Organic Photosensitizers for Catalytic Solar Fuel Generation

Abstract

In recent years, various organic dyes have been used as photosensitizers for the photocatalytic reduction of water and carbon dioxide, which is a sustainable approach for fuel generation under noble-metal free conditions. Recent development of organic chromophores, which are characterized by a populated triplet excited state, have greatly facilitated their applications in solar fuel production. In this review, the photophysical properties of organic dyes are discussed in relation to their applications in photocatalytic reduction of water and carbon dioxide. In particular, common synthetic strategies for enhancing the population of their triplet states, which are important in promoting photoredox reactions, are described. This is followed by a review on recent developments of photocatalytic reduction of water and carbon dioxide involving various organic photosensitizers.

2021 Pioneers in Energy Research: Vivian Yam

“…The research team of Han 24 reviews advances in synthesis, optical properties, exciton dynamics, and optoelectronic applications of all-inorganic three-dimensional (3D) halide double perovskite nanocrystals and outlines the future challenges and opportunities. Leung and Lau 25 summarize the photophysical properties of organic dyes and recent applications in photocatalytic reduction of water and carbon dioxide. Credi and co-workers 26 provide the state-ofthe-art light-driven artificial molecular machines via implementing photochemical processes within well-designed (supra)molecular assemblies.…”

Exchange Coupling Determines Metal-Dependent Efficiency for Iron- and Cobalt-Catalyzed Photochemical CO2 Reduction

“…The selective and efficient transformation of carbon dioxide into value-added products offers a sustainable approach to generate fuels, foods, materials, and medicines from renewable feedstocks. − Artificial photosynthesis is a potentially powerful strategy toward achieving this goal, − where concept transfer from natural photosynthesis can be incorporated into synthetic systems capable of reducing CO 2 through light-initiated proton- and electron-transfer reactions. In this context, homogeneous artificial photosynthesis platforms offer the capacity to tune system performance using well-defined components, including the molecular catalyst, photosensitizer with an energy-matched reduction potential, and sacrificial electron donor with maximum quenching efficiency. ,− Indeed, recent advances in molecular photocatalysis for the carbon dioxide reduction reaction (CO 2 RR) include metal-dependent enhancement of organic photosensitizers, , the use of hydrogen bonding, electrostatic, ,, or covalent interactions between the photosensitizer and catalyst to improve electron transfer, and additives to increase CO 2 solubility. − …”

Homogeneous Systems Containing Earth‐Abundant Metal Complexes for Photoactivated CO2 Reduction: Recent Advances

“…Several organic chromophores have become desirable in photoredox catalysis [8] and employed as sustainable alternative photosensitizers in the photocatalytic reduction of CO 2 in more recent years. [9] These organic dyes are typically fluorescent, that is, their emissive excited-state is a singlet, which often prevents high efficiency of the photoinduced electron-transfer process, where long-lived excited states are beneficial. Thus, some strategies have been developed to increase spin-orbit coupling to enhance the population of the triplet excite-state.…”