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Theoretical modeling of the solid‐state photocatalysis is one of the important issues as various useful photocatalysts have been developed to date. In this work, we investigated the mechanism of the alcohol photooxidation on niobium oxide (Nb2O5) which was experimentally developed, using the density functional theory (DFT)/time‐dependent (TD)DFT calculations based on the cluster model. The alcohol adsorption and the first hydrogen transfer from hydroxy group to surface occur in the ground state, while the second hydrogen transfer from CH proceeds in the excited states during the photoirradiation of UV or visible light. The spin crossing was identified and the low‐lying triplet states were solved for the reaction pathway. The photoabsorption in the visible light region was characterized as the charge transfer transition from O 2p of alcohol to Nb 4d of the Nb2O5 surface. The spin density and the natural population analysis indicated the generation of spin density in the moiety of carbonyl compound and its dissipation to the interface of the surface, which partly explains the electron paramagnetic resonance measurement. It was confirmed that the rate determining step is the desorption of carbonyl compound and water molecule in agreement with the experimental rate equation analysis. The present findings with the theoretical modeling will provide useful information for the further studies of the solid‐state photocatalysis. [ABSTRACT FROM AUTHOR]

Visible light photocatalysis has established itself as a promising sustainable and powerful strategy to access reactive intermediates, i.e. radicals and radical ions, under mild reaction conditions using visible light irradiation. This field enables the development of formerly challenging or even previously inaccessible organic transformations. In this tutorial review, an overview of the essential concepts and techniques of visible-light-mediated chemical processes and the most common types of photochemical activation of organic molecules, i.e. photoredox catalysis and photosensitization, are discussed. Selected photocatalytic alkene functionalization reactions are included as examples to illustrate the basic concepts and techniques with particular attention given to the understanding of their reaction mechanisms. 1 Introduction 2 Photocatalysts 3 Photophysical and Electrochemical Properties 3.1 Excited-State Energy 3.2 Ground-State Redox Potentials 3.3 Excited-State Redox Potentials 3.4 Local Absorbance Maximum for Lowest Energy Absorption 3.5 Excited-State Lifetime 3.6 [Ru(bpy)3 ]2+ as a Case Study 3.7 Basic Laws and Equations of Photochemistry and Photocatalysis 3.8 Common Terminology in Photochemistry and Photocatalysis 4 Activation Modes in Photocatalysis 4.1 Photoinduced Electron Transfer 4.2 Photoinduced Energy Transfer 5 Conclusions and Outlook [ABSTRACT FROM AUTHOR]

Photosensitization associated with electron/energy transfer represents the central science of natural photosynthesis. Herein, we proposed a protocol to dramatically improve the sensitizing ability of metal–organic frameworks (MOFs) by switching their excited state distribution from 3MLCT (metal‐to‐ligand charge transfer) to 3IL (intraligand). The hierarchical organization of 3IL MOFs and Co/Cu catalysts facilitates electron transfer for efficient photocatalytic H2 evolution with a yield of 26 844.6 μmol g−1 and CO2 photoreduction with a record HCOOH yield of 4807.6 μmol g−1 among all the MOF photocatalysts. Systematic investigations demonstrate that strong visible‐light‐absorption, long‐lived excited state and ingenious multi‐component synergy in the 3IL MOFs can facilitate both interface and intra‐framework electron transfer to boost photocatalysis. This work opens up an avenue to boost solar‐energy conversion by engineering sensitizing centers at a molecular level. [ABSTRACT FROM AUTHOR]

Photosensitization associated with electron/energy transfer represents the central science of natural photosynthesis. Herein, we proposed a protocol to dramatically improve the sensitizing ability of metal–organic frameworks (MOFs) by switching their excited state distribution from 3MLCT (metal‐to‐ligand charge transfer) to 3IL (intraligand). The hierarchical organization of 3IL MOFs and Co/Cu catalysts facilitates electron transfer for efficient photocatalytic H2 evolution with a yield of 26 844.6 μmol g−1 and CO2 photoreduction with a record HCOOH yield of 4807.6 μmol g−1 among all the MOF photocatalysts. Systematic investigations demonstrate that strong visible‐light‐absorption, long‐lived excited state and ingenious multi‐component synergy in the 3IL MOFs can facilitate both interface and intra‐framework electron transfer to boost photocatalysis. This work opens up an avenue to boost solar‐energy conversion by engineering sensitizing centers at a molecular level. [ABSTRACT FROM AUTHOR]

