35 research outputs found

    Long wavelength quantum-dot lasers selectively populated using tunnel injection

    Full text link
    Using measured amplified spontaneous emission data, we have derived and analysed the carrier distribution of a five-layer tunnelling injection quantum-dot structure at temperatures of 300 K and 350 K. The results are consistent with the direct injection of electrons from the injector well into a subset of lower energy dot states. The carrier distribution spectra contain features which suggest that dots of a particular size within the ensemble are preferentially populated leading to a reduced spectral broadening of the emission.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58108/2/sst7_5_018.pd

    A framework for the successful implementation of food traceability systems in China

    Get PDF
    Implementation of food traceability systems in China faces many challenges due to the scale, diversity and complexity of China’s food supply chains. This study aims to identify critical success factors specific to the implementation of traceability systems in China. Twenty-seven critical success factors were identified in the literature. Interviews with managers at four food enterprises in a pre-study helped identify success criteria and five additional critical success factors. These critical success factors were tested through a survey of managers in eighty-three food companies. This study identifies six dimensions for critical success factors: laws, regulations and standards; government support; consumer knowledge and support; effective management and communication; top management and vendor support; and information and system quality

    Self-organized InAs/InGaAsP quantum dot tube lasers

    No full text
    We report the achievement of a semiconductor tube laser that can operate in the optical communication wavelength range for applications in the emerging Si-photonics. Such nanoscale devices are fabricated from self-organized InAs/InGaAsP quantum dotnanomembranes through a strain-driven self-rolling mechanism using standard photolithography process. Under continuous wave optical pumping, the devices exhibit an ultralow lasing threshold of 3c1.26\u2009\u3bcW at 82\u2009K, with multiple emission wavelengths in the S band of optical communications. The spontaneous emission coupling factor and Purcell factor are estimated to be 3c0.30 and 3c4.8, respectively.Peer reviewed: YesNRC publication: Ye

    Two-photon photocurrent in InGaN/GaN nanowire intermediate band solar cells

    No full text
    Intermediate band solar cells have the ability to reach efficiencies similar to multijunction cells using a single semiconductor junction. Here, enhanced two-photon carrier generation is demonstrated on a silicon substrate in an InGaN/GaN quantum dot-in-nanowire heterostructure intermediate band solar cell

    Binary molecular-semiconductor p–n junctions for photoelectrocatalytic CO2 reduction

