Mimic of Ferroalloy To Develop a Bifunctional Fe–Organic Framework Platform for Enhanced Gas Sorption and Efficient Oxygen Evolution Electrocatalysis

It
is well-known that the formation of ferroalloy with the addition of
the second or third metal during the steel-making process usually
can improve the performance of the iron. Inspired by ferroalloy materials,
it is speculated that the pore environment, framework charge, and
catalytic properties of metal–organic frameworks (MOFs) could
be optimized dramatically via the introduction of ferroalloy-like
inorganic building blocks. However, different to ferroalloy, the accurate
integration of different metals into one MOF platform is still challenging.
Herein, taking advantages of the good compatibility for metals in
trigonal prismatic trinuclear cluster, a series of Fe-based alloy-like
[M3O­(O2C)6] motifs (M3 = Fe3, Fe1.5Ni1.5, Fe1.5Co1.5, Fe1.5Ti1.5, FeCoNi, and FeTiCo)
are successfully generated, which further lead to a robust Fe–MOF
material family (SNNU-5s). These multicomponent MOFs not only provide
a good chance to explore the impact of pore environment on gas adsorption/separation
but also offer an opportunity to the efficient electrocatalytic reaction
directly. Accordingly, compared with the SNNU-5-Fe parent structure,
the pore characters of heterometallic SNNU-5 MOFs are clearly regulated
by the type of alloy-like building blocks. SNNU-5-FeTi displays more
superior gas separation performance for CO2/CH4, C2H2/CH4, C2H4/CH4, and C2H2/CO2 gas
mixtures. What is more, benefited from the multimetallic active sites
and their catalytic synergy, FeCoNi-ternary alloy-like cluster-based
SNNU-5 MOF material exhibits an exceptional oxygen evolution reaction
activity in aqueous solution at pH = 13, which delivers a low overpotential
(ηj=10 = 317 mV), a fast reaction
kinetics (Tafel slope = 37 mV dec–1), and excellent
catalytic stability. This facile multialloy-like building block strategy
holds promise to accurately design and improve the performance of
MOFs, as well as open an avenue to understand the related mechanisms.