A Self-Assembled Organic/Metal Junction for Water Photo-Oxidation

High-efficiency photocatalytic degradation of rhodamine 6G by organic semiconductor tetrathiafulvalene in weak acid-base environment

Tetrathiafulvalene (TTF) was successfully applied to degrade rhodamine 6G (Rh6G) in photocatalytic system. The results exhibited that TTF had excellent suitability in the range of weak acid to weak base (pH = 5-9). Multiple reactive oxygen species (˙OH, ¹O₂, H₂O₂ and ˙O₂^-) as well as h⁺ and e^- were generated in photocatalytic process, causing the rapid degradation of Rh6G. This study provides new ideas for the development of catalysts in photocatalytic system and the broader applications of organic semiconductor materials.

Visible-light driven water oxidation and oxygen production at soft interfaces

The visible light driven water oxidation reaction (WOR) by the organic electron acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (TCNQF₄) was studied at the water|butyronitrile interface. The WOR was performed at neutral pH, and without any metal or organometallic catalysts. The oxygen generated was measured by GC-MS and cyclic voltammetry, and the protons produced were monitored by measuring the aqueous pH. This work opens novel perspectives for water photo-oxidation in liquids and artificial photosynthesis.

Visible-Light-Driven Water Oxidation on Self-Assembled Metal-Free Organic@Carbon Junctions at Neutral pH

Sustainable water oxidation requires low-cost, stable, and efficient redox couples, photosensitizers, and catalysts. Here, we introduce the in situ self-assembly of metal-atom-free organic-based semiconductive structures on the surface of carbon supports. The resulting TTF/TTF^•+@carbon junction (TTF = tetrathiafulvalene) acts as an all-in-one highly stable redox-shuttle/photosensitizer/molecular-catalyst triad for the visible-light-driven water oxidation reaction (WOR) at neutral pH, eliminating the need for metallic or organometallic catalysts and sacrificial electron acceptors. A water/butyronitrile emulsion was used to physically separate the photoproducts of the WOR, H⁺ and TTF, allowing the extraction and subsequent reduction of protons in water, and the in situ electrochemical oxidation of TTF to TTF^•+ on carbon in butyronitrile by constant anode potential electrolysis. During 100 h, no decomposition of TTF was observed and O₂ was generated from the emulsion while H₂ was constantly produced in the aqueous phase. This work opens new perspectives for a new generation of metal-atom-free, low-cost, redox-driven water-splitting strategies.

Electrocatalytic Behavior of Tetrathiafulvalene (TTF) and Extended Tetrathiafulvalene (exTTF) [FeFe] Hydrogenase Mimics

TTF- and exTTF-containing [(μ-S₂)Fe₂(CO)₆] complexes have been prepared by the photochemical reaction of TTF or exTTF and [(μ-S₂)Fe₂(CO)₆]. These complexes are able to interact with PAHs. In the absence of air and in acid media an electrocatalytic dihydrogen evolution reaction (HER) occurs, similarly to analogous [(μ-S₂)Fe₂(CO)₆] complexes. However, in the presence of air, the TTF and exTTF organic moieties strongly influence the electrochemistry of these systems. The reported data may be valuable in the design of [FeFe] hydrogenase mimics able to combine the HER properties of the [FeFe] cores with the unique TTF properties.

Bimodal Heterogeneous Functionality in Redox-Active Conjugated Microporous Polymer toward Electrocatalytic Oxygen Reduction and Photocatalytic Hydrogen Evolution

The designing and development of heterogeneous catalysts for conversion of renewable energy to chemical energies by electrochemical as well as photochemical processes is at the forefront of energy research. In this work, two new donor-acceptor-based redox-active conjugated microporous polymers (CMPs) (TAPA-OPE-mix and TAPA-OPE-gly) are synthesized through Schiff base condensation reaction using a microwave synthesizer. Notably, the asymmetric and symmetric bola-amphiphilic nature of the OPE struts results in distinct nanostructuring and morphologies in the CMPs. Interestingly, both CMPs show impressive heterogeneous catalytic activity toward electrochemical O₂ reduction and photocatalytic H₂ evolution reactions, and therefore, act as bimodal electro- and photocatalytic porous organic materials. Furthermore, the redox-active property of the CMPs is exploited for in situ generation and stabilization of platinum nanoparticles (Pt), and these Pt@CMPs exhibit significantly enhanced photocatalytic activity.