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 .
Low-cost and high-efficiency oxygen reduction reaction (ORR) electrocatalysts are the basis for large-scale applications of electrochemical energy storage and conversion technologies such as fuel cells and metal-air batteries. Herein, cobalt and oxygen vacancy-rich cobalt oxide encapsulated in nitrogen-doped carbon and carbon nanotubes (Co/CoO@NC-CNTs) have been prepared by direct solid-state pyrolysis of Co-MOF. The carbon morphology, oxygen vacancy content and type of nitrogen can be finely tuned by mixing Co-MOF with proper amounts of melamine. The optimized material has an interwoven CNT structure with abundant micro-and mesopores, suitable nitrogen type and certain number of oxygen vacancies and exhibiting outstanding ORR electrocatalytic performance in alkaline media with an onset potential of 0.96 V and a half-wave potential of 0.88 V vs RHE, which is higher than 20 wt% Pt/C, as well as being highly stable and well resistant to methanol.
Zeolitic Imidazolate Frameworks (ZIFs) derived nitrogen-doped porous carbon (NPC) materials have been proposed as promising metal-free electrocatalysts for oxygen reduction reactions (ORR). Herein, we report a strategy to control the morphology of ZIF-8 and ZIF material-derived NPC materials by the amount of L-cysteine. The prepared NPC electrocatalysts exhibit different morphologies and ORR properties. The best of these catalysts exhibited a nanosheet-like morphology with an onset potential of 0.95 V and a half-wave potential of 0.87 V in alkaline media, which are comparable to those of commercial Pt/C (20 wt%) catalysts. In addition, this catalyst exhibited high stability and methanol resistance. This work not only reveals the effect of L-cysteine amount on the growth process of ZIF, but also provides a strategy for designing various excellent catalysts in the fuel cell field.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.