In situ Formed Co(TCNQ)₂ Metal‐Organic Framework Array as a High‐Efficiency Catalyst for Oxygen Evolution Reactions

Abstract

Energy conversion and storage systems such as water splitting devices and metal-air batteries need excellent and energy-efficiency oxygen evolution reaction (OER) catalysts. This work reports the in situ development of sawtooth-like Co(TCNQ) (TCNQ=tetracyanoquinodimethane) metal-organic framework array on Co foil (Co(TCNQ) /Co) by means of a solution immersion method at room temperature. As an oxygen-evolving catalyst, the resulting Co(TCNQ) /Co demonstrates superior OER activity with overpotential of 310 mV to drive a geometrical catalytic current density of 15 mA cm in 1.0 M KOH. Notably, it also shows good long-term electrochemical durability with its activity being retained for at least 20 h and achieves a high turnover frequency of 0.66 mol O s at overpotential of 380 mV.

Cobalt-Based MOF-on-MOF Two-Dimensional Heterojunction Nanostructures for Enhanced Oxygen Evolution Reaction Electrocatalytic Activity

“…The analogous phenomena are repeated at the other steps, indicating the excellent conductivity, mass transportation, and mechanical robustness of the as-obtained Co-based MOF-on-MOF heterojunction electrode. 22,38 After that, we investigated the phase and morphology of the Co-BPDC/Co-BDC-3 heterojunction catalyst by employing XRD and FESEM technologies. As shown in Figure 8a, the diffraction peaks of CoOOH significantly increased after continuously catalyzing for 80 h, which further confirmed that in-situ-formed CoOOH acted as the OER catalyst in actuality.…”

“…However, to further enhance the electrocatalytic activity of the above catalysts, some novel synthetic strategies were developed. Among these strategies, the metal–organic frameworks (MOFs) precursor/template route was paid much attention, because the catalysts prepared from this method exhibited improved catalytic performance. − Nevertheless, it still remains a challenge to directly utilize MOFs as OER catalysts, because of their low conductivity, small mass permeability, low reactivity of metal centers derived from their saturation with the ligands, and difficulty in controlling the desired morphology. − Thus, some efforts have been made to promote the catalytic activity of MOF catalysts, including synthesizing a two-dimensional (2D) morphology to expose more catalytic sites, − introducing different metal centers to obtain synergistic effect of heterometals, ,,, and hybridizing with a secondary conductive phase, such as metal substrates and graphene, to enhance electrode conductivity. − However, it is not reported yet in the literature employing the same metal with two different ligands to construct MOF-on-MOF heterojunction nanostructures as OER catalysts to enhance OER electrocatalytic activity.…”

Remarkably stable metal–organic frameworks on an inert substrate: M-TCNQ on graphene (M = Ni, Fe, Mn)

“…As the organic linker we utilize a TCNQ molecule (7,7,8,8-tetracyanoquinodimethane), which is a strong electron acceptor and a popular choice for MOF synthesis both on-surface 7,9,[18][19][20][21][22] and in solution. 23,24 TCNQ-based 2D MOFs are also intensively studied computationally, [25][26][27][28][29][30][31] but the simulated free-standing systems are not directly comparable to metal-supported nor solution-based MOFs. To provide a more relevant model system, we chose epitaxial graphene/Ir(111) as the supporting substrate, which is chemically inert and which only shows minimal geometric and work function corrugation across the moiré unit cell.…”

TiO2 Nanotube Arrays Decorated with Reduced Graphene Oxide and Cu–Tetracyanoquinodimethane as Anode Materials for Photoelectrochemical Water Oxidation

“…Until now, the Cu-based charge-transfer complex (also called the conducting polymer) has not been reported as an OER co-catalyst to enhance PEC water oxidation. In particular, copper-tetracyanoquinodimethane (Cu–TCNQ) has been considered an excellent semiconducting material due to its high electrical conductivity (π-stacking interactions) and excellent electrocatalytic effect. − …”