Inspired by nature, improving photosensitization represents a vital direction for the development of artificial photosynthesis. The sensitization ability of photosensitizers (PSs) reflects in their electron-transfer ability, which highly depends on their excited-state lifetime and redox potential. Herein, for the first time, we put forward a facile strategy to improve sensitizing ability via finely tuning the excited state of Ru(II)-PSs (Ru-1 – Ru-4) for efficient CO2 reduction. Remarkably, [Ru(Phen)2(3-pyrenylPhen)]2+ (Ru-3) exhibits the best sensitizing ability among Ru-1 – Ru-4 , over 17 times higher than that of typical Ru(Phen)32+. It can efficiently sensitize a dinuclear cobalt catalyst for CO2-to-CO conversion with a maximum turnover number of 66 480. Systematic investigations demonstrate that its long-lived excited state and suitable redox driving force greatly contributed to this superior sensitizing ability. This work provides a new insight into dramatically boosting photocatalytic CO2 reduction via improving photosensitization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Importantly, we have tried to clearly show corroles complexes could be excellent photosensitizers due to their robust triplet excited states and singlet oxygen formation, and photocatalysts in driving chemical reactions. • We are providing a very comprehensive overview of the photophysics of corrole and intimately related systems, highlighting their potential as versatile materials for emerging technologies. • Many studies are described about elucidating the excited triplet and singlet oxygen, time-settled electron paramagnetic reverberation (TREPR) analysis of corrole systems. • We cover the uses of corrole systems as photocatalysts, photosensitizers, and biomolecule docking agents. • The systematic progress of nonlinear optical (NLO) properties of corroles is discussed. The scientific research field of corrole systems has witnessed an explosion of interest in recent years owing to unique optical and electronic properties that are very promising for various applications. This timely review gives a thorough treatment of the primary literature of the photophysics of corrole systems, with a specific spotlight on the impacts of solvents, pH, heavy atoms, core-metal insertion, dyads, and aggregation. The inventory of features is helping pave the way towards new advancements. Many studies have been carried out by focusing on elucidating the excited triplet and singlet state lifetimes, and time-settled electron paramagnetic reverberation (TREPR) analysis of corrole systems. Furthermore, our review covers the auspicious uses of corrole systems as photocatalysts, photosensitizers, and biomolecule docking agents. Finally, the systematic progress of nonlinear optical (NLO) properties of corroles is discussed. We are hereby providing a comprehensive overview of the photophysics of corrole and intimately related systems, highlighting their potential as versatile materials for emerging technologies. [ABSTRACT FROM AUTHOR]

A study on C9‐imide acridinium photocatalysts with enhanced photoredox catalytic activity with respect to the well‐established C9‐mesityl acridinium salt is presented. The differences observed rely on the diverse accessibility of singlet charge‐transfer excited states, which have been proven by CASPT2/CASSCF calculations, fluorescence and quenching studies. [ABSTRACT FROM AUTHOR]

