Aerogels have interconnected networks and preeminent pore structures. When used as the catalysts for oxygen reduction reaction (ORR), they can facilitate the mass transfer and expose more active sites. Here, we synthesized the Fe-doped titanium oxide-based aerogels (TA/Fes) by the sol–gel method combined with thermal treatment. The specific surface areas of the TA/Fes ranged from 475 to 774 m2·g−1, and the pore volumes varied from 0.96 to 1.72 cm3·g−1. The doping effect of the Fe ions and the oxygen vacancies in anatase enhance the electrical conductivity, leading to the low Rct (313.3–828.2 Ω). All samples showed excellent stability (2.0–4.5 mV) and 4e−pathway. The limiting current density of TA/Fe3 reached 5.34 mA·cm−2, which was comparable to that of commercial Pt/C. The preparation method is inspiring and the as-prepared aerogel catalysts have potential in promoting the scale of fuel cells.Keywords:TiO2aerogel;Fe ion doping;oxygen vacancy;pore structure;catalysis;ORR
Flexible surface-enhanced Raman spectroscopy (SERS) substrates have received more and more attention for their non-invasive sample collection ability. However, majority of them have poor stability and reproducibility because noble metal is easily oxidized and led to lose SERS activity. Herein, SiO 2 -TiO 2 -Ag hybrids aerogel (STAHA) material is first applied as a flexible SERS substrate for explosives and dyes long-term sensitive detection. The sensitive non-invasive detection of 3-nitro-1, 2, 4-triazol-5-one (NTO) residues can be achieved with a limit of 1 × 10 −6 m by wiping sample collection method. Meanwhile, similar SERS sensitivity from long-term (50 days) kept substrates is observed compared with fresh-made substrates. This long-term sensitivity is contributed to electronic transfer compensation from TiO 2 aerogel. This proposed flexible STAHA enrich the type of SERS substrates, and their long-term sensitivity can provide a prospective application for trace analyses of explosives and other hazardous residues in criminal forensic, military, and security check.
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