open access publication

Article, 2023

Moderate heat treatment of CoFe Prussian blue analogues for enhanced oxygen evolution reaction performance

Journal of Energy Chemistry, ISSN 2095-4956, Volume 78, Pages 476-486, 10.1016/j.jechem.2022.11.050

Contributors

Diao, Fangyuan [1] Kraglund, Mikkel Rykaer 0000-0002-1229-1007 [1] Cao, Huili 0000-0001-8632-0969 [1] Yan, Xiaomei 0000-0003-1882-4713 [1] Liu, Pei [1] Engelbrekt, Christian 0000-0003-3679-3666 (Corresponding author) [1] Xiao, Xinxin 0000-0002-0240-0038 (Corresponding author) [1] [2]

Affiliations

  1. [1] Technical University of Denmark
    2. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
  2. [2] Aalborg University
    3. [NORA names: AAU Aalborg University; University; Denmark; Europe, EU; Nordic; OECD]

Abstract

Prussian blue analogues (PBAs) with inherent ordered structures and abundant metal ion sites are widely explored as precursors for various electrochemical applications, including oxygen evolution reaction (OER). Using a range of characterization techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), this work discloses the process of replacement of K+ by NH4 + in the interstitial spaces of the CoFe PBA by a hot aqueous urea solution, which influences the transformation of PBAs under further heat treatment and the OER performance of the derivatives. After heat treatment at 400 °C under Ar flow, high-resolution transmission electron microscopy (HRTEM) images reveal that CoFe alloy nanoparticles grew on the crystalline cubes of CoFe PBA with K+, while CoFe PBA cubes with NH4 + become amorphous. Besides, the derivative of CoFe PBA with NH4 + (Ar-U-CoFe PBA) performs better than the derivative of CoFe PBA with K+ (Ar-CoFe PBA) in OER, registering a lower overpotential of 305 mV at 10 mA cm−2, a smaller Tafel slope of 36.1 mV dec−1, and better stability over a testing course of 20 h in 1.0 M KOH. A single-cell alkaline electrolyzer, using Ar-U-CoFe PBA and Pt/C for the anodic and cathodic catalyst, respectively, requires an initial cell voltage of 1.66 V to achieve 100 mA cm−2 at 80 °C, with negligible degradation after 100 h.

Keywords

Ar flow, CoFe, CoFe Prussian blue analogues, CoFe alloy nanoparticles, FT-IR, Fourier transform infrared spectroscopy, K+, NH4, Prussian blue analogues, Pt/C, Tafel, Tafel slope, X-ray, X-ray diffraction, X-ray photoelectron spectroscopy, alkaline electrolyzer, alloy nanoparticles, analogues, applications, aqueous urea solutions, catalyst, cathode catalyst, cell voltage, characterization, characterization techniques, cm-2, course, crystalline cubes, cube, degradation, derivatives, diffraction, dispersive spectroscopy, electrochemical applications, electrolyzer, electron microscopy, energy, energy dispersive spectroscopy, enhanced oxygen evolution reaction performance, evolution reaction, flow, heat, heat treatment, high-resolution transmission electron microscopy, images, infrared spectroscopy, initial cell voltage, interstitial space, ion sites, metal ion sites, microscopy, moderate heat treatment, nanoparticles, overpotential, oxygen, oxygen evolution reaction, oxygen evolution reaction performance, performance, photoelectron spectroscopy, precursor, process, reaction, reaction performance, replacement of K+, sites, slope, solution, space, spectroscopy, stability, technique, test, test course, transformation, transmission electron microscopy, treatment, urea solution, voltage

Funders

  • China Scholarship Council

Data Provider: Digital Science

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