High Catalytic Selectivity of Electron/Proton Dual-Conductive Sulfonated Polyaniline Micropore Encased IrO2 Electrocatalyst by Screening Effect for Oxygen Evolution of Seawater Electrolysis

Abstract

Acidic seawater electrolysis offers significant advantages in high efficiency and sustainable hydrogen production. However, in situ electrolysis of acidic seawater remains a challenge. Herein, a stable and efficient catalyst (SPTTPAB/IrO₂) is developed by coating iridium oxide (IrO₂) with a microporous conjugated organic framework functionalized with sulfonate groups (-SO₃H) to tackle these challenges. The SPTTPAB/IrO₂ presents a -SO₃H concentration of 5.62 × 10⁻⁴ mol g⁻¹ and micropore below 2 nm numbering 1.026 × 10¹⁶ g⁻¹. Molecular dynamics simulations demonstrate that the conjugated organic framework blocked 98.62% of Cl⁻ in seawater from reaching the catalyst. This structure combines electron conductivity from the organic framework and proton conductivity from -SO₃H, weakens the Cl⁻ adsorption, and suppresses metal-chlorine coupling, thus enhancing the catalytic activity and selectivity. As a result, the overpotential for the oxygen evolution reaction (OER) is only 283 mV@10 mA cm⁻², with a Tafel slope of 16.33 mV dec⁻¹, which reduces 13.8% and 37.8% compared to commercial IrO₂, respectively. Impressively, SPTTPAB/IrO₂ exhibits outstanding seawater electrolysis performance, with a 35.3% improvement over IrO₂ to 69 mA cm⁻²@1.9 V, while the degradation rate (0.018 mA h⁻¹) is only 24.6% of IrO₂. This study offers an innovative solution for designing high-performance seawater electrolysis electrocatalysts.