Hybrid electrodes comprising metal oxides and vertically aligned graphene (VAG) are promising for high-performance supercapacitor applications because they enhance the synergistic effect owing to the large contact area between the two constituent materials. However, it is difficult to form metal oxides (MOs) up to the inner surface of a VAG electrode with a narrow inlet using conventional synthesis methods. Herein, we report a facile approach to fabricate SnO 2 nanoparticle-decorated VAG electrodes (SnO 2 @ VAG) with excellent areal capacitance and cyclic stability using sonicationassisted sequential chemical bath deposition (S-SCBD). The sonication treatment during the MO decoration process induced a cavitation effect at the narrow inlet of the VAG electrode, allowing the precursor solution to reach the inside of the VAG surface. Furthermore, the sonication treatment promoted MO nucleation on the entire VAG surface. Thus, the SnO 2 nanoparticles uniformly covered the entire electrode surface after the S-SCBD process. SnO 2 @VAG exhibited an outstanding areal capacitance (4.40 F cm −2 ) up to 58% higher than that of VAG electrodes. The symmetric supercapacitor with SnO 2 @VAG electrodes showed an excellent areal capacitance (2.13 F cm −2 ) and a cyclic stability of 90% after 2000 cycles. These results suggest a new avenue for sonication-assisted fabrication of hybrid electrodes in the field of energy storage.
Advanced anodic SnO2 nanoporous structures
decorated
with Cu2O nanoparticles (NPs) were employed for creatinine
detection. Anodization of electropolished Sn sheets in 0.3 M aqueous
oxalic acid electrolyte under continuous stirring produced complete
open top, crack-free, and smooth SnO2 nanoporous structures.
Structural analyses confirm the high purity of rutile SnO2 with successful functionalization of Cu2O NPs. Morphological
studies revealed the formation of self-organized and highly-ordered
SnO2 nanopores, homogeneously decorated with Cu2O NPs. The average diameter of nanopores is ∼35 nm, while
the average Cu2O particle size is ∼23 nm. Density
functional theory results showed that SnO2@Cu2O hybrid nanostructures are energetically favorable for creatinine
detection. The hybrid nanostructure electrode exhibited an ultra-high
sensitivity of around 24343 μA mM–1 cm–2 with an extremely lower detection limit of ∼0.0023
μM, a fast response time (less than 2 s), and wide linear detection
ranges of 2.5–45 μM and 100 μM to 15 mM toward
creatinine. This is ascribed to the creation of highly active surface
sites as a result of Cu2O NP functionalization, SnO2 band gap diminution, and the formation of heterojunction
and Cu(1)/Cu(ll)–creatinine complexes through secondary amines
which occur in the creatinine structure. The real-time analysis of
creatinine in blood serum by the fabricated electrode evinces the
practicability and accuracy of the biosensor with reference to the
commercially existing creatinine sensor. The proposed biosensor demonstrated
excellent stability, reproducibility, and selectivity, which reflects
that the SnO2@Cu2O nanostructure is a promising
candidate for the non-enzymatic detection of creatinine.
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