Stainless Steel as A Bi-Functional Electrocatalyst—A Top-Down Approach

Abstract

For a hydrogen economy to be viable, clean and economical hydrogen production methods are vital. Electrolysis of water is a promising hydrogen production technique with zero emissions, but suffer from relatively high production costs. In order to make electrolysis of water sustainable, abundant, and efficient materials has to replace expensive and scarce noble metals as electrocatalysts in the reaction cells. Herein, we study activated stainless steel as a bi-functional electrocatalyst for the full water splitting reaction by taking advantage of nickel and iron suppressed within the bulk. The final electrocatalyst consists of a stainless steel mesh with a modified surface of layered NiFe nanosheets. By using a top down approach, the nanosheets stay well anchored to the surface and maintain an excellent electrical connection to the bulk structure. At ambient temperature, the activated stainless steel electrodes produce 10 mA/cm2 at a cell voltage of 1.78 V and display an onset for water splitting at 1.68 V in 1M KOH, which is close to benchmarking nanosized catalysts. Furthermore, we use a scalable activation method using no externally added electrocatalyst, which could be a practical and cheap alternative to traditionally catalyst-coated electrodes.

Solar-Driven Water Splitting at 13.8% Solar-to-Hydrogen Efficiency by an Earth-Abundant Electrolyzer

“…The reduction treatment resulted in a lowering of the total oxygen:metal ratio from 2.05:1.00 to 1.24:1.00 while also promoting reduced oxidation numbers in the metals along with pure metallic states (XPS, Figure S1). Similar reduction methods are commonly employed to activate HER catalysts such as in stainless steel, NiO, and NiMo catalysts, where the reduced material is found more active, as a result of more optimal adsorption energies and higher electrical conductivity. ,, The nanoflake structures of the NiFeMo-NF catalysts are concurrently transformed into nanoparticle (NP) structures, as highlighted by the SEM images in Figure d. The SEM images also reveal that the catalyst particles remain firmly attached to the NCNT network with a homogeneous coverage of the NCNT/CP support, as indicated by the SEM-EDS images in Figure S2.…”

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

“…The pristine metal substrates, such as powders, foams, and plates, always exhibit low catalytic activity for water splitting. [ 49–52 ] These metal substrates can be corroded with continuous material dissolution to produce metal ions by some strong corrodents such as O 2 , Fe 3+ , H 2 O 2 , or S 2 O 8 2− , [ 53–56 ] meanwhile these metal ions coordinate with hydroxyl groups or other electronegative radicals to form sediments. After the corrosion reaction, there are some nanosheet‐like corrosion layers generated on the surfaces of metal substrates, which can be employed as the HER or OER active materials.…”

Anodized Steel: The Most Promising Bifunctional Electrocatalyst for Alkaline Water Electrolysis in Industry

“…The steel can be used not only as a current collector in alkaline electrolyzers but also potentially as an electrocatalyst, where its catalytic performance can be improved by anodization. [27,29] However, the performance of steel for electrocatalysis is still far away from practical application. The key questions to its industrial application for commercial green-hydrogen production include: how to select a suitable steel that can be easily produced on large scale and how to achieve the highest activity by an effective process.…”