    No full text
    Your institute does not have access to this article Relevant articles Open Access articles citing this article. Photocathode functionalized with a molecular cobalt catalyst for selective carbon dioxide reduction in water Palas Baran Pati, Ruwen Wang … Marc Robert Nature Communications Open Access 13 July 2020 Access options Access to this article via Universite Libre De Bruxelles is not available. Change institution Subscribe to Journal Get full journal access for 1 year 111,95 € only 9,33 € per issue Subscribe Tax calculation will be finalised during checkout. Rent or Buy article Get time limited or full article access on ReadCube. from$8.99 Rent or Buy All prices are NET prices. Additional access options: Log in Learn about institutional subscriptions Data availability The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request. References 1. Hammarström, L. & Hammes-Schiffer, S. Artificial photosynthesis and solar fuels. Acc. Chem. Res. 42, 1859–1860 (2009). Article Google Scholar 2. Barber, J. Photosynthetic energy conversion: natural and artificial. Chem. Soc. Rev. 38, 185–196 (2009). Article Google Scholar 3. Morris, A. J., Meyer, G. J. & Fujita, E. Molecular approaches to the photocatalytic reduction of carbon dioxide for solar fuels. Acc. Chem. Res. 42, 1983–1994 (2009). Article Google Scholar 4. Chen, S., Takata, T. & Domen, K. Particulate photocatalysts for overall water splitting. Nat. Rev. Mater. 2, 17050 (2017). Article Google Scholar 5. Grätzel, M. Photoelectrochemical cells. Nature 414, 338–344 (2001). Article Google Scholar 6. Hagfeldt, A., Boschloo, G., Sun, L., Kloo, L. & Pettersson, H. Dye-sensitized solar cells. Chem. Rev. 110, 6595–6663 (2010). Article Google Scholar 7. Han, Z. & Eisenberg, R. Fuel from water: the photochemical generation of hydrogen from water. Acc. Chem. Res. 47, 2537–2544 (2014). Article Google Scholar 8. Li, F. et al. Organic dye-sensitized tandem photoelectrochemical cell for light driven total water splitting. ‎J. Am. Chem. Soc. 137, 9153–9159 (2015). Article Google Scholar 9. Kamire, R. J. et al. Photodriven hydrogen evolution by molecular catalysts using Al2O3-protected perylene-3,4-dicarboximide on NiO electrodes. Chem. Sci. 8, 541–549 (2017). Article Google Scholar 10. Ding, C., Shi, J., Wang, Z. & Li, C. Photoelectrocatalytic water splitting: significance of cocatalysts, electrolyte, and interfaces. ACS Catal. 7, 675–688 (2017). Article Google Scholar 11. Smieja, J. M. et al. Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO. Proc. Natl Acad. Sci. USA 109, 15646–15650 (2012). Article Google Scholar 12. Liu, C., Colón, B. C., Ziesack, M., Silver, P. A. & Nocera, D. G. Water splitting–biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis. Science 352, 1210–1213 (2016). Article Google Scholar 13. Sahara, G. et al. Photoelectrochemical reduction of CO2 coupled to water oxidation using a photocathode with a Ru(II)–Re(I) complex photocatalyst and a CoOx/TaON photoanode. J. Am. Chem. Soc. 138, 14152–14158 (2016). Article Google Scholar 14. Gu, J. et al. Water reduction by a p-GaInP2 photoelectrode stabilized by an amorphous TiO2 coating and a molecular cobalt catalyst. Nat. Mater. 15, 456–460 (2015). Article Google Scholar 15. Schreier, M. et al. Efficient photosynthesis of carbon monoxide from CO2 using perovskite photovoltaics. Nat. Commun. 6, 7326 (2015). Article Google Scholar 16. Crespo-Quesada, M. et al. Metal-encapsulated organolead halide perovskite photocathode for solar-driven hydrogen evolution in water. Nat. Commun. 7, 12555 (2016). Article Google Scholar 17. Boettcher, S. W. et al. Photoelectrochemical hydrogen evolution using Si microwire arrays. J. Am. Chem. Soc. 133, 1216–1219 (2011). Article Google Scholar 18. Benck, J. D. et al. Designing active and stable silicon photocathodes for solar hydrogen production using molybdenum sulfide nanomaterials. Adv. Energy Mater. 4, 1400739 (2014). Article Google Scholar 19. Hu, S. et al. Amorphous TiO2 coatings stabilize Si, GaAs, and GaP photoanodes for efficient water oxidation. Science 344, 1005–1009 (2014). Article Google Scholar 20. Chu, S. et al. Roadmap on solar water splitting: current status and future prospects. Nano Futures 1, 022001 (2017). Article Google Scholar 21. White, J. L. et al. Light−driven heterogeneous reduction of carbon dioxide: photocatalysts and photoelectrodes. Chem. Rev. 115, 12888–12935 (2015). Article Google Scholar 22. Nayak, A. et al. Synthesis and photophysical characterization of porphyrin and porphyrin-Ru(II) polypyridyl chromophore-catalyst assemblies on mesoporous metal oxides. Chem. Sci. 5, 3115–3119 (2014). Article Google Scholar 23. Lapides, A. M. et al. Synthesis, characterization, and water oxidation by a molecular chromophore-catalyst