Effective use of photogenerated electrons and holes in a system: Photocatalytic selective oxidation of aromatic alcohols to aldehydes and hydrogen production.

Graphical abstract Highlights • Photogenerated electrons and holes were effectively used in one system. • Aromatic alcohols were oxidated into corresponding aldehydes by the photogenerated holes. • Protons were photocatalytically reduced to hydrogen by the photogenerated electrons. • Increased photocatalytic performance and reaction mechanism were investigated. Abstract Effective utilization of photogenerated electrons and holes in a system is always a research hotspot. Photocatalysis has been identified as a promising solution to tackle the current environmental and energy issues. However, photogenerated holes or electrons were wasted in the traditional photocatalytic process. In the paper, a dual-function photocatalytic reaction system was constructed using dispersed Pt x -modified 2D-3D Zn 3 In 2 S 6 hierarchical structures (x = 1–4). In the system, aromatic alcohols were photocatalytically selectively oxidated into aldehydes and protons were reduced to hydrogen by photogenerated holes and electrons, respectively. In the reaction process, one aromatic alcohol is first dehydrogenated into aromatic aldehyde and two H+ via the corresponding carbon-centered radical by consuming of two holes, and then two H+ ions dehydrogenated from OH group and α C H of alcohol are evolved into H 2 by depleting of two electrons. Atomically dispersed Pt x could offer the maximum atom efficiency and significantly promote visible light absorption and separation of photogenerated electron-hole pairs. The cooperative photoredox system exhibits remarkable photocatalytic activity for visible light-driven splitting of aromatic alcohols. Under visible light irradiation for 6 h, The H 2 output over 2.14% Pt/Zn 3 In 2 S 6 reaches up to 950 μmol, which is around 7.5, 5.3 and 3.8 times higher than that over Zn 3 In 2 S 6 , Pt-nanoparticle/Zn 3 In 2 S 6 and MoS 2 /Zn 3 In 2 S 6 , respectively. The apparent quantum efficiency (AQE) of 2.14% Pt/Zn 3 In 2 S 6 at 400 nm is about 4.6%. The utilization rate of photogenerated electrons to holes could be achieved 98.2%. Moreover, Pt/Zn 3 In 2 S 6 hybrid shows high stability even when Zn 3 In 2 S 6 was stored for 12 months. Compared with two half-reactions: the photocatalytic selective organics transformation under O 2 atmosphere and the water splitting with sacrificial reagents, such designed dual-purpose photocatalytic reaction not only could effective use of photogenerated electrons and holes for organics transformation and hydrogen production simultaneously but also shows much higher photocatalytic activity than two half-reactions. At the same time, the work also expands the research field of photocatalysis, such as N 2 fixation and CO 2 reduction by using of the as-produced H+. [ABSTRACT FROM AUTHOR]