The comprehensive understanding of intrinsic contribution of nickel foam as a conductive substrate in water splitting

Using nickel foam as a substrate for an electrocatalyst to report overpotential in a manuscript is a popular method in electrochemical testing or water-splitting i.e., the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). However, use of coated Nickel foam as substrate methodology is, in essence, not reasonable for studying the intrinsic chemistry difference of electrocatalysts. To assess water-splitting devices, Ni-foam is a valid substrate if nanoparticles are grown uniformly; however, when drop-casted ink methodology is used or there is inhomogeneous growth of nanoparticles, it becomes difficult to determine whether a particular electrocatalyst is intrinsically active or not. In order to gain a rational understanding of the electrochemical activity and overpotential findings of a specific catalyst, it is essential to recognize the limitations of Ni-foam in reflecting its intrinsic role in electrocatalytic activity. In this study, the same catalyst was drop-casted on three different substrates, namely glassy carbon electrode (GCE), carbon fiber paper (CFP) and nickel foam (NF). It was observed that electrochemical results, such as overpotential, Tafel slope, turnover frequency, and others, varied significantly between NF and CFP or GCE. Therefore, it is concluded that NF should not be preferred as a conductive substrate during electrochemical testing (ET). On the contrary, other neutral substrates like CFP and GCE should be employed.