Spatial Well‐defined Bimetallic Two‐Dimensional Polymers with Single‐Layer Thickness for Electrocatalytic Oxygen Evolution Reaction

Abstract

Innovative bimetallic materials provide more possibilities for further improving the performance of oxygen evolution reaction (OER) electrocatalysts. However, it is still a great challenge to rationally design bimetallic catalysts because there is not a practical way to decouple the factors influencing the intrinsic activity of active sites from others, thus hindering in-depth understanding of the mechanism. Herein, we provide a rational design of bimetallic Ni, Co two-dimensional polymer model OER catalyst. The well-defined architecture, identical density of active sites and monolayer characteristic allow us to decouple the intrinsic activity of active sites from other factors. The results confirmed that the relative position and local coordination environment has significant effect on the synergistic effect of the bimetallic centres. The highest electrocatalytic activity with the turnover frequency value up to 26.19 s À 1 was achieved at the overpotential of 500 mV.

Regulating the Synergistic Effect in Bimetallic Two‐Dimensional Polymer Oxygen Evolution Reaction Catalysts by Adjusting the Coupling Strength Between Metal Centers

“…Cobalt porphyrins, with unique carbon‐rich macrocycle and inherent cobalt‐nitrogen coordination, are effective catalysts for OER. Incorporating the cobalt porphyrin into a covalent skeleton can efficiently avoid the agglomeration of cobalt porphyrins and further improve the activity [6, 7] . In this work, to obtain 2DPs with different periodicity, three bipyridine‐dialdehyde monomers (Bpy‐1, Bpy‐2 and Bpy‐3) with different skeleton lengths were selected to condensate with Co porphyrin monomer by Schiff base condensation, respectively.…”

“…Incorporating the cobalt porphyrin into a covalent skeleton can efficiently avoid the agglomeration of cobalt porphyrins and further improve the activity. [6,7] In this work, to obtain 2DPs with different periodicity, three bipyridinedialdehyde monomers (Bpy-1, Bpy-2 and Bpy-3) with different skeleton lengths were selected to condensate with Co porphyrin monomer by Schiff base condensation, respectively. Then, the Ni metal was introduced by post-modification of these monometallic 2DPs, the structure of obtained three bimetallic 2DPs with different metal center spacing (CoTAPP-Ni-1-2DP, CoTAPP-Ni-2-2DP and CoTAPP-Ni-3-2DP) are shown in Scheme S2-4.…”

“…In a previous work, we have design and synthesized a series of 2DPs with identical backbone structure and intermetal connections, but regulated the relative position and coordination environment of the metal centers, the results illustrated that these two factors significantly influence the electronic structure of the metal active atoms, thereby affecting the metal synergistic effect and the OER performance of the 2DP catalysts. [6] However, how the structural factors of 2DPs such as the intermetal distance and structure of the linkage affect the coupling strength between the two metal centers, and in turn the synergistic effect in bimetallic catalysts, remains unknown. In the current work, we attempted to construct a series of bimetallic CoÀ Ni 2DPs with a single layer thickness and spatial well-defined metal sites, and try to regulate the coupling strength between the two metal centers by adjusting the spacing between metal centers or the conjugation degree of bridge skeleton.…”

Development of Anion Exchange Membrane Water Electrolysis and the Associated Challenges: A Review

“…[98,99] The application of non-noble transition metal (Ni, Co and Fe, etc.) [100] materials as anode catalysts makes the AEMWE a very attractive technology due to the lower capital cost compared to PEMWE. However, the anodic reaction in AEMWE, the OER, has sluggish kinetics and it is associated with high overpotential.…”

Green and Scalable Synthesis of Atomic-Thin Crystalline Two-Dimensional Triazine Polymers with Ultrahigh Photocatalytic Properties

“…Two-dimensional (2D) polymers, which are composed of periodic covalent connection of organic repeating units in the 2D plane and ideally are one-atom thick, have recently received great interest as a new extension of Staudinger’s polymerization concept. − In comparison with traditional 2D inorganic materials, 2D polymers show the features of light weight and nontoxicity, excellent structural designability and facilely tailored functionality, as well as uniform and abundant in-plane porosity, which make them very promising in various applications. − Great efforts have been devoted to rational synthesis of 2D polymers at the atomic or molecular level through various connection bonds such as imine, amide, imide, triazine, and so forth, which could offer a broad family of 2D functional materials with desired structures, properties, and functions. − Among these kinds of 2D polymers, 2D triazine polymers (2D-TPs) constructed via robust aromatic triazine linkage have demonstrated unique characteristics such as excellent chemical and thermal stability, 2D conjugated structures, and plentiful active triazine groups, thus holding great potential in catalysis, energy storage, and optoelectronics. − So far, like other 2D polymers, two main strategies, namely, top-down and bottom-up, have been employed to prepare 2D-TPs. − The top-down strategy involves physical or chemical exfoliation of the presynthesized bulk framework materials, that is, covalent triazine frameworks (CTFs). − However, due to the relatively large micron size, irregular layered structure, and extensive interlayer π–π stacking interaction of the bulk CTF materials, this approach is frequently limited by low exfoliation yield, multilayer thickness, inhomogeneous morphology, and/or decreased crystallinity for the obtained 2D-TPs. As for the bottom-up strategy, this method is generally implemented with the assistance of interfaces such as gas–liquid and liquid–liquid interface as the soft templates for the 2D polymerization of monomers. , However, such a strategy suffers from low yield, poor scalability, multiple layer structure, and insufficient crystallinity of the 2D-TPs due to the lack of adequate thermodynamic driving force under mild reaction conditions.…”