Construction of Fe2+/Fe3+ cycle system at dual-defective carbon nitride interfaces for photogenerated electron utilization

Electrocatalytic reforming of polyethylene terephthalate waste plastics into high-value-added chemicals with green hydrogen generation

Electrochemical reforming offers a sustainable strategy for converting plastic waste into high-value-added chemicals and hydrogen fuel. Herein, a cost-effective NiFe-filmed electrode with a Tremella-like nanostructure was developed using an ultrasonic immersion etching method. This electrode enabled the electro-reforming of ethylene glycol (EG, a monomer of polyethylene terephthalate (PET)) into valuable commodity chemicals, with coproduction of hydrogen fuel. This system demonstrated notable electrocatalytic performance, achieving a current density of 100 mA/cm2 at a low overpotential of 1.52 V vs. reversible hydrogen electrode (RHE). It also exhibits notable selectivity (94.4 %) and Faradaic efficiency (94.3 %) for formate production. Furthermore, in a proof-of-concept demonstration, real-world PET plastic waste was successfully utilized to produce potassium diformate and terephthalic acid with properties comparable to those of commercial products. This study provides a comprehensive strategy for designing cost-effective catalysts for plastic electro-upcycling and lays a foundation for advancing the circular economy of plastic waste.

Incorporation of Cu5FeS4 QDs with Abundant Oxygen Vacancy TiO2 QDs/TiO2 OVs: Double S-Scheme Photocatalysts for Effectual N2 Conversion to NH3 under Simulated Solar Light

Photocatalytic N2 conversion to NH3 is a green, sustainable pathway with renewable energy sources and carbon neutrality. In this research, ternary TiO2 QDs/TiO2 OVs/Cu5FeS4 nanocomposites were prepared by an easy and affordable procedure and utilized to produce clean ammonia energy without a sacrificial agent. The amount of produced green ammonia by the optimum nanocomposite achieved was 17,274 μmol L-1 g-1, which was approximately 20.9, 6.48, 4.45, 2.26, and 1.45 times higher than those of commercial TiO2, TiO2 QDs, TiO2 OVs, Cu5FeS4, and TiO2 QDs/TiO2 OVs photocatalysts, respectively. Lattice compatibility through the developed homojunction within TiO2 QDs/TiO2 OVs and the integration of Cu5FeS4 nanoparticles led to the establishment of a double S-scheme homo/heterojunction system, which improved the photocatalytic activity by maintaining electrons and holes with high oxidation and reduction power and greatly reduced the recombination of charges, which led to the acceleration of charge transfer and migration. Besides, the promoted surface area compared to the pure components, introducing oxygen vacancies, and reducing the particle size boosted the photocatalytic N2 conversion to NH3. The results of this research are a basis for the rational design of homojunction/heterojunction visible-light-responsive systems for photocatalytic nitrogen fixation reactions.

Well-Defined Iron Sites in Crystalline Carbon Nitride

Carbon nitride materials can be hosts for transition metal sites, but Mössbauer studies on iron complexes in carbon nitrides have always shown a mixture of environments and oxidation states. Here we describe the synthesis and characterization of a crystalline carbon nitride with stoichiometric iron sites that all have the same environment. The material (formula C6N9H2Fe0.4Li1.2Cl, abbreviated PTI/FeCl2) is derived from reacting poly(triazine imide)·LiCl (PTI/LiCl) with a low-melting FeCl2/KCl flux, followed by anaerobic rinsing with methanol. X-ray diffraction, X-ray absorption and Mössbauer spectroscopies, and SQUID magnetometry indicate that there are tetrahedral high-spin iron(II) sites throughout the material, all having the same geometry. The material is active for electrocatalytic nitrate reduction to ammonia, with a production rate of ca. 0.1 mmol cm-2 h-1 and Faradaic efficiency of ca. 80% at -0.80 V vs RHE.