Heterojunction of the CoMn Metal–Organic Framework with Lanthanum for Enhanced Oxygen Evolution Reaction

Abstract

Surface and interfacial electron transfer tends to be the ratelimiting step in multiple electron electrocatalytic reactions such as oxygen evolution reaction (OER). Constructing a heterojunction structure is an effective approach to strengthen the processes. Here, CoMnLa x -MOF/CF has been synthesized via a one-pot solvothermal pathway to integrate the charge transport advantage of the heterojunction and the mass-transfer superiority of high porosity of the metal−organic framework (MOF), wherein the heterojunction is formed by introducing La in preparing the CoMn-MOF process. The results demonstrate that the as-prepared CoMnLa x -MOF/CF possesses flower-like/flower-bud microstructures with a CoMn-MOF/La-MOF heterojunction topology, resulting in superior OER performance. The enhanced OER property originates from reduced charge-transfer resistance and an enlarged activated surface area. At a molar ratio of n La :n Co :n Mn = 0.2:1:1, the CoMnLa 0.2 -MOF/CF presents optimal performance. In 1 M KOH, the overpotential is only 201 mV to reach 10 mA cm −2 current density. There appears no significant current density degeneration in the 25 h stability test. This work demonstrates one facile pathway for directly building the heterojunction in CoMn-MOF to achieve superb OER activity.

N-Doped Graphene Quantum Dots Incorporated into NiCo Bimetallic-Organic Framework as an Electrocatalyst for Alkaline Water Splitting

“…As seen, NGQD/NiCo-MOF-5 shows excellent stability at each current density and fast potential response by altering the current density, reflecting its remarkable mechanical robustness and fast charge and mass transportation toward the OER in a 1 M KOH medium. 49 Overall, the obtained results showed that the incorporation of NGQDs into NiCo bimetallic-organic frameworks is suitable for the catalysis of the OER in electrochemical water splitting systems.…”

“…Besides, the weak peaks at locations of 860.3 and 878.8 eV were ascribed to shakeup satellite peaks. 49 Similarly, the high-resolution spectrum of Co 2p for both samples in Figure 5f showed two prominent peaks at around 780.3 and 796.0 eV, which are, respectively, associated with the Co 2p 3/2 and Co 2p 1/2 along with corresponding satellite peaks (785.2 and 801.5 eV). 50 Notably, compared to pristine NiCo-MOF, it can be observed that the XPS spectra of Ni and Co for NGQD/NiCo-MOF have a negative shift in the binding energy, which may be due to the changes in the coordination media between metal centers and Hmim ligands after NGQD loading.…”

Boosting Plant Photosynthesis with Carbon Dots: A Critical Review of Performance and Prospects

“…Advancement in the manufacturing of novel composites through incorporating selected molecules or ions in the host's lattice for such low‐dimensional nanomaterials will later find other significant utility in the photo‐, or electrocatalysis mechanism for the photosynthesis machinery [ 152–155 ] since these highly confined systems are with controlled charge transfer and optical alignments between two different entities. Growth pathways have yet not been established to produce such non‐carbon‐based nanomaterials over a large‐scale production.…”

“…Enhancing the catalytic activity toward hydrogen generation in the process of photo-electrocatalysis within the plants, can be possibly achieved by controlling the defective sites across the tungsten diselenide nanomaterials. [150,151] Advancement in the manufacturing of novel composites through incorporating selected molecules or ions in the host's lattice for such low-dimensional nanomaterials will later find other significant utility in the photo-, or electrocatalysis mechanism for the photosynthesis machinery [152][153][154][155] since these highly confined systems are with controlled charge transfer and optical alignments between two different entities. Growth pathways have yet not been established to produce such non-carbon-based nanomaterials over a large-scale production.…”

Self-Reconstructed Two-Dimensional Cluster-Based Co–Organic Layer Heterojunctions for Enhanced Oxygen Evolution Reactions

“…Metal–organic frameworks (MOFs), a family of porous materials formed by connecting metal nodes with organic ligands via coordination chemistry, have received special attention due to their flexible tunability (e.g., composition, structure, and morphology) and are considered one of the most promising materials for OER catalysts without precious metals. − Nevertheless, the intrinsic activity of MOF catalysts is greatly hindered by their weak mass/charge transfer capabilities. − In addition, the performance of catalytic materials is highly dependent on the bonding strength of key reactants at the surface active sites, and the bonding energies of OER-related intermediates (e.g., *O, *OH, and *OOH) are correlated with each other according to a linear scaling relationship, resulting in a “volcano diagram” type of performance map . To address these issues, the construction of heterojunction structures has emerged as one of the most effective approaches to enhance catalytic performance.…”