Bimetallic CPM-37(Ni,Fe) metal-organic framework: enhanced porosity, stability and tunable composition

• Published in: Dalton transactions : an international journal of inorganic chemistry 2024-03, Vol.53 (11), p.4937-4951
• Main Authors: Abdpour, Soheil, Fetzer, Marcus N. A, Oestreich, Robert, Beglau, Thi Hai Yen, Boldog, István, Janiak, Christoph
• Format: Article
• Language: English
• Subjects: Bimetals; Intermetallic compounds; Iron; Iron compounds; Metal-organic frameworks; Nickel compounds; Oxygen evolution reactions
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt03695b

A newly synthesized series of bimetallic CPM-37(Ni,Fe) metal-organic frameworks with different iron content (Ni/Fe 2, 1, 0.5, named CPM-37(Ni 2 Fe), CPM-37(NiFe) and CPM-37(NiFe 2 )) demonstrated high N 2 -based specific S BET surface areas of 2039, 1955, and 2378 m 2 g −1 for CPM-37(Ni 2 Fe), CPM-37(NiFe), and CPM-37(NiFe 2 ), having much higher values compared to the monometallic CPM-37(Ni) and CPM-37(Fe) with 87 and 368 m 2 g −1 only. It is rationalized that the mixed-metal nature of the materials increases the structural robustness due to the better charge balance at the coordination bonded cluster, which opens interesting application-oriented possibilities for mixed-metal CPM-37 and other less-stable MOFs. In this work, the CPM-37-derived α,β-Ni(OH) 2 , γ-NiO(OH), and, plausibly, γ-FeO(OH) phases obtained via decomposition in the alkaline medium demonstrated a potent electrocatalytic activity in the oxygen evolution reaction (OER). The ratio Ni : Fe 2 from CPM-37(Ni 2 Fe) showed the best OER activity with a small overpotential of 290 mV at 50 mA cm −2 , low Tafel slope of 39 mV dec −1 , and more stable OER performance compared to RuO 2 after 20 h chronopotentiometry at 50 mA cm −2 . CPM-37 MOFs demonstrate enhanced stability for mixed metal variants, which ensure favorable local charge distribution/balance. The decomposition of these MOFs leads to mixed metal oxides with lower Tafel slope in the OER than for the RuO 2 benchmark.