assembly prepared by atomic layer deposition. The “mummy” strategy. Chem. Sci. 6, 6398–6406 (2015). Article Google Scholar 24. Gross, M. A., Creissen, C. E., Orchard, K. L. & Reisner, E. Photoelectrochemical hydrogen production in water using a layer-by-layer assembly of a Ru dye and Ni catalyst on NiO. Chem. Sci. 7, 5537–5546 (2016). Article Google Scholar 25. Shan, B. et al. Photogeneration of hydrogen from water by a robust dye-sensitized photocathode. Energy Environ. Sci. 9, 3693–3697 (2016). Article Google Scholar 26. Shan, B. et al. Modulating hole transport in multilayered photocathodes with derivatized p-type nickel oxide and molecular assemblies for solar-driven water splitting. J. Phys. Chem. Lett. 8, 4374–4379 (2017). Article Google Scholar 27. Gibson, E. A. Dye-sensitized photocathodes for H2 evolution. Chem. Soc. Rev. 46, 6194–6209 (2017). Article Google Scholar 28. Odobel, F. et al. Recent advances and future directions to optimize the performances of p-type dye-sensitized solar cells. Coord. Chem. Rev. 256, 2414–2423 (2012). Article Google Scholar 29. Farnum, B. H., Wee, K.-R. & Meyer, T. J. Self-assembled molecular p/n junctions for applications in dye-sensitized solar energy conversion. Nat. Chem. 8, 845–852 (2016). Article Google Scholar 30. Chu, S. et al. Tunable syngas production from CO2 and H2O in an aqueous photoelectrochemical cell. Angew. Chem. Int. Ed. 55, 14262–14266 (2016). Article Google Scholar 31. Wang, Y. et al. A monolithically integrated gallium nitride nanowire/silicon solar cell photocathode for selective carbon dioxide reduction to methane. Chem. Eur. J. 22, 8809–8813 (2016). Article Google Scholar 32. Vanka, S. et al. High efficiency Si photocathode protected by multifunctional GaN nanostructures. Nano Lett. 18, 6530–6537 (2018). Article Google Scholar 33. Persson, C. et al. Optical and reduced band gap in n- and p-type GaN and AlN. J. Appl. Phys. 92, 3207–3216 (2002). Article Google Scholar 34. Hanson, K. et al. Self-assembled bilayer films of ruthenium(II)/polypyridyl complexes through layer-by-layer deposition on nanostructured metal oxides. Angew. Chem. Int. Ed. 51, 12782–12785 (2012). Article Google Scholar 35. Norris, M. R. et al. Synthesis of phosphonic acid derivatized bipyridine ligands and their ruthenium complexes. Inorg. Chem. 52, 12492–12501 (2013). Article Google Scholar 36. Lehn, J.-M. & Ziessel, R. Photochemical reduction of carbon dioxide to formate catalyzed by 2,2′-bipyridine- or 1,10-phenanthroline-ruthenium(II) complexes. J. Organomet. Chem. 382, 157–173 (1990). Article Google Scholar 37. Chardon-Noblat, S., Deronzier, A., Ziessel, R. & Zsoldos, D. Selective synthesis and electrochemical behavior of trans(Cl)- and cis(Cl)-[Ru(bpy)(CO)2Cl2] complexes (bpy = 2,2′-bipyridine): comparative studies of their electrocatalytic activity toward the reduction of carbon dioxide. Inorg. Chem. 36, 5384–5389 (1997). Article Google Scholar 38. Kuriki, R., Sekizawa, K., Ishitani, O. & Maeda, K. Visible‐light‐driven CO2 reduction with carbon nitride: enhancing the activity of ruthenium catalysts. Angew. Chem. Int. Ed. 54, 2406–2409 (2015). Article Google Scholar 39. Kuriki, R., Ishitani, O. & Maeda, K. Unique solvent effects on visible-light CO2 reduction over ruthenium(II)-complex/carbon nitride hybrid photocatalysts. ACS Appl. Mater. Interfaces 8, 6011–6018 (2016). Article Google Scholar 40. Hanson, K. et al. Stabilization of [Ru(bpy)2(4,4′-(PO3H2)bpy)]2+ on mesoporous TiO2 with atomic layer deposition of Al2O3. Chem. Mater. 25, 3–5 (2013). Article Google Scholar 41. Wang, J. C., Violette, K., Ogunsolu, O. O. & Hanson, K. Metal ion mediated electron transfer at dye–semiconductor interfaces. Phys. Chem. Chem. Phys. 19, 2679–2682 (2017). Article Google Scholar 42. Shan, B. et al. Controlling vertical and lateral electron migration using a bifunctional chromophore assembly in dye-sensitized photoelectrosynthesis cells. J. Am. Chem. Soc. 140, 6493–6500 (2018). Article Google Scholar 43. Bonhôte, P. et al. Efficient lateral electron transport inside a monolayer of aromatic amines anchored on nanocrystalline metal oxide films. J. Phys. Chem. B 102, 1498–1507 (1998). Article Google Scholar 44. Shan, B., Farnum, B. H., Wee, K. & Meyer, T. J. Generation of long-lived redox equivalents in self-assembled bilayer structures on metal oxide electrodes. J. Phys. Chem. C 121, 5882–5890 (2017). Article Google Scholar 45. Ardo, S. & Meyer, G. J. Characterization of photoinduced self-exchange reactions at molecule–semiconductor interfaces by transient polarization spectroscopy: lateral intermolecular energy and hole transfer across sensitized TiO2 thin films. J. Am. Chem. Soc. 133, 15384–15396 (2011). Article Google Scholar 46. Hu, K. et al. A high-valent metal-oxo species produced by