Reduction Reaction in Transition Metal-Nitrogen-Carbon Electrocatalysts
AU - Artyushkova, Kateryna
AU - Serov, Alexey
AU - Rojas-Carbonell, Santiago
AU - Atanassov, Plamen
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/11/19
Y1 - 2015/11/19
N2 - Development and optimization of non-platinum group metal (non-PGM) electrocatalysts for oxygen reduction reaction (ORR), consisting of transition metal-nitrogen-carbon (M-N-C) framework, is hindered by the partial understanding of the reaction mechanisms and precise chemistry of the active site or sites. In this study, we have analyzed more than 45 M-N-C electrocatalysts synthesized from three different families of precursors, such as polymer-based, macrocycles, and small organic molecules. Catalysts were electrochemically tested and analyzed structurally using exactly the same protocol for deriving structure-to-property relationships. We have identified possible active sites participating in different ORR pathways: (1) metal-free electrocatalysts support partial reduction of O2 to H2O2; (2) pyrrolic nitrogen acts as a site for partial O2 reduction to H2O2; (3) pyridinic nitrogen displays catalytic activity in reducing H2O2 to H2O; (4) Fe coordinated to N (Fe-Nx) serves as an active site for four-electron (4e-) direct reduction of O2 to H2O. The ratio of the amount of pyridinic and Fe-Nx to the amount of pyrrolic nitrogen serves as a rational design metric of M-N-C electrocatalytic activity in oxygen reduction reaction occurring through the preferred 4e- reduction to H2O.
AB - Development and optimization of non-platinum group metal (non-PGM) electrocatalysts for oxygen reduction reaction (ORR), consisting of transition metal-nitrogen-carbon (M-N-C) framework, is hindered by the partial understanding of the reaction mechanisms and precise chemistry of the active site or sites. In this study, we have analyzed more than 45 M-N-C electrocatalysts synthesized from three different families of precursors, such as polymer-based, macrocycles, and small organic molecules. Catalysts were electrochemically tested and analyzed structurally using exactly the same protocol for deriving structure-to-property relationships. We have identified possible active sites participating in different ORR pathways: (1) metal-free electrocatalysts support partial reduction of O2 to H2O2; (2) pyrrolic nitrogen acts as a site for partial O2 reduction to H2O2; (3) pyridinic nitrogen displays catalytic activity in reducing H2O2 to H2O; (4) Fe coordinated to N (Fe-Nx) serves as an active site for four-electron (4e-) direct reduction of O2 to H2O. The ratio of the amount of pyridinic and Fe-Nx to the amount of pyrrolic nitrogen serves as a rational design metric of M-N-C electrocatalytic activity in oxygen reduction reaction occurring through the preferred 4e- reduction to H2O.
UR - http://www.scopus.com/inward/record.url?scp=84947983018&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.5b07653
DO - 10.1021/acs.jpcc.5b07653
M3 - Article
AN - SCOPUS:84947983018
SN - 1932-7447
VL - 119
SP - 25917
EP - 25928
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 46
ER -