La-Doped CoFe₂O₄/alk-MXene Hybrids for Boosted Overall Water Splitting via Interface Engineering

Abstract

This study reported the loading of a lanthanum (La)-doped CoFe₂O₄ spinel catalyst onto alkalized MXene. The La-doped CoFe₂O₄ electrocatalyst was prepared via in situ doping and growth. Importantly, the inherent stacking flexibility of MXene was exploited to engineer the interface. NaOH etching induced the formation of surface wrinkles, thereby mitigated the issue of layer re-stacking. Additionally, the etching process increased the surface density of -OH functional groups on the MXene surface, enabling these negatively charged groups to bind more readily with cations. As a result, the MXene’s affinity for hetero-bonding with transition metal compounds was enhanced. La doping was demonstrated to have enhanced intermediate adsorption/desorption capacity, attributed to La’s ability to facilitate electron transfer from Co to Fe, thereby increasing the electron density of Fe and improving catalytic performance. The electrocatalyst exhibited remarkable activity for both hydrogen evolution and oxygen evolution reactions, with overpotentials of 164 and 263 mV at − 10 and 10 mA cm⁻², respectively. Furthermore, the overall water-splitting system Maintained a low cell voltage, stabilized at 1.638 V at a current density of 10 mA cm⁻². In summary, La₀.₂CoFe₁.₈O₄/alkalized-MXene overcame the aforementioned challenges, demonstrated excellent bifunctional catalytic capabilities, and maintained high performance and stability. This work proposed a novel and practical strategy employing alkalized MXene as a substrate and incorporating rare earth elements into the spinel structure to enhance catalyst performance.

Graphical Abstract

La₀.₂CoFe₁.₈O₄/MX exhibits outstanding OER performance in alkaline environments; La doping of the spinel structure CoFe₂O₄ with rare-earth lanthanum.