{"id":90052,"date":"2021-04-27T07:41:56","date_gmt":"2021-04-27T05:41:56","guid":{"rendered":"https:\/\/news.bio-based.eu\/?p=87304"},"modified":"2021-09-09T21:06:21","modified_gmt":"2021-09-09T19:06:21","slug":"this-hydrogen-fuel-machine-could-be-the-ultimate-guide-to-self-improvement","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/this-hydrogen-fuel-machine-could-be-the-ultimate-guide-to-self-improvement\/","title":{"rendered":"This Hydrogen Fuel Machine Could Be the Ultimate Guide to Self-Improvement"},"content":{"rendered":"

Three years ago, scientists at the University of Michigan discovered an artificial photosynthesis device made of silicon and gallium nitride (Si\/GaN) that harnesses sunlight into carbon-free hydrogen for fuel cells with twice the efficiency and stability of some previous technologies.<\/strong><\/p>\n

\"Guosong
Guosong Zeng (left), a postdoctoral scholar, and Francesca Toma, a staff scientist, both in Berkeley Lab\u2019s Chemical Sciences Division, test an artificial photosynthesis device made of gallium nitride. Toma and Zeng discovered that the device, rather than degrading over time, improves with use. (Credit: Thor Swift\/Berkeley Lab).<\/figcaption><\/figure>\n

Now, scientists at the Department of Energy\u2019s (DOE\u2019s) Lawrence Berkeley National Laboratory (Berkeley Lab) \u2013 in collaboration with the University of Michigan and Lawrence Livermore National Laboratory (LLNL) \u2013 have uncovered a surprising, self-improving property in Si\/GaN that contributes to the material\u2019s highly efficient and stable performance in converting light and water into carbon-free hydrogen. Their findings, reported in the journal Nature Materials<\/a>, could help radically accelerate the commercialization of artificial photosynthesis technologies and hydrogen fuel cells.<\/p>\n

\u201cOur discovery is a real game-changer,\u201d said senior author Francesca Toma<\/a>, a staff scientist in the Chemical Sciences Division at the Department of Energy\u2019s Lawrence Berkeley National Laboratory (Berkeley Lab). Usually, materials in solar fuels systems degrade, become less stable and thus produce hydrogen less efficiently, she said. \u201cBut we discovered an unusual property in Si\/GaN that somehow enables it to become more efficient and stable. I\u2019ve never seen such stability.\u201d<\/p>\n

Previous artificial photosynthesis materials are either excellent light absorbers that lack durability; or they\u2019re durable materials that lack light-absorption efficiency.<\/p>\n

But silicon and gallium nitride are abundant and cheap materials that are widely used as semiconductors in everyday electronics such as LEDs (light-emitting diodes) and solar cells, said co-author Zetian Mi, a professor of electrical and computer engineering at the University of Michigan who invented Si\/GaN artificial photosynthesis devices a decade ago.<\/p>\n

When Mi\u2019s Si\/GaN device achieved a record-breaking 3 percent solar-to-hydrogen efficiency<\/a>, he wondered how such ordinary materials could perform so extraordinarily well in an exotic artificial photosynthesis device \u2013 so he turned to Toma for help.<\/p>\n

HydroGEN: Taking a Team Science approach to solar fuels<\/h3>\n

Mi had learned of Toma\u2019s expertise in advanced microscopy techniques for probing the nanoscale (billionths of a meter) properties of artificial photosynthesis materials through HydroGEN, a five-national lab consortium supported by the DOE\u2019s Hydrogen and Fuel Cell Technologies Office<\/a>, and led by the National Renewable Energy Laboratory to facilitate collaborations between National Labs, academia, and industry for the development of advanced water-splitting materials. \u201cThese interactions of supporting industry and academia on advanced water-splitting materials with the capabilities of the National Labs are precisely why HydroGEN was formed \u2013 so that we can move the needle on clean hydrogen production technology,\u201d said Adam Weber, Berkeley Lab\u2019s Hydrogen and Fuel Cell Technologies Lab Program Manager and Co-Deputy Director of HydroGEN.<\/p>\n

Toma and lead author Guosong Zeng, a postdoctoral scholar in Berkeley Lab\u2019s Chemical Sciences Division, suspected that GaN might be playing a role in the device\u2019s unusual potential for hydrogen production efficiency and stability.
\nGuosong Zeng, a postdoctoral scholar in Berkeley Lab\u2019s Chemical Sciences Division, at work testing an artificial photosynthesis device made of gallium nitride. Zeng, along with Berkeley Lab staff scientist Francesca Toma, discovered that the device improves with use.<\/p>\n

