In the current era of green energy adoption for reaching the zero-carbon target, the mobility sector is extensively working together to use hydrogen as a major source of energy, especially in vehicles with long range requirements. For this, Proton Exchange Membrane Fuel Cells (PEMFC) are employed to convert the chemical energy of hydrogen back into electricity. Acceptability of PEMFC in the automotive field mostly depends on system efficiency, durability & cost of the FC stack. In PEMFC, the bipolar plate (BPP) is a critical component of the system, which realizes the transport of gases to the electrodes, evacuates reactant product water and ensures electrical current collection. In some applications, graphite is used as material for bipolar plates due to good chemical stability and corrosion resistance, whereas it is also a rather brittle material with some manufacturing challenges. In mobile applications, metallic bipolar plates are widely used, as they allow for a significantly higher power density of the stack and have good mechanical strength & electric conductivity. Metallic bipolar plates usually feature a protective coating to improve the durability of the system. In this paper, the role of bipolar plates is discussed, and different coating materials are evaluated for performance & cost. An in-house testing strategy is defined to validate coated metallic bipolar plates, which are tested under various operating conditions. Subsequently, test results are discussed to check the improvement of using noble metal free material over available PGM (Platinum Group Metal) coating materials.

Paired electrolysis offers an auspicious strategy for the generation of high-value chemicals, at both the anode and cathode, in an integrated electrochemical reactor. Through efficient electron utilization, routine product misuse at overlooked electrodes can be prevented. Here, an original paired electrosynthetic system is reported that can convert CO2 to ethylene (C2H4) at the cathode, and water to hydrogen peroxide (H2O2) at the anode under a single pass of electric charge. Amongst various investigated copper (Cu) nanomorphologies, the bespoke mixed Cu nanowire/nanoparticle catalyst recorded a peak C2H4 Faraday efficiency (FE) of 60% following 370 h of electrolysis at 200 mA cm(-2), while the tailored boron-doped diamond (BDD) anode accumulated an unprecedented approximate to 1% w/w of H2O2 in 4 m K2CO3 upon applying 300 mA cm(-2) for 10 h. When paired, the dual C2H4-H2O2 electrochemical cell attains a combined FE of 120% for 50 h at 200 mA cm(-2), a combined energy efficiency (EE) of 69%, and a 50% decrease in the overall electrical energy consumption (EEC) compared to the individual electrosynthesis of C2H4 and H2O2.

The electrochemical reduction of CO2 continues to see significant interest as a viable means of both producing important chemical materials and lowering carbon emissions. The primary challenge to making this process economically viable is the design of catalyst, electrode and reactor components that can selectively produce just one of the many possible CO2 reduction products. In this work, we report the use of hydrophobic 1-octadecanethiol coatings at copper coated gas diffusion electrodes to enhance the production of ethylene. This thiol coating gives a substantial increase in the production of ethylene at low current densities as well as a change in the rate determining step, as indicated by the substantial reduction in the Tafel slope. The observed changes to the CO2 reduction reaction indicate that the thiol layer provides a triphasic interface within the gas diffusion electrode catalyst layer.

CO2 reduction is a rapidly expanding area, and a key part of the global mission to reduce carbon emissions and lessen our impact on our environment. The CO2 reduction reaction (CO2RR) offers a synthetic route to a number of key materials, such as methane,[1] ethylene,[2] formate[3] and carbon monoxide.[4] This provides a two-fold environmental benefit, since CO2 could be captured from industrial processes rather than being released into the environment, and then used to produce a material that would usually be sourced from fossil fuels. Much work has been dedicated to the CO2RR at copper electrodes thanks to its ability to produce C2 species such ethylene with reasonable selectivity. Additional advances come from using gas diffusion electrodes (GDEs), which circumvents issues around the low solubility of CO2 in aqueous electrolytes. However, the currently attainable selectivity is not yet sufficient for practical applications. The outflow from CO2RR reactors contains mixtures of a number of possible CO2RR products, along with a substantial amount of H2 formed by water reduction at the same applied potentials. Here, we improve the selectivity of copper GDEs towards ethylene using Polymers with Intrinsic Microporosity (PIMs). These PIMs can be easily drop-cast onto the GDE surface, forming a microporous layer at the catalyst – electrolyte interface. The microporous structure stores gases in a triphasic interface at the electrode surface,[5] which has previously been shown to improve catalyst activity towards oxygen reduction.[6] We show that the introduction of a PIMs triphasic interface to copper GDEs substantially improves the performance of the CO2RR towards ethylene. This is evidenced by an increased Faradaic efficiency, increased GDE stability and shift in the reduction wave to lower overpotentials. The impact of the PIMs is significantly dependent on the loading at the catalyst surface, with thin PIMs layers enhancing performance, but thicker PIMs layers having a surprisingly detrimental effect. This work acts as a proof of concept, demonstrating that triphasic interfaces can enhance the activity of GDEs for CO2RR towards ethylene production. References: 1. Y. Hori, H. Wakebe, T. Tsukamoto, O. Koga, Surf. Sci. 1995, 335, 258-263. 2. C.-T. Dinh, T. Burdyny, M. G. Kibria, A. Seifitokaldani, C. M. Gabardo, F. P. García de Arquer, A. Kiani, J. P. Edwards, P. De Luna, O. S. Bushuyev, C. Zou, R. Quintero-Bermudez, Y. Pang, D. Sinton, E. H. Sargent, Science 2018, 360, 783-787. 3. S. Gao, Y. Lin, X. Jiao, Y. Sun, Q. Luo, W. Zhang, D. Li, J. Yang, Y. Xie, Nature 2016, 529, 68. 4. J. L. DiMeglio, J. Rosenthal, J. Am. Chem. Soc. 2013, 135, 8798-8801. 5. F. Marken, E. Madrid, Y. Zhao, M. Carta, N. B. McKeown, ChemElectroChem 2019, 6, 1-12. 6. E. Madrid, J. P. Lowe, K. J. Msayib, N. B. McKeown, Q. Song, G. A. Attard, T. Düren, F. Marken, ChemElectroChem 2019, 6, 252-259. Figure 1

CO2 reduction offers an attractive alternative green synthetic route for ethylene, especially where CO2 could be sourced from industrial exhausts and in combination with green power sources. However, practical applications are currently limited due to the unfortunately low selectivity of cathode materials towards ethylene. This work uses polymers with intrinsic microporosity (PIMs) to improve the performance of copper gas diffusion electrodes for CO2 reduction to ethylene. We report an improved selectivity and activity towards ethylene with the addition of a thin PIMs layer, which is seen as improved Faradaic efficiency, increased stability and a shift in the reduction to lower overpotential. This improvement is highly dependent on the thickness of the added polymer layer, with too thick a layer having a detrimental impact on the hydrophobicity of the gas diffusion layer. With a compromise in loading, PIMs can be used to enhance the activity and selectivity of catalysts for targeted CO2 reduction to ethylene.