Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Review Article
  • Published:

Hole utilization in solar hydrogen production

Nature Reviews Chemistry volume 6, pages 243–258 (2022)Cite this article

Subjects

Abstract

In photochemical production of hydrogen from water, the hole-mediated oxidation reaction is the rate-determining step. A poor solar-to-hydrogen efficiency is usually related to a mismatch between the internal quantum efficiency of photon-induced hole generation and the apparent quantum yield of hydrogen. This waste of photogenerated holes is unwanted yet unavoidable. Although great progress has been made, we are still far away from the required level of dexterity to deal with the associated challenges of wasted holes and its consequential chemical effects that have placed one of the greatest bottlenecks in attaining high solar-to-hydrogen efficiency. A critical assessment of the hole and its related phenomena in solar hydrogen production would, therefore, pave the way moving forward. In this regard, we focus on the contextual and conceptual understanding of the dynamics and kinetics of photogenerated holes and its critical role in driving redox reactions, with the objective of guiding future research. The main reasons behind and consequences of unused holes are examined and different approaches to improve overall efficiency are outlined. We also highlight yet unsolved research questions related to holes in solar fuel production.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Thermodynamics and kinetics of photocatalytic hydrogen production from water.
Fig. 2: Hole is a catalyst in a redox reaction.
Fig. 3: Chemistry perspective of hole generation and separation.
Fig. 4: Relaxation, recombination, separation and transport of dissociated charge carriers.
Fig. 5: Hole transport kinetics at the interface of a photocatalyst and molecular adsorbate.
Fig. 6: Innovation in catalyst design for utilization of wasted holes.

Similar content being viewed by others

References

  1. Rahman, M. Z., Kibria, M. G. & Mullins, C. B. Metal-free photocatalysts for hydrogen evolution. Chem. Soc. Rev. 49, 1887–1931 (2020).

    Article  CAS  PubMed  Google Scholar 

  2. Global warming of 1.5°C (IPCC, 2018).

  3. Timothy, M. L. et al. Climate tipping points — too risky to bet against. Nature 575, 592–595 (2019).

    Article  Google Scholar 

  4. Bard, A. J. Photoelectrochemistry. Science 207, 139–144 (1980).

    Article  CAS  PubMed  Google Scholar 

  5. Voiry, D., Shin, H. S., Loh, K. P. & Chhowalla, M. Low-dimensional catalysts for hydrogen evolution and CO2 reduction. Nat. Rev. Chem. 2, 0105 (2018).

    Article  CAS  Google Scholar 

  6. Davis, S. J. et al. Net-zero emissions energy systems. Science 360, eaas9793 (2018).

    Article  PubMed  Google Scholar 

  7. Dresselhaus, M. S. & Thomas, I. L. Alternative energy technologies. Nature 414, 332–337 (2001).

    Article  CAS  PubMed  Google Scholar 

  8. Creutzig, F. et al. The underestimated potential of solar energy to mitigate climate change. Nat. Energy 2, 1714 (2017).

    Article  Google Scholar 

  9. Lewis, N. S. & Nocera, D. G. Powering the planet: chemical challenges in solar energy utilization. Proc. Natl Acad. Sci. USA 103, 15729–15735 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Ciamician, G. The photochemistry of the future. Science 36, 385–394 (1912).

    Article  CAS  PubMed  Google Scholar 

  11. Chen, S., Takata, T. & Domen, K. Particulate photocatalysts for overall water splitting. Nat. Rev. Mater. 2, 17050 (2017).

    Article  CAS  Google Scholar 

  12. Serpone, N., Emeline, A. V., Horikoshi, S., Kuznetsov, V. N. & Ryabchuk, V. K. On the genesis of heterogeneous photocatalysis: a brief historical perspective in the period 1910 to the mid-1980s. Photochem. Photobiol. Sci. 11, 1121–1150 (2012). This article reports a brief historical perspective on the origins of photocatalysis and enumerates the timescale contribution from the pioneer researchers in developing this field.

    Article  CAS  PubMed  Google Scholar 

  13. Kisch, H. Semiconductor photocatalysis — mechanistic and synthetic aspects. Angew. Chem. Int. Ed. 52, 812–847 (2013).

    Article  CAS  Google Scholar 

  14. Roth, H. D. The beginnings of organic photochemistry. Angew. Chem. Int. Ed. 28, 1193–1207 (1989).

    Article  Google Scholar 

  15. Fujishima, A. & Honda, K. Electrochemical photolysis of water at a semiconductor electrode. Nature 238, 37–38 (1972). This article demonstrates the first practical realization of water splitting using simulated solar energy.

    Article  CAS  Google Scholar 

  16. Wang, Q. & Domen, K. Particulate photocatalysts for light-driven water splitting: mechanisms, challenges, and design strategies. Chem. Rev. 120, 919–985 (2020).

    Article  CAS  PubMed  Google Scholar 

  17. Wang, Z., Li, C. & Domen, K. Recent developments in heterogeneous photocatalysts for solar-driven overall water splitting. Chem. Soc. Rev. 48, 2109–2125 (2019).

