Understanding the Role of Varying Ti3C2Tx MXene in Ni/Ti3C2Tx for the Oxygen Evolution Reaction

The current state-of-the-art catalysts for the oxygen evolution reaction (OER) in an anion exchange membrane (AEM) electrolyser are not efficient enough to surpass green H₂ produced by other electrolyser technologies, such as Proton Exchange Membrane (PEM) electrolysers. One reason for this is due to the AEM catalysts not being active enough and lacking long-term stability. In this work, we combine Ni based material with Ti₃C₂T_x MXene at different loadings (1, 5 and 10 %) to understand the effect of the MXene on the OER activity and stability. Our results show that the amount of MXene not only affects the OER performance, but the materials surface is also altered. Interestingly, the Ti₃C₂T_x is still present in the bulk for all composites but the surface of the composites contains different amounts of oxidized Ti₃C₂T_x i.e. TiO₂. The optimum material in this study for the OER is the NiO_x/1 %Ti₃C₂T_x which can be rationalized by the lower Ti/Ni ratio in the starting materials hence producing less overall surface TiO₂ during OER. Additionally, when the pure NiO_x and the 1 % Ni-Ti₃C₂T_x are compared by operando Raman spectroscopy, the NiO_x/1 %Ti₃C₂T_x exhibits β-NiOOH at lower overpotentials, which is known to be present for efficient OER on Ni materials.