πMIDLINE HORIZONTAL ELLIPSISπ interaction directed 2D FeNi-LDH nanosheets from 2D Hofmann-MOFs for the oxygen evolution reaction

Layered double hydroxides (LDHs) have attracted much attention for the oxygen evolution reaction (OER) in electrochemical water splitting. In this work, we use a two-dimensional (2D) MOF transformation strategy to synthesize FeNi layered double hydroxides (FeNi LDHs). 2D FeNi Hofmann MOFs ([Fe(L)(2)Ni(CN)(4)]) with a similar structure but different ligands (L = py, ISOQ) are synthesized as precursors. Accordingly, hydrolysis transformation assisted by NaBH4 leads to the growth of 2D FeNi-LDH nanosheets from 2D Hofmann-MOFs. During hydrolysis, OH- ions preferentially attack the coordination bond of [Fe(L)(2)Ni(CN)(4)], which allows FeNi-LDHs to form quickly on the surface of 2D MOFs. This rapid conversion process can effectively avoid the self-accumulation of LDHs. The hydrogen bubbles produced by NaBH4 can also inhibit the self-stacking of LDHs, which expose ample active species for the OER. Meanwhile, the synergistic effect between Fe and Ni contributes to the outstanding OER performance of FeNi-py-LDH, which shows an overpotential of 238 mV at 10 mA cm(-2), a Tafel slope of 22 mV dec(-1) and an excellent stability for 15 h. This work provides a universal synthesis method for ultra-thin FeNi-LDHs, which avoids the self-stacking of nanosheets and offers new insights into the OER.

Automated summary

This study successfully synthesized FeNi layered double hydroxides (FeNi LDHs) with excellent OER performance using a two-dimensional MOF transformation strategy, providing a universal synthesis method that avoids self-accumulation.