    Article  CAS  PubMed  Google Scholar 

  18. Mesa, C. A. et al. Multihole water oxidation catalysis on haematite photoanodes revealed by operando spectroelectrochemistry and DFT. Nat. Chem. 12, 82–89 (2020). This article reports a new mechanism for hole-mediated heterogeneous water oxidation on a metal oxide surface.

    Article  CAS  PubMed  Google Scholar 

  19. Dau, H. et al. The mechanism of water oxidation: from electrolysis via homogeneous to biological catalysis. ChemCatChem 2, 724–761 (2010).

    Article  CAS  Google Scholar 

  20. Renger, G., Christen, G., Karge, M., Eckert, H. J. & Irrgang, K. D. Application of the Marcus theory for analysis of the temperature dependence of the reactions leading to photosynthetic water oxidation: results and implications. J. Biol. Inorg. Chem. 3, 360–366 (1998).

    Article  CAS  Google Scholar 

  21. Matheu, R. et al. The development of molecular water oxidation catalysts. Nat. Rev. Chem. 3, 331–341 (2019).

    Article  CAS  Google Scholar 

  22. Fountaine, K. T., Lewerenz, H. J. & Atwater, H. A. Efficiency limits for photoelectrochemical water-splitting. Nat. Commun. 7, 13706 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  23. Xiang, C. et al. Modeling, simulation, and implementation of solar-driven water-splitting devices. Angew. Chem. Int. Ed. 55, 12974–12988 (2016).

    Article  CAS  Google Scholar 

  24. Akimov, A. V., Neukirch, A. J. & Prezhdo, O. V. Theoretical insights into photoinduced charge transfer and catalysis at oxide interfaces. Chem. Rev. 113, 4496–4565 (2013).

    Article  CAS  PubMed  Google Scholar 

  25. Le Formal, F. et al. Rate law analysis of water oxidation on a hematite surface. J. Am. Chem. Soc. 137, 6629–6637 (2015). This article reports a rate law analysis of the order of water oxidation as a function of surface hole density and provides direct evidence for the multihole catalysis of water oxidation by hematite.

    Article  PubMed  PubMed Central  Google Scholar 

  26. Cadiau, A. et al. A titanium metal–organic framework with visible-light-responsive photocatalytic activity. Angew. Chem. Int. Ed. 59, 13468–13472 (2020).

    Article  CAS  Google Scholar 

  27. Rahman, M. Z., Davey, K. & Mullins, C. B. Tuning the intrinsic properties of carbon nitride for high quantum yield photocatalytic hydrogen production. Adv. Sci. 5, 1800820 (2018).

    Article  Google Scholar 

  28. Schneider, J. & Bahnemann, D. W. Undesired role of sacrificial reagents in photocatalysis. J. Phys. Chem. Lett. 4, 3479–3483 (2013).

    Article  CAS  Google Scholar 

  29. Segev, G., Beeman, J. W., Greenblatt, J. B. & Sharp, I. D. Hybrid photoelectrochemical and photovoltaic cells for simultaneous production of chemical fuels and electrical power. Nat. Mater. 17, 1115–1121 (2018). This article demonstrates the conceptual design of a hybrid photovoltaic–photoelectrochemical device for the extraction of unused holes as electric current.

    Article  CAS  PubMed  Google Scholar 

  30. Luo, N. et al. Visible-light-driven coproduction of diesel precursors and hydrogen from lignocellulose-derived methylfurans. Nat. Energy 4, 575–584 (2019).

    Article  CAS  Google Scholar 

  31. Rahman, M. Z., Moffatt, J. & Spooner, N. Topological carbon nitride: localized photon absorption and delocalized charge carrier separation at intertwined photocatalyst interfaces. Mater. Horiz. 5, 553–559 (2018).

    Article  CAS  Google Scholar 

  32. Navarro-Jaén, S. et al. Highlights and challenges in the selective reduction of carbon dioxide to methanol. Nat. Rev. Chem. 5, 564–579 (2021).

    Article  Google Scholar 

  33. Wagner, A., Sahm, C. D. & Reisner, E. Towards molecular understanding of local chemical environment effects in electro- and photocatalytic CO2 reduction. Nat. Catal. 3, 775–786 (2020).

    Article  CAS  Google Scholar 

  34. Nosaka, Y. & Nosaka, A. Y. Generation and detection of reactive oxygen species in photocatalysis. Chem. Rev. 117, 11302–11336 (2017).

    Article  CAS  PubMed  Google Scholar 

  35. Studer, A. & Curran, D. P. The electron is a catalyst. Nat. Chem. 6, 765–773 (2014).

    Article  CAS  PubMed  Google Scholar 

  36. Luca, O. R., Gustafson, J. L., Maddox, S. M., Fenwick, A. Q. & Smith, D. C. Catalysis by electrons and holes: formal potential scales and preparative organic electrochemistry. Org. Chem. Front. 2, 823–848 (2015).

    Article  CAS  Google Scholar 

  37. Hazlehurst, T. H. Acid-base reactions. Their analogy to oxidation-reduction reactions in solution. J. Chem. Educ. 17, 466 (1940).

