Exploration and Application of the Self-Optimization Phenomenon of a Trimetal-Based MOF Electrocatalyst in the Oxygen Evolution Reaction

Abstract

Metal−organic frameworks (MOFs) have emerged as a promising class of catalysts due to their large specific surface area, high porosity, and dispersed metal sites. However, the inherent low electrical conductivity of organic ligands limits their application as electrocatalysts. Herein, we constructed a trimetal FeCoNi MOF/NF catalyst for oxygen evolution reaction (OER) on nickel foam substrates by electrodeposition and hydrothermal methods. The FeCoNi MOF/NF catalyst shows a unique self-optimization phenomenon, which originates from the increase in the pore structure on the topography, the increase in the valence state of Co and Ni ions, and the formation of crystalline/amorphous interfaces. The selfoptimizing stabilized FeCoNi MOF/NF has excellent electrocatalytic performance, which achieves a low overpotential of 267 mV at the current density of 10 mA cm −2 in 1 M KOH with a small Tafel slope of 37.6 mV dec −1 . The self-optimization transformation process proposed in this work provides a new insight for the understanding and application of the active center of MOFs during the OER catalytic process.

Amorphous–Crystalline Heterostructure with Ample Oxygen Vacancy In Situ Evolved from Heterojunction Ni(OH)2@V–Ni3S2/NF toward Efficient Water Electrolysis

“…The Nyquist plots and the fitted data (panels e and f of Figure ) indicate that the R ct value of Ni­(OH) 2 @V–Ni 3 S 2 /NF (0.098 Ω) is smaller than that of V–Ni 3 S 2 /NF (0.101 Ω), Ni 3 S 2 /NF (0.228 Ω), and Ni­(OH) 2 /NF (0.229 Ω), proving its faster charge-transfer process and OER kinetics. Ni­(OH) 2 @V–Ni 3 S 2 /NF also transcends other recently reported Ni-based catalysts − at 10 mA cm –2 , as depicted in Figure g and Table S4 of the Supporting Information, such as MoS 2 /NiS 2 /CC, NiFe–P/NF, Ni–Fe/NiMoN x /NF, W–NiS 2 /MoO 2 @CC, etc. Electrochemical stability is a critical factor to assess the practical OER applicability comprehensively.…”

Facile Synthesis of Co2P Nanoparticles Embedded in N- and P-Doped Mesoporous Carbon Composite as an Efficient Electrocatalyst for Oxygen Evolution Reaction

“…This is also in excellent accordance with Raman spectra observations, further indicating that the surface of Co 2 P nanoparticles is in situ converted to Co (oxy)­hydroxides progressively during the OER cycling test. These findings confirm that Co 2 P@NPC indeed undergoes a partial surface oxidation process to form an amorphous Co (oxy)­hydroxide overlayer, thereby forming a core@shell structure. − The Co 2 P core can act as a conductive support to further facilitate electron transfer to the exterior active components. Moreover, a thin shell layer of Co (oxy)­hydroxides on the surface of the phosphides can be beneficial to alleviate the Co 2 P phases in bulk from further electro-oxidation even after CV 2000 OER cycles. , This not only renders high reaction kinetics but also ensures the intrinsic conductivity and robust stability.…”

(FeMnCe)-co-doped MOF-74 with significantly improved performance for overall water splitting

“…Among all the as-synthesized samples, FeMn 6 Ce 0.5 -MOF-74/NF exhibits the best OER electrocatalytic activity with the lowest overpotential. In particular, the OER performance of FeMn 6 Ce 0.5 -MOF-74/NF is also far superior to that of most of the previously reported pristine MOF-74 materials, as shown in Table S2,† 11,20,25,30,46,60–66 suggesting that the 3d–4f mixed metal strategy can accelerate the oxygen evolution reaction and decrease the overpotential.…”