Hydrogen is a clean and sustainable energy carrier, which is important for the sustainable development of the society. Hydrogen fuel cells are the most important technology for converting the chemical energy in hydrogen into electricity. Yet, polymer electrolyte membrane fuel cells (PEMFC) utilize scarce and geopolitically problematic platinum (Pt) as a catalyst to promote the hydrogen oxidation reaction (HOR). Most studies on HOR, from the aspect of catalysts, concern the activity and stability, while only a few investigations study gas transport, which also affects the HOR rate and thus the overall efficiency of a fuel cell. Here, enlightened by lungs’ supply of oxygen to human with multistage bronchi and pulmonary alveoli, we have aimed to improve hydrogen gas diffusion at the catalyst layer (CL) by constructing multistage superaerophilic gas channels (MSGC) that are all open to the gas source and penetrate deep into CL, where catalysts and electrolytes are located and HOR takes place. The overall aim is to improve the overall efficiency while reducing the amount the precious Pt in the catalyst and thus achieving more sustainable conversion of chemical energy into electricity in PEMFCs.
The scientific goal of the HydrogenLung action is to construct lung-like MSGC for a hydrogen electrode of a fuel cell to accelerate hydrogen diffusion and thus promote the HOR. As shown in Figure 1a, one of the HydrogeLung action targets was to develop a procedure for synthesizing a catalyst with low Pt loading but high activity for promoting HOR using specific tungsten based nanoarray support. As shown in Figure 1b,the second target was to develop the wettability controlled gas channel structure for promoting gas transfer by utilizing the optimized Pt-on-tungsten electrocatalyst. As shown in Figure 1c, the ultimate goal was to integrate the developed and optimized electrode structure in a PEMFC setup to showcase its relevance by achieving similar or higher power density than with a commercial reference electrode but with lower precious Pt metal loading.
Hydrogen technologies are one of the key technologies in the ongoing Green Transition. Fuel cells convert the chemical bond energy of hydrogen into electricity with a relatively good efficiency and, importantly, without other emissions but water. Among the various fuel cell technologies, the PEMFC is the most attractive alternative for applications requiring high power and energy density alongside with operational flexibility, e.g. heavy duty vehicles. However, PEMFC, similar to many other Green Transition technologies, relay on utilizing metals extracted from non-renewable minerals. To enable sustainable Green Transition, we must develop these technologies so that they utilize efficiently these non-renewable precious metals so that their amount can be reduced - while still sustaining or improving energy efficient operation. Hence, the HydrogenLung action furthers Green Transition by introducing one approach to improve sustainability of PEMFCs. This approach can also be applied to other electrochemical devices with gaseous reactants, such as waste CO2 electrochemical valorization to chemicals.
