1
|
Barrio J, Pedersen A, Sarma SC, Bagger A, Gong M, Favero S, Zhao CX, Garcia-Serres R, Li AY, Zhang Q, Jaouen F, Maillard F, Kucernak A, Stephens IEL, Titirici MM. FeNC Oxygen Reduction Electrocatalyst with High Utilization Penta-Coordinated Sites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2211022. [PMID: 36739474 DOI: 10.1002/adma.202211022] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 01/11/2023] [Indexed: 06/18/2023]
Abstract
Atomic Fe in N-doped carbon (FeNC) electrocatalysts for oxygen (O2 ) reduction at the cathode of proton exchange membrane fuel cells are the most promising alternative to platinum-group-metal catalysts. Despite recent progress on atomic FeNC O2 reduction, their controlled synthesis and stability for practical applications remain challenging. A two-step synthesis approach has recently led to significant advances in terms of Fe-loading and mass activity; however, the Fe utilization remains low owing to the difficulty of building scaffolds with sufficient porosity that electrochemically exposes the active sites. Herein, this issue is addressed by coordinating Fe in a highly porous nitrogen-doped carbon support (≈3295 m2 g-1 ), prepared by pyrolysis of inexpensive 2,4,6-triaminopyrimidine and a Mg2+ salt active site template and porogen. Upon Fe coordination, a high electrochemical active site density of 2.54 × 1019 sites gFeNC -1 and a record 52% FeNx electrochemical utilization based on in situ nitrite stripping are achieved. The Fe single atoms are characterized pre- and post-electrochemical accelerated stress testing by aberration-corrected high-angle annular dark field scanning transmission electron microscopy, showing no Fe clustering. Moreover, ex situ X-ray absorption spectroscopy and low-temperature Mössbauer spectroscopy suggest the presence of penta-coordinated Fe sites, which are further studied by density functional theory calculations.
Collapse
Affiliation(s)
- Jesús Barrio
- Department of Materials, Royal School of Mines, Imperial College London, London, SW7 2AZ, UK
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Angus Pedersen
- Department of Materials, Royal School of Mines, Imperial College London, London, SW7 2AZ, UK
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Saurav Ch Sarma
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Alexander Bagger
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Mengjun Gong
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London, W12 0BZ, UK
| | - Silvia Favero
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Chang-Xin Zhao
- Department of Chemical Engineering, Tsinghua University, 1 Tsinghua Road, Beijing, 100084, P. R. China
| | - Ricardo Garcia-Serres
- Chemistry and Biology of Metals Laboratory, CNRS, CEA, IRIG, University Grenoble Alpes, 17 Rue Des Martyrs, Grenoble, 38000, France
| | - Alain Y Li
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Qiang Zhang
- Department of Chemical Engineering, Tsinghua University, 1 Tsinghua Road, Beijing, 100084, P. R. China
| | - Frédéric Jaouen
- Institute of Molecular Chemistry and Materials Sciences, CNRS, ENSCM, University of Montpellier, 1919 route de Mende, Montpellier, 34293, France
| | - Frédéric Maillard
- Laboratory of Electrochemistry and Physico-Chemistry of Materials and Interfaces (LEPMI), CNRS, University Savoie Mont-Blanc, Grenoble-INP, University Grenoble Alpes, Grenoble, 38000, France
| | - Anthony Kucernak
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London, W12 0BZ, UK
| | - Ifan E L Stephens
- Department of Materials, Royal School of Mines, Imperial College London, London, SW7 2AZ, UK
| | - Maria-Magdalena Titirici
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai, Miyagi, 980-8577, Japan
| |
Collapse
|