Isomorphous Heterometallic Mn/Zn/Co‐CPs as Robust Photoelectrocatalysts for Water Oxidation: Structural and Performance Insights

ABSTRACT The cooperative effects between different metal centers play a crucial role in photoelectrocatalytic applications. Therefore, the design and synthesis of heterometallic coordination polymers (CPs) have become a significant research direction. Herein, we report the solvothermal synthesis and characterization of three novel isomorphous heterometallic CPs, namely {[M 1 M 2 (H 2 O) 6 (DODDA)]·4H 2 O} n ( SNUT‐42‐MnZn , M 1 M 2 = MnZn; SNUT‐42‐CoZn , M 1 M 2 = CoZn; SNUT‐42‐CoMn , M 1 M 2 = CoMn), based on the tetracarboxylic ligand H 4 (DODDA) (1‐(3,5‐dicarboxyphenyl)‐4‐oxo‐1,4‐dihydropyridazine‐3,5‐dicarboxylic acid). Single‐crystal X‐ray diffraction analysis indicates that all three compounds adopt identical crystal structures, characterized by a distinctive one‐dimensional ladder‐type double‐chain framework. The photoelectrocatalytic performance varied significantly among the three compounds, as evidenced by their oxygen evolution reaction (OER) activities— SNUT‐42‐CoMn exhibiting the lowest overpotential (η = 107 mV at 10 mA cm −2 ) and the smallest Tafel slope (135.41 mV dec −1 ) within the series, suggesting favorable reaction kinetics among the prepared catalysts. Mott‐Schottky analysis confirms n‐type semiconductor behavior with bandgap energies of 2.34 eV, 2.35 eV, and 2.41 eV correlating with photocurrent densities of 1.26, 1.42, and 1.71 mA cm −2 achieved at 1.23 V vs. RHE, respectively. Thermal gravimetric analysis highlights stability up to 300°C, with dehydration mass losses matching theoretical values. The synergistic interplay between redox‐active metal pairs enhances carrier separation, as evidenced by PL quenching and EIS data, positioning these materials as robust candidates for solar‐driven water oxidation.