Asymmetric CoN₃ P₁ Trifunctional Catalyst with Tailored Electronic Structures Enabling Boosted Activities and Corrosion Resistance in an Uninterrupted Seawater Splitting System.

Abstract

Employing seawater splitting systems to generate hydrogen can be economically advantageous but still remains challenging, particularly for designing efficient and high Cl^- -corrosion resistant trifunctional catalysts toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Herein, single CoNC catalysts with well-defined symmetric CoN₄ sites are selected as atomic platforms for electronic structure tailoring. Density function theory reveals that P-doping into CoNC can lead to the formation of asymmetric CoN₃ P₁ sites with symmetry-breaking electronic structures, enabling the affinity of strong oxygen-containing intermediates, moderate H adsorption, and weak Cl^- adsorption. Thus, ORR/OER/HER activities and stability are optimized simultaneously with high Cl^- -corrosion resistance. The asymmetric CoN₃ P₁ structure based catalyst with boosted ORR/OER/HER performance endows seawater-based Zn-air batteries (S-ZABs) with superior long-term stability over 750 h and allows seawater splitting to operate continuously for 1000 h. A self-driven seawater splitting powered by S-ZABs gives ultrahigh H₂ production rates of 497 μmol h^-1 . This work is the first to advance the scientific understanding of the competitive adsorption mechanism between Cl^- and reaction intermediates from the perspective of electronic structure, paving the way for synthesis of efficient trifunctional catalysts with high Cl^- -corrosion resistance.