Nitrite anodic oxidation at Ni()/Ni()-decorated mesoporous SnO and its analytical applications

• Published in: Analyst (London) Vol. 148; no. 23; pp. 628 - 635
• Main Authors: Mihai, Marius Alexandru, Spataru, Tanta, Somacescu, Simona, Moga, Olivia Georgeta, Preda, Loredana, Florea, Mihaela, Kuncser, Andrei, Spataru, Nicolae
• Format: Journal Article
• Published: 20.11.2023
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/d3an01249b

Hydrothermally formed mesoporous SnO 2 was used as a support for nickel chemical deposition and, after subsequent thermal treatment, a high specific surface area (36 m 2 g −1 ) Ni/SnO 2 material was obtained. XPS analysis has shown that in the Sn 3d region the spectrum is similar to that of pristine SnO 2 , whereas Ni species are present on the surface as NiO, Ni 2 O 3 and Ni(OH) 2 . Mixing Ni/SnO 2 with a small amount of Black Pearls (BP) leads to a significant enhancement of the resulting Ni/SnO 2 -BP composite activity for nitrite anodic oxidation, presumably due to the higher surface area (115 m 2 g −1 ), to better electrical conductivity and to a certain contribution of the BP to an increase in surface density of the active sites. Ni/SnO 2 -BP also outperforms pristine BP (in terms of Tafel slopes and electron-transfer rates), most likely due to the fact that the Ni( ii )/Ni( iii ) couple can act as an electrocatalyst for nitrite oxidation. A voltammetric method is proposed for the determination of nitrite, over a concentration range of three orders of magnitude (0.05 to 20 mM), with good reproducibility, high stability and excellent sensitivity. The high upper limit of the dynamic range of the analytically useful response might provide a basis for the reliable quantification of nitrite in wastewater. Mesoporous Ni/SnO 2 was hydrothermally obtained and, mixed with a small amount of Black Pearls, exhibited excellent analytical figures of merit for nitrite voltammetric determination.