Transition-metal−organic frameworks (MOFs) have been regarded as one of the most intriguing electrocatalysts because of its low cost and diversity in functional organic groups and metal centers. Different from the common strategies of tuning the ratio of metal centers in multivariate MOFs, here, ultralow-content Fe 2 O 3 is decorated on the surface of monometallic Ni-MOF-74 based on the fast "phenol−iron (Fe)" surface reaction between Fe 2+ and the surface hydroxyl group in Ni-MOF-74. Benefiting from this flexible method, the Fe loading can be finely modulated and thus a series of Fe-decorated Ni-MOF-74 with different Fe contents are prepared. The optimized 0.6 wt % Fe 2 O 3 @Ni-MOF-74 with the Fe loading of 0.6 wt % only needs the overpotential of 264 mV to deliver 10 mA cm −2 , which obviously outperforms Fe-free Ni-MOF-74 (323 mV) and other Fe 2 O 3 @Ni-MOF-74 and is even superior to the commercial IrO 2 benchmark (300 mV). X-ray photoelectron spectroscopy results disclose that Fe decoration can obviously modulate the electronic structure of Ni center in Ni-MOF-74, thereby resulting in enhanced oxygen evolution reaction activity. This work opens up a new avenue to fabricate excellent MOF-based electrocatalysts for direct utilization in an electrocatalytic process.
Most studies are devoted to the use of metal–organic frameworks (MOFs) as templates to construct desirable electrocatalysts in situ by high‐temperature pyrolysis. The emergence of heterostructures invokes new opportunities to use the full potential of pristine MOFs as efficient catalysts in the oxygen evolution reaction (OER). Here, a MOF surface‐reaction strategy is developed to synthesize MOF‐based heterostructures without pyrolysis. Uniform Fe(OH)3 nanosheets are grown controllably on the Co‐MOF‐74 surface by a fast “phenol–Fe” reaction that takes advantage of the hydroxyl sites in Co‐MOF‐74. The resulting Fe(OH)3@Co‐MOF‐74 heterostructure delivers an excellent performance in the OER with a low overpotential of 292 mV at 10 mA cm−2. Notably, the introduction of Fe can improve the intrinsic activity of the original Co atom significantly. The turnover frequency in Fe(OH)3@Co‐MOF‐74 (1.209 s−1) is more than 25 times higher than that in Co‐MOF‐74 (0.048 s−1). This work presents a fresh concept for the fundamental design of advanced pure‐MOF‐based heterostructures and, thereby, provides a new avenue for the fabrication of other energy‐conversion and ‐storage materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.