Ein neuer Dreh: Drei Arten N-invertierter Corrolisomere (NCCs) wurden synthetisiert, und ihre Strukturen wurden mithilfe von Einkristall-Röntgenstrukturanalyse aufgeklärt. Die Position des invertierten Pyrrolrings im NCC wirkt sich stark auf die optischen Eigenschaften und die Anionenbindung aus. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
Water splitting via a photocatalysis-electrolysis hybrid system has been investigated as a potentially scalable and economically feasible means of producing renewable H2. However, there are no reports demonstrating a scalable system for stoichiometric water splitting using an efficient and stable photocatalyst, and the key operating conditions for efficiently driving the entire system have not been established. Herein, we address the issues required to efficiently drive the entire system of a Cs+, Fe2+, and H+ ion-modified WO3 (denoted as H-Fe-Cs-WO3) photocatalyst fixed reactor combined with a polymer electrolyte membrane (PEM)-type electrolyzer. In electrochemical H2 production using Fe2+, the current density improved as the concentration of both H+ and Fe2+ increased, and we determined the optimum conditions for a hybrid system using high concentrations of HClO4 and Fe(ClO4)3, which differ from those reported for photocatalysis alone. No performance deterioration of the H-Fe-Cs-WO3 photocatalyst was observed even after light irradiation for more than 10 000 h under strong acidic conditions. The accumulated Fe2+ ions were extremely stable and did not oxidize even when exposed to air for more than two months. As for the stepwise operation that takes advantage of the characteristics of the hybrid system, the contribution factor of the photocatalyst in the photocatalysis-electrolysis hybrid system for H2 evolution (CP@STHap) under an applied bias was estimated to be 0.24%, which is a value comparable to that of the solar-to-chemical (STC) conversion efficiency (0.31%). The efficiency difference (0.07%) corresponds to the overpotential of the electrolytic reaction and indicates that water splitting via the photocatalysis-electrolysis hybrid system proceeds efficiently at a small overpotential of 0.06 V (∼11.6 kJ mol–1).
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Photocatalysis–electrolysis hybrid systems are attractive candidates for cost-effective green hydrogen production. For these systems, it is crucial to improve the O2 evolution activity of the aqueous solution containing the redox mediators. In this study, a kinetic analysis was conducted, for the first time, to determine the role of WO3 modified at various temperatures onto Cr- and Sb-codoped TiO2. The kinetic analysis successfully elucidated the factor that contributed to the higher activity. Based on this implication, it was revealed that the WO3 species increased the amount of Fe3+ ions at the sliding surface owing to the low isoelectric point of WO3, resulting in improved O2 evolution activity. Thus, this study proposes a strategy based on kinetic analysis for the design and development of photocatalysts with improved activity in the O2 evolution reaction.
The conversion of glycerol, a major byproduct of the biodiesel industry, into value-added chemicals is a topic of significant academic and industrial importance because it can potentially decrease production costs and waste amounts. This process may become even greener if the conversion of glycerol is driven by renewable energy in ambient temperature instead of conventional thermochemical reactions. Herein, we have developed an energy-efficient method for the photoelectrochemical oxidation of glycerol to dihydroxyacetone (DHA), a high-value-added chemical, over a Ta-doped BiVO4/WO3/F-doped tin oxide (FTO) (Ta:BiVO4) photoanode with higher acid resistance than a conventional non-doped BiVO4/WO3/FTO photoanode (BiVO4). The DHA selectivity of the Ta:BiVO4 anode was close to 100%, and the amounts of undesirable products, such as glyceraldehyde and formic acid, were negligible. By tuning the acidity and composition of the reaction solution, the Faradaic efficiency for the oxidation of glycerol to DHA over the acid-resistant Ta:BiVO4 photoanode increased from 61% for a 25 mM H2SO4 solution to 80% for a 100 mM H2SO4 solution to 96% for a 100 mM H2SO4 solution containing acetone. Conversely, the undoped BiVO4 photoanode was unstable in the 25 mM H2SO4 solution, and its current density decreased by 27%.
Global warming caused by greenhouse gas emissions must be mitigated by switching from fossil fuels to renewable energy sources, which is a critical issue for modern society. Against this background, the use of particulate photocatalysts to convert solar energy from water to green and inexpensive H 2 has attracted much attention. 1 Freshwater is essential for ingestion and agriculture and is sometimes considered a valuable resource in developing countries and remote islands. 2 Therefore, seawater and brine, which constitutes more than 97% of the water on Earth, are worth studying from this perspective. Seawater contains about 500 mM Cl – ion, which is involved in oxidation reactions. Cl – ion is oxidized to chlorine (Cl 2 ), hypochlorous acid (HClO), and hypochlorite ion (ClO – ) under acidic, neutral, and basic conditions, respectively. Therefore, the simultaneous production of H 2 and Cl 2 through photocatalytic seawater splitting is worth investigating as an economically and practically feasible system. In this study, we devised an overall brine splitting process for concurrently producing H 2 and Cl 2 with a particulate photocatalyst (Fig. 1(a)). Gas evolution reactions from brine at various pH under 365 nm light irradiation were monitored over time (Fig. 1(b)) 4 . Under acidic condition (pH 1), H 2 and Cl 2 were preferentially produced, although a small amount of O 2 was also produced. The e – /h + ratio of the product, which was initially 3.4, decreased with time and eventually reached almost unity, indicating that the reaction proceeded stoichiometrically. Under neutral and basic conditions, H 2 and a small amount of O 2 occurred stably, while Cl 2 and HClO were not detected by colorimetric measurements. Furthermore, the e – /h + ratio of the final product in those scenarios was clearly not unity. This is likely due to photolysis of HClO or ClO – . The Pt-loaded TiO 2 provided stable linear production of H 2 and Cl 2 for more than 10 hours under acidic conditions (Fig. 1(c)). After 14 h, the ClO – concentration exceeded 4 mM, a concentration sufficient for disinfection-related applications 5 . This result indicates that oxidation of Cl – ion occurred preferentially, even though O 2 is thermodynamically easier to generate than Cl 2 . The apparent quantum yield of the overall brine splitting reaction in acidic media (about 0.6% at 365 ± 20 nm) is comparable to that previously reported for TiO 2 photocatalytic water splitting reactions 6 . Furthermore, the calculated turnover number of H 2 PtCl 6 (about 10 3 ) indicates that Cl 2 was generated from the Cl – ion in solution. Thus, this result establishes the reliability of a new artificial photosynthesis system that can simultaneously produce H 2 and Cl 2 from brine. [1] J. Whitehead, P. Newman, J. Whitehead and K. L. Lim, J. Sustainable E arth Rev. , 6, 1 (2023). [2] C. Klassert, J. Yoon, K. Sigel, B. Klauer, S. Talozi, T. Lachaut, P. Selby, S. Knox, N. Avisse, A. Tilmant, J. J. Harou, D. Mustafa, J. Medellı ́nAzuara, B. Bataineh, H. Zhang, E. Gawel and S. M. Gorelick, Nat Sustainability , 6, 1406-1417 (2023). [3] R. K. B. Karlsson and A. Cornell, Chem. Rev. , 116, 2982-3028 (2016). [4] T. Okada, M. Korera, Y. Miseki, H. Kusama, T. Gunji, K. Sayama, Chem. Commun . , 60, 3299-3302 (2024). [5] E. W. Rice, R. M. Clark, C. H. Johnson, Emerging Infect. Dis. , 5, 461–463 (1999). [6] K. Maeda, Chem. Commun., 49, 8404-8406 (2013). Figure 1
