Highly Durable and Active Pt‐Based Nanoscale Design for Fuel‐Cell Oxygen‐Reduction Electrocatalysts

Abstract

Fuel cells are one of the promising energy-conversion devices due to their high efficiency and zero emission. Although recent advances in electrocatalysts have been achieved using various material designs such as alloys, core@shell structures, and shape control, many issues still remain to be resolved. Especially, material design issues for high durability and high activity are recently accentuated owing to severe instability of nanoparticles under fuel-cell operating conditions. To address these issues, fundamental understanding of functional links between activity and durability is timely urgent. Here, the activity and durability of nanoscale materials are summarized, focusing on the nanoparticle size effect. In addition to phenomenological observation, two major degradation origins, including atomic dissolution and particle size increase, are discussed related to the activity decrease. Based on the fundamental understanding of nanoparticle degradation, recent promising strategies for durable Pt-based nanoscale electrocatalysts are introduced and the role of each design for durability enhancement is discussed. Finally, short comments related to the future direction of nanoparticle issues are provided in terms of nanoparticle synthesis and analysis.

Tungsten as “Adhesive” in Pt2CuW0.25 Ternary Alloy for Highly Durable Oxygen Reduction Electrocatalysis

“…The Pt x Cu y W y alloy NPs are synthesized through thermal reduction of Pt(acac) 2 and Cu(acac) 2 precursors with the injection of appropriate amount of W(CO) 6 at 220 °C which also induces the NP nucleation. The W(CO) 6 has been used by Zhang and Fang as both reducing and morphology-regulating agent to prepare the cubic-shaped Pt or Pt-based alloy NCs.…”

“…The W(CO) 6 has been used by Zhang and Fang as both reducing and morphology-regulating agent to prepare the cubic-shaped Pt or Pt-based alloy NCs. [27] The injection of W(CO) 6 quickly releases a large amount of highly reductive CO species that can reduce the metal precursors and nucleate the NPs. [27] The injection of W(CO) 6 quickly releases a large amount of highly reductive CO species that can reduce the metal precursors and nucleate the NPs.…”

“…[27] The high-resolution transmission electron microscopy (HRTEM) images taken from individual NP show well-defined fringes with the spacing of 0.22 nm, corresponding to the (111) lattice plane (Figure 1b). The successful inclusion of W can be ascribed to the hot injection of W(CO) 6 and the existence of highly reductive CO species which can collaboratively inhibit the "escape" of W atoms from the NPs. The successful inclusion of W can be ascribed to the hot injection of W(CO) 6 and the existence of highly reductive CO species which can collaboratively inhibit the "escape" of W atoms from the NPs.…”

“…Chemical: Platinum(II) acetylacetonate (Pt(acac) 2 , 98%), copper acetylacetonate (Cu(acac) 2 , 98%), nickel(II) acetylacetonate (Ni(acac) 2 , 98%), tungsten hexacarbonyl (W(CO) 6 , 98%) were purchased from Sigma-Aldrich. Oleylamine (>80%), oleic acid (90%), and dibenzyl ether (95%) were purchased from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China).…”

“…[26] Herein, we incorporate the W atoms into the bulk of Pt x Cu y NCs through a nucleation-trapping strategy and synthesize Pt x Cu y W z alloy nanoparticles (NPs) by quickly injecting W(CO) 6 to reduce Pt(acac) 2 and Cu(acac) 2 precursors. We have previously reported a surface W-doping strategy for the ternary PtCuNi alloy, which demonstrates that the W-doping induces the re-arrangement of surface atoms and effectively increases the number of active sites.…”