photoinduced one-electron, two-proton transfer reactivity. Inorg. Chem. 57, 486–494 (2018). Article Google Scholar 47. Anderson, P. A. et al. Designed synthesis of mononuclear tris(heteroleptic) ruthenium complexes containing bidentate polypyridyl ligands. Inorg. Chem. 34, 6145–6157 (1995). Article Google Scholar 48. Nickita, N. et al. Synthesis, structure, spectroscopic properties, and electrochemical oxidation of ruthenium(II) complexes incorporating monocarboxylate bipyridine ligands. Inorg. Chem. 46, 8638–8651 (2007). Article Google Scholar 49. Bonhôte, P. et al. Long-lived photoinduced charge separation and redox-type photochromism on mesoporous oxide films sensitized by molecular dyads. J. Am. Chem. Soc. 121, 1324–1336 (1999). Article Google Scholar 50. Zhou, Q. et al. CuO nanorod arrays shelled with amorphous NiFe layered double hydroxide film for enhanced electrocatalytic water oxidation activity. ACS Appl. Energy Mater. 1, 1364–1373 (2018). Article Google Scholar Download references Acknowledgements The research on molecular assemblies and the design and fabrication of photocathodes and photoelectrocatalysis was supported by the US Department of Energy (DOE) Office of Science, Office of Basic Energy Sciences, under award number DE-SC0015739 (to B.S., T.-T.L. and T.J.M.). The design and synthesis of Si | n-GaN photocathodes was supported by the HydroGEN Advanced Water Splitting Materials Consortium, which was established as part of the Energy Materials Network under the US DOE Office of Energy Efficiency and Renewable Energy Fuel Cell Technologies Office under award number DE-EE0008086 (S.V. and Z.M.). The experiments with nanosecond transient absorption and using the fluorimeter and solar simulator were performed with the instruments within the AMPED EFRC Instrumentation Facility established by the Alliance for Molecular PhotoElectrode Design for Solar Fuels, an Energy Frontier Research Center funded by the US DOE Office of Science, Office of Basic Energy Sciences under award DE-SC0001011. The ALD experiments were performed at the Chapel Hill Analytical and Nanofabrication Laboratory—a member of the North Carolina Research Triangle Nanotechnology Network supported by the National Science Foundation (grant ECCS-1542015) as part of the National Nanotechnology Coordinated Infrastructure. Author information Affiliations Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Bing Shan, Ting-Ting Li, Ludovic Troian-Gautier, M. Kyle Brennaman & Thomas J. Meyer Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA Srinivas Vanka & Zetian Mi Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec, Canada Srinivas Vanka Research Center of Applied Solid State Chemistry, Ningbo University, Ningbo, China Ting-Ting Li Contributions T.J.M. and B.S. conceived the research. T.J.M., B.S., Z.M. and S.V. designed the experiments. B.S., S.V., T.-T.L., L.T.-G. and M.K.B. performed the experiments and measurements. B.S. synthesized NPhN, RuCt and the surface diluent. L.T.-G. synthesized Ru(CP)22+. S.V. and Z.M. synthesized the Si | n-GaN electrode. T.J.M. and B.S. wrote the paper with input from all authors. Corresponding author Correspondence to Thomas J. Meyer. Ethics declarations Competing interests The authors declare no competing interests. Additional information Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Supplementary information Supplementary Information Supplementary Figures 1–33, Supplementary Tables 1–5, Supplementary Methods, Supplementary References Rights and permissions Reprints and Permissions About this article Verify currency and authenticity via CrossMark Cite this article Shan, B., Vanka, S., Li, TT. et al. Binary molecular-semiconductor p–n junctions for photoelectrocatalytic CO2 reduction. Nat Energy 4, 290–299 (2019). https://doi.org/10.1038/s41560-019-0345-y Download citation Received 10 August 2018 Accepted 30 January 2019 Published 11 March 2019 Issue Date April 2019 DOI https://doi.org/10.1038/s41560-019-0345-y Subjects Artificial photosynthesis Molecular self-assembly Photocatalysis Further reading Ru(bpy)32+-sensitized {001} facets LiCoO2 nanosheets catalyzed CO2 reduction reaction with 100% carbonaceous products Shuaiyu Jiang Junxian Liu Huijun Zhao Nano Research (2022) Photocathode functionalized with a molecular cobalt catalyst for selective carbon dioxide reduction in water Palas Baran Pati Ruwen Wang Marc Robert Nature Communications (2020) Improved performance of photoelectrochemical water oxidation from nanostructured hematite photoanode with an immobilized molecular cobalt salophen catalyst Yan Mei Ting-Ting Li Yue-Qing Zheng Journal of Materials Science (2020) Access to this article via Universite Libre De Bruxelles is not available. Change institution Buy or subscrib
    corecore