xianfeng

Nature Chemistry, Published online: 02 November 2020; doi:10.1038/s41557-020-00562-5

The chemistry of artificial photoreduction of CO₂ is comprehensively described, offering an understanding of the background, mechanisms, and methods for characterization of CO₂ photoreduction. Recent advancements in using metal–organic frameworks (MOFs)/covalent organic frameworks (COFs) for the photoreduction of CO₂ into carbon‐neutral products are discussed. This Progress Report underlines the paramount importance of progress in reticular materials in the context of solving global energy issues.

Abstract

Because of the energy crisis facing the planet, reducing fossil fuel reliance is an urgent scientific task. Alternative fuels have recently been in high demand. Taking into account the enormous amount of CO₂ released from combustion, converting CO₂ into high value‐added products using photochemistry—the catalytic transformation is activated by the ubiquitous sunlight mimicking the photosynthesis of natural plants—is of paramount importance. Scientists have developed various photocatalysts for the CO₂ photoreduction. Among them, reticular materials including metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have been employed for many applications during the past decade and have emerged as advanced catalytic platforms for the photoreduction of CO₂. This Progress Report aims to provide the fundamentals, mechanism, and methods of characterization to gain insight into the process of CO₂ photoreduction. In addition, this Progress Report highlights the achievements in using reticular materials as advanced catalysts for the photoreduction of CO₂ and discusses the relationship between structural features of MOFs/COFs with their photocatalytic performance. Based on the comprehension of advancements, opportunities, and challenges of reticular materials for the CO₂ photoreduction, the future prospects of this technology are discussed to direct the exciting research in designing better CO₂ reduction photocatalysts.

A new ferrocene containing monomer is synthesized and its copolymerization with a water‐solubility promoting comonomer is investigated. The electrochemical and solution characteristics of a corresponding polymer are studied in detail. With a coulombic efficiency of >99.8% in an aqueous redox flow battery setup at 60 °C, a cheap, robust system for use at elevated temperatures is presented.

Abstract

Water‐soluble, and ferrocene‐containing methacrylamide copolymers with different comonomer ratios of the solubility‐promoting comonomer [2‐(methacryloyloxy)‐ethyl]‐trimethylammonium chloride (METAC) are synthesized in order to obtain a novel, temperature‐stable electrolyte for aqueous redox flow batteries. The electrochemical properties of one chosen polymer are studied in detail by cyclic voltammetry and rotating disc electrode (RDE) investigations. Additionally, the diffusion coefficient and the charge transfer rate are obtained from these measurements. The diffusion coefficient from RDE is compared to the value from synthetic boundary experiments at battery concentrations, using an analytical ultracentrifuge, yielding diffusion coefficients of a similar order of magnitude. The polymer is further tested in a redox flow battery setup. While performing charge and discharge experiments against the well‐established bis‐(trimethylammoniumpropyl)‐viologen, the polymer reveals high columbic efficiencies of >99.8% and desirable apparent capacity retention, both at room temperature as well as at 60 °C. Further experiments are conducted to verify the stability of the active compounds under these conditions in both charge states. Lastly, the electrochemical behavior is linked to the characteristics of the polymers concerning absolute values of the molar mass and diffusion coefficients.