Oxygen vacancy and size controlling endow tin dioxide with remarked electrocatalytic performances towards vanadium redox reactions

AbstractAntimony is perhaps the most frequently used doping element of tin dioxide. Although antimony of different oxidation states have been used in the synthesis, the effect of dopant’s valence on ion exchange properties has not been investigated critically. In our study the valence of antimony had clear effects on the metal uptake properties of Sb-doped SnO2 materials. Extremely high Tc uptake (Kd > 100 000 mL g−1) on Sb(III)-doped material was observed in conditions under which Sb(V)-doped material did not show any Tc uptake. However, the Sb(V)-doped material showed good Ni2+ uptake properties (Kd up to 33 000 mL g−1), even at pH values below the material’s point of zero charge (pzc), while the Sb(III)-doped material showed Ni2+ uptake only at pH above its pzc. The cation uptake of Sb-doped SnO2 resembles typical weakly acidic cation exchanger character but the uptake of TcO4- does not follow a typical anion exchange pattern. Instead, we propose a sorption process related to redox reactions as the probable Tc uptake process.

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Synergistic Catalysis of SnO2/Reduced Graphene Oxide for VO2+/VO2+ and V2+/V3+ Redox Reactions

Molecules ◽

10.3390/molecules26165085 ◽

2021 ◽

Vol 26 (16) ◽

pp. 5085

Author(s):

Yongguang Liu ◽

Yingqiao Jiang ◽

Yanrong Lv ◽

Zhangxing He ◽

Lei Dai ◽

...

Keyword(s):

Graphene Oxide ◽

Metal Oxide ◽

Reduced Graphene Oxide ◽

Surface Area ◽

Redox Reaction ◽

Redox Reactions ◽

Transport Processes ◽

Electrochemical Kinetics ◽

Reduced Graphene ◽

Vanadium Redox

In spite of their low cost, high activity, and diversity, metal oxide catalysts have not been widely applied in vanadium redox reactions due to their poor conductivity and low surface area. Herein, SnO2/reduced graphene oxide (SnO2/rGO) composite was prepared by a sol–gel method followed by high-temperature carbonization. SnO2/rGO shows better electrochemical catalysis for both redox reactions of VO2+/VO2+ and V2+/V3+ couples as compared to SnO2 and graphene oxide. This is attributed to the fact that reduced graphene oxide is employed as carbon support featuring excellent conductivity and a large surface area, which offers fast electron transfer and a large reaction place towards vanadium redox reaction. Moreover, SnO2 has excellent electrochemical activity and wettability, which also boost the electrochemical kinetics of redox reaction. In brief, the electrochemical properties for vanadium redox reactions are boosted in terms of diffusion, charge transfer, and electron transport processes systematically. Next, SnO2/rGO can increase the energy storage performance of cells, including higher discharge electrolyte utilization and lower electrochemical polarization. At 150 mA cm−2, the energy efficiency of a modified cell is 69.8%, which is increased by 5.7% compared with a pristine one. This work provides a promising method to develop composite catalysts of carbon materials and metal oxide for vanadium redox reactions.

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