Morphological Transformation of NiCoMoSeOx from Nanosheets to Nanorods for Enhanced Oxygen Evolution

Green hydrogen production via water electrolysis has emerged as a promising technology to address the environmental crisis and to achieve sustainability. However, the anodic oxygen evolution reaction (OER) of water electrolysis is kinetically sluggish, which requires the development of highly efficient catalysts to materialize this technology. Herein, we report the facile synthesis of two-dimensional NiCoMoSeOx nanosheets, which can be further transformed into one-dimensional nanorods. Structural characterizations confirm the existence of amorphous and crystalline domains in the nanosheets while the nanorods feature high crystallinity. The progressive nanosheets-to-nanorods transformation was also accompanied with composition variation and further oxidation. Excitingly, when employed as catalysts for alkaline OER, the nanorods exhibit a dramatic overpotential drop of 123 and 158 mV at 10 and 200 mA cm–2, respectively, relative to the nanosheet counterpart. Moreover, the nanorods also exhibit superior durability than the nanosheets at various current density and could largely maintain its performance for 200 h at 300 mA cm‒2. In situ spectroscopic analysis confirms the critical role of low-valence Mo species in suppressing the Se leaching from nanorods, which greatly stabilizes the structure for improved durability. This work offers an effective approach to produce nanorods via structural transformation, together with valuable insights into the structure-performance relation for enhanced electrocatalysis.