Fuel Cells - Page 6

Researchers at the Case Western Reserve University have made a step towards making low-cost catalysts commercially available, which could, in turn, reduce the cost to generate clean energy from PEM fuel cells--the most common cell being tested and used in cars and stationary power plants.

The researchers examined a non-metal catalyst to perform in acid because the standard bearer among fuel cells, the PEM (proton exchange membrane/polymer electrolyte membrane) cell uses an acidic electrolyte. The catalyst is based on a porous structure, with sheets of nitrogen-doped graphene mixed with carbon nanotubes and carbon black particles in a solution, freeze-dried into composite sheets and hardened.

Researchers led by Prof. Andre Geim discovered that graphene, impermeable to gases and liquids, allows protons to pass. This is a breakthrough discovery that could make graphene suitable for use as a proton-conducting membrane, essential in fuel cell technology.

The scientists were surprised to find out that protons manage to pass through graphene with relative ease, especially in high temperatures, because graphene usually demonstrates barrier-like qualities. Fuel cells use oxygen and hydrogen as fuel and convert the input chemical energy unto electricity, with a significant issue of fuel leaks across traditional proton membranes (thus reducing efficiency). The scientists claim graphene membranes may fix that problem and make create much more efficient fuel cells.

In 2013, Rice University researchers developed a simple method to reduce coal into graphene quantum dots (GQDs). Now the researchers combined these GQDs with small graphene oxide (GO) sheets to create an excellent catalyst for fuel-cells.

To create the new materials, the researchers boiled a solution of GQDs and GO sheets - which combined them into self-assembling platelets. Treating those platelets with nitrogen and boron created a material with an abundance of edges for chemical reactions (for oxygen reduction), and excellent conductivity.

Researchers from the US and Saudi Arabia developed a micron-sized microbial fuel cell (MFC) containing multilayer graphene that works using saliva or other waste liquids. Such an MFC (that can produce almost 1µW in power) may find applications in bioelectronics (lab-on-a-chip and point-of-care diagnostics, for example).

Microbial fuel cells (MFCs) rely on bacteria to generate electricity from waste. The bacteria in the device break down organic matter and this process releases electrons that can be collected at an anode. The electrons then travel through an external circuit to the cathode to produce electrical current.

Angstron Materials (owned by Nanotek Instruments and based in Ohio, USA) is a graphene nanoplatelets (GNPs) and single-layer graphene sheets developer and producer.

Ian Fuller, the company's marketing and business development chief, was kind enough to answer a few questions we had regarding the company's technology and business. Ian joined Nanotek Instruments in 2006, focusing on fuel cells. He later joined the Angstron Materials team.

Researchers from Korea's Ulsan institute developed a high performance Oxygen Reduction Reaction (ORR) electrocatalyst using chemical functionalized (doped) graphene oxide. ORR electrocatalysts, which split hydrogen gas to make electricity are critical components in fuel cells and some batteries.

The researchers used covalent functionalization of various small organic molecules with a subsequent thermal treatment, which resulted in thin films. The researchers say they achieved a simple approach to introduce nitrogen atoms on graphene oxide sheets, without a toxic gas precursor and with a good doping degree control.

Researchers from Korea's Ulsan National Institute of Science and Technology (UNIST), Case Western Reserve University and University of North Texas developed a new low-cost metal-free fuel cell catalyst that is based on edge-halogenated graphene nanoplatelets (XGnPs). They say that this new catalyst is a potential replacement for Platinum based ones currently used in fuel cells.

The researchers created the edge-selectively halogenated graphene nanoplatelets by ball-milling graphite flake with chlorine, bromine, or iodine. Experiments have shown that those XGnPs have great oxygen reduction reaction (ORR) activities with higher tolerance to methanol crossover/CO poisoning effects and longer-term stability (this compared to the original graphite and commercial Pt/C electrocatalysts).

Researchers from the DOE's Brookhaven National Laboratory developed a new catalyst (made from Graphene, molybdenum and soybeans) and that could replace platinum in hyroden-production processes. This new catalyst is the best non-noble-metal one ever developed, and it's even better than a catalyst made from bulk platinum. It can be used to split water into hydrogen and oxygen. The hydrogen can then be used regenerated into H2 and then be used as fuel.

To make the new catalyst, the researchers ground soybeans into a powder and then mixed it it with ammonium molybdate. Using a high-temperature carburization made the molybdenum react with the carbon and nitrogen in the soybean and that produced molybdenum carbides and molybdenum nitrides. The material was then anchored on sheets of graphene - and this makes the catalyst effecting in devices such as batteries, supercapacitors, fuel cells, and water electrolyzers.

Researchers from Brown University designed the world's best non-platinum catalyst, based on cobalt-graphene. This can be used to replace Platinum with a more durable and less expensive material as a fuel-cell catalyst.

To create this new material, the researchers used a self-assembly method. First, they dispersed cobalt nanoparticles and graphene in separate solutions. The two solutions were then combined and pounded with sound waves to make sure they mixed thoroughly. That caused the nanoparticles to attach evenly to the graphene in a single layer. Using a centrifuge, the material was removed from the solution, and it was then dried. Exposing it to air, the outside layers of atomic cobalt on each nanoparticle are oxidized which forms a shell of cobalt-oxide that helps protect the cobalt core.

Researchers from the US DOE's Pacific Northwest National Laboratory (PNNL) and Princeton University found a way to combine Graphene and indium tin oxide (ITO) nanoparticles to create cheaper and more durable fuel cells.

Fuel cells work by chemically breaking down oxygen and hydrogen gases to create an electrical current, producing water and heat in the process. The centerpiece of the fuel cell is the chemical catalyst — usually a metal such as platinum — sitting on a support that is often made of black carbon. A good supporting material spreads the platinum evenly over its surface to maximize the surface area with which it can attack gas molecules and is also electrically conductive.