Design and Application of Foams for Electrocatalysis

Abstract

Developing low cost and efficient anode and cathode materials toward electrocatalysis are regarded as one of the most desirable yet challenging research directions, which are intimately related to the pressing energy, environmental and human health issues. Currently, 3 D foam (such as Ni foam, Cu foam, and graphene foam) based heterogeneous catalysts have been intensively explored for actively catalyzing the electrode reactions. Their inherent characteristics of stereo‐network structure, high specific area and large pore volume not only provide better mass transport of reactants to electrode surfaces, but also pave 3 D electron transport pathways. Herein, recent significant progress and rational design of foam‐based electrocatalysts are reviewed. In addition, some insights into current challenges and future directions of foams for efficient electrocatalysis are proposed and discussed.

Thin‐Layered Cobalt‐Based Catalysts on Stainless‐Steel Microfibers for the Efficient Electrolysis of Water

“…Recently, the design of three‐dimensional (3 D) Co‐based oxygen‐evolving nanoarray catalysts exhibiting high activities under neutral conditions was reported . Despite the high popularity of porous 3 D electrodes in electrochemical energy applications, the authors did not directly or quantitatively analyze the impact of the 3 D structure on the catalytic performance of the Co‐OECs . The reason might be related to the presumption that Co‐OECs are porous enough for efficient proton transport, which has turned out to be true under certain circumstances .…”

“…Despite the high popularity of porous 3 D electrodes in electrochemical energy applications, the authors did not directly or quantitatively analyze the impact of the 3 D structure on the catalytic performance of the Co‐OECs . The reason might be related to the presumption that Co‐OECs are porous enough for efficient proton transport, which has turned out to be true under certain circumstances . Although Co‐OECs exhibit volume activity owing to their porous, hydrated structure, recent work revealed that their reaction rates could be much higher at the surface exposed to the electrolyte owing to proton‐transport limitations .…”

Amorphous Nickel‐Cobalt‐Borate Nanosheet Arrays for Efficient and Durable Water Oxidation Electrocatalysis under Near‐Neutral Conditions

“…The high‐performance of 3D NiCo‐Bi/NF electrode can be attributed to several factors: the intrinsically high activity of the NiCo‐Bi nanosheet arrays with the amorphous state and the high valence of the metal acting as active sites during the whole electrolysis; the unique morphology of interconnected NiCo‐Bi nanosheets array on macroporous NF, which enables large working surface area and excellent gas bubble dissipation ability; and the low resistance of the as‐prepared electrode because the catalyst is directly converted from NiCo‐LDH on highly conductive NF, avoiding using chemical binders (such as Nafion) which tends to impede charge transport during catalytic reactions.…”

Core–Shell‐Structured NiS2@Ni‐Bi Nanoarray for Efficient Water Oxidation at Near‐Neutral pH

“…Traditionally, water splitting is an ideal way to mass produce hydrogen, especially in comparison to natural gas reforming. The oxygen evolution reaction (OER), as one of the most formidable tasks in the development of modern electrochemistry, has been identified as the bottleneck of water splitting . The OER suffers from sluggish kinetics arising from proton‐coupled four‐electron transfer and the formation of an oxygen–oxygen bond, which result in a high overpotential that hinders the efficiency of both photon‐driven and electricity‐driven water splitting .…”