    Article  CAS  Google Scholar 

  38. Rahman, M. Z., Batmunkh, M., Bat-Erdene, M., Shapter, J. G. & Mullins, C. B. p-Type BP nanosheet photocatalyst with AQE of 3.9% in the absence of a noble metal cocatalyst: investigation and elucidation of photophysical properties. J. Mater. Chem. A 6, 18403–18408 (2018).

    Article  CAS  Google Scholar 

  39. Smith, W. A., Sharp, I. D., Strandwitz, N. C. & Bisquert, J. Interfacial band-edge energetics for solar fuels production. Energy Environ. Sci. 8, 2851–2862 (2015).

    Article  CAS  Google Scholar 

  40. Voznyy, O., Sutherland, B. R., Ip, A. H., Zhitomirsky, D. & Sargent, E. H. Engineering charge transport by heterostructuring solution-processed semiconductors. Nat. Rev. Mater. 2, 17026 (2017).

    Article  CAS  Google Scholar 

  41. Zhang, Z. & Yates, J. T. Jr Band bending in semiconductors: chemical and physical consequences at surfaces and interfaces. Chem. Rev. 112, 5520–5551 (2012).

    Article  CAS  PubMed  Google Scholar 

  42. Peter, L. M. in Photocatalysis: Fundamentals and Perspectives (eds Schneider, J. et al.) 1–28 (Royal Society of Chemistry, 2016).

  43. Peter, L. Fundamental aspects of photoelectrochemical water splitting at semiconductor electrodes. Curr. Opin. Green Sustain. Chem. 31, 100505 (2021).

    Article  Google Scholar 

  44. Wurfel, P. Physics of Solar Cells 2nd edn (Wiley, 2010).

  45. Sato, N. Electrochemistry at Metal and Semiconductor Electrodes (Elsevier, 1998).

  46. Peter, L. M. Energetics and kinetics of light-driven oxygen evolution at semiconductor electrodes: the example of hematite. J. Solid State Electrochem. 17, 315–326 (2012).

    Article  Google Scholar 

  47. Emeline, A. V., Kuznetsov, V. N., Ryabchuk, V. K. & Serpone, N. in New and Future Developments in Catalysis (ed. Suib, S. L.) 1–47 (Elsevier, 2013).

  48. Bard, A. J., Bocarsly, A. B., Fan, F. R. F., Walton, E. G. & Wrighton, M. S. The concept of Fermi level pinning at semiconductor/liquid junctions. Consequences for energy conversion efficiency and selection of useful solution redox couples in solar devices. J. Am. Chem. Soc. 102, 3671–3677 (1980).

    Article  CAS  Google Scholar 

  49. Sze, S. M. Physics of Semiconductor Devices (Wiley, 1969).

  50. Otero, R., Vázquez de Parga, A. L. & Gallego, J. M. Electronic, structural and chemical effects of charge-transfer at organic/inorganic interfaces. Surf. Sci. Rep. 72, 105–145 (2017).

    Article  CAS  Google Scholar 

  51. Haneef, H. F., Zeidell, A. M. & Jurchescu, O. D. Charge carrier traps in organic semiconductors: a review on the underlying physics and impact on electronic devices. J. Mater. Chem. C 8, 759–787 (2020).

    Article  CAS  Google Scholar 

  52. Rahman, M. Z. & Mullins, C. B. Understanding charge transport in carbon nitride for enhanced photocatalytic solar fuel production. Acc. Chem. Res. 52, 248–257 (2019).

    Article  CAS  PubMed  Google Scholar 

  53. Clarke, T. M. & Durrant, J. R. Charge photogeneration in organic solar cells. Chem. Rev. 110, 6736–6767 (2010).

    Article  CAS  PubMed  Google Scholar 

  54. Grave, D. A. et al. Extraction of mobile charge carrier photogeneration yield spectrum of ultrathin-film metal oxide photoanodes for solar water splitting. Nat. Mater. 20, 833–840 (2021).

    Article  CAS  PubMed  Google Scholar 

  55. Bakulin, A. A. et al. The role of driving energy and delocalized states for charge separation in organic semiconductors. Science 335, 1340–1344 (2012).

    Article  CAS  PubMed  Google Scholar 

  56. Hayes, D. et al. Electronic and nuclear contributions to time-resolved optical and X-ray absorption spectra of hematite and insights into photoelectrochemical performance. Energy Environ. Sci. 9, 3754–3769 (2016).

    Article  CAS  Google Scholar 

  57. Nozik, A. J. Multiple exciton generation in semiconductor quantum dots. Chem. Phys. Lett. 457, 3–11 (2008).

    Article  CAS  Google Scholar 

  58. Zhao, D. et al. Boron-doped nitrogen-deficient carbon nitride-based Z-scheme heterostructures for photocatalytic overall water splitting. Nat. Energy 6, 388–397 (2021).

    Article  CAS  Google Scholar 

  59. Wang, Z. et al. Sequential cocatalyst decoration on BaTaO2N towards highly-active Z-scheme water splitting. Nat. Commun. 12, 1005 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  60. Takata, T. et al. Photocatalytic water splitting with a quantum efficiency of almost unity. Nature 581, 411–414 (2020).

