Nonprecious Intermetallic Al₇Cu₄Ni Nanocrystals Seamlessly Integrated in Freestanding Bimodal Nanoporous Copper for Efficient Hydrogen Evolution Catalysis

Abstract

Tremendous demands for renewable hydrogen generated from water splitting have stimulated intensive research on developing earth-abundant, non-noble, and versatile metal catalysts toward the hydrogen evolution reactions (HER). Here, self-supported Cu-Ni-Al hybrid electrodes that are composed of electroactive Al 7 Cu 4 Ni@Cu 4 Ni core/shell nanocrystals seamlessly integrated in selfsupported 3D bimodal nanoporous Cu skeleton (Bi-NP Cu/Al 7 Cu 4 Ni@Cu 4 Ni) as robust HER electrocatalysts in alkaline electrolyte are reported. As a result of the proper architecture, in which the Bi-NP Cu skeleton not only facilitates both electron and electrolyte transports but also provides high specific surface areas to fully use high electrocatalytic activity of Al 7 Cu 4 Ni@Cu 4 Ni core/shell nanocrystals, the Bi-NP Cu/Al 7 Cu 4 Ni@Cu 4 Ni hybrid catalysts exhibit a low onset overpotential of 60 mV and a small Tafel slope of 110 mV dec −1 , enabling the catalytic current density of 10 mA cm −2 at a low overpotential of 139 mV. The highly stable electrochemical performance makes them promising candidates as cathode catalysts in alkaline-based devices.

Evolution of Nanoporous Surface Layers on Gas-Atomized Ti60Cu39Au1 Powders during Dealloying

“…The final porous structure inherits the characteristics of the initial microstructure of the precursor alloys [ 28 , 34 , 35 , 36 ]. The precursor alloys with optimal chemical compositions and the well-controlled initial microstructures, such as amorphous Ti 60 Cu 39 Pd 1 and Ti 60 Cu 39 Pt 1 alloys [ 37 ], and Al 7 Cu 4 Ni nanocrystals [ 38 ] help with the formation of the ultrafine NP Cu with a characteristic pore size of less than 10 nm, which is similar with reported NP Au. It is worthy to state that the dimensions and shapes of the precursor alloys also affect the final nanoporous structures.…”

“…It is worthy to state that the dimensions and shapes of the precursor alloys also affect the final nanoporous structures. Up to date, the different precursor alloys, such as thin film alloy [ 3 , 13 , 39 , 40 , 41 ], nanoparticles [ 42 , 43 , 44 , 45 ], nanowires [ 46 , 47 , 48 , 49 , 50 ], ribbons of as-spun alloys [ 5 , 8 , 24 , 25 , 26 , 27 , 31 , 32 , 33 , 37 , 38 ], and bulk alloys [ 1 , 9 , 18 , 22 , 38 ], etc., have been used as the precursors for NPMs. Compared with ion implantation [ 13 ], anodization [ 14 ], the top-down process in metallic melts [ 15 ], and template methods [ 16 ], etc., gas atomization is easily handled and free of contamination from the templates, anodizing solutions, or high-temperature melts.…”

Flexible Honeycombed Nanoporous/Glassy Hybrid for Efficient Electrocatalytic Hydrogen Generation

“…[12][13][14][15][16][17] The uniform bicontinuous nanoporosity produced by dealloying/etching can offer nanoporous materials satisfactory electrocatalytic activities, high-efficiency electron transportation, and improved selectivity for various redox reactions. [20][21][22][23][24][25] However, the brittleness of the dealloyed nanoporous architectures remains "the Achilles' heel" for their industrialization in flexible/stable electrode devices. [20][21][22][23][24][25] However, the brittleness of the dealloyed nanoporous architectures remains "the Achilles' heel" for their industrialization in flexible/stable electrode devices.…”

“…[18,19] To date, numerous nanoporous materials, especially nanoporous transition metals and their oxides, have been reported for efficient catalysts toward HER in alkaline electrolyte. [20][21][22][23][24][25] However, the brittleness of the dealloyed nanoporous architectures remains "the Achilles' heel" for their industrialization in flexible/stable electrode devices. More recently, metallic glass (MG) ribbons with good mechanical flexibility have been suggested to be active electrocatalysts for HER due to their metastable state and richness of low-coordination sites at the surface.…”

Coupling NiCo Alloy and CeO2 to Enhance Electrocatalytic Hydrogen Evolution in Alkaline Solution

“…In terms of overpotential at 10 mA cm −2 and Tafel slope, NiCo-CeO 2 /GP also outperforms most of the reported (Figure 3d) as well as other HER electrocatalysts (Table S2, Supporting Information). [16][17][18][40][41][42][43] To further estimate the intrinsic activities of the synthesized electrocatalysts, electrochemical active surface areas (ECSAs) of electrodes derived from the double-layer capacitances (C dl ) were tested ( Figure S15, Supporting Information). As shown in Figure S16, Supporting Information, NiCo-CeO 2 /GP shows the largest C dl and thus possesses the highest ECSA that is relative to graphite plate (see Supporting Information for details).…”