A Mononuclear Co^II Coordination Complex Locked in a Confined Space and Acting as an Electrochemical Water‐Oxidation Catalyst: A “Ship‐in‐a‐Bottle” Approach

Abstract

Preparing efficient and robust water oxidation catalyst (WOC) with inexpensive materials remains a crucial challenge in artificial photosynthesis and for renewable energy. Existing heterogeneous WOCs are mostly metal oxides/hydroxides immobilized on solid supports. Herein we report a newly synthesized and structurally characterized metal-organic hybrid compound [{Co3 (μ3 -OH)(BTB)2(dpe)2} {Co(H2O)4(DMF)2}0.5]n ⋅n H2O(Co-WOC-1) as an effective and stable water-oxidation electrocatalyst in an alkaline medium. In the crystal structure of Co-WOC-1, a mononuclear Co(II) complex {Co(H2O)4(DMF)2}(2+) is encapsulated in the void space of a 3D framework structure and this translationally rigid complex cation is responsible for a remarkable electrocatalytic WO activity, with a catalytic turnover frequency (TOF) of 0.05 s(-1) at an overpotential of 390 mV (vs. NHE) in 0.1 m KOH along with prolonged stability. This host-guest system can be described as a "ship-in-a-bottle", and is a new class of heterogeneous WOC.

Co (II) Boron Imidazolate Framework with Rigid Auxiliary Linkers for Stable Electrocatalytic Oxygen Evolution Reaction

“…The electrochemical impedance spectrum (EIS) analysis, and electrochemical double-layer capacitance (C dl ) test, further confirmed that the function of Fe 3+ in enhancing OER activity is through decreasing the charge transfer impedance and enlarging the catalytically active surface area in comparison Adv. [12,17,[24][25][26][27][28][29][30] Importantly, the Fe, Co co-contained Fe@BIF-91 electrocatalyst, showed enhanced OER activity greater than Fe-containing-only Fe@BIF-89. 2019, 6, 1801920 with BIF-91 ( Figures S6 and S7, Supporting Information).…”

Isostructural NiII Metal–Organic Frameworks (MOFs) for Efficient Electrocatalysis of Oxygen Evolution Reaction and for Gas Sorption Properties

“…Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) werep erformedi n0 .1 m KOH solution at pH 13 with as tandard three-electrode system.T he CV and LSV were performed while the working electrode was rotating at a rotationr ate of 1600 rpm in order to keep au niform concentration around the working electrode and also to prevent the accumulation of O 2 bubbles.T he detailed experimental procedure and calculations for the electrochemical analysis are given in Experimental Section. [35,47] The probable mechanism for TA-MOF and NH 2 TA-MOF mediated water oxidation is outlined in Figure S14. The CV analysis of Ni MOFs reveals an apparent quasireversible oxidation peak at peak potentialo f1 .40 V versusR HE which corresponds to the oxidation process of Ni 2 + to Ni 3 + (Ni II /Ni III ) ( Figure 3a).…”

“…[8][9][10][11] Amongt he TMOs, cobalt-based spinel oxides have been shown as outstanding OER electrocatalysts. [28][29][30][31][32][33][34][35] However,o nly af ew examples of MOFs that are directlyu tilized as active OER catalysts have been reported to date. [14][15][16][17] MOFs have attracted immense attention during the past few years fort heir fascinating, diverse structural architectures,a nd more importantly for their novel intrinsic and extrinsic properties.…”

Electrochemical Water Oxidation Catalyzed by an In Situ Generated α‐Co(OH)2 Film on Zeolite‐Y Surface

“…[18] Thus, cobalt oxygen-evolution catalysts (Co-OECs) have received immense attentioni nr ecent years. [19][20][21][22][23][24] Among Co-OECs, CoOx has extensively been studied as an efficient catalyst that works over aw ide pH range. [25] Co 3 O 4 has also been described as aC o-OEC.…”