Functionalized and Platinum-Decorated Multi-Layer Oxidized Graphene as a Proton, and Electron Conducting Separator in Solid Acid Fuel Cells

Abstract

In the present article, electrodes containing a composite of platinum on top of a plasma-oxidized multi-layer graphene film are investigated as model electrodes that combine an exceptional high platinum utilization with high electrode stability. Graphene is thereby acting as a separator between the phosphate-based electrolyte and the platinum catalyst. Electrochemical impedance measurements in humidified hydrogen at 240 °C show area-normalized electrode resistance of 0.06 Ω·cm−2 for a platinum loading of ∼60 µgPt·cm−2, resulting in an outstanding mass normalized activity of almost 280 S·mgPt−1, exceeding even state-of-the-art electrodes. The presented platinum decorated graphene electrodes enable stable operation over 60 h with a non-optimized degradation rate of 0.15% h−1, whereas electrodes with a similar design but without the graphene as separator are prone to a very fast degradation. The presented results propose an efficient way to stabilize solid acid fuel cell electrodes and provide valuable insights about the degradation processes which are essential for further electrode optimization.

Ultra-Low Loading of Iron Oxide and Platinum on CVD-Graphene Composites as Effective Electrode Catalysts for Solid Acid Fuel Cells

“…While the iron ions NPs are undesired for many applications and considered as contamination [52], they exhibit catalytic activity toward hydrogen electrooxidation and high stability on the CVD-graphene material, even with direct contact to the cesium dihydrogen phosphate (acid media) under anode SAFCs conditions. The through-plane proton/electron conductivity of the CVD-graphene samples is inversely proportional to the number of layers of CVD-graphene film used [14]. Thick layer CVD-graphene membranes hamper the hydrogen, proton, and electron diffusion, and thus, increase the ANR values [14].…”

“…The through-plane proton/electron conductivity of the CVD-graphene samples is inversely proportional to the number of layers of CVD-graphene film used [14]. Thick layer CVD-graphene membranes hamper the hydrogen, proton, and electron diffusion, and thus, increase the ANR values [14]. In terms of through-plane proton/electron conductivity, the optimal membranes to assess the electrochemical efficiency and stability of iron oxide nanoparticles during the SAFC process are monolayer CVD-graphene membranes (Supplementary Materials, Figure S1a,d).…”

“…In comparison to combustion engines, fuel cells are a more environmentally friendly alternative to fossil fuel-based energy sources, converting chemical energy directly and continuously into electrical energy, and vice versa, with high efficiency and low/or no pollutant emissions [1][2][3][4][5][6]. An intermediate temperature fuel cell, which is based on a new class of electrolytes called solid acid caesium dihydrogen phosphate (CsH 2 PO 4 , CDP), is cited as a promising solution to the energy crisis [7][8][9][10][11][12][13][14]. The unique characteristics of the CDP electrolyte present several challenges for the optimization of the solid acid fuel cell (SAFC), specifically in relation to the cathode microstructure.…”

Platinum deposition on functionalised graphene for corrosion resistant oxygen reduction electrodes

“…6 Functionalisation of the carbonaceous support can anchor the platinum particles to the surface, controlling both metal deposition and subsequent activity. Both covalent 7 and non-covalent 8 introduction of oxygen functionalities can provide sufficient interaction to increase the stability of the electrocatalyst on graphene. However, the nature of the functional group stabilising the Pt nanoparticle and the extent of functionalisation will affect the nanoparticle size and thus, the platinum efficiency.…”

“…6 Functionalisation of the carbonaceous support is used to anchor the platinum particles to the surface, controlling both deposition and subsequent evolution. One study showed that the presence of oxygen functionalities is important to efficiently anchor the particles to the carbon surface, thus achieving a higher platinum utilisation; 7 another work reported the exfoliation of graphite with 1-pyrenecarboxylic acid and how this moiety stabilised the Pt nanoparticles on the graphene layers in a homogeneous manner. 8 However, the nature of the functional group stabilising the Pt nanoparticle and the extent of functionalisation will affect the nanoparticle size and thus, on platinum efficiency.…”