Fuel Cells - Page 3

The following is a sponsored post by XFNano

XFNano's graphene materials were recently used in two fascinating research work focused on advanced energy applications.

The first is a work by teams from Anhui Normal University, Chinese Academy of Sciences (CAS) and the University of the Chinese Academy of Sciences which developed a fast, one-step strategy to prepare sandwiched metal hydroxide/graphene composites through a kinetically controlled coprecipitation under room temperature. Such NiCo-HS@G nano-composite exhibits good electrocatalytic activity for OER, superior to most of the reported OER catalysts. Such performance and the facile preparation of NiCo-HS@G opens up a new avenue for the cost-effective and low-energy-consumption production of various sandwiched metal hydroxides/graphene composites as efficient OER electrocatalysts with desired morphology and competing performance for the applications in diverse energy devices.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory are part of a scientific collaboration that has identified a new electrocatalyst that efficiently converts CO₂ to carbon monoxide (CO), a highly energetic molecule.

There are many ways to use CO, says Eli Stavitski, a scientist at Brookhaven and an author on the paper. You can react it with water to produce energy-rich hydrogen gas, or with hydrogen to produce useful chemicals, such as hydrocarbons or alcohols. If there were a sustainable, cost-efficient route to transform CO₂ to CO, it would benefit society greatly. Indeed, scientists have been looking for a way to do just that, but traditional electrocatalysts can't effectively initiate the reaction. That’s because a competing reaction, called the hydrogen evolution reaction (HER) or water splitting, takes precedence over the CO₂ conversion reaction.

Rice University scientists, led by Prof. James Tour, along with teams from the University of Texas at San Antonio and the Chinese Academy of Sciences, Beijing, China have detected a deception in graphene catalysts that, until now, gone unnoticed. Graphene has been widely tested as a replacement for expensive platinum in applications like fuel cells, where the material catalyzes the oxygen reduction reaction (ORR) essential to turn chemical energy into electrical energy.

Since graphene isn't naturally metallic, researchers have been baffled by its catalytic activity when used as a cathode. The Rice team has now discovered that trace quantities of manganese contamination from graphite precursors or reactants hide in the graphene lattice. Under the right conditions, those metal bits activate the ORR. Tour said they also provide insight into how ultrathin catalysts like graphene can be improved.

Researchers at The University of Manchester have found a new and exciting physical effect in graphene membranes that could be used in devices to artificially mimic photosynthesis.

The new findings demonstrated an increase in the rate at which the material conducts protons when it is simply illuminated with sunlight. The 'photo-proton' effect, as it has been named, could be utilized to design devices able to directly harvest solar energy to produce hydrogen gas, a promising green fuel. It might also be of interest for other applications, such as light-induced water splitting, photo-catalysis and for making new types of highly efficient photodetectors.

Researchers at UC Santa Cruz South and the China University of Technology have developed a graphene-based nanostructured composite material that shows impressive performance as a catalyst for the electrochemical splitting of water to produce hydrogen. An efficient, low-cost catalyst is essential for realizing the promise of hydrogen as a clean, environmentally friendly fuel.

The team has been investigating the use of carbon-based nanostructured materials as catalysts for the reaction that generates hydrogen from water. In a recent study, they obtained good results by incorporating ruthenium ions into a sheet-like nanostructure composed of carbon nitride. Performance was further improved by combining the ruthenium-doped carbon nitride with graphene, to form a layered composite.

Researchers from Rice University have discovered that nitrogen-doped carbon nanotubes or modified graphene nanoribbons could potentially replace platinum, one of the most expensive facets in fuel cells, for performing fast oxygen reduction—a crucial reaction that transforms chemical energy into electricity.

The researchers used computer simulations to see how carbon nanomaterials can be improved for fuel-cell cathodes and discovered the atom-level mechanisms by which doped nanomaterials catalyze oxygen reduction reactions. The simulations also revealed why graphene nanoribbons and carbon nanotubes modified with nitrogen and/or boron are so sluggish and how they can be improved.

Samsung has announced the development of a unique "graphene ball" that could make lithium-ion batteries last longer and charge faster. In fact, Samsung Advanced Institute of Technology (SAIT) said that using the new graphene ball material to make batteries will increase their capacity by 45% and make their charging speed five times faster. It was also said that batteries that use graphene ball can maintain a temperature of 60 degrees Celsius that is required for use in electric cars.

SAIT's team used a chemical vapor deposition process to grow a graphenesilica assembly, called a graphene ball. Each graphene ball is composed of a SiO_x nanoparticle center and surrounding graphene layers, constituting a 3D popcorn-like structure. The graphene-ball coating improves cycle life and fast charging capability by suppressing detrimental side reactions and providing efficient conductive pathways.

Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory have developed a mix of metal nanocrystals wrapped in graphene that may open the door to the creation of a new type of fuel cell by enabling enhanced hydrogen storage properties.

ultrathin oxide layer (oxygen atoms shown in red) coating graphene-wrapped magnesium nanoparticles (orange) still allows in hydrogen atoms (blue) for hydrogen storage applications

The team studied how graphene can be used as both selective shielding, as well as a performance increasing factor in terms of hydrogen storage. The study drew upon a range of Lab expertise and capabilities to synthesize and coat the magnesium crystals, which measure only 3-4 nanometers (billionths of a meter) across; study their nanoscale chemical composition with X-rays; and develop computer simulations and supporting theories to better understand how the crystals and their carbon coating function together.

Researchers from Rice University have transformed wood into an electrical conductor by turning its surface into graphene. The team used its LIG technique to blacken a thin film pattern onto a block of pine.

Previous work with LIG included heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Rather than a flat sheet of hexagonal carbon atoms, LIG is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.

Researchers from Florida State University, Penn State University, Tsinghua University in China and the Institute of Carbon Science and Technology in Japan have come to fascinating conclusions on how to produce pure hydrogen, a green energy fuel by splitting water.

After experimenting with ways to use the compound molybdenum disulfide to split water, the team realized that the compound’s protons did not overlap well with that of hydrogen. They ultimately determined that the best way to split the hydrogen was to create an alloy with the molybdenum disulfide. They created a thin film with alternating graphene and tungsten-molybdenum layers.