Oxygen-enriched carbon quantum dots from coffee waste: Extremely active organic photocatalyst for sustainable solar-to-H2O2 conversion.

Solar-driven artificial photosynthesis offers a promising avenue for hydrogen peroxide (H2O2) generation, an efficient and economical replacement for current methods. The efficiency and selectivity hurdles of the two-electron oxygen reduction reaction (ORR) in solar-to- H2O2 conversion are substantial barriers to large scale production. In this manuscript, a simple biomass-assisted synthesis was performed to produce oxygen-enriched carbon quantum dots (OE-CQDs) from spent coffee waste, acting as an efficient photocatalyst for solar-powered H2O2 production. OE-CQDs can stabilize and store light-generated electrons effectively, boosting charge separation and enhancing photocatalytic performance with longevity. The maximal photocatalytic H2O2 production was achieved viz the utilization of OE-CQDs with generation rate of 356.86 µmol g-1 h-1 by retaining 80% activity without any external sacrificial donors. The outstanding performance of synthesized OE-CQDs under light exposure at wavelength (λ) of 280 nm has been ensured by the quantum yield value of 9.4% upon H2O2 generation. The combinatorial benefits of OE-CQDs with their authentic crystalline structure and oxygen enrichment, is expected to be enhancing the ORR activity through accelerating charge transfer, and optimizing oxygen diffusion. Consequently, our eco-friendly method holds considerable promise for creating highly efficient, metal-free photocatalysts for artificial H2O2 production.

Iron-engineered mesoporous biocarbon composite and its adsorption, activation, and regeneration approach for removal of paracetamol in water.

Three-dimensional multi-porous Iron Oxide/carbon (Fe2O3/C) composites derived from tamarind shell biomass were synthesized by a single-step co-pyrolysis technique and utilized for Paracetamol (PAC) dismissal in the combined adsorption, and advanced oxidation such as electrochemical regeneration techniques. The Fe2O3/C composites were prepared by different pyrolysis temperatures, and named as TS750 (without Fe2O3at 750 °C), MTS450 BCs (Low-450 °C), MTS600 BCs (Moderate-600 °C) and MTS750 BCs (high-750 °C), respectively. As-prepared Fe2O3/C composite was characterized by FE-SEM, XRD, BET, and XPS analysis. The specific surface area and the spatial interaction between the interlayers of Fe2O3 and C were significantly improved by increasing the pyrolysis temperatures from 450 to 750 °C, which improved the adsorption capacity of Fe2O3/C composites in terms of higher rate constants and chemisorption kinetics. The Pseudo-second-order kinetics model fitted in the adsorption test results of Fe2O3/C composites with the highest correlation co-efficiency. The Langmuir-isotherms model fitted in the adsorption test of the TS750 and MTS450 BCs. The Freundlich isotherms model is more fit with MTS600 and MTS750 BCs. Based on the isotherm results, the MTS750 BCs achieved 46.9 mg/g of maximum PAC adsorption capacity. The optimized MTS750 composites could be completely recovered by using an advanced electrochemical oxidation regeneration approach within 180 min. Also, with the adsorption and recovery process, the TOC removal rate improved to ∼79.4%. After the 6th cycle electrochemical oxidation process, the obtained results of the re-adsorption test showed the stabile adsorption activity of the sorbent material. The data outcomes herein propose that this type of combined adsorption and electrochemical approach will be useful in commercial water treatment plants.

Novel pure α-, ß-, and mixed-phase α/ß-Bi2O3 photocatalysts for enhanced organic dye degradation under both visible light and solar irradiation.

Combining the pure α- and ß-phases of bismuth oxide enhances its photocatalytic activity under both visible and solar irradiation. α-Bi2O3, ß-Bi2O3, and α/ß-Bi2O3 were synthesized by a solvothermal calcination method. The structural, optical, and morphological properties of the as-synthesized catalysts were analyzed using XRD, UV-DRS, XPS, SEM, TEM, and PL. The bandgaps of α/ß-Bi2O3, α-Bi2O3, and ß-Bi2O3 were calculated to be 2.59, 2.73, and 2.34 eV, respectively. The photocatalytic activities of the catalysts under visible and solar irradiation were examined by the degradation of carcinogenic reactive blue 198 and reactive black 5 dyes. The kinetic plots of the degradation reactions followed pseudo-first-order kinetics. α/ß-Bi2O3 exhibited higher photocatalytic activity (∼99%) than α-Bi2O3 and ß-Bi2O3 under visible and solar irradiation. The TOC and COD results confirmed the maximum degradation ability of α/ß-Bi2O3, and the decolorization percentage remained above 90%, even after five cycles under visible irradiation. The photocatalytic dye degradation mechanism employed by α/ß-Bi2O3 was proposed based on active species trapping experiments.

Topologically immobilized catalysis centre for long-term stable carbon dioxide reforming of methane.

Methane reforming at low temperatures is of growing importance to mitigate the environmental impact of the production of synthesis gas, but it suffers from short catalyst lifetimes due to the severe deposition of carbon byproducts. Herein, we introduce a new class of topology-tailored catalyst in which tens-of-nanometer-thick fibrous networks of Ni metal and oxygen-deficient Y2O3 are entangled with each other to form a rooted structure, i.e., Ni#Y2O3. We demonstrate that the rooted Ni#Y2O3 catalyst stably promotes the carbon-dioxide reforming of methane at 723 K for over 1000 h, where the performance of traditional supported catalysts such as Ni/Y2O3 diminishes within 100 h due to the precluded mass transport by accumulated carbon byproducts. In situ TEM demonstrates that the supported Ni nanoparticles are readily detached from the support surface in the reaction atmosphere, and migrate around to result in widespread accumulation of the carbon byproducts. The long-term stable methane reforming over the rooted catalyst is ultimately attributed to the topologically immobilized Ni catalysis centre and the synergistic function of the oxygen-deficient Y2O3 matrix, which successfully inhibits the accumulation of byproducts.

Synthesis of nano-cuboidal gold particles for effective antimicrobial property against clinical human pathogens.

Algae could offer a potential source of fine chemicals, pharmaceuticals and biofuels. In this study, a green synthesis of dispersed cuboidal gold nanoparticles (AuNPs) was achieved using red algae, Gelidium amansii reacted with HAuCl4. It was found to be 4-7 nm sized cubical nanoparticles with aspect ratio of 1.4 were synthesized using 0.5 mM of HAuCl4 by HRSEM analysis. The crystalline planes (111), (200), (220), (311) and elemental signal of gold was observed by XRD and EDS respectively. The major constitutes, galactose and 3,6-anhydrogalactose in the alga played a critical role in the synthesis of crystalline AuNPs with cubical dimension. Further, the antibacterial potential of synthesized AuNPs was tested against human pathogens, Escherichia coli and Staphylococcus aureus. The synthesized AuNPs found biocompatible up to 100 ppm and high concentration showed an inhibition against cancer cell. This novel report could be helped to exploration of bioresources to material synthesis for the application of biosensor and biomedical application.