Design of Hierarchical Structured Catalysts: SnO2-Modified TiO2 Nanotube Arrays Enabling Ultra-Low Overpotential Acidic Oxygen Evolution Reaction

The construction of the strong oxid-support interaction (SOSI) between the support and the active component is crucial for regulating the atomic conTuration and electronic structure of the catalyst. In this study, the electrocatalytic oxygen evolution (OER) performance of IrO _x in acidic electrolyte was significantly improved by constructing titanium dioxide nanotube array (TNT) and SnO ₂ double intermediate layer. The overpotential of TNT/SnO ₂ /IrO _x at the current density of 10 mA cm ^-2 is 220 mV, which is 69 mV and 93 mV lower than that of directly loaded TNT/IrO _x (289 mV) and TNT/IrO ₂ (313 mV), respectively. In addition, the introduction of SnO ₂ significantly improved the stability of the catalyst, and after 100 h static chronopotentiometry (CP) test at the current density of 10 mA cm ^-2 , the potential change was only 18 mV, much lower than that of TNT/IrO ₂ (175 mV) and TNT/IrO _x (50 mV). Through in-depth surface morphology and structure analysis, it is found that IrO _x is anchored on the SnO ₂ meslayer and uniformly dispersed. At the same time, TNT array has strong interaction with IrO _x , and the addition of the intermediate layer SnO ₂ can effectively stabilize Ir from being reduced. The results showed that the synergistic effect of SnO ₂ and TNT significantly enhanced the catalytic activity of IrO _x . In summary, this study successfully developed an efficient and stable acidic OER catalyst through multistage interface engineering design, providing a new solution for the industrial application of low iridium supported catalysts.