Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes

Abstract

Shape- and size-controlled supported metal and intermetallic nanocrystallites are of increasing interest because of their catalytic and electrocatalytic properties. In particular, intermetallics PtX (X = Bi, Pb, Pd, Ru) are very attractive because of their high activity as fuel-cell anode catalysts for formic acid or methanol oxidation. These are normally synthesized using high-temperature techniques, but rigorous size control is very challenging. Even low-temperature techniques typically produce nanoparticles with dimensions much greater than the optimum <6 nm required for fuel cell catalysis. Here, we present a simple and robust, chemically controlled process for synthesizing size-controlled noble metal or bimetallic nanocrystallites embedded within the porous structure of ordered mesoporous carbon (OMC). By using surface-modified ordered mesoporous carbon to trap the metal precursors, nanocrystallites are formed with monodisperse sizes as low as 1.5 nm, which can be tuned up to ∼3.5 nm. To the best of our knowledge, 3-nm ordered mesoporous carbon-supported PtBi nanoparticles exhibit the highest mass activity for formic acid oxidation reported to date, and over double that of Pt-Au.

Highly Durable Platinum Single‐Atom Alloy Catalyst for Electrochemical Reactions

“…[19] The formic acid oxidation reaction (FAOR) occurs at the anode of the DFAFCs and is known to have two different reaction mechanisms; a direct pathway of dehydrogenation (HCOOH → HCOO ads + H + + e − → CO 2 + 2H + + 2e − ) and an indirect pathway of dehydration (HCOOH → CO ads + H 2 O → CO 2 + 2H + + 2e − ). [22][23][24] High activity and selectivity toward the direct pathway could be obtained by controlling the Pt Single atomic Pt catalyst can offer efficient utilization of the expensive platinum and provide unique selectivity because it lacks ensemble sites. However, designing such a catalyst with high Pt loading and good durability is very challenging.…”

Small palladium islands embedded in palladium–tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction

“…The preparation of the catalyst is performed by a microwave-assisted synthesis, which avoids the problems of a hydrophobic OMCs support and hydrophilic catalyst salts 29 , and is pursued without any use of carbon support functionalization or polymer coating of nanoparticles as previously utilized to overcome this problem 30 . The synthesis is schematically described in Fig.…”

Cobalt and Nitrogen Co-Doped Nano-Porous Carbon: Synthesis and Application for Lithium-Sulfur Battery

“…Additionally, polysulfides shuttle effect [9] [10] remains a significant challenges to practical applications of the Lithium-sulfur batter. Therefore, storage and immobilization of dissolved polysulfides is of great importance to avoid low coulombic efficiency and self-discharge behavior in designing a Li-S battery with long cycle life.…”