Ultraviolet-Induced Bi-gradient Gas Diffusion Electrode for High-Performance Fuel Cells

The high power density of fuel cells is attributed to the synergetic effect associated with the superior oxygen reduction reaction (ORR) electrocatalysts and rational cathode structure, which can efficiently enhance the electrochemical process of the sluggish cathodic reaction. On the basis of our previous works about the ORR electrocatalysts of Ni/N-doped carbon-supported Pt nanoparticles, we develop an in situ ultraviolet-induced method to prepare a bi-gradient gas diffusion electrode (GDE) involving gradient Pt deposition (Pt concentrations increasing first and then decreasing from the proton exchange membrane side to the carbon paper side) in the catalyst layer and gradient hydrophobicity (high-hydrophobic side near the catalyst layer and low-hydrophobic side near the gas flow channel) in the gas diffusion layer (g-CL/g-GDL). Owing to the enhancement of the electrochemical process, the bi-gradient g-CL/g-GDL shows superior performance with large power densities compared to the non-gradient or single-gradient GDE. The finite element calculation results demonstrate that the improved performance of g-CL/g-GDL was due to the balance of reactant (oxygen and proton) concentration at the highly reactive region and the rapid departure of products (water) simultaneously.