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.

在从水中光化学生产氢气中，空穴介导的氧化反应是决速步骤。较差的太阳能转化为氢气的效率通常与光子诱导空穴产生的内量子效率与氢气的表观量子产率之间的不匹配有关。这种光生空穴的浪费是不受欢迎的，但却是不可避免的。尽管已经取得了很大进展，但我们仍远未达到所需的灵巧水平来应对空穴浪费及其随之而来的化学效应的相关挑战，这些挑战已成为实现高太阳能制氢效率的最大瓶颈之一。因此，对空洞及其在太阳能制氢过程中的相关现象的批判性评估将为前进铺平道路。在这方面，我们专注于对光生空穴的动力学和动力学及其在驱动氧化还原反应中的关键作用的背景和概念理解，目的是指导未来的研究。研究了未使用孔背后的主要原因和后果，并概述了提高整体效率的不同方法。我们还强调了与太阳能燃料生产中的漏洞相关的尚未解决的研究问题。