A review of anode catalysis in the direct methanol fuel cell

Recent advances in activity and durability enhancement of Pt/C catalytic cathode in PEMFC. Part II: Degradation mechanism and durability enhancement of carbon supported platinum catalyst

The research and development of catalysts with high activity and high durability is a significant issue for proton exchange membrane fuel cell (PEMFC). Nitrogen-doped carbon nanostructures and their composites demonstrate promising potential for PEMFC catalysts application. The nitrogen doping strategies of carbon nanostructures and the electrocatalytic aspects of nitrogen-containing carbon with and without catalytic metals on it are reviewed. Pt-based catalysts with nitrogen-doped carbon as support exhibit enhanced catalytic activity and durability toward oxygen reduction and methanol oxidation, which can be attributed to the high dispersion of Pt nanoparticles and the modified interaction between Pt nanoparticles and the support. For most of the non-Pt metal catalysts (Fe, Co, etc.) presently investigated for potential application in PEMFC, nitrogen is the indispensable element, and even though there are still controversies, the pyridinic type nitrogen is generally considered to be responsible for the catalytic sites. But the catalytic activity is still low and the stability issue is another challenging problem for non-Pt metal catalysts. Nitrogen-doped carbon, without catalytic metals on it, also shows enhanced catalytic activity. But many issues still need further investigation in order to get catalysts with targeted activity and durability.

Nitrogen-doped carbon nanostructures and their composites as catalytic materials for proton exchange membrane fuel cell

Single wall carbon nanotube (SWCNT) architecture when employed as conducting scaffolds in a TiO2 semiconductor based photoelectrochemical cell can boost the photoconversion efficiency by a factor of 2. Titanium dioxide nanoparticles were dispersed on SWCNT films to improve photoinduced charge separation and transport of carriers to the collecting electrode surface. The shift of ∼100 mV in apparent Fermi level of the SWCNT−TiO2 system as compared to the unsupported TiO2 system indicates the Fermi level equilibration between the two systems. The interplay between the TiO2 and SWCNT of attaining charge equilibration is an important factor for improving photoelectrochemical performance of nanostructured semiconductor based solar cells. The feasibility of employing a SWCNT−TiO2 composite to drive the water photoelectrolysis reaction has also been explored.

Single wall carbon nanotube scaffolds for photoelectrochemical solar cells. Capture and transport of photogenerated electrons.

Catalyst support materials exhibit great influence on the cost, performance, and durability of polymer electrolyte membrane (PEM) fuel cells. This feature article summarizes several important kinds of novel support materials for PEM fuel cells (including direct methanol fuel cells): nanostructured carbon materials (carbon nanotubes, carbon nanofibers, mesoporous carbon), conductive doped diamonds and nanodiamonds, conductive oxides (tin oxide/indium tin oxide, titanium oxide, tungsten oxide), and carbides (tungsten carbides). The advantages and disadvantages, the acting mechanism to promote electrocatalytic performance, and the strategies to improve present catalyst support materials and search for new ones are discussed. This is expected to shed light on future development of catalyst supports for PEM fuel cells.

Novel catalyst support materials for PEM fuel cells : current status and future prospects

Composite electrodes made of Pt nanoparticles deposited on carbon nanotubes grown on fuel cell backings

Metal catalyst particles are deposited on carbon nanotubes by preparing a silane solution of a metal catalyst salt, e.g. platinum or ruthenium chloride, immersing an electrically conducting substrate carrying nanotubes in the silane solution to yield a composite structure of substrate, nanotubes and catalyst, and reducing the composite structure to yield a composite of substrate, carbon nanotubes and metallic catalyst particles.

Depositing metal particles on carbon nanotubes

3D carbon nanotube network based on a hierarchical structure grown on carbon paper backing

http://www.eng.uwo.ca/people/asun/Paper/Controlled%20synthesis%20of%20pointed%20carbon%20nanotubes.pdf

Controlled synthesis of pointed carbon nanotubes

A newly designed gas phase thermal decomposition reactor, ohmically heating the catalytic sites, has been used to synthesize multiwall carbon nanotubes (MWCNTs) on carbon paper and stainless steel screen. Co-Ni catalyst particles were dispersed by a silane intermediate layer adsorbed onto the carbon fibers or the stainless steel threads of the supports. MWCNTs were obtained on both substrates by a tip grown mechanism. They are about 20 μm in length and 15–50 nm in diameter. A methanol pretreatment of the carbon fibers significantly increased the density of the tubes on the carbon paper, but the same treatment had a negative effect on stainless steel. The MWCNTs, which adhere firmly to the carbon paper and the stainless steel screen, may find applications as electrodes in fuel cells, sensors and in photonics.

Ruying Li

Papers

Composite electrodes made of Pt nanoparticles deposited on carbon nanotubes grown on fuel cell backings

Depositing metal particles on carbon nanotubes

3D carbon nanotube network based on a hierarchical structure grown on carbon paper backing

Controlled synthesis of pointed carbon nanotubes

Formation of carbon nanotubes on carbon paper and stainless steel screen by ohmically heating catalytic sites