    Article  CAS  PubMed  Google Scholar 

  61. Rahman, M., Boschloo, G., Hagfeldt, A. & Edvinsson, T. On the mechanistic understanding of photovoltage loss in iron pyrite solar cells. Adv. Mater. 32, e1905653 (2020).

    Article  PubMed  Google Scholar 

  62. Rahman, M., Tian, H. & Edvinsson, T. Revisiting the limiting factors for overall water-splitting on organic photocatalysts. Angew. Chem. Int. Ed. 59, 16278–16293 (2020).

    Article  CAS  Google Scholar 

  63. Merschjann, C. et al. Photophysics of polymeric carbon nitride: an optical quasimonomer. Phys. Rev. B 87, 205204 (2013).

    Article  Google Scholar 

  64. Rao, A. et al. The role of spin in the kinetic control of recombination in organic photovoltaics. Nature 500, 435–439 (2013).

    Article  CAS  PubMed  Google Scholar 

  65. Burke, T. M., Sweetnam, S., Vandewal, K. & McGehee, M. D. Beyond Langevin recombination: how equilibrium between free carriers and charge transfer states determines the open-circuit voltage of organic solar cells. Adv. Energy Mater. 5, 1500123 (2015).

    Article  Google Scholar 

  66. Vandewal, K. et al. Efficient charge generation by relaxed charge-transfer states at organic interfaces. Nat. Mater. 13, 63–68 (2014).

    Article  CAS  PubMed  Google Scholar 

  67. Sachs, M. et al. Tracking charge transfer to residual metal clusters in conjugated polymers for photocatalytic hydrogen evolution. J. Am. Chem. Soc. 142, 14574–14587 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  68. Rahman, M. Z., Tang, Y. & Kwong, P. Reduced recombination and low-resistive transport of electrons for photo-redox reactions in metal-free hybrid photocatalyst. Appl. Phys. Lett. 112, 253902 (2018).

    Article  Google Scholar 

  69. Walter, M. G. et al. Solar water splitting cells. Chem. Rev. 110, 6446–6473 (2010).

    Article  CAS  PubMed  Google Scholar 

  70. Rahman, M. Z. & Alam, M. J. SRH recombination strength of interstitial iron in solar grade silicon. Photonics Lett. Poland 5, 118–120 (2013).

    Article  Google Scholar 

  71. Marcus, R. A. On the theory of oxidation-reduction reactions involving electron transfer. I. J. Chem. Phys. 24, 966–978 (1956). In this article, a quantitative theory of the rates of oxidation–reduction reactions involving electron transfer in solution is presented.

    Article  CAS  Google Scholar 

  72. Hush, N. S. Adiabatic theory of outer sphere electron-transfer reactions in solution. Trans. Faraday Soc. 57, 557–580 (1961).

    Article  CAS  Google Scholar 

  73. Liu, L. & Corma, A. Structural transformations of solid electrocatalysts and photocatalysts. Nat. Rev. Chem. 5, 256–276 (2021).

    Article  CAS  Google Scholar 

  74. Eberson, L. in Dislocation and the Reactivity of Organic Solids: Advances in Physical Organic Chemistry Vol. 18 (eds Gold, V. & Bethell, D.) 79–185 (Academic, 1982).

  75. Tilley., R. J. D. Defects in Solids (Wiley, 2008).

  76. Thomas, J. M. & Williams, J. O. Dislocations and the reactivity of organic solids. Prog. Solid State Chem. 6, 119–154 (1971).

    Article  CAS  Google Scholar 

  77. Lohmann, F. & Mehl, W. Dark injection and radiative recombination of electrons and holes in naphthalene crystals. J. Chem. Phys. 50, 500–506 (1969).

    Article  CAS  Google Scholar 

  78. Shluger, A. L., McKenna, K. P., Sushko, P. V., Ramo, D. M. & Kimmel, A. V. Modelling of electron and hole trapping in oxides. Model. Simul. Mater. Sci. Eng. 17, 084004 (2009).

    Article  Google Scholar 

  79. Rettie, A. J. E., Chemelewski, W. D., Emin, D. & Mullins, C. B. Unravelling small-polaron transport in metal oxide photoelectrodes. J. Phys. Chem. Lett. 7, 471–479 (2016).

    Article  CAS  PubMed  Google Scholar 

  80. Franchini, C., Reticcioli, M., Setvin, M. & Diebold, U. Polarons in materials. Nat. Rev. Mater. 6, 560–586 (2021).

    Article  CAS  Google Scholar 

  81. Carneiro, L. M. et al. Excitation-wavelength-dependent small polaron trapping of photoexcited carriers in alpha-Fe2O3. Nat. Mater. 16, 819–825 (2017).

    Article  CAS  PubMed  Google Scholar 

  82. Pastor, E. et al. In situ observation of picosecond polaron self-localisation in α-Fe2O3 photoelectrochemical cells. Nat. Commun. 10, 3962 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  83. Lohaus, C., Klein, A. & Jaegermann, W. Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes. Nat. Commun. 9, 4309 (2018).

    Article  PubMed  PubMed Central  Google Scholar 

  84. deQuilettes, D. W. et al. Charge-carrier recombination in halide perovskites. Chem. Rev. 119, 11007–11019 (2019).

