Electronic Doping of Metal‐Organic Frameworks for High‐Performance Flexible Micro‐Supercapacitors

Abstract

The combination of high specific surface areas, well‐defined porous structures, and redox‐active sites renders the organic frameworks as promising electrode materials for next‐generation energy storage devices. Despite the recent advancements in the fabrication of conductive metal‐organic frameworks (MOFs), they generally require tedious synthesis procedures, which hinder their energy‐related applications. Herein, a doping strategy using electron acceptor molecules is demonstrated to tune the ohmic electrical conductivity of MOF thin‐film electrodes. For instance, the conductivity of MOF Cu3(BTC)2 film is enhanced over 40 times after doping with 7,7,8,8‐tetracyanoquinododimethane (TCNQ). Thereby, asymmetric in‐plane micro‐supercapacitors (MSCs) are constructed utilizing in situ‐grown TCNQ@Cu3(BTC)2 as the cathode and activated carbon as the anode, which delivers remarkable areal capacitance of 95.1 mF cm−2 at a scan rate of 5 mV s−1, superior to those of the reported MSCs (0.1–50 mF cm−2). Moreover, the fabricated devices show long‐term stability with 94.1% capacitance retention up to 5000 charge‐discharge cycles at 10 mA cm−2. The molecular doping engineering of organic framework materials with excellent electronic properties for energy storage and conversion applications is inspired.

2D Graphitic Carbon Nitride for Energy Conversion and Storage

“…(Figure 24), and electrode materials are the core of supercapacitors. [237,238] Different electrode materials have different energy storage mechanisms for supercapacitors. Therefore, according to the different energy storage mechanism, supercapacitors can be divided into three types: electric double-layer capacitors (EDLCs), pseudocapacitors, and hybrid supercapacitors.…”

Identification of Catalytic Active Sites for Durable Proton Exchange Membrane Fuel Cell: Catalytic Degradation and Poisoning Perspectives

“…[192,237] Furthermore, atomically dispersed active sites with high metal-loading (density of active sites) are formed by optimizing the ratio of metal contents and heteroatom source or other templates. [238][239][240][241] For example, atomically dispersed dual Co-Ni sites encapsulated in N-doped hollow carbon (CoNi-SAs/NC) were obtained through annealing of dopamine coated MOF (Figure 9b). [242] The CoNi-SAs/NC as an ORR electrocatalyst demonstrated excellent activity with E onset of 0.88 V and E 1/2 of 0.76 V, revealing that catalytically active sites were exposed when the catalyst was changed from nano-sized metallic agglomerates to isolated metal single atoms.…”

Design and Fabrication of Hierarchical NiCoP–MOF Heterostructure with Enhanced Pseudocapacitive Properties

“…[20][21][22][23][24][25][26] Among these materials, most of MOFs suffer from the low active site utilization and intrinsically limited conductivity, which often results in the low capacity and poor rate capability during the charge storage process. [24,25,27] In this regard, two strategies are mainly used to address these issues for the realization of superior HSCs. One strategy is to judiciously manipulate the architecture of MOF materials via various accessible conversion processes for further elevating their physicochemical properties.…”