Fabrication of Three-Dimensional Multiscale Porous Alloy Foams at a Planar Substrate for Efficient Water Splitting

Abstract

The electrolysis of water to produce hydrogen and oxygen is a simple and attractive approach to store renewable energies in the form of chemical fuels, in which the key fact depends on the innovative exploration of high-performance electrocatalysts. Herein, we describe a novel electrochemical deposition method for synthesizing three-dimensional NiCo, NiCu, and CoCu alloy foams at a planar electrode substrate for the hydrogen evolution reaction (HER) and NiFe alloy foam for the oxygen evolution reaction (OER). The electrodes are composed of multiscale porous structure caused by concomitant hydrogen gas bubbles evolved during cathodic deposition. The unique electrode structure is beneficial for exposing more catalytic active sites, enhancing mass transport, and accelerating dissipation of gas bubbles generated during water electrolysis. The twoelectrode alkaline water electrolyzers constructed with these alloy foams can afford a current density of 400 mA cm −2 at a cell voltage of 1.73 V for Ni 30 Fe||NiCo and at 1.71 V for Ni 30 Fe||NiCu and exhibit excellent durability in prolonged bulk electrolysis. The strategy developed in this study highlights construction of three-dimensional, multiscale porous electrocatalysts at a planar electrode substrate which is significant for catalysis application.

Intrinsic activity modulation and structural design of NiFe alloy catalysts for an efficient oxygen evolution reaction

“…8d–f ). 90 As shown in Fig. 8g , the largest current density was achieved for the Ni 30 Fe alloy foam with a low onset overpotential of 240 mV.…”

Transforming Damage into Benefit: Corrosion Engineering Enabled Electrocatalysts for Water Splitting

“…Self‐supporting electrocatalysts are a series of electrochemically active materials grown on conductive substrates, such as carbon clothes, [ 115–117 ] carbon papers, [ 118,119 ] metal foams and plates, [ 120–124 ] which usually possess the advantages of prominent conductivity, ample porous structure and high specific surface area. Importantly, self‐supporting electrocatalysts can be directly utilized as the electrode for water‐splitting devices without adding organic binders, which overcome the shortcomings of lowered conductivity and covered active sites for powder catalysts.…”

Duplex Interpenetrating-Phase FeNiZn and FeNi3 Heterostructure with Low-Gibbs Free Energy Interface Coupling for Highly Efficient Overall Water Splitting

“…At the current density of 100 and 500 mA cm −2 , the overpotentials of FeNiZn/FeNi 3 @NiFe-24 h sample are only 102 and 177 mV, which are much lower than those of other electrodes. Moreover, the HER activity of FeNiZn/FeNi 3 @NiFe-24 h sample is superior to the comparable electrocatalysts reported previously as shown in Table S2, especially under the high current density [ 19 , 20 , 24 , 26 , 38 , 44 , 48 – 51 , 53 ]. As stated above, it is regarded that the free-standing multimodal porous interpenetrating-phase heterostructure is responsible for the unique HER activity of FeNiZn/FeNi 3 @NiFe-24 h sample in virtue of high density of active sites and fluent mass transfer [ 3 ].…”