Tailoring cobalt spinel oxide with site-specific single atom incorporation for high-performance electrocatalysis

Abstract

Universal incorporation of metals into cobalt spinel oxide (CSO) has emerged as a versatile and promising strategy to enhance catalytic performance. However, the uncontrolled reactivity of early transition metal and metalloid precursors with water has presented a significant challenge in achieving atomic-scale metal incorporation within CSO. This study presents a groundbreaking approach for the atomic-scale integration of diverse dopants, including Hf, Ta, W, Ti, Pd, Ga, and Ge, while elucidating the atomic stabilization sites for these metal cations within CSO. Notably, certain metals, such as Ta, W, and Ge exhibit greater stability at the surface rather than within the core of CSO, resulting in a Co2+-enriched surface that serves as a both catalytically active and protective shell. Exploiting these remarkable features, Ta-doped Co3O4 demonstrates the lowest overpotential, registering a mere 378 mV at 10 mA cm-2, while maintaining its catalytic activity for over 140 hours in acidic electrolyte. Ta5+ dopants tend to stabilize on the surface of Co3O4, significantly increasing the surface Co2+ species. This dopant-rich shell and the high density of surface Co2+ provide active and protective layers, resulting in high-performance in acidic OER.