Spinels: Controlled Preparation, Oxygen Reduction/Evolution Reaction Application, and Beyond

Abstract

Spinels with the formula of ABO (where A and B are metal ions) and the properties of magnetism, optics, electricity, and catalysis have taken significant roles in applications of data storage, biotechnology, electronics, laser, sensor, conversion reaction, and energy storage/conversion, which largely depend on their precise structures and compositions. In this review, various spinels with controlled preparations and their applications in oxygen reduction/evolution reaction (ORR/OER) and beyond are summarized. First, the composition and structure of spinels are introduced. Then, recent advances in the preparation of spinels with solid-, solution-, and vapor-phase methods are summarized, and new methods are particularly highlighted. The physicochemical characteristics of spinels such as their compositions, structures, morphologies, defects, and substrates have been rationally regulated through various approaches. This regulation can yield spinels with improved ORR/OER catalytic activities, which can further accelerate the speed, prolong the life, and narrow the polarization of fuel cells, metal-air batteries, and water splitting devices. Finally, the magnetic, optical, electrical, and catalytic applications beyond the OER/ORR are also discussed. The future applications of spinels are considered to be closely related to environmental and energy issues, which will be aided by the development of new species with precise preparations and advanced characterizations.

Hollow‐Structured Metal Oxides as Oxygen‐Related Catalysts

“…[79] Oxygen vacancy can be considered for the fabrication of hollowed oxides, because it can greatly enhance the electrical conductivity, expose more of the catalytic active site, accelerate the formation process of metaloxygen intermediates and thus effectively promote its oxygenrelated catalytic activity. [79] Oxygen vacancy can be considered for the fabrication of hollowed oxides, because it can greatly enhance the electrical conductivity, expose more of the catalytic active site, accelerate the formation process of metaloxygen intermediates and thus effectively promote its oxygenrelated catalytic activity.…”

Nanocarbon‐Based Electrocatalysts for Rechargeable Aqueous Li/Zn‐Air Batteries

“…As an extend, the rotating ring-disk electrode (RRDE) technique, in which the coaxial ring electrode could detect the products generated from the disk electrode, can distinguish whether the ORR processes via a two-electron way to generate H 2 O 2 or a four-electron pathway to generate OH À [30,31] by the following two equations: As an extend, the rotating ring-disk electrode (RRDE) technique, in which the coaxial ring electrode could detect the products generated from the disk electrode, can distinguish whether the ORR processes via a two-electron way to generate H 2 O 2 or a four-electron pathway to generate OH À [30,31] by the following two equations:…”

Electrochemical assessment of Ca3Co4O9 nanofibres obtained by Solution Blow Spinning

“…Platinum is among the best catalysts for these electrochemical reactions [3]. However, due to its high cost, efforts have been made to develop metal oxide catalysts that can combine improved electrochemical activity with low cost [4]. Moreover, calcium-cobaltites (such as Ca 3 Co 4 O 9 , hereafter called C349) have been widely investigated for energy-related applications [5][6][7].…”