Dual-fractal design of hierarchical RuO2/NiO heterojunction for efficient seawater electrooxidation under optical field

Abstract

fractal structure; heterojunction; photo-assisted electrocatalysis; seawater oxidation Photo-assisted electrocatalysis provides an effective approach to remarkably improve the performance of electrocatalytic reactions in seawater. However, the application of this technology requires the catalysts to exhibit high photo-responsiveness, efficient carrier transfer, and strong resistance to Cl–-induced corrosion. Moreover, the fundamental mechanisms that drive the performance enhancement in optical fields still need to be further investigated. This study presents a novel design of a dual fractal RuO2/NiO heterojunction with sheet-like fractal NiO support and branched fractal RuO2 load (denoted as RuO2(B)/NiO(S)), possessing the features of enhanced photogenerated carriers, efficient directed carrier transfer, and inhibition of Cl−-induced corrosion. In comparison to its single-fractal and non-fractal counterparts, RuO2(B)/NiO(S) exhibits significantly enhanced catalytic activity, superior durability, and morphological and chemical compositional stability during the photo-assisted oxygen evolution reaction (OER) in seawater. Both experiments and theoretical calculations indicate that the significant improvement in photo-assisted OER performance of RuO2(B)/NiO(S) results from the synergistic effects associated with dual fractal structures, which include more photogenerated carriers in the sheet-like fractal NiO support, rapid directed carrier transfer into the branched fractal RuO2 load, and its high resistance to Cl−-induced corrosion.