dJPAPBEJournal of Physics D: Applied PhysicsJPhysDJ. Phys. D: Appl. Phys.0022-37271361-6463IOP Publishingdac6f9710.1088/1361-6463/ac6f97ac6f97JPhysD-129688.R1RoadmapThe 2022 solar fuels roadmap0000-0002-6175-3458SegevGideon1*gideons1@tauex.tau.ac.il0000-0002-9219-816XKibsgaardJakob20000-0002-2772-6341HahnChristopher30000-0001-7746-5920XuZhichuan J40000-0003-3233-4606ChengWen-Hui (Sophia)50000-0001-6577-1226DeutschTodd G6XiangChengxiang70000-0003-4407-5621ZhangJenny Z80000-0002-9933-9084HammarströmLeif90000-0001-5055-320XNoceraDaniel G100000-0002-7749-1624WeberAdam Z110000-0003-3066-4791AgboPeter120000-0002-5009-2383HisatomiTakashi13140000-0002-9288-3407OsterlohFrank E150000-0001-7995-4832DomenKazunari13160000-0001-5631-0620AbdiFatwa F170000-0002-3044-1662HaussenerSophia18MillerDaniel J120000-0001-7162-6826ArdoShane190000-0002-7498-831XMcIntyrePaul C200000-0002-6307-9831HannappelThomas210000-0002-5041-0169HuShu220000-0001-9435-0201AtwaterHarry230000-0002-2863-5265GregoireJohn M240000-0003-1994-9024ErtemMehmed Z250000-0001-5238-7487SharpIan D260000-0003-1945-8794ChoiKyoung-Shin27LeeJae Sung280000-0001-9557-7854IshitaniOsamu290000-0001-9334-9751AgerJoel W3031PrabhakarRajiv Ramanujam120000-0002-5738-4645BellAlexis T12320000-0001-8971-9123BoettcherShannon W330000-0001-6444-9382VincentKylie340000-0001-5374-9451TakanabeKazuhiro350000-0002-6148-8471ArteroVincent360000-0003-1602-7825NapierRyan370000-0002-8025-307XCuenyaBeatriz Roldan380000-0001-6777-4594KoperMarc T M370000-0003-4399-399XVan De KrolRoel1739*roel.vandekrol@helmholtz-berlin.de0000-0001-5571-2548HouleFrances12*fahoule@lbl.gov Department of Physical Electronics, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark Materials Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States of America School of Material Science and Engineering, Nanyang Technological University, Singapore, Singapore Department of Materials Science and Technology, National Cheng Kung University, Tainan 701, Taiwan National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, United States of America Department of Applied Physics and Material Science, California Institute of Technology, Pasadena, CA 91125, United States of America Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom Department of Chemistry-Ångström Laboratories, Uppsala University, Box 523, SE75120 Uppsala, Sweden Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, United States of America Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 4-17-1 Wakasato, Nagano-shi, Nagano 380-8553, Japan JST-PRESTO, 4-17-1 Wakasato, Nagano-shi, Nagano 380-8553, Japan, Japan Department of Chemistry, University of California at Davis, Davis, CA 95616, United States of America Office of University Professors, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany Laboratory of Renewable Energy Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 9, Lausanne 1015, Switzerland Department of Chemistry, Department of Chemical & Biomolecular Engineering, Department of Materials Science & Engineering, University of California Irvine, Irvine, CA 92697, United States of America Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, United States of America Fundamentals of Energy Materials, Institute of Physics, Technische Universität Ilmenau, Ilmenau, Thuringia, 98693, Germany Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06520, United States of America Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, United States of America Division of Engineering and Applied Science and Liquid Sunlight Alliance, California Institute of Technology, Pasadena, CA, 91024, United States of America Chemistry Division, Brookhaven National Laboratory, Upton, NY, 11973, United States of America Walter Schottky Institute and Physics Department, Technische Universität München, 85748 Garching, Germany Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States of America Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea Department of Chemistry, Tokyo Institute of Technology, 2-12-1-NE-1, Ookayama, Meguro-ku, Tokyo, Japan Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, United States of America Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, United States of America Department of Chemistry and Biochemistry and the Oregon Center for Electrochemistry, University of Oregon, Eugene, OR 97403, United States of America Department of Chemistry,, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, United Kingdom Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Univ. Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, 17 rue des Martyrs, Grenoble, Cedex, F-38054, France Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands Department of Interface Science, Fritz-Haber Institute of the Max Planck Society, Faradayweg 4-6, Berlin 14195, Germany Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, 10623 Berlin, Germany

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118202222620223152022553232300351120213520221352022452022© 2022 The Author(s). Published by IOP Publishing Ltd2022 Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Abstract

Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO2 reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field.

solar fuelscatalysisCO2 reductionwater splittingKorean Ministry of ScienceNRF-2018R1A2A1A05077909NRF-2019M1A2A2065612U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight HubDE-SC0021266Horizon 2020 Framework Programmehttp://dx.doi.org/10.13039/100010661 864234883264National Science Foundationhttp://dx.doi.org/10.13039/100000001 CBET-1805084Alfred P. Sloan Foundationhttp://dx.doi.org/10.13039/100000879 Thistledown FoundationResearch Corporation for Science Advancementhttp://dx.doi.org/10.13039/100001309 Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschunghttp://dx.doi.org/10.13039/501100001711 155876191299TomKat Foundationhttp://dx.doi.org/10.13039/100018042 Biotechnology and Biological Sciences Research Councilhttp://dx.doi.org/10.13039/501100000268 BB/R011923/1BB/R018413/1U.S. Department of Energyhttp://dx.doi.org/10.13039/100000015 DE-AC36-08GO28308DE-EE0008092DE-SC0004993DE-SC0008707DE-SC0017619DE-SC0021173DE-SC0021266DE-SC0021953DE-SC00493Taiwan Ministry of Education and Taiwan and Ministry of ScienceLawrence Livermore National Laboratoryhttp://dx.doi.org/10.13039/100006227 19-SI-005DE-AC52-07NA27344the Netherlands Ministry of Economic Affairs and Climate PolicyNederlandse Organisatie voor Wetenschappelijk Onderzoekhttp://dx.doi.org/10.13039/501100003246 Agence Nationale de la Recherchehttp://dx.doi.org/10.13039/501100001665 Labex ARCANECBH-EUR-GSANR-17-EURE-0003BEEPEuropean Research CouncilERC-2018-CoG BiocatSusChem 819580Carlsbergfondethttp://dx.doi.org/10.13039/501100002808 CF18-0435Mohammed bin Salman CenterMbSC2030Deutsche Forschungsgemeinschafthttp://dx.doi.org/10.13039/501100001659 3096/103096/19406944504 – SPP 2080981Japan Society for the Promotion of Sciencehttp://dx.doi.org/10.13039/501100001691 JP17H06440JP20H00396German Federal Ministry of Education and Research033RC021A033RC021C03SF0619C03SF0619INSF Chemical Catalysis1955106ccc1361-6463/22/323003+51$33.00printedPrinted in the UKcrossmarkyes