Nanoporous (Pt_1−xFe_x)₃Al intermetallic compounds for greatly enhanced oxygen electroreduction catalysis

Abstract

Here we report a nanoporous (Pt1−xFex)3Al intermetallic compound exhibiting impressive electroreduction catalytic activity and durability for the oxygen reduction reaction.

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

“…Therein, the large channels result from the fast dissolution of the α‐Al whereas the small nanopores form in the subsequent dealloying of intermetallic CuAl 2 compound. With the formation of Bi‐NP Cu skeleton via fully dealloying processes of the constituent α‐Al and CuAl 2 , the preexisted Al 7 Cu 4 Ni nanocrystals are exposed to electrolyte with only a surface etching to yield Cu 4 Ni(110) surface alloy, which in situ grows on the Al 7 Cu 4 Ni(114) planes (Figure c) . This enlists the electroactive Al 7 Cu 4 Ni@Cu 4 Ni nanocrystals to be seamlessly integrated with the conductive Bi‐NP Cu skeleton via metallic bonds (Figure d).…”

“…Their quasi‐periodic distribution with characteristic length of ≈200 nm is distinguished from the binary Cu 20 Al 80 alloy precursor in which only CuAl 2 nanocrystals with diameter of ≈1 nm uniformly distribute in α‐Al matrix (Figure S1c, Supporting Information). This precursor microstructure is expected to generate a bimodal nanoporous architecture of Bi‐NP Cu/Al 7 Cu 4 Ni@Cu 4 Ni hybrid electrocatalysts when selectively etching less‐noble Al component from the α‐Al and CuAl 2 phase . As shown in typical scanning electron microscope (SEM) images for the ≈60‐µm‐thick Bi‐NP Cu/Al 7 Cu 4 Ni@Cu 4 Ni electrocatalyst fabricated by chemically dealloying Cu 18.46 Ni 1.54 Al 80 ( Figure a), it exhibits a uniform bicontinuous nanoporous architecture consisting of interconnective metallic ligaments and bimodal nanopore channels with characteristic lengths of ≈200 nm and ≈10 nm (Figure b and Figure S2, Supporting Information).…”

Highly Stable Pt‐Based Ternary Systems for Oxygen Reduction Reaction in Acidic Electrolytes

“…[57,58] The most common techniques to synthesize intermetallic compounds involve high-temperature annealing under inert or reductive gas. Many ordered compositions, including PtCo, [59] PtFe, [60][61][62] PtNi, [63] PtCu, [64] PtZn, [65] PtNiCo, [66,67] PtFeCo, [68,69] PtFeNi, [68,70] PtCoAl, [71] and PtFeAl, [72] have been synthesized and evaluated against ORR. However, in the early research on intermetallics, such thermal treatment caused sintering of nanoparticles and a serious loss of activity.…”

“…Jiang and coworkers successfully demonstrated the role of Al as a stabilizing agent in nanoporous (Pt 1−x Fe x ) 3 Al and (Pt 1−x Co x ) 3 Al intermetallic alloys synthesized via a two-step annealing process at 300 °C and 950 °C under H 2 /Ar atmosphere. [71,72] Both catalysts exhibited much higher stability in 40 000 cycle durability testing for ORR than commercial Pt. While Fe and Co offer the ligand effect for enhanced ORR kinetics, Al atoms can form strong covalent bonds with Fe (−0.41 eV per atom), Co (−0.45 eV per atom), and Pt atoms (−0.74 eV per atom).…”

Random alloy and intermetallic nanocatalysts in fuel cell reactions

“…158 Researchers around the globe are therefore investing much effort to develop both active and durable industrial electrocatalysts beyond the stateof-the-art Pt/C reported to date. [159][160][161][162][163][164] Enhanced activity of alloy catalysts is due to the reduced adsorption energy of the blocked OH ads by the electronic effect, strain effect, and ordered structure, resulting in a greater number of active sites available for the ORR. A long-standing problem in the study of the ORR has been to determine the reaction mechanism behind the electrocatalytic enhancement.…”