Ligand-Assisted Controllable Growth of Self-Supporting Ultrathin Two-Dimensional Metal–Organic Framework Nanosheet Electrodes for an Efficient Oxygen Evolution Reaction

Abstract

Rational design of metal–organic frameworks (MOFs) into ultrathin two-dimensional (2D) nanosheets with controllable thickness is significantly attractive but is also a significant challenge. Herein, the authors report, for the first time, the synthesis of ultrathin 2D nickel-based MOF nanosheets with a thickness of only about 2 nm via a ligand-assisted controllable growth strategy, which cannot be acquired from the exfoliation of their bulky counterparts or the conventional hydrothermal method. The correlation between 2D nanosheets and crystal growth preference was demonstrated through a judicious choice of a specific [Ni­(BIP)­(p-BDC)­(H2O)2] n framework (BIP = (3,5-bis­(1-imidazoly)­pyridine), p-H2BDC = terephthalic acid) to underlie the geometry of the resultant morphology. Under the modulation by the dosage of terephthalic acid through a corrosion–dissolution–coordination process, the nanosheets of Ni-MOFs with a controllable thickness can be tuned to 50 and 100 nm. Ultrathin 2D Ni-MOF nanosheet-derived N-doped Ni@carbon exhibits a satisfactory electrocatalytic performance with a small overpotential of 170 mV to achieve a current density of 10 mA cm–2, much outperforming the bulk Ni-MOF and the most reported non-noble-metal oxygen evolution reaction electrocatalysts to date. It is believed that this ligand-assisted controllable growth strategy represents a novel and simple path to prepare high-performance MOF-based electrocatalysts for wide applications.

NiFe Nanoparticle-Encapsulated Ultrahigh-Oxygen-Doped Carbon Layers as Bifunctional Electrocatalysts for Rechargeable Zn–Air Batteries

“…The Raman spectrum was deconvoluted into four subpeaks, and by calculating the intensity ratio ( I D / I G ) of the D to G peak area, a quantitative description of the crystallinity was given (Figure a and Table S1). , By comparing the degree of crystallization of different samples, it can be seen that the I D / I G ratios of C-NiFe (0.42), C-Ni (0.51), and C-Fe (0.48) are all lower than that of C (0.53), which indicates that the three samples of C-NiFe, C-Ni, and C-Fe all have more graphitic structure. This may be due to the role of Ni and Fe in catalyzing graphitization during carbonization.…”

“…The Raman spectrum was deconvoluted into four subpeaks, and by calculating the intensity ratio (I D /I G ) of the D to G peak area, a quantitative description of the crystallinity was given (Figure 2a and Table S1). 43,44 By comparing the degree of crystallization of different samples, it can be seen that the I D /I G ratios of C-NiFe (0. The electrocatalytic ORR and OER performance of the asprepared C, C-Fe, C-Ni, and C-NiFe samples was investigated in alkaline solutions (0.1M KOH aqueous solution) by using a standard three-electrode system, and Pt/C (20 wt %) was used as the benchmark reference.…”

Hollow Carbon Nanopillar Arrays Encapsulated with Pd–Cu Alloy Nanoparticles for the Oxygen Evolution Reaction

“…37,38 Furthermore, regarding the hydrogen bonding interaction and HMTA as the linker, and the center metal in Cu-BDC-HMTA as 6-connected node, the supramolecular constructure can be simplified to a pcu topology with the point symbol of {4 12 •6 3 } (Figure 1e). 39,40 Detailed crystallographic data of Cu-BDC-HMTA are listed in Tables S1 and S2.…”

“…While Cu (2) is six-coordinated with an octahedral geometry structure and connected with one N atom and five O atoms, two O atoms are from two BDC ligands, the other two O atoms are provided by the same nitrate group, and the last one O is from the coordinate water molecule as well as one N atom provided by the N-donor ligand. As shown in Figure d, adjacent layers can be stacked into a supramolecular architecture through hydrogen-bond interactions. , Furthermore, regarding the hydrogen bonding interaction and HMTA as the linker, and the center metal in Cu-BDC-HMTA as 6-connected node, the supramolecular constructure can be simplified to a pcu topology with the point symbol of {4 12 ·6 3 } (Figure e). , Detailed crystallographic data of Cu-BDC-HMTA are listed in Tables S1 and S2.…”

“…The peaks located at 530.3, 531.2, and 532.4 eV are assigned to the Cu–O, oxygen vacancy regions, and adsorbed water of the as-prepared samples, , respectively. Moreover, in the deconvoluted spectrum of C 1s, the four peaks located at about 288.1, 286.3, 285.0, and 284.0 eV correspond to carboxyl, carbonyl, and C–N bonds and graphitic carbon, , respectively (Figure i).…”