Titanium Felt LGDL: titanium felt liquid gas diffusion layerLGDL: liquid gas diffusion layerCL: catalyst layer To reduce the interfacial resistivity between the LGDL and CL. There are two different surface treatments: sputter coating and thermal nitriding. Firstly, as shown in Figure 1, sputter coating is a physical vapor deposition (PVD) method of thin film deposition