Self-activating Ti3AlC2 MAX phase - Ni/Ni–Al composite electrodes for hydrogen evolution in alkaline media

MAX phases are promising precursors for MXenes, but their behaviour as phases embedded in metallic electrodes for water electrolysis remains largely unexplored. This work explored the processing of two MAX phase-based composite electrodes as electrocatalysts for the hydrogen evolution reaction (HER) in strong alkaline media. Two electrode architectures were explored: i) the Ti 3 AlC 2 MAX phase (10 wt%) with varying the Al content in the initial powder mixture composition (Ti:Al:C = 2:1.5:1 to 2:4:1) co-pressed with Ni and ii) the Ti 3 AlC 2 MAX phase (30 wt%) in a porous Ni–Al intermetallic-rich matrix. After 4 days of chronoamperometric operation at −1.3 V vs. Hg|HgO, both electrodes showed progressive surface restructuring, including partial Al removal, increased porosity and surface roughness, resulting in a self-activation behaviour. MAX phase/Ni–Al composite electrodes exhibited superior mechanical integrity and electrochemical performance. A scaled-up 35 mm electrode tested under intermittent operation demonstrated stable performance, with current densities near 400 mA/cm 2 .