Exploring highly efficient and cost-effective electrocatalysts with more feasible synthesis strategies toward oxygen evolution reaction (OER) is highly desirable for a broad range of advanced sustainable energy conversion systems. Herein, we develop a feasible electrospinning strategy for the facile fabrication of a Co 3 O 4 /CeO 2 heterostructure in situ embedded in N-doped carbon nanofibers (h-Co 3 O 4 /CeO 2 @N-CNFs) as a high-performance electrocatalyst for the OER. Unlike previously reported Co 3 O 4 /CeO 2 composites, the as-prepared Co 3 O 4 /CeO 2 heterostructure presents hollow and porous features. The nanopores can develop within Co 3 O 4 /CeO 2 nanocrystals with an analogous mechanism to void formation in the Kirkendall effect. Electrochemical measurements demonstrate that h-Co 3 O 4 /CeO 2 @N-CNFs can enable high OER activity with a low overpotential of 310 mV to achieve 10 mA cm −2 current density and good stability that can maintain 40 000 s without perceptible attenuation, outperforming those of the commercial RuO 2 catalyst. The outstanding OER performance originates from the important synergies by combining hollow Co 3 O 4 /CeO 2 heterostructures and three-dimensional porous N-CNF networks.

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In this study, miniaturized portable/online UVC-LED spectrophotometers have been developed for fast detection of nitrate nitrogen and dissolved organic matter, using 235 and 275 nm light-emitting diodes (LEDs) as the light sources and GaN-based photodiodes as UV detectors. The application of the wide-band gap GaN-based photodiodes eliminated the influences of parasitic visible emission of UVC-LEDs. Using Orange G as the test absorbing compound, the portable UVC-LED spectrophotometer showed high linear upper detection limits and a negligible stray light. The portable spectrophotometer showed good linearity for NO3 ––N concentration in the range of 0–15 mg/L (R 2 > 0.99), while a loss of sensitivity was observed at higher NO3 ––N concentration. This nonlinearity was attributed to the intrinsic stray light arising from the incomplete overlap between the 235 nm LED emission spectra and the nitrate absorption spectra. With the empirical correction coefficient α being determined from natural water and municipal wastewater samples, the UVC-LED spectrophotometers have comparable accuracy to the standard spectrophotometric method. The results of size exclusion chromatography further elucidated that it was the fraction of humic substances that determined the correction coefficient α for the UV spectrophotometric detection of nitrate in natural water and municipal wastewater samples.

Polyurethane (PU) synthetic leathers possess an intricate plastic composition, including polyester (PET) base fabrics and upper PU resin, but the release of fragments from the complexes is unclear. Therefore, we investigated the photodegradation trends of PET base fabrics with PU coating (PET-U) as a representative of composite plastics. Attention was paid to the comparison of the photoaging process of PET-U with that of pure PET base fabric (PET-P). To reveal the potential for chain scission, physical and chemical changes (e.g., surface morphology, molecular weight, and crystallinity) of the two fabrics were explored. The generation of microplastic fibers (MPFs) and microplastic particles (MPPs) was distinguished. Compared with PET-P, PET-U showed a similar but delayed trend in various characteristics and debris release rate as the photoaging time prolonged. Even so, after 360 h of illumination, the generated number of MPs (including MPFs and MPPs) rose considerably to 9.32 × 10 7 MPs/g, and the amount of released nanoplastics (NPs) increased to 2.70 × 10 11 NPs/g from PET-U. The suppression of MP formation from PET-U was potentially directed by the physical shielding of the upper PU layer and the dropped MPs, which resisted the photochemical radical effect. The components of dissolved organic matter derived from plastics (P-DOM) were separated by molecular weight using a size-exclusion chromatography−diode array detector−organic carbon detector/organic nitrogen detector (SEC-DAD-OCD/ OND), and the results showed that a larger amount of carbon-and nitrogen-containing chemical substances were generated in PET-U, accompanied by more aromatic and fluorescent compounds. The results provided theoretical bases and insights for future research on the risks of plastic debris from PU synthetic leathers on aquatic organisms and indicated feasible directions for exploring combined pollution studies of plastics.