Self‐Sacrificial Template‐Directed Vapor‐Phase Growth of MOF Assemblies and Surface Vulcanization for Efficient Water Splitting

Abstract

Direct use of metal–organic frameworks (MOFs) with robust pore structures, large surface areas, and high density of coordinatively unsaturated metal sites as electrochemical active materials is highly desirable (rather than using as templates and/or precursors for high‐temperature calcination), but this is practically hindered by the poor conductivity and low accessibility of active sites in the bulk form. Herein, a universal vapor‐phase method is reported to grow well‐aligned MOFs on conductive carbon cloth (CC) by using metal hydroxyl fluorides with diverse morphologies as self‐sacrificial templates. Specifically, by further partially on‐site generating active Co3S4 species from Co ions in the echinops‐like Co‐based MOF (EC‐MOF) through a controlled vulcanization approach, the resulting Co3S4/EC‐MOF hybrid exhibits much enhanced electrocatalytic performance toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with overpotentials of 84 and 226 mV required to reach a current density of 10 mA cm−2, respectively. Density functional theory (DFT) calculations and experimental results reveal that the electron transfer between Co3S4 species and EC‐MOF can decrease the electron density of the Co d‐orbital, resulting in more electrocatalytically optimized adsorption properties for Co. This study will open up a new avenue for designing highly ordered MOF‐based surface active materials for various electrochemical energy applications.

Nitrogen Engineering on 3D Dandelion‐Flower‐Like CoS2 for High‐Performance Overall Water Splitting

“…Nevertheless, their widespread applications are severely limited by their high cost and scarcity. To this end, tremendous efforts have been devoted to develop highly efficient and cost‐effective electrocatalysts, such as transition metal oxides, selenides, borides, phosphides, nitrides, carbides, and sulfides . However, catalysts both used for OER and HER in the same electrolyte for water electrolysis taking the advantages of both simplifying the system and reducing the cost, usually suffer from low stability and inferior performance, which greatly impede their practical applications as bifunctional electrocatalysts.…”

Recent Advances in Metal‐Organic Frameworks and Their Derived Materials for Electrocatalytic Water Splitting

“…Liu et al. synthesized surface vulcanized Co−MOF arrays (Co 3 S 4 /EC−MOF) as effective electrocatalysts for HER and OER (Figure a) . In the process of preparation, the echinops‐like metal hydroxyl fluoride arrays (EC−Co(OH)F) which were grown on carbon cloth as the self‐sacrificial templates were annealed under an Ar atmosphere with imidazole to obtain the Co−MOF (EC−MOF) which showed a high stability in alkaline solution.…”

Recent Approaches to Design Electrocatalysts Based on Metal–Organic Frameworks and Their Derivatives

“…Tremendous research efforts have been devoted to substrate engineering for the activity improvement of MOF‐derived electrocatalysts . A typical example of the substrate engineering was reported by Liu et al . They firstly prepared well‐aligned MOFs on conductive carbon cloth (CC) via a vapour‐phase method, and then produced Co 3 S 4 species on the surface of MOFs through an on‐site controlled vulcanization method.…”