Electrochemical supercapacitor performance of SnO2 quantum dots

Abstract

Metal oxide nanostructures are widely used in energy applications like super capacitors and Liion battery. Smaller size nanocrystals show better stability, low ion diffusion time, higher-ion flux and low pulverization than bigger size nanocrystals during electrochemical operation.Studying the distinct properties of smaller size nanocrystals such as quantum dots (QDs) can improve the understanding on reasons behind the better performance and it will also help in using QDs or smaller size nanoparticles (NPs) more efficiently in different applications. Aqua stable pure SnO 2 QDs with compositional stability and high surface to volume ratio are studied as an electrochemical super capacitor material and compared with bigger size NPs of size 25 nm.Electron energy-loss spectroscopic study of the QDs revealed dominant role of surface over the bulk. Temperature dependent study of low frequency Raman mode and defect Raman mode of QDs indicated no apparent volume change in the SnO 2 QDs within the temperature range of 80-300 K. The specific capacitance of these high surface area and stable SnO 2 QDs has showed only 9% loss while increasing the scan rate from 20 mV/S to 500 mV/S. Capacitance loss for the QDs is less than 2% after 1000 cycles of charging discharging, whereas for the 25 nm SnO 2 NPs, the capacitance loss is 8% after 1000 cycles. Availability of excess open volume in QDs leading to no change in volume during the electro-chemical operation and good aqua stability is attributed to the better performance of QDs over bigger sized NPs.

Advanced Electrode Materials Comprising of Structure‐Engineered Quantum Dots for High‐Performance Asymmetric Micro‐Supercapacitors

“…Moreover, the MoS 2 ‐QDs electrode shows a long‐term cycling stability with 86.5% retention of its initial capacitance after 6000 cycles (Figure S8, Supporting Information), which is much better than those of other reported MoS 2 ‐based nanomaterials: MoS 2 /PANI hybrid materials (60.9% retention after 1000 cycles), MoS 2 /RGO@PANI (82.5% retention after 3000 cycles), and MoS 2 /Mn 3 O 4 nanostructure (69.3% retention after 2000 cycles) . The superior durability is probably due to its unique 3D structure and the extreme small size of MoS 2 ‐QD which can provide a large contact area, effectively shorten the ion diffusion distance, and buffer the volume change during the intercalation/deintercalation processes . The above electrochemical results indicate that MoS 2 ‐QDs with nanoscale size, high surface area, and enriched defects are promising positive material.…”

“…Inspired by the excellent capacitive behavior of N‐GQDs and MoS 2 ‐QDs shown in half‐cells, the asymmetric MSCs were successfully constructed with capacitor‐type of N‐GQDs and battery‐type of MoS 2 ‐QDs as negative and positive materials, respectively. In this configuration, a wide potential window can be obtained by taking the advantage of the different stable potential window of the N‐GQDs anode and the MoS 2 ‐QDs cathode as well as their relatively high overpotentials for HER and OER . The low‐magnification scanning electron microscopy (SEM) images ( Figure 5 a,b) show that the interdigital electrodes are alternately covered by N‐GQDs and MoS 2 ‐QDs, both of which exhibit a unique 3D structure, beneficial for easy access of electrolyte and fast transportation of electron/charge.…”

Sub-wavelength waveguide properties of 1D and surface-functionalized SnO2 nanostructures of various morphologies

“…In both the cases, the synthesized SnO 2 QDs of diameter 2.4 nm were used as a precursor material. The synthesis of SnO 2 QDs was discussed in our earlier report [18]. In the case of VLS growth, a mixture of SnO 2 QDs of diameter 2.4 nm and graphite powder (Alfa Aesar, 99.9995%) in a 3:1 weight ratio was placed in a high purity Al 2 O 3 (99.99 %) boat.…”

“…SnO 2 NSs have been used in several other areas such as sub-wavelength waveguide sensors [4], microelectronics [6], Li-ion batteries [16], and lubricants [17]. Oxygen vacancy related defects in SnO 2 nanoparticles [18] have been reported in our previous studies. We have also deciphered strong correlations of various defects in SnO 2 NSs for chemical gas sensing [13] and wettability properties [19].…”

Preparation of SnO2 Thin Film Nanostructure for CO Gas Sensor Using Ultrasonic Spray Pyrolysis and Chemical Bath Deposition Technique

“…SnO 2 has been identified as a potential semiconductor material with many applications, including acting as a supercapacitor [8], catalyst [9], energy storage [10] and as gas sensor [11]. SnO 2 is preferable and has been investigated by many researchers for gas sensor application because SnO 2 is highly sensitive * corresponding author; e-mail: brian@tf.itb.ac.id to various pollutant gases.…”