Harnessing Photoexcited Redox Centers of Semiconductor Photocatalysts for Advanced Synthetic Chemistry

Abstract

Solar photocatalysis is emerging as an environment‐friendly and sustainable energy approach for the production of fine chemicals and pharmaceuticals with high industrial and academic importance. Due to photochemical stability, tunable redox capability, and facile recyclability, semiconductor photocatalysts display remarkable advantages over molecular photocatalysts, thus attracting increasing attention. More importantly, photoexcited hole–electron pairs on semiconductor photocatalysts can accomplish two aligned redox reactions on the same semiconductor surface, resulting in unique designs of several semiconductor photocatalysis models. This review surveys recent advances in rational harnessing of photoexcited hole–electron pairs in semiconductor photocatalysts for oxidative and reductive synthetic transformations for chemical and pharmaceutical production. Depending on the catalytic behavior of the photogenerated redox centers, there are three major semiconductor photoredox reaction modes: 1) photoexcited hole‐induced oxidations, 2) photoexcited electron‐induced reductions, and 3) photoexcited electron–hole pairs co‐induced redox‐neutral reactions. The characteristics, reaction scopes, and mechanisms of these three semiconductor photocatalysis modes are discussed. Finally, the major challenges and future opportunities regarding the rational design of photoexcited redox centers in advanced synthetic chemistry are provided.

In situ growth of Cs3Bi2Br9 on ultrathin BiVO4 nanosheets to fabricate heterojunction intimate interfaces for enhancing photocatalytic activity

“…The conversion of organic pollutants produced by industrial processes such as textile, paint, and printing 1–3 into harmless substances is a major challenge to be explored and solved, which is essential for the health of living organisms and the sustainable development of society. Among the various degradation techniques, photocatalysis 4–7 has been regarded as an ideal method to address the intricate problems of organic pollutant transformation due to its advantages such as environmental friendliness and low energy consumption. 8,9 Early photocatalytic studies primarily focused on conventional semiconductor materials, including metal oxides TiO 2 , 10,11 ZnO, 12,13 metal sulfur compounds CdS, 14 CdSe, 15,16 etc.…”

Efficient heterogeneous photocatalytic C–C coupling of halogenated arenes mediated by metal cocatalyst

“…A series of recent studies in heterogeneous photocatalysis reveals that proper engineering of the surface by decorating it with metal cocatalysts is crucial to achieve a high performance in H 2 evolution, CO 2 reduction, and synthetic chemistry. 15–28 It has been shown that the metal/semiconductor heterojunction facilitates the charge separation of the photogenerated charge carriers and the storage of free electrons on the metal cocatalyst. 29–31 Additionally, catalytic studies reveal that an optimum adsorption free energy (Δ G ) of photogenerated reactive species ( i.e.…”

“…A series of recent studies in heterogeneous photocatalysis reveals that proper engineering of the surface by decorating it with metal cocatalysts is crucial to achieve a high performance in H 2 evolution, CO 2 reduction, and synthetic chemistry. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] It has been shown that the metal/semiconductor heterojunction facilitates the charge separation of the photogenerated charge carriers and the storage of free electrons on the metal cocatalyst. [29][30][31] Additionally, catalytic studies reveal that an optimum adsorption free energy (ΔG) of photogenerated reactive species (i.e., H atoms, methoxy, and Br • ) on the metal cocatalyst can be achieved by alloying and facet-engineering to boost the kinetics of several photocatalytic reactions (i.e., hydrogen evolution, CO 2 reduction, N 2 fixation).…”

Efficient Visible‐Light‐Initiated Dehydrogenative Coupling of Amines for Coproduction of Imines and Hydrogen over NiS/ZnIn2S4

“…Instead, a more attractive strategy for the synthesis of imines is the oxidative coupling of amines, in particular, to realize this transformation using abundant solar energy. [ 3 ] The light‐initiated oxidative coupling of amines to produce imines involves the activation of amines by the photogenerated holes to form a carbocationic species, which is followed by a consecutive dehydrogenative coupling of amine to yield imines. [ 4 ] In this process, molecular O 2 acts as the acceptor for photogenerated electrons and consume the surface‐adsorbed H atoms released from the amino groups to push the formation of the imines.…”