Cosynergistic Molybdate Oxo‐Anionic Modification of FeNi‐Based Electrocatalysts for Efficient Oxygen Evolution Reaction

Abstract

Catalytic synergy is an unresolved activity descriptor in energy conversion reactions. Here, this study reports the synergistically enhanced intrinsic oxygen evolution reaction activity of a FeNi model catalyst modified with molybdate oxo‐anions via concertedly boosted surface/interface interactions such as interfacial charge transfer, surface intermediate adsorption, in situ phase transformation, and gas bubble evolution. Capturing such cosynergistic impact reveals the accelerated transition of oxygen deprotonation to oxyhydroxide state, ready‐to‐function Fe and Ni active sites, the instant transformation of Fe and Ni local microenvironments to γ ‐FeOOH and β ‐NiOOH phases, and ultrafast gas bubble growth and release. The accelerated oxygen bubble evolution dynamic is monitored in operando with a decreased dynamic variation of the interfacial Faradaic resistance. Such cosynergistic molybdate modification results in a tenfold increase in oxygen evolution turnover frequency as well as a 55 mV decrease in the overpotentials to deliver 10 and 1000 mA cm−2 with respect to the FeNi‐model catalyst.

Oxygen Corrosion Engineering of Nonprecious Ternary Metal Hydroxides toward Oxygen Evolution Reaction

“…The Bode-resistance plot for FeNi/FF also depicts a gradual decline with increasing OER potential at a varying frequency range (Figure f). The occurrence of low frequency-dominant processes at the onset of OER until higher potentials for FeNiCr/FF indicates a plausible synergistic effect by the remaining Cr species, besides the structure regulating effect, which together accelerate the electron transfer rate during the adsorption of OH charge carriers as well as the deprotonation of OH to O intermediates …”

“…The occurrence of low frequency-dominant processes at the onset of OER until higher potentials for FeNiCr/FF indicates a plausible synergistic effect by the remaining Cr species, besides the structure regulating effect, which together accelerate the electron transfer rate during the adsorption of OH charge carriers as well as the deprotonation of OH to O intermediates. 48 The regulating effect of Cr dopants on Ni active sites is further investigated by long-term cyclic voltammetry (CV), where the characteristic Ni oxidation peak shifts from 1.46 V to 1.51 V, in contrast to the stable redox peaks of Ni in the binary system (Figure 5g,h). This verifies the expedited in situ phase transformation to β-NiOOH phase in the presence of Cr.…”

Vanadium-Based Trimetallic Metal-Organic-Framework Family as Extremely High-Performing and Ultrastable Electrocatalysts for Water Splitting

“…28,36,37 In its high-resolution Fe 2p spectra, two peaks of Fe 2p 3/2 are located at 710.66 and 714.24 eV (Figure 1h), confirming the co-existence of Fe 2+ and Fe 3+ in Fe 2 V-MOF. 38,39 The detailed XPS spectra for Mg 2 V-MOF can be obtained in the Supporting Information.…”

Anchoring Ce-modified Ni(OH)2nanoparticles on Ni-MOF nanosheets to enhances the oxygen evolution performance

“…9–12 Relying on its own advantages, researchers modified Ni-MOFs by a variety of strategies to optimize the OER performance, such as designing the ultra-thin MOF nanosheet structure, 13,14 introducing heterogeneous atoms, and constructing heterostructures. 15–18 Therein, heterostructures can increase the contact interface/surface and enhance charge transfer, leading to improved OER activities, 19 such as MnCo 2 O 4 /CeO 2 , 20 CeO 2 –CoS 1.97 , 21 and CoP/CeO x . 22…”

“…[9][10][11][12] Relying on its own advantages, researchers modified Ni-MOFs by a variety of strategies to optimize the OER performance, such as designing the ultra-thin MOF nanosheet structure, 13,14 introducing heterogeneous atoms, and constructing heterostructures. [15][16][17][18] Therein, heterostructures can increase the contact interface/surface and enhance charge transfer, leading to improved OER activities, 19 such as MnCo 2 O 4 /CeO 2 , 20 CeO 2 -CoS 1.97 , 21 and CoP/CeO x . 22 Because of the unique 4f electronic properties of cerium, Ce oxide possesses the potential to improve the OER performance by modulating the electronic structure and improving the charge transfer capability.…”