    Article  CAS  PubMed  Google Scholar 

  85. Godin, R., Kafizas, A. & Durrant, J. R. Electron transfer dynamics in fuel producing photosystems. Curr. Opin. Electrochem. 2, 136–143 (2017).

    Article  CAS  Google Scholar 

  86. Appavoo, K., Liu, M., Black, C. T. & Sfeir, M. Y. Quantifying bulk and surface recombination processes in nanostructured water splitting photocatalysts via in situ ultrafast spectroscopy. Nano Lett. 15, 1076–1082 (2015).

    Article  CAS  PubMed  Google Scholar 

  87. Pastor, E. et al. Spectroelectrochemical analysis of the mechanism of (photo)electrochemical hydrogen evolution at a catalytic interface. Nat. Commun. 8, 14280 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  88. Ferry, V. E., Polman, A. & Atwater, H. A. Modeling light trapping in nanostructured solar cells. ACS Nano 5, 10055–10064 (2011).

    Article  CAS  PubMed  Google Scholar 

  89. Godin, R., Wang, Y., Zwijnenburg, M. A., Tang, J. & Durrant, J. R. Time-resolved spectroscopic investigation of charge trapping in carbon nitrides photocatalysts for hydrogen generation. J. Am. Chem. Soc. 139, 5216–5224 (2017).

    Article  CAS  PubMed  Google Scholar 

  90. Martindale, B. C. M. et al. Enhancing light absorption and charge transfer efficiency in carbon dots through graphitization and core nitrogen doping. Angew. Chem. Int. Ed. 56, 6459–6463 (2017).

    Article  CAS  Google Scholar 

  91. Kasap, H. et al. Solar-driven reduction of aqueous protons coupled to selective alcohol oxidation with a carbon nitride–molecular Ni catalyst system. J. Am. Chem. Soc. 138, 9183–9192 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  92. Mefford, J. T. et al. Correlative operando microscopy of oxygen evolution electrocatalysts. Nature 593, 67–73 (2021). This report establishes a link between the oxygen evolution activity and the local operational chemical, physical and electronic nanoscale structure of the catalyst.

    Article  CAS  PubMed  Google Scholar 

  93. Dral, P. O. & Barbatti, M. Molecular excited states through a machine learning lens. Nat. Rev. Chem. 5, 388–405 (2021).

    Article  CAS  Google Scholar 

  94. Villarreal, T. L., Gómez, R., Neumann-Spallart, M., Alonso-Vante, N. & Salvador, P. Semiconductor photooxidation of pollutants dissolved in water: a kinetic model for distinguishing between direct and indirect interfacial hole transfer. I. photoelectrochemical experiments with polycrystalline anatase electrodes under current doubling and absence of recombination. J. Phys. Chem. B 108, 15172–15181 (2004).

    Article  CAS  Google Scholar 

  95. Bahnemann, D. W., Hilgendorff, M. & Memming, R. Charge carrier dynamics at TiO2 particles: reactivity of free and trapped holes. J. Phys. Chem. B 101, 4265–4275 (1997).

    Article  CAS  Google Scholar 

  96. Ji, Y., Wang, B. & Luo, Y. A comparative theoretical study of proton-coupled hole transfer for H2O and small organic molecules (CH3OH, HCOOH, H2CO) on the anatase TiO2(101) surface. J. Phys. Chem. C 118, 21457–21462 (2014).

    Article  CAS  Google Scholar 

  97. Chu, W. et al. Ultrafast dynamics of photongenerated holes at a CH3OH/TiO2 rutile interface. J. Am. Chem. Soc. 138, 13740–13749 (2016).

    Article  CAS  PubMed  Google Scholar 

  98. Mesa, C. A. et al. Kinetics of photoelectrochemical oxidation of methanol on hematite photoanodes. J. Am. Chem. Soc. 139, 11537–11543 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  99. Chen, Z., Zhang, Q. & Luo, Y. Experimental identification of ultrafast reverse hole transfer at the interface of the photoexcited methanol/graphitic carbon nitride system. Angew. Chem. Int. Ed. 57, 5320–5324 (2018).

    Article  CAS  Google Scholar 

  100. Kolesov, G., Vinichenko, D., Tritsaris, G. A., Friend, C. M. & Kaxiras, E. Anatomy of the photochemical reaction: excited-state dynamics reveals the C–H acidity mechanism of methoxy photo-oxidation on titania. J. Phys. Chem. Lett. 6, 1624–1627 (2015).

    Article  CAS  PubMed  Google Scholar 

  101. Shen, M. & Henderson, M. A. Identification of the active species in photochemical hole scavenging reactions of methanol on TiO2. J. Phys. Chem. Lett. 2, 2707–2710 (2011).

    Article  CAS  Google Scholar 

  102. Phillips, K. R., Jensen, S. C., Baron, M., Li, S. C. & Friend, C. M. Sequential photo-oxidation of methanol to methyl formate on TiO2(110). J. Am. Chem. Soc. 135, 574–577 (2013).

    Article  CAS  PubMed  Google Scholar 

  103. Fu, C. et al. Site sensitivity of interfacial charge transfer and photocatalytic efficiency in photocatalysis: methanol oxidation on anatase TiO2 nanocrystals. Angew. Chem. Int. Ed. 60, 6160–6169 (2021).

