Cobalt phosphotungstate-based composites as bifunctional electrocatalysts for oxygen reactions - Archive ouverte HAL Access content directly
Journal Articles Catalysts Year : 2022

Cobalt phosphotungstate-based composites as bifunctional electrocatalysts for oxygen reactions

(1, 2) , (1) , (1) , (3) , (1) , (1)
1
2
3

Abstract

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key reactions in energy-converting systems, such as fuel cells (FCs) and water-splitting (WS) devices. However, the current use of expensive Pt-based electrocatalysts for ORR and IrO$_2$ and RuO$_2$ for OER is still a major drawback for the economic viability of these clean energy technologies. Thus, there is an incessant search for low-cost and efficient electrocatalysts (ECs). Hence, herein, we report the preparation, characterization (Raman, XPS, and SEM), and application of four composites based on doped-carbon materials (CM) and cobalt phosphotungstate (MWCNT_N8_Co4, GF_N8_Co4, GF_ND8_Co4, and GF_NS8_Co4) as ORR and OER electrocatalysts in alkaline medium (pH = 13). Structural characterization confirmed the successful carbon materials doping with N and/or N, S, and the incorporation of the cobalt phosphotungstate. Overall, all composites showed good ORR performance with onset potentials ranging from 0.83 to 0.85 V vs. RHE, excellent tolerance to methanol crossover with current retentions between 88 and 90%, and good stability after 20,000 s at E = 0.55 V vs. RHE (73% to 82% of initial current). In addition, the number of electrons transferred per O$_2$ molecule was close to four, suggesting selectivity to the direct process. Moreover, these composites also presented excellent OER performance with GF_N8_Co4 showing an overpotential of 0.34 V vs. RHE (for j = 10 mA cm$^{-2}$) and jmax close to 70 mA cm$^{-2}$. More importantly, this electrocatalyst outperformed state-of-the-art IrO$_2$ electrocatalyst. Thus, this work represents a step forward toward bifunctional electrocatalysts using less expensive materials.
Fichier principal
Vignette du fichier
catalysts-12-00357.pdf (6.74 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

cea-03624074 , version 1 (30-03-2022)

Licence

Attribution - CC BY 4.0

Identifiers

Cite

Ndrina Limani, Inês Marques, Bruno Jarrais, António Fernandes, Cristina Freire, et al.. Cobalt phosphotungstate-based composites as bifunctional electrocatalysts for oxygen reactions. Catalysts, 2022, 12 (4), pp.357. ⟨10.3390/catal12040357⟩. ⟨cea-03624074⟩
32 View
12 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More