Lattice confinement of cerium dopants via quenching enables d-band center engineering for high-performance anion exchange membrane water electrolyzers

A metallic salt solution quenching strategy enables lattice-confined Ce doping in Fe 9 S 10 /FeS nanoflowers, overcoming surface adsorption limitations. • Quenching-induced grain boundaries and lattice strain narrow the Fe d -band width and downshift the d -band center, optimizing oxygen intermediate adsorption. • The optimized electronic structure lowers the OER rate-determining energy barrier from 2.22 eV to 1.82 eV, achieving an overpotential of 274 mV and 300 h AEMWE stability. Lattice confinement of large-radius cerium enables atomic-level electronic modulation for oxygen evolution reaction (OER) electrocatalysts in anion exchange membrane water electrolyzer (AEMWE) applications but remains challenging. Herein, a metallic salt solution quenching strategy achieves lattice-confined cerium doping in iron sulfide composite nanoflowers (Fe 9 S 10 /FeS). The ultrafast cooling generates abundant grain boundaries and lattice strain, which collectively reduce Fe Fe orbital overlap, narrow the Fe d -band width, and shift the d -band center upward. These electronic modifications consequently optimize the adsorption energetics of oxygen-containing intermediates on the pristine Fe 9 S 10 /FeS surface, mitigating their excessively strong binding. According to density functional theory (DFT) calculations, the energy barrier for the rate-determining step is reduced from 2.22 eV to 1.82 eV. Consequently, the cerium-doped iron sulfide catalyst (Ce-FeS-4th) exhibits a low overpotential of 274 mV at 10 mA cm −2 and a Tafel slope of 68 mV dec −1 . An AEMWE using this anode achieves 1.0 A cm −2 at 2.48 V and operates stably for over 300 h. Overall, this work establishes quenching-induced lattice confinement as a versatile paradigm for d -band center engineering in advanced electrocatalysts. Download: Download high-res image (81KB) Download: Download full-size image