Sr‐induced Fermi Engineering of β‐FeOOH for Multifunctional Catalysis

Abstract Designing a multifunctional electrocatalyst to produce H 2 from water, urea, urine, and wastewater, is highly desirable yet challenging because it demands precise Fermi‐engineering to realize stronger π ‐donation from O 2 p to electron(e − )‐deficient metal (t 2g ) d ‐orbitals. Here a Sr‐induced phase transformed β ‐FeOOH/ α ‐Ni(OH) 2 catalyst anchored on Ni‐foam (designated as pt ‐NFS) is introduced, where Sr produces plenteous Fe 4+ (Fe 3+ → Fe 4+ ) to modulate Fermi level and e − ‐transfer from e – ‐rich Ni 3+ (t 2g )‐orbitals to e – ‐deficient Fe 4+ (t 2g )‐orbitals, via strong π ‐donation from the π‐symmetry lone‐pair of O bridge. pt ‐NFS utilizes Fe‐sites near the Sr‐atom to break the H─O─H bonds and weakens the adsorption of *O while strengthening that of *OOH, toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Invaluably, Fe‐sites of pt ‐NFS activate H 2 ‐production from urea oxidation reaction (UOR) through a one‐stage pathway which, unlike conventional two‐stage pathways with two NH 3 ‐molecules, involves only one NH 3 ‐molecule. Owing to more suitable kinetic energetics, pt ‐NFS requires 133 mV (negative potential shift), 193 mV, ≈1.352 V, and ≈1.375 V versus RHE for HER, OER, UOR, and human urine oxidation, respectively, to reach the benchmark 10 mA cm −2 and also demonstrates remarkable durability of over 25 h. This work opens a new corridor to design multifunctional electrocatalysts with precise Fermi engineering through d‐band modulation.