Two-Dimensional Corrugated Porous Carbon-, Nitrogen-Framework/Metal Heterojunction for Efficient Multielectron Transfer Processes with Controlled Kinetics

Abstract

The material choice for efficient electrocatalysts is limited because it is necessary to be highly active as well as highly stable. One direction to solve this issue is to understand elementary steps of electrode processes and build an unconventional strategy for a conversion of inert and, therefore, stable materials into efficient catalysts. Herein, we propose a simple concept for obtaining catalysts from inert and hence stable materials by forming their heterojunctions, namely, covering inert Au with corrugated carbon-nitrogen-based two-dimensional porous frameworks. It shows more than 10 times better activity for the hydrogen evolution reaction than for the pure Au surface, and it also demonstrates the high catalytic activity for the oxygen reduction reaction (ORR) via an effective four-electron reduction mechanism, which is different from the usual two-electron reduction typical for ORR on Au surfaces. This activity induced by formation of a heterojunction was analyzed by a conjugation of computational and experimental methods and found to originate from alternative efficient reaction pathways that emerged by the corrugated porous framework and the Au surface. This work provides not only the method for creating active surface but also the knowledge on elementary steps of such complicated multielectron transfer reactions, thereby leading to intriguing strategies for developing energy conversion reactions based on materials which had never been considered as catalysts before.

Advances in Zeolite Imidazolate Frameworks (ZIFs) Derived Bifunctional Oxygen Electrocatalysts and Their Application in Zinc–Air Batteries

“…The optimal oxygen electrode exhibited the highest content of pyridinic N (38.4%), followed by graphitic N (35.3%). The pyri-N is considered to increase the surface wettability [234] and onset potential [53,235] whereas grap-N is known to enhance the diffusion-limited properties. [236] As per density functional theory (Figure 20e), the analysis of the highest occupied molecular orbitals (HOMOs) revealed that the coupling of Co and pyridinic N causes higher HOMO energy (−4.647 eV) in contrast with Co and pyrrolic N (−4.765 eV), implying that the coupling of Co and pyridinic N is more conducive to ORR, which is also in agreement with previous reports.…”

Emergent electrochemical functions and future opportunities of hierarchically constructed metal–organic frameworks and covalent organic frameworks

“…40,146 MOFs/COFs are recently used as buildingblocks to construct novel-type heterojunction electrocatalysts, which interestingly suggested not only to improve activities but also selectivity at the same time by taking advantage of molecular-level structural designability. [147][148][149][150] Considering that the meso-/macroporosity of the metallic electrodes plays a pivotal role in control of the electrode process, 40,77,144,145 designing hierarchical constructions of the electrodes with MOFs/COFs as building-blocks can provide further control of the electrode process including the activity and the selectivity.…”

Advances and challenges for experiment and theory for multi-electron multi-proton transfer at electrified solid–liquid interfaces

“…Moreover, a clear interpretation of activation mechanisms of electrode processes will help to discover electrocatalysts having better or comparable activity to Pt-based materials or to find a way to solve present issues in non-Pt electrocatalysts (see the ''In silico electrocatalyst design'' in Section 7). 78,80,[100][101][102][103][104][105][106][107] 3.3.2. How to confirm further details on quantum electrode processes?…”

“…11C and D). 105 In this work, a model heterojunction electrode of the 2D COF/Au was used to investigate the effect of a 2D COF as a porous-architecture to control electrocatalytic activity and showed that the additional thin COF layer is the key to improving activity or selectivity of the reactions. 105 The identical concept was applied to a Au single crystal (111) surface and again confirmed that a thin COF layer can improve the HER activity.…”

“…105 In this work, a model heterojunction electrode of the 2D COF/Au was used to investigate the effect of a 2D COF as a porous-architecture to control electrocatalytic activity and showed that the additional thin COF layer is the key to improving activity or selectivity of the reactions. 105 The identical concept was applied to a Au single crystal (111) surface and again confirmed that a thin COF layer can improve the HER activity. 148 These advanced materials science efforts can contribute to understanding further details of microscopic mechanisms in quantum electrode processes together with other classes of well-defined modern designer materials, for instance molecular electrocatalysts ( Fig.…”