Design and Synthesis of MnN4 Macrocyclic Complex for Efficient Oxygen Reduction Reaction Electrocatalysis

Publication date: Available online 3 December 2019Source: Inorganic Chemistry CommunicationsAuthor(s): Vinod Kumar Vashistha, Anuj KumarAbstractThe Pt-based materials were considered to be the most promising catalysts for the oxygen reduction reaction (ORR) in fuel cell technology but poor abundance and prohibitive cost limit their further use. Herein, we designed and synthesized a novel MnN4 macrocyclic complex and its nanocomposite, MnN4@rGO, with reduced graphene oxide (rGO). Both the MnN4 complex and MnN4@rGO composite were characterized by using multiple spectroscopies. On the basis of spectral analysis, octahedral geometry was assigned to MnN4 complex. Relevant to their performance for ORR electrocatalysis, the composite MnN4@rGO showed significant good ORR performance (+0.91 V and +0.86 V, onset and formal potential, respectively). Further, the Mn3+/Mn2+ redox potential and its role as activity indicator for ORR were correlated to the low energy gap between HOMO of Mn metal ion and LUMO of dioxygen, leading to effective overlapping between Mn3+/Mn2+ and ORR onset potentials for 4e- ORR. The SCN- poison effect on the ORR active sites showed the establishment of the Mn3+ state that could anticipate the redox (Mn3+/Mn2+) process, and decrease in available active site for oxygen adsorption, ORR declined.Graphical abstract
Source: Inorganic Chemistry Communications - Category: Chemistry Source Type: research