Dual-Functional Photocatalysis for Simultaneous Hydrogen Production and Oxidation of Organic Substances

The present review showcases the scientific progress in the field of dual-functional photocatalysis for hydrogen evolution coupled with the oxidation of chemical substances. Considering that hydrogen is a promising alternative to fossil fuels, photocatalytic water splitting represents an approach to produce hydrogen using abundant solar energy. However, the industrialization of this process has not occurred yet, mainly due to limitations related to the high cost, toxicity, poor stability, or low efficiency of the majority of the photocatalytic systems employed for water reduction. An approach to tackle these limitations is by taking advantage of the oxidative energy of the holes and by replacing the expensive and often toxic sacrificial electron donors with either organic pollutants (targeting their degradation) or organic substances that can be oxidized to added-value products. Following this 2-fold strategy, the production of sustainable hydrogen is accompanied by either the oxidative degradation of pollutants or the valorization of organic processes, in a single process. Herein, a detailed overview of the advancements in this dual-purpose field is offered, along with a discussion of the basic principles, the differences between similar fields, and how these can be distinguished. Although in its infancy, this dual-purpose technology has received radically increasing scientific interest over the past few years; this is expected, as the utilization of this approach can overcome multiple major environmental challenges, such as global warming, water scarcity, and pollution.