Self-supported non-noble metal binary electrocatalysts for alkaline overall water splitting: Synergistic enhancement of hydrogen and oxygen evolution

The practical application of alkaline water electrolysis relies on developing durable, self-supported non-noble metal electrodes that eliminate the need for polymeric binders and costly porous transport layers. In this work, an electrodeposition strategy is used to construct binder-free NiCo nanoflower arrays for the hydrogen evolution reaction (HER) and NiFe hydroxide nanosheet arrays for the oxygen evolution reaction (OER) directly on nickel mesh (NM) substrates. Systematic investigations reveal that the morphological architecture of NiCo 3 /NM nanoflowers and Ni 1.5 Fe(OH) 2 -PN@NM nanosheets significantly enhances the electrochemically active surface area and facilitates rapid mass transport. Concurrently, electronic modulations are identified, namely weakened Ni-H bonding in NiCo 3 /NM and electron transfer between Ni and Fe in NiFe hydroxide, which optimize intrinsic kinetics and yield lower Tafel slopes of 37.73 mV·dec -1 and 49.02 mV·dec -1 , respectively. Leveraging their self-supported structural integrity, both electrodes exhibit exceptional durability at high current densities. Notably, an alkaline electrolyzer assembled using these two self-supported electrodes requires a cell voltage of only 1.58 V to deliver 100 mA·cm -2 and maintains robust long-term stability. These results demonstrate that the synergistic optimization of morphology and electronic structure, combined with the mechanical robustness of the self-supported architecture, substantially enhances the electrocatalytic performance of non-noble metal catalysts for next-generation anion exchange membrane water electrolyzers.