Durable MRuOx direct seawater electrolysis enabled by the synergistic effect between p-block dopants and active site Ru

Abstract

Direct seawater electrolysis offers a promising solution to hydrogen energy industrialization while alleviating freshwater scarcity. However, the complex seawater environment poses severe challenges to the activity, selectivity and stability of catalysts. RuO₂ is recognized as a benchmark catalyst for the acidic oxygen evolution reaction (OER), demonstrating superior activity compared to IrO₂. However, its limited stability, which is inferior to IrO₂, hinders large-scale application. In this study, we have systematically designed 9 p-block element-doped RuO₂ (M–RuO₂) catalysts and screened 4 promising candidates with enhanced activity, selectivity and stability for direct seawater electrolysis using density functional theory (DFT). Among them, Te-doped RuO₂ demonstrates superior catalytic performance with a significantly reduced OER overpotential of 0.18 V, simultaneously suppressing the competing chloride oxidation reaction under seawater conditions. Furthermore, we have investigated the origin of catalytic activity and the impact of pH on activity and selectivity. Our findings reveal that the doping strategy suppresses the lattice oxygen mechanism, thereby improving the stability. Significantly, we have established a volcano-type relationship between the free energy barrier of the potential determining step (ΔG_PDS) of the investigated M–RuO₂ catalysts and the ratio of the dopant's electronegativity to its axial M–O bond length. This correlation unveils the fundamental link between the OER activity and the intrinsic properties of p-block elements. This work provides valuable theoretical insights for designing and developing advanced catalysts for direct seawater electrolysis.