Hollow Co‐Based Layered Double Hydroxide Decorated with Ag Nanoparticles for the Oxygen Evolution Reaction

Abstract

Developing cost-effective and efficient oxygen evolution reaction (OER) catalysts is very important for electrochemical water splitting devices. Herein, hollow Co-based layered double hydroxide (LDH) decorated with Ag nanoparticles (Ag@HÀ Co-À LDH) was constructed using ion etching of zeolitic imidazolate frameworks-67 (ZIF-67), followed by simple stirring with Ag salts. Hollow double layered structure could expose rich active centers and improve electron transfer and mass transport. Meanwhile, the introduction of Ag species greatly increases the electrical conductivity and enhances cobalt species to form highly catalytically active Co 4 + . Therefore, the as-obtained Ag@HÀ CoÀ LDH exhibits a distinguished OER activity with a low overpotential of 298 mV to provide an oxygen evolution current density of 10 mA cm À 2 , which is superior to that of CoÀ LDH and even commercial RuO 2 .

Surface Engineering Route to Non-pyrolysis MOFs with High-Density Co–Nx Sites and 3D Conductive Networks for Efficient Oxygen Reduction

“…However, for ZIF-67@HITP, the percentage of Co 3+ is almost 10 times that of Co 2+ (Co 2+ : 9.52 at %, Co 3+ : 90.48 at %), indicating the transformation of the Co valence state induced by the modification of HITP on the ZIF-67 surface. The increased Co 3+ content can be ascribed to the electronic interaction between ZIF-67 and HITP, which probably tailors the adsorption of intermediates during the ORR catalysis process . The change of the cobalt oxidation state is consistent with the results of previously reported literature related to the modification of ZIF-67 with a considerable variation in the relative ratio of Co 2+ and Co 3+ .…”

“…The increased Co 3+ content can be ascribed to the electronic interaction between ZIF-67 and HITP, which probably tailors the adsorption of intermediates during the ORR catalysis process. 42 The change of the cobalt oxidation state is consistent with the results of previously reported literature related to the modification of ZIF-67 with a considerable variation in the relative ratio of Co 2+ and Co 3+ . 34 3.2.…”

Silver-integrated cobalt hydroxide hybrid nanostructured materials for improved electrocatalytic oxygen evolution reaction

“…54–57 Furthermore, the relatively low cost and favorable stability of silver (Ag) in alkaline environments produces a heterogeneous interface with other compounds and improves catalytic activity. 58–60 The oxidation state of cobalt and electron transfer between the metal and metal hydroxides plays a significant role in the OER performance. The good electrical conductivity and high electronegativity of Ag/Au facilitate the oxidation of Co 2+ and improve the interfacial charge transfer and OER activity of cobalt hydroxides/oxides.…”

A silver and manganese dioxide composite with oxygen vacancies as a high-performance cathode material for aqueous zinc-ion batteries

“…21 Silver, owing to its high electrical conductivity (6.3 × 10 7 S m −1 ), 22 has garnered substantial attention in the realm of electrochemistry. 23 Liang and co-workers 24 synthesized a Ag 0.4 V 2 O 5 cathode material by introducing Ag ions into vanadium pentoxide which exhibited a high capacity of 216 mAh g −1 at a high current density of 5 A g −1 after 1000 cycles as well as good rate capability.…”