Photoenzymes use light to initiate biochemical reactions. Although rarely found in nature, their study has advanced understanding of how light energy can be harnessed to facilitate enzyme catalysis, which is also of importance to the design and engineering of man-made photocatalysts. Natural photoenzymes can be assigned to one of two families, based broadly on the nature of the light-sensing chromophores used, those being chlorophyll-like tetrapyrroles or flavins. In all cases, light absorption leads to excited state electron transfer, which in turn initiates photocatalysis. Reviewed here are recent findings relating to the structures and mechanisms of known photoenzymes. We highlight recent advances that have deepened understanding of mechanisms in biological photocatalysis. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (PCN) has been extensively employed in peroxymonosulfate (PMS) activation for water decontamination. However, limited photocatalytic efficiency can be achieved by pristine PCN due to its intrinsic deficiencies like high electron-hole recombination rate and resistance to charge transfer. Herein, in a two-stage thermal treatment process, the nontoxic and stable Na and K were successfully anchored among the PCN skeleton with surface defects created, leading to an elevated photocatalytic activity for PMS activation. The SO 4 ·- and 1O 2 were identified as the dominant reactive oxygen species, which were generated from electron transfer processes between PMS and catalyst. Experimental and theoretical analyses suggested that the defective structures and metal dopants improved the optical properties of catalyst, endowing it a wider light absorption range and a lower energy barrier for electron transitions. The modified structures were also beneficial to electron transfer processes due to the weaker electron confinement effect, accelerating the production of SO 4 ·- on the defective sites and 1O 2 on the metal sites. The synergy of radical and non-radical species weakened the influence of side reactions between radicals from PMS and coexisting inorganic anions in practical water, hence to promote the resistance of modified catalysts in complex water matrices. [Display omitted] • Alkali metal dopants and defects were simultaneously introduced into PCN. • Sulfate radical and singlet oxygen dominated the degradation process. • Alkali metal dopants and defects show a synergy on elevating optical properties. • Alkali metal dopants oriented the electron transfer from PMS to catalyst. • Defective structures significantly promoted the separation of electron-hole pairs. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (PCN) has been extensively employed in peroxymonosulfate (PMS) activation for water decontamination. However, limited photocatalytic efficiency can be achieved by pristine PCN due to its intrinsic deficiencies like high electron-hole recombination rate and resistance to charge transfer. Herein, in a two-stage thermal treatment process, the nontoxic and stable Na and K were successfully anchored among the PCN skeleton with surface defects created, leading to an elevated photocatalytic activity for PMS activation. The SO 4 ·- and 1O 2 were identified as the dominant reactive oxygen species, which were generated from electron transfer processes between PMS and catalyst. Experimental and theoretical analyses suggested that the defective structures and metal dopants improved the optical properties of catalyst, endowing it a wider light absorption range and a lower energy barrier for electron transitions. The modified structures were also beneficial to electron transfer processes due to the weaker electron confinement effect, accelerating the production of SO 4 ·- on the defective sites and 1O 2 on the metal sites. The synergy of radical and non-radical species weakened the influence of side reactions between radicals from PMS and coexisting inorganic anions in practical water, hence to promote the resistance of modified catalysts in complex water matrices. [Display omitted] • Alkali metal dopants and defects were simultaneously introduced into PCN. • Sulfate radical and singlet oxygen dominated the degradation process. • Alkali metal dopants and defects show a synergy on elevating optical properties. • Alkali metal dopants oriented the electron transfer from PMS to catalyst. • Defective structures significantly promoted the separation of electron-hole pairs. [ABSTRACT FROM AUTHOR]

In natural photosynthetic system, sunlight is harvested by chlorophyll, subsequent funneling of the excitation energy to redox centers to trigger redox reaction. In contrast, the functions of light absorption, intersystem crossing and redox reaction were integrated into a single species (i.e. Ru(bpy) 3 2+ ) in traditional catalytic system. Inspired by nature, we explore a strategy to introduce the strong absorbing dyes into Ru redox center and regulate their excited states by increasing the π-conjugation of dyes to afford a series of Ru(II) complexes-chromophore dyads (Ru-1 – Ru-5). Experimental and theoretical investigations reveal a forward singlet energy transfer following a backward triplet energy transfer between chromophore/Ru center in Ru-5 , presenting a bidirectional sensitization, which not only achieve the functional separation among components in photosensitizer but also promote the efficient collaboration between Ru(II) center and chromophore. Remarkably, Ru-5 exhibited a strong visible light absorption at 463 nm (ε = 50500 M−1cm−1) and its triplet lifetime reached to 122.5 μs, over 400 times longer than the single component complex Ru-1. These advantages enable Ru-5 a significantly higher catalytic activity than the typical Ru(bpy) 3 2+ for both energy- and electron-transfer reactions. This work opens up a new avenue to improve photosensitization for efficient photosynthesis by learning from nature. A bidirectional sensitization in Ruthenium(II)-antenna dyad (Ru-5) was achieved by a forward singlet energy transfer following a backward triplet energy transfer between chromophore/Ru center, which endowed its a strong visible absorption (ε = 50500 M−1cm−1) and long excited state lifetime (τ = 122.5 μs). [Display omitted] • An efficient strategy to improve sensitizing ability has been developed by mimicking the energy flow of biological model. • The optimal PS (Ru-5) possesses both strong visible light harvesting ability and long excited state lifetime (122.5 μs), 400 times longer than that of Ru(bpy) 3 2+ . • Ru-5 can efficiently drive both energy- and electron-transfer reactions with a yield of over 90% for the most phenols. [ABSTRACT FROM AUTHOR]