About this Research Topic
The development of green and renewable sources of energy represents a cornerstone of a sustainable economy. Sunlight constitutes perhaps the most attractive renewable source of energy, considering its wide availability and its immense content of energy (in the order of 1kW/m2). The direct utilization of sunlight is often impractical, also considering its intrinsic intermittency and fluctuating intensity. Therefore, the conversion of light into a more convenient form of energy, like chemical energy, is highly desirable. The strategies aimed at harnessing sunlight to produce fuels and chemicals from abundant resources are called “artificial photosynthesis”, inspired by natural processes taking place in green plants and bacteria.
The term “artificial photosynthesis” encompasses a wide variety of strategies. Generally speaking, a system capable of converting light into chemical energy contains a light harvesting unit (i.e. a sensitizer) and one (or more) catalysts. Two main strategies have been followed so far for the development of both sensitizers and catalysts: the utilization of solid-state materials or molecular-based ones. The two classes offer complementary advantages: molecular components possess a precisely defined structure, which enables in-depth mechanistic studies and fine-tuning of electronic properties via structural modifications. Conversely, solid-state materials are typically more robust and exhibit higher stability, sometimes with self-healing properties, but are limited by low tunability and poor product selectivity. The recent development of hybrid systems aims at merging the best of both strategies. For instance, molecular catalysts and/or photosensitizers attached onto semiconductor materials, as well as the combination of solid-state catalysts with molecular-based light-harvesting units, have proven to be beneficial for light assisted substrate conversion. In fact, such systems combine the tunability and selectivity of molecular systems with the robustness and recyclability of heterogenous materials.
Many challenges have to be solved yet to realize efficient and stable systems of practical application. The aim of this Research Topic is to collect the most recent and promising examples of molecular and hybrid systems, with the goal of stimulating new designs and concepts.
The scope of this Research Topic is focused on the different kinds of systems used for the conversion of light into chemical bonds. More specifically, we are interested in systems in which molecularly defined components play a major role. We welcome Original Research, Review, Mini Review and Perspective articles, in themes including, but not limited to:
• Systems based on purely molecular catalysts and photosensitizers
• Hybrid systems, i.e. materials functionalized with molecular catalysts
• Photoelectrodes including molecular catalysts and photosensitizers
• Mechanistic studies of such systems
• Improvement of multielectron transfer processes that are core to artificial photosynthesis
We are interested in different kinds of fuels (e.g. H2, products of CO2 reduction) as well as in the development of related processes (e.g. water oxidation, organic substrate oxidation, N2 reduction).
Keywords: artificial photosynthesis, molecular catalyst, hybrid system, photoelectrode, photosensitizer
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