CoMn-LDH@carbon nanotube composites: Bifunctional electrocatalysts for oxygen reactions

• Type: Article in International Scientific Journal
• Date: 2018

Authors

Marta F. P. Duarte (Author) Other; Inês M. Rocha (Author) Other; José Luís Figueiredo (Author) Other; Cristina Freire (Author) FCUP; Manuel Fernando R. Pereira (Author) FEUP

Journal

Title: Catalysis Today

Vol. 301

Pages: 17-24

ISSN: 0920-5861

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 46 Citations

Scopus - 47 Citations

Associated Projects

AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable North Region of Portugal2020

Other information

Authenticus ID: P-00N-7P6

DOI: 10.1016/j.cattod.2017.03.046

Abstract (EN): In the present work, a set of five Layered Double Hydroxides, LDH, containing Co and Mn derived electrocatalysts was prepared for the oxygen electrode, evaluating their performances in ORR and OER. A LDH with a Co/Mn ratio of 4, CoMn4, was the reference electrocatalyst of the set, presenting the typical hydrotalcite structure with a trace of MnCo2O4, with a surface area of 76 m(2) g(-1). HNO3 oxidized carbon nanotubes (CNT_HNO3) and CNT_HNO3 with a low content of carboxylic acids (CNT_HNO(3)tt350), were incorporated into the CoMn4 synthesis, obtaining CoMn4@CNT_HNO3 and CoMn4@CNT_HNO(3)tt350 with surface areas of 111 and 167 m(2) g(-1), respectively. According to X-ray diffraction (XRD), the oxide phase of CoMn4@CNT_HNO3 is composed by a mixture of LDH with MnCo2O4, while the low% COOH on the carbon surface promoted the synthesis of LDHs as the only oxide structure at CoMn4@ CNT_HNO(3)tt350. Moreover, after a thermal treatment of the latter electrocatalyst, the LDHs were totally converted into MnCo2O4. All electrocatalysts showed to have activity over both oxygen reactions when the KOH solution was saturated with O-2. A detailed ORR study showed that the LDH structures mixed with CoMn oxides, present at CoMn4@CNT_HNO3, play a relevant role in ORR, exhibiting an onset potential, E-ORR, of -0.274 V. On the other hand, CoMn4@CNT_HNO(3)tt350 led to a four-electron mechanism for ORR, similar to the Pt/C standard. The best OER potential (0.636 V) was also obtained for CoMn4@CNT_HNO(3)tt350. Regarding the oxygen electrode bifunctionality, a good balance between ORR and OER was observed for the CoMn4@CNT_HNO(3)tt350_N-2 composite.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8