Tag Archives: photocatalysts

Speeding up the process for converting carbon dioxide into hydrocarbon fuel

This is a personal thrill; it’s the first time in seven years that I’ve received a press release directly from an institution in Asia.

A March 10, 2015 MANA, the International Center for Materials Nanoarchitectonics at NIMS (National Institute for Materials Science) press release announces and describes hydrocarbon fuel research from Japan and China first published online in Nov. 2014 and later in print in January 2015,

A combination of semiconductor catalysts, optimum catalyst shape, gold-copper co-catalyst alloy nanoparticles and hydrous hydrazine reducing agent enables an increase of hydrocarbon generation from CO2 by a factor of ten.

“Solar-energy-driven conversion of CO2 into hydrocarbon fuels can simultaneously generate chemical fuels to meet energy demand and mitigate rising CO2 levels,” explain Jinhua Ye and her colleagues at the International Center for Materials Nanoarchitectonics in their latest report. Now the research team have identified the conditions and catalysts that will maximise the yield of hydrocarbons from CO2, generating ten times previously reported production rates.

Carbon dioxide can be converted into a hydrocarbon by means of ‘reduction reactions’ -a type of reaction that involves reducing the oxygen content of a molecule, increasing the hydrogen content or increasing the electrons. In photocatalytic reduction of CO2 light activates the catalyst for the reaction.

Ye and his team introduced four approaches that each contributed to an increased reaction rate. First, they combined two known semiconductor photocatalysts strontium titanate (STO) and titania [titanium dioxide] (TiO2) – which led to the separation of the charges generated by light and hence a more effective photocatalyst. Second, the high surface area of the nanotubes was made greater by holes in the tube surfaces, which enhances catalysis by increasing the contact between the gases and catalysts. Third, the tubes were decorated with gold-copper (Au3Cu) nanoparticle co-catalysts to further enhance the catalysis, and fourth, they used hydrous hydrazine (N2H4•H2O) as the source of hydrogen.

Although the high hydrogen content of hydrous hydrazine is widely recognised in the context of hydrogen storage there are no previous reports of its use for reduction reactions. The researchers demonstrated that the reducing properties of hydrous hydrazine were so great that oxidation of the co-catalytic nanoparticles – a problem when water or hydrogen are used – was avoided.

The researchers conclude their report, “This opens a feasible route to enhance the photocatalytic efficiency, which also aids the development of photocatalysts and co-catalysts.”

Affiliations

The researchers on this project are associated with the following institutions:

International Center for Materials Nanoarchitectonics (MANA), and the Environmental Remediation Materials Unit,  National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo 060-0814, Japan

TU-NIMS Joint Research Center, School of Material Science and Engineering, Tianjin University 92 Weijin Road, Tianjin,  P.R. China

Here’s a link to and a citation for the paper,

Photocatalytic Reduction of Carbon Dioxide by Hydrous Hydrazine over Au–Cu Alloy Nanoparticles Supported on SrTiO3/TiO2 Coaxial Nanotube Arrays by Dr. Qing Kang, Dr. Tao Wang, Dr. Peng Li, Dr. Lequan Liu, Dr. Kun Chang, Mu Li, and Prof. Jinhua Ye. Angewandte Chemie International Edition Volume 54, Issue 3, pages 841–845, January 12, 2015 DOI: 10.1002/anie.201409183 Article first published online: 24 NOV 2014

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This research is behind a paywall.

Nanotechnology-enabled Catalytic Clothes look good and clean the air

There’s a great video on the RIA Novosti website featuring interviews about an art/science collaboration between Professor Helen Storey at the London College of Fashion and Professor Tony Ryan, a scientist at the University of Sheffield. The two have created clothing that cleans the air of pollution. From the University of Sheffield June 15, 2011 news release,

Catalytic Clothing is a radical partnership between the University of Sheffield and London College of Fashion University of the Arts London that brings together the worlds of fashion and chemistry with the potential to clean the air we breathe. Employing existing technology in a new way, it seeks to explore how clothing and textiles can be used as a catalytic surface to purify air. It is the brainchild of artist/designer Professor Helen Storey MBE and chemist Professor Tony Ryan OBE – people from two very differing worlds who are using their diametric approaches to achieve great things. Previous projects include the groundbreaking Wonderland project which has now been seen by over 11 million people worldwide.


