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This study investigates the synthesis, characterization, and performance of nanoscale zero-valent iron/reduced graphene oxide (nZVI/rGO) nanohybrids for the efficient removal of per- and polyfluoroalkyl substances (PFAS). The magnetic nanohybrids were fabricated using an innovative thermal co-reduction method, enabling scalable production under inert conditions. Comprehensive characterization confirmed successful integration of nZVI onto rGO sheets, and nanohybrids exhibited high surface area, strong magnetic properties, and effective adsorption and photocatalytic degradation capabilities for PFAS. PFAS removal was explored through sequential adsorption followed by photocatalytic degradation under UVC irradiation. Batch experiments demonstrated rapid adsorption equilibrium within 3 hours, removing 98.2% of perfluorooctanoic acid (PFOA) and 97.6% of perfluorooctane sulfonate (PFOS) under dark conditions. Subsequent oxygen-free UVC treatment with nZVI/rGO significantly degraded PFOS and PFOA, reducing their concentrations from 1 mg/L to 0.775 and 1.013 μg/L, respectively, with the formation of short-chain PFAS. Defluorination reached 64.2% for PFOA and 57.8% for PFOS after 72 hours, demonstrating effective PFAS degradation by nZVI/rGO. Desorption studies confirmed the potential for nanohybrid regeneration and reuse, while iron release analysis demonstrated minimal leaching. These results indicate that thermally reduced nZVI/rGO nanohybrids offer a scalable, efficient material for PFAS remediation, particularly through adsorption followed by degradation under oxygen-free UVC irradiation. 

Thioredoxin reductases (TrxR) activate thioredoxins (Trx) that regulate the activity of diverse target proteins essential to prokaryotic and eukaryotic life. However, very little is understood of TrxR/Trx systems and redox control in methanogenic microbes from the domain Archaea (methanogens), for which genomes are abundant with annotations for ferredoxin:thioredoxin reductases [Fdx/thioredoxin reductase (FTR)] from group 4 of the widespread FTR-like family. Only two from the FTR-like family are characterized: the plant-type FTR from group 1 and FDR from group 6. Herein, the group 4 archetype (AFTR) from Methanosarcina acetivorans was characterized to advance understanding of the family and TrxR/Trx systems in methanogens. The modeled structure of AFTR, together with EPR and Mössbauer spectroscopies, supports a catalytic mechanism similar to plant-type FTR and FDR, albeit with important exceptions. EPR spectroscopy of reduced AFTR identified a transient [4Fe−4S]1+ cluster exhibiting a mixture of S = 7/2 and typical S = 1/2 signals, although rare for proteins containing [4Fe−4S] clusters, it is most likely the on-pathway intermediate in the disulfide reduction. Furthermore, an active site histidine equivalent to residues essential for the activity of plant-type FTR and FDR was found dispensable for AFTR. Finally, a unique thioredoxin system was reconstituted from AFTR, ferredoxin, and Trx2 from M. acetivorans, for which specialized target proteins were identified that are essential for growth and other diverse metabolisms. 

Using methane as a reagent to synthesize high-value chemicals and high-energy density fuels through C−C coupling has attracted intense attention in recent decades, as it avoids completely breaking all C−H bonds in CH4. In the present study, we demonstrated that the coupling of HCHO with the CH3 species from CH4 activation to produce ethanol can be accomplished on the single Pd atom−In2O3 catalyst based on the results of density functional theory (DFT) calculations. The results show that the supported single Pd atom stabilizes the CH3 species following the activation of one C−H bond of CH4, while HCHO adsorbs on the neighboring In site. Facile C−C coupling of HCHO with the methyl species is achieved with an activation barrier of 0.56 eV. We further examined the C−C coupling on other single metal atoms, including Ni, Rh, Pt, and Ag, supported on In2O3 by following a similar pathway and found that a balance of the three key steps for ethanol formation, i.e., CH4 activation, C−C coupling, and ethoxy hydrogenation, was achieved on Pd/In2O3. Taking the production of acetaldehyde and ethylene on the Pd/In2O3 catalyst into consideration, the DFT-based microkinetic analysis indicates that ethanol is the dominant product on the Pd/In2O3 catalyst. The facile C−C coupling between HCHO and dissociated CH4 makes formaldehyde a potential C1 source in the conversion and utilization of methane through an energy- and atom-efficient process.