Directly grown carbon nanotube based hybrid electrodes with enhanced thermo-cell performances

Abstract

Hybrid electrodes exhibit intriguing properties due to the synergetic effect of different components that are propitious for the practical applications of thermo-cells (TECs). In this study, Ag-carbon nanotube (CNT) hybrid electrodes were prepared using two simple and effective steps, involving the direct growth of CNTs on stainless steel substrates without any external catalyst, followed by decorating the CNTs with Ag nanoparticles. Ag-CNT electrodes were characterized via scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy and were applied in TECs for the first time. The TEC performances of the Ag-CNT electrodes were significantly enhanced compared to that of the pristine CNT electrode due to their better conductivity and thermal conductivity, as well as more activation sites. The results show that the construction of Ag-CNT hybrid electrodes can effectively improve the TEC performances of CNT electrodes, which is promising for heat energy harvesting by CNT-based electrodes.

Carbon Nanotube-Graphene Hybrid Electrodes with Enhanced Thermo-Electrochemical Cell Properties

“…Im et al reported that the CNT-Pt hybrid nanostructure could achieve much higher conversation efficiency in comparison with the pristine CNTs for the faster kinetics and larger electroactive sites [12]. Our investigation showed that CNT-Ag hybrids exhibited better TEC performances due to higher electric and thermal conductivities, as well as more activation sites [11]. Romano et al reported that the TEC performances of single-walled CNT-reduced graphene oxide hybrid electrodes were improved significantly compared to the pristine CNT sample, due to the enhancement of the mass transport property [13].…”

“…XRD and Raman characterizations were applied to check the compositions of the products, as shown in Figure 3. XRD result (Figure 3a) indicates that the peak at 26.4° belongs to (002) crystallographic planes of CNT [10,11,23], and other four peaks should be attributed to the (111), (110), (200), and (220) planes of the stainless steel substrate, respectively [10,11]. As shown in Figure 3b, the Raman spectrum shows three typical characteristic peaks of the CNTs, i.e., D band (1350 cm −1 ), G band (1585 cm −1 ), and G’ (2706 cm −1 ), respectively [11,24].…”

“…The CNT and the CNT-based hybrid electrodes were tested by the Cup-Shaped TEC equipment and the Cup-Shaped device of TEC and characterization of TEC performance were described in other reports and our previous investigations [4,5,11]. Briefly, two test electrodes were immersed in the potassium ferri/ferrocyanide (0.4 mol·L −1 , Aladdin) aqueous solution, the temperatures of two test sides were controlled by the heating tape and ice water, respectively, and measured by OMEGA thermocouple probes.…”

“…Similarly, the material with high thermal conductivity means lower thermal resistances, which can benefit for decreasing the temperature loss at the bodies of two electrodes, leading to higher energy conversation efficiency of the TEC [4,5,7]. Due to good electric and thermal conductivities, excellent chemical stability, and unique structural properties, carbon nanotubes (CNTs) showed promising properties in the TEC application [4,5,7,8,9,10,11,12,13,14], and the electrophoretic deposition (EPD) method was applied to fabricate CNT TECs for merits of process simplicity and large-scale capability [5,10,15]. The graphene, with priorities of large surface area, high electric/thermal conductivities, and high chemical/electrochemical stabilities, has been widely investigated in the energy storage and conversation applications [16,17,18,19,20].…”

“…The graphene, with priorities of large surface area, high electric/thermal conductivities, and high chemical/electrochemical stabilities, has been widely investigated in the energy storage and conversation applications [16,17,18,19,20]. Recently, CNT-based hybrid electrodes, i.e., the electrodes with at least two composition materials, were applied to fabricate TEC electrodes with improved energy conversation efficiency because of the synergetic effect between different materials [8,11,12,13]. Im et al reported that the CNT-Pt hybrid nanostructure could achieve much higher conversation efficiency in comparison with the pristine CNTs for the faster kinetics and larger electroactive sites [12].…”