6 research outputs found
Ga-doped Pt-Ni Octahedral Nanoparticles as a Highly Active and Durable Electrocatalyst for Oxygen Reduction Reaction
Bimetallic PtNi nanoparticles have been considered as a promising electrocatalyst for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs) owing to their high catalytic activity. However, under typical fuel cell operating conditions, Ni atoms easily dissolve into the electrolyte, resulting in degradation of the catalyst and the membrane-electrode assembly (MEA). Here, we report gallium-doped PtNi octahedral nanoparticles on a carbon support (Ga-PtNi/C). The Ga-PtNi/C shows high ORR activity, marking an 11.7-fold improvement in the mass activity (1.24 A mgPt-1) and a 17.3-fold improvement in the specific activity (2.53 mA cm-2) compare to the commercial Pt/C (0.106 A mgPt-1 and 0.146 mA cm-2). Density functional theory calculations demonstrate that addition of Ga to octahedral PtNi can cause an increase in the oxygen intermediate binding energy, leading to the enhanced catalytic activity toward ORR. In a voltage-cycling test, the Ga-PtNi/C exhibits superior stability to PtNi/C and the commercial Pt/C, maintaining the initial Ni concentration and octahedral shape of the nanoparticles. Single cell using the Ga-PtNi/C exhibits higher initial performance and durability than those using the PtNi/C and the commercial Pt/C. The majority of the Ga-PtNi nanoparticles well maintain the octahedral shape without agglomeration after the single cell durability test (30,000 cycles). This work demonstrates that the octahedral Ga-PtNi/C can be utilized as a highly active and durable ORR catalyst in practical fuel cell applications
Ga-doped Pt-Ni Octahedral Nanoparticles as a Highly Active and Durable Electrocatalyst for Oxygen Reduction Reaction
Bimetallic PtNi nanoparticles have been considered as a promising electrocatalyst for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs) owing to their high catalytic activity. However, under typical fuel cell operating conditions, Ni atoms easily dissolve into the electrolyte, resulting in degradation of the catalyst and the membrane-electrode assembly (MEA). Here, we report gallium-doped PtNi octahedral nanoparticles on a carbon support (Ga-PtNi/C). The Ga-PtNi/C shows high ORR activity, marking an 11.7-fold improvement in the mass activity (1.24 A mgPt-1) and a 17.3-fold improvement in the specific activity (2.53 mA cm-2) compare to the commercial Pt/C (0.106 A mgPt-1 and 0.146 mA cm-2). Density functional theory calculations demonstrate that addition of Ga to octahedral PtNi can cause an increase in the oxygen intermediate binding energy, leading to the enhanced catalytic activity toward ORR. In a voltage-cycling test, the Ga-PtNi/C exhibits superior stability to PtNi/C and the commercial Pt/C, maintaining the initial Ni concentration and octahedral shape of the nanoparticles. Single cell using the Ga-PtNi/C exhibits higher initial performance and durability than those using the PtNi/C and the commercial Pt/C. The majority of the Ga-PtNi nanoparticles well maintain the octahedral shape without agglomeration after the single cell durability test (30,000 cycles). This work demonstrates that the octahedral Ga-PtNi/C can be utilized as a highly active and durable ORR catalyst in practical fuel cell applications
3D Porous Cobalt鈥揑ron鈥揚hosphorus Bifunctional Electrocatalyst for the Oxygen and Hydrogen Evolution Reactions
A 3D porous Co鈥揊e鈥揚
foam fabricated using electrodeposition
is presented as a high-performance and durable catalyst for both oxygen
and hydrogen evolution reactions. To establish optimal Fe/Co ratio
of the catalyst, Co鈥揊e鈥揚 films were electrodeposited
with Fe/Co ratio of 0.2, 0.4, 1.1, and 3.3. Among the prepared samples,
the Co鈥揊e鈥揚 film with the Fe/Co ratio of 1.1 (Co鈥揊e鈥揚-1.1)
exhibited the highest activity for the oxygen evolution reaction,
which could be attributed to the transfer of the valence electron
from Co to Fe and P. To improve performance of the Co鈥揊e鈥揚-1.1,
a 3D porous foam structure was adopted using the electrodeposition.
The Co鈥揊e鈥揚 foam had 94 times larger electrochemical
active surface area (ECSA) than the Co鈥揊e鈥揚 film with
similar Fe/Co ratios of 1.1, resulting in an distinguished activity
for the oxygen evolution reaction (294 mV at 10 mA/cm<sup>2</sup>)
and hydrogen evolution reaction (73 mV at 10 mA/cm<sup>2</sup>) in
an alkaline solution. Since the electrodeposited Co鈥揊e鈥揚
foam itself can be directly used as an electrode, it is free from
binders, and microstructure of the electrode can be engineered by
controlling the electrodeposition condition, leading to the enlarged
ECSA and improved performance. Thus, the Co鈥揊e鈥揚 foam
presented in this study offers a facile and controllable synthesis
of catalyst and electrode through an easy electrodeposition process
Fabrication of Al-Ni Alloys for Fast Hydrogen Production from Hydrolysis in Alkaline Water
Hydrogen generation through the hydrolysis of aluminum alloys has attracted significant attention because it generates hydrogen directly from alkaline water without the need for hydrogen storage technology. The hydrogen generation rate from the hydrolysis of aluminum in alkaline water is linearly proportional to its corrosion rate. To accelerate the corrosion rate of the aluminum alloy, we designed Al-Ni alloys by continuously precipitating an electrochemically noble Al3Ni phase along the grain boundaries. The Al-0.5~1 wt.% Ni alloys showed an excellent hydrogen generation rate of 16.6 mL/cm2路min, which is about 6.4 times faster than that of pure Al (2.58 mL/cm2路min). This excellent performance was achieved through the synergistic effects of galvanic and intergranular corrosion on the hydrolysis of Al. By raising the solution temperature to 50 掳C, the optimal rate of hydrogen generation of Al-1 wt.% Ni in 10 wt.% NaOH solutions at 30 掳C can be further increased to 54.5 mL/cm2路min