Conductivity Modulation of 3D‐Printed Shellular Electrodes through Embedding Nanocrystalline Intermetallics into Amorphous Matrix for Ultrahigh‐Current Oxygen Evolution

Abstract

Scaling up commercial hydrogen production by water electrolysis requires efficient oxygen evolution reaction (OER) electrodes that can deliver large current densities (more than 500 mA cm−2) at low overpotentials. Here, a highly active and conductive shell‐based cellular (Shellular) electrode is developed through a strategy of embedding nanocrystalline Ni3Nb intermetallics into an amorphous NiFe‐OOH matrix. The tailor‐made laser remelting process enables the dispersive precipitation of corrosion‐resistant nanocrystalline Ni3Nb in large numbers. After in situ electrochemical activation in the self‐developed growth‐mode‐control electrolyte, the amorphous NiFe‐OOH nanosheets and nanocrystalline Ni3Nb are formed on the as‐printed Inconel 718. The conductive atomic force microscopy (C‐AFM) studies and density functional theory (DFT) calculations elucidate that nanocrystalline Ni3Nb can simultaneously enhance the conductivity and activity of the catalyst film. Additionally, a Shellular structure inspired by nature is designed, interestingly, its specific surface area keeps constant with increases in porosity. This design can result in a large surface area and high porosity but with less material cost. Using this electrochemically activated Shellular electrode for OER, a high current density of 1500 mA cm−2 is achieved at a record‐low overpotential of 261 mV with good durability. This development may open the door for large‐scale industrial water electrolysis.

Electrochemical preparation of nano/micron structure transition metal-based catalysts for the oxygen evolution reaction

“…To date, various transition metal-based OER electrocatalysts for electrochemical synthesis have been evaluated with different OER performances (Table 1). 1,11,20,34,74,84,90,92,99–101,106,108,117,118,125,144,151,155,160,163,165,166,176,178,179,181–208 Since transition metal-based metals and alloys cannot survive when placed directly in harsh acidic and alkaline media, they usually need to be stabilized by hosts (such as carbon materials) or saturated with high electronegative elements. Transition-metal oxides and (oxy)hydroxides have been widely studied, and they exhibit considerable OER catalytic performance and are considered to be a group of promising candidates for OER electrocatalysts.…”

Kinetic Regulation Engineering and In‐Situ Spectroscopy Studies on Transition‐Metal‐Based Electrocatalysts for Water Splitting

“…In addition, novel core-branched structures TiO 2 @Ni 2 S 3 with highly exposed (2 ĭ 10) high index facets, [85] (003) facet exposed Ni 3 S 2 , [86] (1 ĭ 20) high index facets of NiC x nanosheets, [87] and facet engineered NiÀ Co hydroxide nanoarrays [88] were also prepared and showed significant electrocatalytic activity for both HER and OER. A highly active and conductive shell-based cellular (shcellular) electrode with excellent OER performance (Fig- ure 4d) was developed by Chang et al [89] DFT calculations show that nanocrystalline Ni 3 Nb can simultaneously improve the conductivity and activity of the catalyst film. The control of crystal slicing can elucidate an in-depth comprehension of the correlation between the surface properties and electrocatalytic activity, thus guiding the design of high-performance electrocatalysts.…”

Stereolithography of 3D Sustainable Metal Electrodes towards High‐Performance Nickel Iron Battery

“…Physical realization of a designed and optimized electrode architecture can directly boost active material loading for better electrochemical performance. Presently, printing methods among the most matured techniques for 3D printing of metals are selective laser melting (SLM) and electron beam melting (EBM), [20][21][22] but these technologies are cost-prohibitive, and resolution remains limited. Digital light processing (DLP) technology is a powerful and widely used tool for 3D printing by utilizing photopolymerization, capable of high resolution, complex geometries at build rates that are much faster than traditional stereolithographic apparatus.…”