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. 2024 Nov 19;14(22):1849.
doi: 10.3390/nano14221849.

Free-Standing Carbon Nanofiber Films with Supported Cobalt Phosphide Nanoparticles as Cathodes for Hydrogen Evolution Reaction in a Microbial Electrolysis Cell

Gerard Pérez-Pi  1 , Jorge Luque-Rueda  2 , Pau Bosch-Jimenez  2 , Eduard Borràs Camps  2 , Sandra Martínez-Crespiera  1
Affiliations

Free-Standing Carbon Nanofiber Films with Supported Cobalt Phosphide Nanoparticles as Cathodes for Hydrogen Evolution Reaction in a Microbial Electrolysis Cell

Gerard Pérez-Pi et al. Nanomaterials (Basel). .

Abstract

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H2) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have been prepared by means of an up-scalable electrospinning process followed by a thermal treatment under controlled conditions. The produced cobalt phosphide-supported CNF films show to be nanoporous (pore volume up to 0.33 cm3 g-1) with a high surface area (up to 502 m2 g-1) and with a suitable catalyst mass loading (up to 0.49 mg cm-2). Values of overpotential less than 140 mV at 10 mA cm-2 have been reached for the HER in alkaline media (1 M KOH), which demonstrates a high activity. The high electrical conductivity together with the mechanical stability of the free-standing CNF films allowed their direct use as cathodes in a MEC reactor, resulting in an exceptionally low voltage operation (0.75 V) with a current density demand of 5.4 A m-2. This enabled the production of H2 with an energy consumption below 30 kWh kg-1 H2, which is highly efficient.

Keywords: carbon nanofiber (CNF); cathodes; cobalt phosphide; electrocatalyst; electrospinning; free-standing films; hydrogen evolution reaction (HER); microbial electrolysis cells (MECs); nanoparticles.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Pictures of the nanofiber films before (left) and after (right) the thermal treatment.
Figure 2
Figure 2
XRD patterns of all CNFs samples including CoP, Co2P, and Co3O4 diffraction patterns.
Figure 3
Figure 3
XPS of Co2P@2h(165): (a) full spectrum, and (b) high resolution XPS spectra for C 1s, N 1s, P 2p, and Co 2p, respectively.
Figure 4
Figure 4
Raman spectra of the samples Co2P@2h(165) and Co2Pox@2h(110).
Figure 5
Figure 5
HRSEM and TEM images of the sample Co2P@2h(165) (above) and SAED pattern (below).
Figure 6
Figure 6
LSV curves (a) and Tafel plots (b) for CNFs samples compared to the Pt/C used as reference.
Figure 7
Figure 7
LSV performed at initial (straight lines) and after 1000 cycles (dotted lines) for Pt/C and Co2P@2h(140) electrodes.
Figure 8
Figure 8
MEC reactors for assessing cathodes performances (a) and scheme of functioning (b).
Figure 9
Figure 9
Polarization curves, j vs. V, (a) and electrode potentials followed up (b) for comparison of Co2P@2h(140) and Pt/C cathodes while operating in MEC reactors.
Figure 10
Figure 10
HRSEM images of Co2P@2h(140), after being operated in the MEC reactor.
See this image and copyright information in PMC

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