Introducing a Synergistic Ligand Containing an Exotic Metal in Metal-Organic Framework Nanoarrays Enabling Superior Electrocatalytic Water Oxidation Performance

Designing and fabricating well-aligned metal-organic framework nanoarrays (MOF NAs) with high electrocatalytic activity and durability for water oxidation at large current density remain huge challenges. Here the vertical NiFc-MOF NAs constructed from agaric-like nanosheets were fabricated by introducing a ligand containing an exotic Fe atom to coordinate with Ni ion using Ni(OH)(2) NAs as a self-sacrificing template. The NiFc-MOF NAs exhibited superior water oxidation performance with a very low overpotential of 161 mV at the current density of 10 mA cm (-2). Chronoamperometry was tested at an overpotential of 250 mV, which delivered an initial industrial-grade current density of 702 mA cm(-2) and still remained at 694 mA cm(-2) after 24 h. Furthermore, it possessed fast reaction kinetics with a small Tafel slope of 29.5 mV dec(-1). The superior electrocatalytic performance can be ascribed to the structural advantage of vertically grown agaric-like NAs and the synergistic electron coupling between Ni and Fe atoms, namely, electron transfer from Ni to Fe atoms in NiFc-MOF NAs. The exposed density and valence state of active Ni sites were synchronously increased. Furthermore, the energy barrier for the adsorption/desorption of oxygenated intermediates was ultimately optimized for water oxidation. This work provides a novelty orientation to accelerate electrocatalytic performance of MOF NAs by introducing self-sacrificing templates containing one metal and synergistic ligand containing dissimilar metal.

Automated summary

This research fabricates vertical NiFc-MOF NAs with well-aligned agaric-like nanosheets using a self-sacrificing template. The NiFc-MOF NAs exhibit superior electrocatalytic performance due to their vertically grown structure and synergistic electron coupling between Ni and Fe atoms.