An exclusive film starring Erin O’Connor with soundtrack by Radiohead is already going viral with millions of views.

Here’s a brief preview of the film,

Here’s a link to the Catalytic Clothing website where you can see the entire film.

For those interested in the science part of the Catalytic Clothing story (from the Catalytic Clothing website, Scientific Background/FAQS page),

What is the science behind Catalytic Clothing?

Catalytic Clothing harnesses the power of a photocatalyst to break down air borne pollutants. A catalyst is a term used to describe something that makes a reaction proceed at a greater rate but isn’t actually consumed during that reaction. A photocatalyst gains the energy it needs to be active from light.

Where do the pollutants come from?

The two biggest sources of air borne pollutants are industry and motor vehicles. Although the majority of the pollutants are prevented from reaching the air, using technology such as catalytic converters, some do escape. It is these pollutants that Catalytic Clothing will break down.

How are the pollutants broken down?

When the light shines on the photocatalyst, the electrons in the material are rearranged and they become more reactive. These electrons are then able to react with the water in the air and break it apart into 2 radicals. A radical is an extremely reactive molecule. These radicals then react with the pollutants and cause them to break down into non-harmful chemicals.

What happens to the pollutants after they’ve been broken down?

The Catalytic Clothing technology is designed to breakdown the pollutants straight away. However, some pollutants may become attached without being broken down. In this case, the pollutants will be washed off during subsequent laundering. This actually already happens with normal clothing.

Is this technology used in any other products?

Photocatalysts have been incorporated into several commercially available products that possess de-polluting properties. These products include paints, cements and paving stones. [Note 1: In the RIA Novosti video, Ryan mentions titanium dioxide specifically. Note 2: Coatings for pavements in Germany are mentioned in my August 2, 2010 posting; scroll down 1/2 way.]

How is the technology delivered to the surface of the clothing?

The photocatalyst is delivered to the surface of the clothing during the traditional laundry procedure as an additive within a standard product such as a fabric conditioner. The active agent is packaged within a shell that is attracted towards, and subsequently binds to, the surface of the clothing during the washing cycle.

Why do we need mass participation to produce a noticeable reduction in the level of pollution?

Although any garment that is treated with the product becomes active, a single garment is only able to remove a small proportion of the air borne pollutants. Therefore, a large number of individuals, all acting together, is required to produce a noticeable reduction in the level of pollution.

How many people would need to participate to produce a noticeable reduction in the level of pollution?

An estimate of the required level of uptake for the Catalytic Clothing indicates that a significant reduction in the level of air borne pollutants in a large city such as London could be achieved if, for every metre of pavement width, 30 people wearing Catalytic Clothes walked past each minute.

Would someone wearing Catalytic Clothing be at a greater risk of exposure to pollutants?

No. The Catalytic Clothing technology won’t actively attract any pollutants. Instead, it will break down anything that comes within very close proximity of the photocatalyst’s surface.

How would society benefit if Catalytic Clothing was widely introduced?

Exposure to air borne pollutants presents a risk to human health and also has a detrimental effect on ecosystems and vegetation. Air pollution is currently estimated to reduce the life expectancy of every person in the UK by an average of 7-8 months. The widespread introduction of Catalytic Clothing would dramatically reduce the level of air borne pollutants, thereby improving the quality of life for all members of society.

The main sponsor for the project is Ecover (from the news release),

Ecover, who are the main sponsors of the Catalytic Clothing cultural campaign, are one of the world´s leading suppliers of green and sustainable cleaning products. All of their products are made with fully renewable plant-based ingredients and produced using a totally biochemical process. Ecover has been recognised by the United Nations Environment programme (UNEP) for their outstanding practical achievements for the protection and improvement of our environment.

Here’s the Ecover website.

This really is the last posting for today. Happy Weekend!

ETA July 11, 2011: Here’s a posting by Jasmin Malik Chua about the project at the Ecouterre website.