“…As far as the investigation methods are concerned, the following approaches have been reported in the literature: (i) open circuit potential measurements [6][7][8][9][10][11][12][13][14], (ii) potentiostatic polarisation [6][7][8][9][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], (iii) polarisation resistance [26,30,31], (iv) linear-sweep voltammetry [6,32,33], (v) I-V and I-P curves as well as a limited number of life time tests in fuel cell assemblies [23,[34][35][36]. A few instances of compositional measurements on films formed on stainless steel have also been reported, based on XPS [18,29] and EDS [2,27,28]. Further characterisation of the surface resistivity of BP materials is sometimes carried out by resistance measurements under kn...…”