Promoting electrocatalytic water oxidation via crafting Co–O–W bridge bonds on an amorphous core/shell NiCo-ZIF@POM catalyst

Abstract

The oxygen evolution reaction (OER) requires the development of a strong and efficient electrocatalyst due to its slow mechanism and high overpotential. Hence, we assembled POM and NiCo-ZIF-67 to obtain the amorphous hollow core–shell material NiCo-ZIF-67@POM (denoted as NiCo-ZIF@POM) with high catalytic activity. NiCo-ZIF@POM (1 : 3) presents a low overpotential (η ≈ 150 mV@10 mA cm⁻²), a small Tafel slope (100 mV dec⁻¹), and great stability for the OER in 1 M KOH solution. Theoretical calculations indicate that the excellent activity of NiCo-ZIF@POM might be attributed to the charge rearrangement due to the interaction between Co and W. In addition, the low electronegativity of P and the high oxidation state of W in POM could accelerate the rapid OH⁻ transfer and induce the intermediates to adsorb on the Co–O–W bridge bond conformation, which improves the performance of the catalytic OER. This study provides a new idea for the secondary assembly of POM and MOF materials.