{"id":11497,"date":"2017-06-23T14:41:51","date_gmt":"2017-06-23T21:41:51","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=11497"},"modified":"2017-06-23T14:41:51","modified_gmt":"2017-06-23T21:41:51","slug":"full-spectrum-solar-generated-hydrogen","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/full-spectrum-solar-generated-hydrogen\/","title":{"rendered":"Full-Spectrum Solar-Generated Hydrogen"},"content":{"rendered":"

Osaka University researchers have created a new material <\/a>based on gold and black phosphorus to produce clean hydrogen fuel using the full spectrum of sunlight.\u00a0 Most solar apparatus used in \u201cwater splitting\u201d rely on materials such as titanium dioxide.\u00a0 These are limited to obtaining energy from the ultraviolet (UV) part of the solar spectrum, however.\u00a0 The rest of the spectrum is wasted.<\/p>\n

Osaka\u2019s team \u201cdeveloped a material to harvest a broader spectrum of sunlight,\u201d using a three-part composite.\u00a0 The different parts maximize absorption of light and enhance the efficiency of the unit for water splitting.\u00a0 The core, a \u201ctraditional\u201d semiconductor of lanthanum titanium oxide (LTO) is coated with tiny nanoparticle specks of gold.\u00a0 The gold-covered LTO is then mixed with ultrathin sheets of black phosphorus (BP), which acts as a light absorber.<\/p>\n

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LTO, BP and gold combine to produce greater excitation on solar-collecting surface. Electron microscope images of visible-NIR (near infrared) light responsive photocatalyst composed with black phosphorous (BP), lanthanum titanate (LA2Ti2O7, LTO), and gold nanoparticles (Au)<\/p><\/div>\n

Bonding the gold-coated LTO to the BP layer makes a serendipitous combination.\u00a0 Team leader Tetsuro Majima says. \u201cBP is a wonderful material for solar applications because we can tune the frequency of light just by varying its thickness, from ultrathin to bulk. This allows our new material to absorb visible and even near-infrared light, which we could never achieve with LTO alone.\u201d<\/p>\n

The report continues, \u201cBy absorbing this broad sweep of energy, BP is stimulated to release electrons, which are then conducted to the gold nanoparticles coating the LTO. Gold nanoparticles also absorb visible light, causing some of its own electrons to be jolted out. The free electrons in both BP and gold nanoparticles are then transferred into the LTO semiconductor, where they act as an electric current for water splitting.\u201d<\/p>\n

Absorbing a broader spectrum of light and conducting electrons more efficiently, the \u201cunique interface\u201d between BP and LTO results in a material 60 times more active than LTO along.<\/p>\n

Majima says, \u201cBy efficiently harvesting solar energy to generate clean fuel, this material could help to clean up the environment. \u00a0Moreover, we hope our study of the mechanism will spur new advances in photocatalyst technology.\u201d<\/p>\n

The abstract for their paper can be found on the web site for the Angewandte Chemie International Edition, 2017<\/a>.
\nAbstract<\/strong>: Efficient utilization of solar energy is a high-priority\u00a0target and the search for suitable materials as photocatalysts\u00a0that not only can harvest the broad wavelength of solar light,\u00a0from UV to near-infrared (NIR) region, but also can achieve\u00a0high and efficient solar-to-hydrogen conversion is one of the\u00a0most challenging missions.Herein, using Au\/La2Ti2O7\u00a0(BP-Au\/LTO) sensitized with black phosphorus (BP), a broadband\u00a0solar response photocatalyst was designed and used as efficient\u00a0photocatalyst for H2\u00a0production. The optimum H2\u00a0production\u00a0rates of BP-Au\/LTO were about 0.74 and 0.30 mmol g@1h@1 at\u00a0wavelengths longer than 420 nm and 780 nm, respectively. The broad absorption of BP and plasmonic Au contribute to the\u00a0enhanced photocatalytic activity in the visible and NIR light\u00a0regions.Time-resolved diffuse reflectance spectroscopy\u00a0revealed efficient interfacial electron transfer from excited BP\u00a0and\u00a0Au\u00a0to\u00a0LTO. \u00a0which\u00a0is\u00a0in\u00a0accordance\u00a0with\u00a0the\u00a0observed\u00a0high\u00a0photoactivities.<\/p>\n

Mingshan Zhu, Xiaoyan Cai, Mamoru Fujitsuka, Junying Zhang, Tetsuro Majima;\u00a0\u201cAu\/La2Ti2O7 Nanostructures Sensitized with Black Phosphorus for Plasmon-Enhanced Photocatalytic Hydrogen Production in Visible and Near-Infrared Light,\u201d Angewandte Chemie International Edition<\/em>, 2017<\/p>\n

Their findings would seem to have implications for all solar collectors, with greater efficiency possible for solar cells.<\/p>\n