The Application of 2D Graphitic Carbon Nitride (g-C3N4) and Hexagonal Boron Nitride (h-BN) in Low-Temperature Fuel Cells: Catalyst Supports, ORR Catalysts, and Membrane Fillers

Abstract

In recent years, two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) and hexagonal boron nitride (h-BN) have gained remarkable attention due to their resemblance to graphene. These materials have a wide range of applications in energy and other sustainable fields, including heterogeneous catalysis and photocatalysis. g-C₃N₄ and h-BN can play different roles in low-temperature fuel cells. They can be used as catalyst supports, catalysts for oxygen reduction, and membrane fillers. In this work, the application of pure and doped g-C₃N₄ and h-BN, alone or as composite materials, in low-temperature fuel cells is overviewed.

Keywords: catalysts; fuel cells; g-C3N4; h-BN; polymer membranes.

Scheme 1

(a) Triazine and (b) tri-s-triazine (heptazine) structures of g-C₃N₄. In these g-C₃N₄ structures, different nitrogen species (pyridine, amine, imine, and quaternary nitrogen) are present. (a) red dotted circle: triazine unit; (b) red dotted circle: heptazine unit. Reproduced from Ref. [1], copyright 2024, with permission from Elsevier.

Scheme 2

Schematic representation of h-BN nanomaterials: (a,b) h-BN nanosheets (h-BNNSs); (c,d) h-BN nanoribbons (h-BNNRs); (e,f) h-BN nanotubes (h-BNNTs); (g,h) h-BN fullerenes (h-BNFLs); (i) h-BN quantum dots (h-BNQDs). Reproduced from Ref. [2], copyright 2022, with permission from Elsevier.

Figure 1

Layout of a PEMFC. Reproduced from Ref. [4], copyright 2023, with permission from Elsevier.

Scheme 3

The use of g-C₃N₄ and h-BN in low-temperature fuel cells.

Figure 2

DEFC performance of Pt–Ru/MCN, Pt–Ru/t-MWCNTs, Pt–Ru/MWCNTs, and Pt–Ru/Vulcan-XC catalysts at 2 mg cm⁻² for catalyst loading on an anode at 100 °C. Reproduced from Ref. [26], copyright 2014, with permission from Elsevier.

Figure 3

Polarization curves of PEMFCs using (a) Pt/a-CB and (b) Pt/a-CB@pg-CN cathode catalysts for a different number of potential cycles. Reproduced from Ref. [29], copyright 2018, with permission from Elsevier.

Figure 4

(a) Steady-state polarization power-density curves; (b) discharge curves at 0.35 V of the DFFCs using Pd-CNNF-rGO and Pd-rGO as anodes at 60 °C. Reproduced from Ref. [39], copyright 2016, with permission from Elsevier.

Figure 5

(a) CV curves of Pt/p-BN and Pt/C in a N₂-saturated 0.1 M HClO₄ solution at a 50 mV s⁻¹ scan rate; (b) ECSA values; (c) LSV curves in O₂-saturated 0.1 M HClO₄ at a scan rate of 10 mV s⁻¹ and a rotating speed of 1600 rpm; (d) mass and specific activities of Pt/p-BN and Pt/C at 0.85 and 0.90 V reproduced from Ref. [43], copyright 2020, with permission from Elsevier.

Figure 6

Polarization curves of PEMFCs and AFCs with g-CN-CNF-700 and Pt/C cathode catalysts. (a) PEMFC operated at 80 °C; (b) AFC operated at 50 °C. Figures in the background are cross-sectional FE-SEM images of the g-CN-CNF-based MEAs. Reprinted from Ref. [73], Kim et al. Sci. Rep. 2015, 5, 8376. https://creativecommons.org/licenses/by/4.0/ (accessed on 17 April 2025).

Figure 7

Comparison of the polarization curves of g-C₃N₄, FSCN-NS, and Pt/C at 1600 rpm in O₂-saturated electrolyte at 10 mV s⁻¹ in an alkaline (a) and acid (b) media. Reproduced from Ref. [77], copyright 2019, with permission from Elsevier.

Figure 8

(a) CV curves of Cu-g-C₃N₄ and g-C₃N₄ before and after the addition of 1 M CH₃OH; (b) chronoamperometry (CA) of Cu-g-C₃N₄ and Pt/C in O₂-saturated 0.1 M KOH at 0.57 V with 1 M CH₃OH added after 800 s; (c) CA of Cu-g-C₃N₄ and Pt/C at 0.57 V in O₂-saturated KOH solution at 1600 rpm; (d) ORR polarization curves of Cu-g-C₃N₄ at 1600 rpm with 10 mV⁻¹ before and after stability. Reproduced from Ref. [80], copyright 2019, with permission from Elsevier.

Figure 9

Dependence of the current density at 0.3 V and the fraction of H₂O produced on Au, BNNS/Au, Au-BNNS/Au, and Pt electrodes. Reproduced from Ref. [96], copyright 2016, with permission from Elsevier.

Figure 10

(a) CV curves of h-BN/Cu/CNT in O₂-saturated and Ar-saturated 0.1 M KOH. (b) LSV curves and (c) Tafel plots of h-BN/Cu/CNT, h-BN/Cu, Cu/CNT, and Pt/C catalysts in O₂-saturated 0.1 M KOH. Reproduced from Ref. [115], copyright 2023, with permission from Elsevier.

Figure 11

Polarization and power density curves of PEMFCs with (a) SPEEK, SR0, and SR2 membranes at 50 RH% and (b) SR2 and Nafion117 membranes at 75 RH%. Reproduced from Ref. [132], copyright 2022, with permission from Elsevier.

Figure 12

Polarization and power density curves of PEMFCs with SPAES and SPAES/PCN-7.5 membranes at 80 °C under (a) 100 RH% and (b) 60 RH% before and after the durability test. Reproduced from Ref. [141], copyright 2024, with permission from Elsevier.