Choi et al. Visible light driven photocatalysis mediated via ligand-to-metal charge transfer (LMCT): an alternative approach to solar activation of titania

The development and utilization of solar energy in environmental remediation and water splitting is being intensively studied worldwide. During the past few decades, tremendous efforts have been devoted to developing non-toxic, low-cost, efficient and stable photocatalysts for water splitting and environmental remediation. To date, several hundreds of photocatalysts mainly based on metal oxides, sulfides and (oxy)nitrides with different structures and compositions have been reported. Among them, perovskite oxides and their derivatives (layered perovskite oxides) comprise a large family of semiconductor photocatalysts because of their structural simplicity and flexibility. This review specifically focuses on the general background of perovskite and its related materials, summarizes the recent development of perovskite photocatalysts and their applications in water splitting and environmental remediation, discusses the theoretical modelling and calculation of perovskite photocatalysts and presents the key challenges and perspectives on the research of perovskite photocatalysts.

A new method of free radical polymerization is developed on the basis of visible light photocatalysis using Ru(bpy)3Cl2 that initiates and controls the polymerization at ambient temperature. The α-haloester and benzylic halide act as radical initiators that can be activated through the Ru(bpy)3 + photoredox cycle under visible light irradiation. Successful free radical polymerizations of various methacrylates were realized using a Xe arc lamp as well as a household fluorescent lamp as light source. The polymerization is initiated with light on and immediately terminated upon turning the light off. In addition, the molecular weight of polymer can be varied by changing the ratio of monomer and initiator. The present photocatalytic method has merits of the mild reaction conditions with weak light irradiation, ambient temperature, and lower catalyst loading, which could be an alternative to the traditional thermal or photo-based free radical initiation methods. It is also advantageous over other photopolymerization methods in that the radical initiator is separated from the photosensitizer.

Photocatalytic conversion of cellulose to sugars and carbon dioxide with simultaneous production of hydrogen assisted by cellulose decomposition under UV or solar light irradiation was achieved upon immobilization of cellulose onto a TiO2 photocatalyst. This approach enables production of hydrogen from water without using valuable sacrificial agents, and provides the possibility for recovering sugars as liquid fuels.

The alternative charge arrangement on the {010} facet of BiOCl facilitates benzyl oxidation and selectivity for benzoic acid ring-opening reactions, subsequently resulting in remarkably enhanced photocatalytic efficiency.

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