Guosong Zeng, a postdoctoral scholar in Berkeley Lab\u2019s Chemical Sciences Division, at work testing an artificial photosynthesis device made of gallium nitride. Zeng, along with Berkeley Lab staff scientist Francesca Toma, discovered that the device improves with use.<\/p>\n

To find out, Zeng carried out a photoconductive atomic force microscopy experiment at Toma\u2019s lab to test how GaN photocathodes could efficiently convert absorbed photons into electrons, and then recruit those free electrons to split water into hydrogen, before the material started to degrade and become less stable and efficient.<\/p>\n

They expected to see a steep decline in the material\u2019s photon absorption efficiency and stability after just a few hours. To their astonishment, they observed a 2-3 orders of magnitude improvement in the material\u2019s photocurrent coming from tiny facets along the \u201csidewall\u201d of the GaN grain, Zeng said. Even more perplexing was that the material had increased its efficiency over time, even though the overall surface of the material didn\u2019t change that much, Zeng said. \u201cIn other words, instead of getting worse, the material got better,\u201d he said.<\/p>\n

To gather more clues, the researchers recruited scanning transmission electron microscopy (STEM) at the National Center for Electron Microscopy in Berkeley Lab\u2019s Molecular Foundry<\/a>, and angle-dependent X-ray photon spectroscopy (XPS).<\/p>\n

Those experiments revealed that a 1 nanometer layer mixed with gallium, nitrogen, and oxygen \u2013 or gallium oxynitride \u2013 had formed along some of the sidewalls. A chemical reaction had taken place, adding \u201cactive catalytic sites for hydrogen production reactions,\u201d Toma said.<\/p>\n

Density functional theory (DFT) simulations carried out by co-authors Tadashi Ogitsu and Tuan Anh Pham at LLNL confirmed their observations. \u201cBy calculating the change of distribution of chemical species at specific parts of the material\u2019s surface, we successfully found a surface structure that correlates with the development of gallium oxynitride as a hydrogen evolution reaction site,\u201d Ogitsu said. \u201cWe hope that our findings and approach \u2013 a tightly integrated theory-experiments collaboration enabled by the HydroGEN consortium \u2013 will be used to further improve the renewable hydrogen production technologies.\u201d<\/p>\n

Mi added: \u201cWe\u2019ve been working on this material for over 10 years \u2013 we know it\u2019s stable and efficient. But this collaboration helped to identify the fundamental mechanisms behind why it gets more robust and efficient instead of degrading. The findings from this work will help us build more efficient artificial photosynthesis devices at a lower cost.\u201d<\/p>\n

Looking ahead, Toma said that she and her team would like to test the Si\/GaN photocathode in a water-splitting photoelectrochemical cell, and that Zeng will experiment with similar materials to get a better understanding of how nitrides contribute to stability in artificial photosynthesis devices \u2013 which is something they never thought would be possible.<\/p>\n

\u201cIt was totally surprising,\u201d said Zeng. \u201cIt didn\u2019t make sense \u2013 but Pham\u2019s DFT calculations gave us the explanation we needed to validate our observations. Our findings will help us design even better artificial photosynthesis devices.\u201d<\/p>\n

\u201cThis was an unprecedented network of collaboration between National Labs and a research university,\u201d said Toma. \u201cThe HydroGEN consortium brought us together \u2013 our work demonstrates how the National Labs\u2019 Team Science approach can help solve big problems that affect the entire world.\u201d<\/p>\n

Co-authors on the paper include Guiji Liu, Jason Cooper, and Chengyu Song at Berkeley Lab; and Srinivas Vanka at the University of Michigan.<\/p>\n

The Molecular Foundry is a DOE Office of Science user facility at Berkeley Lab.<\/p>\n

This work was supported by the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under DOE\u2019s Office of Energy Efficiency and Renewable Energy.<\/p>\n","protected":false},"excerpt":{"rendered":"

Three years ago, scientists at the University of Michigan discovered an artificial photosynthesis device made of silicon and gallium nitride (Si\/GaN) that harnesses sunlight into carbon-free hydrogen for fuel cells with twice the efficiency and stability of some previous technologies. Now, scientists at the Department of Energy\u2019s (DOE\u2019s) Lawrence Berkeley National Laboratory (Berkeley Lab) \u2013 […]<\/p>\n","protected":false},"author":58,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","nova_meta_subtitle":"","footnotes":""},"categories":[5571],"tags":[10630],"supplier":[5042],"class_list":["post-90052","post","type-post","status-publish","format-standard","hentry","category-co2-based","tag-hydrogen","supplier-lawrence-livermore-national-laboratory"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/90052","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/58"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=90052"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/90052\/revisions"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=90052"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=90052"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=90052"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=90052"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}