Discovery of an unexpected boost for solar water-splitting cells
A research team from Northeastern University and the National Institute of Standards and Technology (NIST) has discovered, serendipitously, that a residue of a process used to build arrays of titania nanotubes - a residue that wasn’t even noticed before this - plays an important role in improving the performance of the nanotubes in solar cells that produce hydrogen gas from water. Their recently published results indicate that by controlling the deposition of potassium on the surface of the nanotubes, engineers can achieve significant energy savings in a promising new alternate energy system.
Scanning electron microscope image of typical titania nanotubes for a photocatalytic cell to produce hydrogen gas from water. Nanotubes average roughly 90-100 nanometers in diameter.
Menon, Northeastern University
Titania (or titanium dioxide) is a versatile chemical compound best known as a white pigment. It’s found in everything from paint to toothpastes and sunscreen lotions. Thirty-five years ago Akira Fujishima startled the electrochemical world by demonstrating that it also functioned as a photocatalyst, producing hydrogen gas from water, electricity and sunlight. In recent years, researchers have been exploring different ways to optimize the process and create a commercially viable technology that, essentially, transforms cheap sunlight into hydrogen, a pollution-free fuel that can be stored and shipped.
Increasing the available surface area is one way to boost a catalyst’s performance, so a team at Northeastern has been studying techniques to build tightly packed arrays of titania nanotubes, which have a very high surface to volume ratio. They also were interested in how best to incorporate carbon into the nanotubes, because carbon helps titania absorb light in the visible spectrum. (Pure titania absorbs in the ultraviolet region, and much of the ultraviolet is filtered by the atmosphere.)
This brought them to the NIST X-ray spectroscopy beamline at the National Synchrotron Light Source (NSLS). The NIST facility uses X-rays that can be precisely tuned to measure chemical bonds of specific elements, and is at least 10 times more sensitive than commonly available laboratory instruments, allowing researchers to detect elements at extremely low concentrations. While making measurements of the carbon atoms, the team noticed spectroscopic data indicating that the titania nanotubes had small amounts of potassium ions strongly bound to the surface, evidently left by the fabrication process, which used potassium salts. This was the first time the potassium has ever been observed on titania nanotubes; previous measurements were not sensitive enough to detect it.
The result was mildly interesting, but became much more so when the research team compared the performance of the potassium-bearing nanotubes to similar arrays deliberately prepared without potassium. The former required only about one-third the electrical energy to produce the same amount of hydrogen as an equivalent array of potassium-free nanotubes. “The result was so exciting,” recalls Northeastern physicist Latika Menon, “that we got sidetracked from the carbon research.” Because it has such a strong effect at nearly undetectable concentrations, Menon says, potassium probably has played an unrecognized role in many experimental water-splitting cells that use titania nanotubes, because potassium hydroxide is commonly used in the cells. By controlling it, she says, hydrogen solar cell designers could use it to optimize performance.
Original publication: C. Richter et al.; "Effect of potassium adsorption on the photochemical properties of titania nanotube arrays"; J. Mater. Chem., published online as an Advanced Article, March 27, 2009
Other news from the department science
These products might interest you
New
MX-scales, MR-scales, MA-scales, LA-scales by Mettler-Toledo
New generation of laboratory balances for a wide range of applications
Excellent performance, durable instruments and simple operation
VICI DBS ZeroAir by VICI
Generate up to 30 L/min of analytically pure air yourself – for stable baseline GC-FID applications
Increase the sensitivity of your GC-FID analysis while reducing costs
Mars 6 by CEM
Everything under Control - with This Intelligent Microwave Digestion System
High Sample Throughput with Just One Click
LabBox by HiTec Zang
Automation made easy for every laboratory
Discover the all-in-one automation solution for greater efficiency
HYDROTHERM by C. Gerhardt
Efficiency in food analysis: Safe and precise total fat determination made easy
Fully automatic acid hydrolysis in 90 minutes - validated for continuous operation
Stainless steel reactors for high pressures and vacuum by JUCHHEIM Laborgeräte
Customized stainless steel reactors - configured for your needs
Perfect for extraction, digestion, hydrolysis, hydrogenation or synthesis
SmartCheck by Mettler-Toledo
Check Pipette Dosing Accuracy - Lightning Fast in Under a Minute
Detect dosing errors before it gets expensive
PG 85 by Miele
Powerful, safe, flexible: Compact lab washers with intelligent wash system
Developed for the reprocessing of laboratory glassware for analytical experiments
CrystalBreeder by Technobis
CrystalBreeder: the next generation multi-reactor crystallization platform
Enhance your early stage solid state screening. New: controlled evaporation & vapor diffusion modes
APU sim by Analytik Jena
APU sim Automatic Preparation Unit
APU sim The Clever Sample Preparation System According to Column Method
Automated Fusion Equipment by XRF Scientific
Automated Fusion Equipment
Sample Preparation at Highest Level
Catalogue: Labware made of precious metals by XRF Scientific
Labware made of precious metals
For sample preparation at highest level
BIOS ANALYTIQUE - Soluciones de Renting y Leasing para laboratorios by Bios Analytique
Specialists in the rental and leasing of scientific equipment for laboratories throughout Europe
Whether you have an unexpected requirement or limited budget, we have the perfect solution for you
OHAUS Laboratory equipment by Ohaus
Do More with OHAUS Laboratory Equipment
Do Not Limit Yourself to Just Measurement! Discover Ingenious Portfolio
Automatische XPR-Waagen by Mettler-Toledo
Production of standards, samples and concentrations - fast and reliable
Automate the weighing processes in your laboratory - ideal also for sample prep at chromatography
OHS Series: Overhead Stirrers by Velp Scientifica
State-of-the-art stirring power for a wide range of applications
Reliable overhead stirrers for different requirements in terms of viscosity and volume
P-50 by Mettler-Toledo
Fast and Error-free Documentation
The all-in-one printing solution
FlowSyn and FlowSyn Maxi by Uniqsis
Continuous Flow Chemistry Systems for reaction optimisation and scale up
Perform reactions up to 300°C and 100 bar from 0.1 - 100 ml /minute
Systec H-Series by Systec
Safe, reproducible and validatable sterilization of liquids, solids and waste
Autoclaves with 65-1580 liters usable space, flexibly expandable for various applications
Get the chemical industry in your inbox
From now on, don't miss a thing: Our newsletter for the chemical industry, analytics, lab technology and process engineering brings you up to date every Tuesday and Thursday. The latest industry news, product highlights and innovations - compact and easy to understand in your inbox. Researched by us so you don't have to.
Most read news
More news from our other portals
See the theme worlds for related content
Topic World Spectroscopy
Investigation with spectroscopy gives us unique insights into the composition and structure of materials. From UV-Vis spectroscopy to infrared and Raman spectroscopy to fluorescence and atomic absorption spectroscopy, spectroscopy offers us a wide range of analytical techniques to precisely characterize substances. Immerse yourself in the fascinating world of spectroscopy!
Topic World Spectroscopy
Investigation with spectroscopy gives us unique insights into the composition and structure of materials. From UV-Vis spectroscopy to infrared and Raman spectroscopy to fluorescence and atomic absorption spectroscopy, spectroscopy offers us a wide range of analytical techniques to precisely characterize substances. Immerse yourself in the fascinating world of spectroscopy!