    Article  CAS  Google Scholar 

  104. Grela, M. A. & Colussi, A. J. Photon energy and photon intermittence effects on the quantum efficiency of photoinduced oxidations in crystalline and metastable TiO2 colloidal nanoparticles. J. Phys. Chem. B 103, 2614–2619 (1999).

    Article  CAS  Google Scholar 

  105. Grela, M. A., Brusa, M. A. & Colussi, A. J. Harnessing excess photon energy in photoinduced surface electron transfer between salicylate and illuminated titanium dioxide nanoparticles. J. Phys. Chem. B 101, 10986–10989 (1997).

    Article  CAS  Google Scholar 

  106. Rahman, M. Z. et al. A benchmark quantum yield for water photoreduction on amorphous carbon nitride. Adv. Funct. Mater. 27, 1702384 (2017).

    Article  Google Scholar 

  107. Boudjemaa, A., Bouarab, R., Saadi, S., Bouguelia, A. & Trari, M. Photoelectrochemical H2-generation over Spinel FeCr2O4 in X2− solutions (X2− = S2− and \({{\rm{SO}}}_{3}^{2-}\)). Appl. Energy 86, 1080–1086 (2009).

    Article  CAS  Google Scholar 

  108. Tsuji, I., Kato, H., Kobayashi, H. & Kudo, A. Photocatalytic H2 evolution reaction from aqueous solutions over band structure-controlled (AgIn)xZn2(1−x)S2 solid solution photocatalysts with visible-light response and their surface nanostructures. J. Am. Chem. Soc. 126, 13406–13413 (2004).

    Article  CAS  PubMed  Google Scholar 

  109. Kawai, T. & Sakata, T. Photocatalytic hydrogen production from liquid methanol and water. J. Chem. Soc. Chem. Commun. 1980, 694–695 (1980).

  110. Rahman, M. Z., Kwong, C. W., Davey, K. & Qiao, S. Z. 2D phosphorene as a water splitting photocatalyst: fundamentals to applications. Energy Environ. Sci. 9, 709–728 (2016).

    Article  CAS  Google Scholar 

  111. Hykaway, N., Sears, W. M., Morisaki, H. & Morrison, S. R. Current-doubling reactions on titanium dioxide photoanodes. J. Phys. Chem. 90, 6663–6667 (1986).

    Article  CAS  Google Scholar 

  112. Memming, R. in Electron Transfer I (ed. Mattay, J.) 105–181 (Springer, 1994).

  113. Segev, G. et al. Quantification of the loss mechanisms in emerging water splitting photoanodes through empirical extraction of the spatial charge collection efficiency. Energy Environ. Sci. 11, 904–913 (2018).

    Article  CAS  Google Scholar 

  114. Segev, G. et al. The spatial collection efficiency of charge carriers in photovoltaic and photoelectrochemical cells. Joule 2, 210–224 (2018).

    Article  CAS  Google Scholar 

  115. Wakerley, D. W. et al. Solar-driven reforming of lignocellulose to H2 with a CdS/CdOx photocatalyst. Nat. Energy 2, 17021 (2017).

    Article  CAS  Google Scholar 

  116. Puga, A. V. Photocatalytic production of hydrogen from biomass-derived feedstocks. Coord. Chem. Rev. 315, 1–66 (2016).

    Article  CAS  Google Scholar 

  117. Kampouri, S. & Stylianou, K. C. Dual-functional photocatalysis for simultaneous hydrogen production and oxidation of organic substances. ACS Catal. 9, 4247–4270 (2019).

    Article  CAS  Google Scholar 

  118. Meng, Q. Y. et al. A cascade cross-coupling hydrogen evolution reaction by visible light catalysis. J. Am. Chem. Soc. 135, 19052–19055 (2013).

    Article  CAS  PubMed  Google Scholar 

  119. Zhao, F. et al. Photocatalytic hydrogen-evolving cross-coupling of arenes with primary amines. Org. Lett. 20, 7753–7757 (2018).

    Article  CAS  PubMed  Google Scholar 

  120. Zheng, Y. W. et al. Photocatalytic hydrogen-evolution cross-couplings: benzene C–H amination and hydroxylation. J. Am. Chem. Soc. 138, 10080–10083 (2016).

    Article  CAS  PubMed  Google Scholar 

  121. Chen, B., Wu, L.-Z. & Tung, C.-H. Photocatalytic activation of less reactive bonds and their functionalization via hydrogen-evolution cross-couplings. Acc. Chem. Res. 51, 2512–2523 (2018).

    Article  CAS  PubMed  Google Scholar 

  122. Wang, H., Gao, X., Lv, Z., Abdelilah, T. & Lei, A. Recent advances in oxidative R1-H/R2-H cross-coupling with hydrogen evolution via photo-/electrochemistry. Chem. Rev. 119, 6769–6787 (2019).

