3D nanoporous iridium-based alloy microwires for efficient oxygen evolution in acidic media

Abstract

Although significant progresses have been achieved recently in developing catalysts for electrochemical oxygen evolution in alkaline electrolytes, high performance catalysts toward oxygen evolution in acidic media have not been realized in spite of the technical importance for the development of promising energy transformation technologies including electrocatalytic water splitting, integrated (photo)electrochemistry cells, rechargeable metal-air batteries, and so on. Here, we synthesized a three-dimensional nanoporous Ir 70 Ni 30-x Co x alloy microwires as oxygen evolution reaction electrocatalyst using a dealloying strategy. The three dimensional binderfree np-Ir 70 Ni 15 Co 15 catalyst in 0.1 M HClO 4 shows a low overpotential (220 mV@ η = 10 mA cm −2), low Tafel slope (44.1 mV dec −1) and excellent corrosion resistance, significantly outperforming commercial IrO 2 catalysts. The excellent performance is attributed to the nanoporous structure and the alloying effect, which promote the permeation of electrolyte, accelerate the transportation of electrons. More importantly, the high valence Ir oxide species with low-coordination structure in np-Ir 70 Ni 15 Co 15 alloy are identified for the real catalytic sites of OER process by the XAS results acquired on synchrotron radiation. This work not only provides fundamental understandings of the correlation between surface activity and stability for OER catalysts, but also paves a new way to advanced electrocatalysts working in acidic media.

Dynamic active-site generation of atomic iridium stabilized on nanoporous metal phosphides for water oxidation

“…Compared with previously reported OER catalysts, np-Ir/NiFeO shows the higher catalytic performance in terms of mass activity, overpotential at 10 mA cm −2 , and Tafel slope in the alkaline solution ( Fig. 2c, d and Supplementary Tables 1, 2) 5, 17,22,27,37,43 .…”

General Synthesis of Nanoporous 2D Metal Compounds with 3D Bicontinous Structure

“…[21][22][23] However, precursor in an acid solution (Figure 1a and method). [34][35][36] Subsequently, Au-M surface alloys were formed by transporting metal-organic precursors on the as-prepared NPG substrate followed by thermal annealing in a CVD system under Ar atmosphere (Figure 1b, Figure S1, and Table S1, Supporting Information). An important feature of the Au-M surface alloy, predicted from their phase diagram ( Figure S2, Supporting Information), [37] is that M atom diffuses into the surface Au spontaneously to form miscible Au-M surface alloy owing to the higher surface energy and heat of evaporation of M than that of Au (Table S2, Supporting Information).…”

Core–Shell Structured NiFeSn@NiFe (Oxy)Hydroxide Nanospheres from an Electrochemical Strategy for Electrocatalytic Oxygen Evolution Reaction

“…Due to the controlled composition and modulated physicochemical properties, alloys have been widely adopted in many fields. [ 41–49 ] One example is oxygen reduction reaction (ORR). [ 41,42 ] Precious metal‐based alloys incorporating transition metals as ORR electrocatalysts could not only lower the cost, but also enhance the catalytic activity.…”

“…However, there are few researches on alloys in the OER system. [ 44,45,50 ] Furthermore, the preparation of alloy always requires harsh conditions, including but not limited to high temperature, long reaction time, hazardous chemicals, and special experimental techniques (magnetron sputtering, [ 44 ] arc melting, [ 45 ] electrospinning, [ 46 ] etc.). In contrast, electrodeposition has been proven to be a cost‐effective, timesaving, scalable, and universal method in the synthesis of nanomaterials with good reproducibility.…”