Hole utilization in solar hydrogen production

Mohammad Z. Rahman*, Tomas Edvinsson*, Jorge Gascon*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

59 Scopus citations


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. [Figure not available: see fulltext.]

Original languageEnglish (US)
Pages (from-to)243-258
Number of pages16
JournalNature Reviews Chemistry
Issue number4
StatePublished - Apr 2022

Bibliographical note

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© 2022, Springer Nature Limited.

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering


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