Symmetry-breaking CoN3S1 centers enable inert chloride ion adsorption for facilitating self-driven overall seawater splitting

Abstract

A self-driven seawater splitting system could efficiently produce hydrogen from abundant seawater. However, high Cl⁻ concentrations in seawater lead to catalyst corrosion and deactivation, impairing performance in the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Here, we adopted single-atom Co-N-C-based catalysts, in which the electronic structure around the central Co site can be controlled and adjusted at an atomic level. Experimentally, the target N and S co-doped hollow carbon sphere (Co-N/S-HCS) catalyst, featuring asymmetric Co-N₃S₁ sites, shows excellent ORR/OER/HER performance. By employing density functional theory and molecular dynamics simulations of real-time simulations, we reveal that the S doped in the asymmetric Co-N₃S₁ model leads to a customized electronic structure around the central Co site, enabling weakened adsorption of the corrosive Cl⁻ and excellent ORR/OER/HER activities. Moreover, the seawater-based Zn-air batteries (S-ZABs) assembled by the Co-N/S-HCS deliver a cycling performance exceeding 650 h, and the overall seawater splitting system can run continuously for 1,100 h.