Better catalyst for solar-powered hydrogen production.


Hydrogen is a “green” fuel that burns cleanly and can generate electricity via fuel cells. One way to sustainably produce hydrogen is by splitting water molecules using the renewable power of sunlight, but scientists are still learning how to control and optimize this reaction with catalysts. At the National Synchrotron Light Source, a research group has determined key structural information about a potential catalyst, taking a step toward designing an ideal material for the job.

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Due to the mechanical and electrical complexity of the water-splitting reaction, there are many requirements in order for a catalyst to perform optimally. Scientists must understand not only a candidate’s local but also its structure over longer ranges – particularly the nanoscale, which tends to be a good indicator of a material’s electronic behavior and therefore its overall .

Scientists are increasingly focusing on a particular group of catalysts: cobalt-based thin films. These films are created via electrodeposition from aqueous solutions of cobalt mixed with an electrolyte. In this study, researchers from Columbia University, Harvard University, and Brookhaven Lab used x-rays to better understand the intermediate-range nanoscale structure of one of these films. They also investigated the structural differences between films grown using two electrolytes: phosphate, a negative phosphorous-oxygen ion, and borate, negative a boron-oxygen ion. The resulting films are denoted CoPi and CoBi, respectively.

X-ray scattering data from the CoPi and CoBi samples, taken at NSLS beamline X7B, indicate that both are nanocrystalline. This means that they consist of nanoscale grains, each ranging from about 1.5 to 3 nanometers (nm) in size with an ordered molecular structure. Aside from this, there are clear and important differences.

The CoBi films consist of 3-4 nm cobalate (cobalt–oxygen) clusters that stack neatly up to three layers deep. The CoPi films consist of significantly smaller clusters that do not stack in an ordered way.

These structural differences seem to tie into the films’ catalytic activity. Electrochemical data show that, as film thickness increased, the CoBi films were more active than CoPi and ultimately displayed a “significantly superior” performance. These findings suggest that the increase in CoBi film thickness also increases the effective surface area available for catalysis, while at the same time preserving the charge-transport properties of the films.

“Our results show a concrete difference between CoBi and CoPi, thus allowing the first insight into a tangible structure-function correlation,” said Harvard chemist and professor Daniel Nocera.

Urine-powered mobile phone charger lets you spend a penny to make a call.


New microbial fuel cells contain bacteria that produce electricity from urine as part of their natural life cycle

A group of researchers from the University of the West of England have invented a method of charging mobile phones using urine.

Key to the breakthrough is the creation of a new microbial fuel cell (MFC) that turns organic matter – in the case, urine – into electricity.

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The MFCs are full of specially-grown bacteria that break down the chemicals in urine as part of their normal metabolic process. The bacteria produce electrons as they consume the matter and it this natural process that creates a small electrical charge to be stored in the MFC.

“No one has harnessed power from urine to do this so it’s an exciting discovery,” said Dr Ioannis Ieropoulos, an engineer at the Bristol Robotics Laboratory where the fuel cells were developed.

“The beauty of this fuel source is that we are not relying on the erratic nature of the wind or the sun; we are actually reusing waste to create energy. One product that we can be sure of an unending supply is our own urine.”

After the urine has been processed by the MFCs the electrical charge is stored in a capacitor. In the first test of the new invention, researchers simply plugged in a commercial Samsung phone charger and were able to charge up the handset.

Although the amount of electricity produced by the fuel cell is relatively small – only enough for a single call on the mobile – researcher believe it might be installed in bathrooms in the future, helping to power electric razors, toothbrushes and lights.

The device is about the size of a car battery, but engineers believe that future versions will be smaller and more portable. With each fuel cell only costing around £1 to produce such devices could provide a new, cheaper way of generating power.

The research was sponsored by public money from the Engineering and Physical Sciences Research Council and the Gates Foundation (the charity run by Microsoft-founder Bill Gates), with the scientists hopeful that the technology could be beneficial in developing countries.

“One [use] would be to put these into domestic situations or it could be used in remote regions of the developing world,” said Dr Ieropoulos.

“The fuel cells we have used to charge a mobile phone with hold around 50ml of urine but the smallest we have had working in the laboratory hold 1ml, so we can make them a lot smaller. Our aim is to have something that can be carried around easily.”

“The concept has been tested and it works – it’s now for us to develop and refine the process so that we can develop MFCs to fully charge a battery.”

Source: http://www.independent.co.uk

 

Silicon chips detect intracellular pressure changes in living cells.


The ability to measure pressure changes inside different components of a living cell is important, because it offers an alternative way to study fundamental processes that involve cell deformation1. Most current techniques such as pipette aspiration2, optical interferometry3 or external pressure probes4 use either indirect measurement methods or approaches that can damage the cell membrane.chip

Here we show that a silicon chip small enough to be internalized into a living cell can be used to detect pressure changes inside the cell. The chip, which consists of two membranes separated by a vacuum gap to form a Fabry–Pérot resonator, detects pressure changes that can be quantified from the intensity of the reflected light. Using this chip, we show that extracellular hydrostatic pressure is transmitted into HeLa cells and that these cells can endure hypo-osmotic stress without significantly increasing their intracellular hydrostatic pressure.