Coordination Stabilization of Fe by Porphyrin-Intercalated NiFe-LDH Under Industrial-Level Alkaline Conditions for Long-Term Electrocatalytic Water Oxidation

The durable and economic electrocatalysts with high current density under industrial alkaline conditions are critical for advancing the industrial production of hydrogen energy by water electrolysis. The industrial highly alkaline electrolyte exacerbates the Fe dissolution of NiFe layered double hydroxide (NiFe-LDH), leading to the dramatic degradation of stability and activity. The NiFe-LDH intercalated Tetrakis(4-carboxyphenyl)porphyrin (TCPP) (NiFe-TCPP), 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) (NiFe-DOTA) and CO32- (NiFe-CO3) are fabricated respectively for electrocatalytic water oxidation under industrial alkaline conditions. In 10 m KOH, compared to NiFe-DOTA (335.0 mV) and NiFe-CO3 (499.2 mV), the resultant NiFe-TCPP exhibits the lowest overpotentials of 290.2 mV at 1000 mA cm-2. The NiFe-TCPP also operates continuously for 1000 h at 500 mA cm-2 with near-zero attenuation. The theoretical and experimental studies reveal that the strong coordination between conjugated carboxylate ligand TCPP and Fe of the laminate inhibits the Fe leaching by increasing the dissolution energy barriers to 4.29 eV and improving the self-healing ability, thus enhancing the stability. Furthermore, the charge redistribution induced by the strong coordination optimizes the d-band centers (-2.81 eV) and decreases the reaction energy barriers (1.47 eV), thereby increasing the catalytic activity. Industrial alkaline conditions of 10m KOH exacerbated the dissolution of Fe in NiFe-CO3 leading to a dramatic decrease in stability. Inhibition of Fe dissolution can be successfully achieved by intercalation of TCPP into NiFe-LDH, which resulted in the stable operation over 1000 h at 500 mA cm-2 and ultralow eta 1000 of 290.2 mV. image