    Article  CAS  PubMed  Google Scholar 

  123. Tang, S. et al. Catalytic oxidative deamination by water with H2 liberation. J. Am. Chem. Soc. 142, 20875–20882 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  124. Tang, S., Ben-David, Y. & Milstein, D. Oxidation of alkenes by water with H2 liberation. J. Am. Chem. Soc. 142, 5980–5984 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  125. Robertson, J. C., Coote, M. L. & Bissember, A. C. Synthetic applications of light, electricity, mechanical force and flow. Nat. Rev. Chem. 3, 290–304 (2019).

    Article  Google Scholar 

  126. Tang, S., Zeng, L. & Lei, A. Oxidative R1–H/R2-H cross-coupling with hydrogen evolution. J. Am. Chem. Soc. 140, 13128–13135 (2018).

    Article  CAS  PubMed  Google Scholar 

  127. Gunanathan, C. & Milstein, D. Applications of acceptorless dehydrogenation and related transformations in chemical synthesis. Science 341, 1229712 (2013).

    Article  PubMed  Google Scholar 

  128. Kohl, S. W. et al. Consecutive thermal H2 and light-induced O2 evolution from water promoted by a metal complex. Science 324, 74–77 (2009).

    Article  CAS  PubMed  Google Scholar 

  129. Liu, J. et al. Metal-free efficient photocatalyst for stable visible water splitting via a two-electron pathway. Science 347, 970–974 (2015).

    Article  CAS  PubMed  Google Scholar 

  130. Jiao, Y., Zheng, Y., Davey, K. & Qiao, S.-Z. Activity origin and catalyst design principles for electrocatalytic hydrogen evolution on heteroatom-doped graphene. Nat. Energy 1, 16130 (2016).

    Article  CAS  Google Scholar 

  131. Zheng, Y., Jiao, Y., Jaroniec, M. & Qiao, S. Z. Advancing the electrochemistry of the hydrogen-evolution reaction through combining experiment and theory. Angew. Chem. Int. Ed. 54, 52–65 (2015).

    Article  CAS  Google Scholar 

  132. Jiao, Y., Zheng, Y., Jaroniec, M. & Qiao, S. Z. Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. Chem. Soc. Rev. 44, 2060–2086 (2015).

    Article  CAS  PubMed  Google Scholar 

  133. Bai, Y. et al. Accelerated discovery of organic polymer photocatalysts for hydrogen evolution from water through the integration of experiment and theory. J. Am. Chem. Soc. 141, 9063–9071 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  134. Masood, H., Toe, C. Y., Teoh, W. Y., Sethu, V. & Amal, R. Machine learning for accelerated discovery of solar photocatalysts. ACS Catal. 9, 11774–11787 (2019).

    Article  CAS  Google Scholar 

  135. Pihosh, Y. et al. Ta3N5-Nanorods enabling highly efficient water oxidation via advantageous light harvesting and charge collection. Energy Environ. Sci. 13, 1519–1530 (2020).

    Article  CAS  Google Scholar 

  136. Nandal, V., Suzuki, Y., Kobayashi, H., Domen, K. & Seki, K. Theoretical perspective of performance-limiting parameters of Cu(In1−xGax)Se2-based photocathodes. J. Mater. Chem. A 8, 9194–9201 (2020).

    Article  CAS  Google Scholar 

  137. Nandal, V. et al. Probing fundamental losses in nanostructured Ta3N5 photoanodes: design principles for efficient water oxidation. Energy Environ. Sci. 14, 4038–4047 (2021).

    Article  CAS  Google Scholar 

  138. Jacobsson, T. J., Fjällström, V., Edoff, M. & Edvinsson, T. Sustainable solar hydrogen production: from photoelectrochemical cells to PV-electrolyzers and back again. Energy Environ. Sci. 7, 2056–2070 (2014).

    Article  CAS  Google Scholar 

  139. Nozik, A. J. Photoelectrolysis of water using semiconducting TiO2 crystals. Nature 257, 383–386 (1975).

    Article  CAS  Google Scholar 

  140. Wang, D., Sheng, T., Chen, J., Wang, H.-F. & Hu, P. Identifying the key obstacle in photocatalytic oxygen evolution on rutile TiO2. Nat. Catal. 1, 291–299 (2018). This article demonstrates unambiguously the influence of the concentration of surface-reaching photoholes as the rate-determining factor of the oxygen evolution reaction.

    Article  CAS  Google Scholar 

  141. Zou, N. et al. Cooperative communication within and between single nanocatalysts. Nat. Chem. 10, 607–614 (2018).

    Article  CAS  PubMed  Google Scholar 

  142. Chen, P. et al. Spatiotemporal catalytic dynamics within single nanocatalysts revealed by single-molecule microscopy. Chem. Soc. Rev. 43, 1107–1117 (2014).

    Article  CAS  PubMed  Google Scholar 

  143. Weckhuysen, B. M. Catalysts live and up close. Nature 439, 548–548 (2006).

    Article  CAS  PubMed  Google Scholar 

  144. Roeffaers, M. B. et al. Spatially resolved observation of crystal-face-dependent catalysis by single turnover counting. Nature 439, 572–575 (2006).

    Article  CAS  PubMed  Google Scholar 

  145. Wu, C. Y. et al. High-spatial-resolution mapping of catalytic reactions on single particles. Nature 541, 511–515 (2017).

    Article  CAS  PubMed  Google Scholar 

  146. Sambur, J. B. et al. Sub-particle reaction and photocurrent mapping to optimize catalyst-modified photoanodes. Nature 530, 77–80 (2016). This article shows that most active sites for water oxidation are also the most important sites for charge carrier recombination.

    Article  CAS  PubMed  Google Scholar 

  147. Zou, N. et al. Imaging catalytic hotspots on single plasmonic nanostructures via correlated super-resolution and electron microscopy. ACS Nano 12, 5570–5579 (2018).

    Article  CAS  PubMed  Google Scholar 

  148. Chen, G. et al. Bimetallic effect of single nanocatalysts visualized by super-resolution catalysis imaging. ACS Cent. Sci. 3, 1189–1197 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  149. Chai, Z. et al. Efficient visible light-driven splitting of alcohols into hydrogen and corresponding carbonyl compounds over a Ni-modified CdS photocatalyst. J. Am. Chem. Soc. 138, 10128–10131 (2016).

    Article  CAS  PubMed  Google Scholar 

  150. O’Neil, M. P. et al. Picosecond optical switching based on biphotonic excitation of an electron donor-acceptor-donor molecule. Science 257, 63–65 (1992).

    Article  PubMed  Google Scholar 

  151. Karlsson, S. et al. Accumulative charge separation inspired by photosynthesis. J. Am. Chem. Soc. 132, 17977–17979 (2010).

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgements

Funding from King Abdullah University of Science and Technology through the CRG programme is gratefully acknowledged. T.E. acknowledges generous supports through funding from the Swedish Research Council (VR-2015-03814), the Swedish Research Council for Sustainable Development (grant no. 2016-00908) and the Swedish Energy Agency (grant no. 44648-1).

Author information

Authors and Affiliations

  1. KAUST Catalysis Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia

    Mohammad Z. Rahman & Jorge Gascon

  2. Department of Materials Science and Engineering, Angström Laboratory, Uppsala University, Uppsala, Sweden

    Tomas Edvinsson

Authors
  1. Mohammad Z. Rahman
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Tomas Edvinsson
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Jorge Gascon
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

M.Z.R. researched data, conceived the structure and wrote the first draft of the manuscript. T.E. and J.G. edited and revised the manuscript. All authors agreed on the manuscript before submission.

Corresponding authors

Correspondence to Mohammad Z. Rahman, Tomas Edvinsson or Jorge Gascon.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information

Nature Reviews Chemistry thanks the anonymous reviewers for their contribution to the peer review of this work.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Related links

Charge carrier: https://en.wikipedia.org/wiki/Charge_carrier

Gibbs free energy: https://www.sciencedirect.com/topics/chemistry/gibbs-free-energy

Photon: https://en.wikipedia.org/wiki/Photon

Valence band: https://www.sciencedirect.com/topics/chemistry/valence-band

Supplementary information

Glossary

Water photolysis

Photon-driven chemical reaction that breaks a water molecule into hydrogen and oxygen.

Co-catalyst

A metal or semiconductor that cooperatively improves the catalytic activity when it embeds into a catalyst without being consumed in the chemical reaction.

Sacrificial reagents

Chemical substance that can either donate electrons or remove holes.

Fermi levels

Measure of the highest energy level that an electron can occupy at absolute zero.

Quasi-Fermi level

A displaced Fermi level from equilibrium due to occupancy of electrons/holes generated by external stimuli.

Redox Fermi level

Fermi level of reductant and oxidant species in solution.

Lattice

A crystal structure composed of a series of atoms in a distinct pattern.

Internal photovoltage

The chemical potential of the separated electrons and holes.

Dielectric constant

Coulomb electrostatic attraction between point charges is inversely proportional to the dielectric constant.

Conduction band

The band of electron orbitals above the Fermi level where electrons can move freely or jump up into from the conduction band when excited.

Emissive state

An excited state of electrons in the conduction band or in energy states below the conduction band.

Valence band

The outermost electron orbital of an atom of any specific material that electrons actually occupy.

Ground state

The lowest energy state where electrons are in equilibrium.

Excitons

Excited electron–hole pairs that are bound by Coulomb electrostatic force.

Impact ionization

Process by which one energetic charge carrier can lose energy by the creation of other charge carriers.

Multiple electron generation

Phenomenon wherein the absorption of a single photon leads to the excitation of multiple electrons from the valence band to the conduction band.

Shockley–Queisser limit

Maximum theoretical efficiency of a single p–n junction solar cell.

Geminate recombination

A process where an electron recombines with the same hole that is created in the photogeneration process.

Auger recombination

When the electron–hole recombine by transferring excess energy to a third electron (or hole).

Shockley–Read–Hall recombination

Trap-assisted recombination of electron–hole pairs.

Hole scavengers

A sacrificial chemical that consumes holes in the photocatalytic process.

Nanostructuring

Scaling down of bulk materials into the nanoscale.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Rahman, M.Z., Edvinsson, T. & Gascon, J. Hole utilization in solar hydrogen production. Nat Rev Chem 6, 243–258 (2022). https://doi.org/10.1038/s41570-022-00366-w

Download citation

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41570-022-00366-w

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing