Featured LetterFabrication of CuCo2S4 nanosheet/carbon cloth as a flexible electrode for high-performance electro-catalysis
Introduction
The high-performance non-precious metal catalysts are faced with an inspiring challenge in the past decades [1]. Ternary chalcogenides, such as NiCo2S4, CuCo2S4, FeCo2S4 and MnCo2S4 are considered as potential candidates, owing to their extensive source, nontoxicity and low cost [2], [3], [4], [5]. Specially, CuCo2S4 with multiple redox states and high electronic conductivity has been widely applied in the catalytic reactions. Numerous efforts have been devoted to engineering the surface structures and exposing effective active sites to improve the electro-catalytic performance [6], [7], [8]. However, it is still an urgent demand to precisely tune the fine CuCo2S4 structure at a nanoscale level and to avoid their agglomeration during fabrications and reactions.
Carbon cloth (CC) has been regularly used as flexible and low-weight conductive substrates in wearable electronic devices. The flexible CC can be integrated with electro-catalytic CuCo2S4 to develop the high-performance devices [9]. Coating electro-catalytic materials on CC can be a promising approach to developing high-efficient electro-catalysis [10], [11]. The conductive carbon fibers are supposed to act as one-dimensional (1D) pathway and thus facilitate fast electron transfer [12]. Moreover, versatile electro-catalysts can be anchored on conductive substrate to avoid from undesirable collapse [13]. However, electro-catalysts are difficult to be decorated on the CC surface due to the hydrophobicity of carbons.
Herein, we facilely developed CuCo2S4 single crystalline nanosheets on the flexible carbon cloth substrate by a one-step hydrothermal process. The time-dependent growth process was carefully investigated. And the electro-catalytic reduction from I3− to I− was employed to estimate the catalytic performance.
Section snippets
Synthesis of CuCo2S4@CC
The carbon cloth was pretreated by HNO3 at 90 °C for 10 h. Cu (CH3COO)2·H2O (1 mM), Co (CH3COO)2·4H2O (1 mM) and thiourea (5 mM) were uniformly dissolved in water/ethylene glycol (V:V = 1:3) (35 ml). The solution was transferred into a 50 ml reaction and maintained at 220 °C for a certain time. The coating-CC was collected, washed with water and ethanol for several times, and then dried at 70 °C for 12 h. The assembly of dye-sensitized solar cells (DSSC) were reported in previous work [14].
Characterizations
The
Results and discussion
CuCo2S4 growth process was investigated according to the reaction time. The small nanoparticles were uniformly emerged on CC at the initial stage (Fig. 1a). With increasing reaction time, the irregular-shaped nanoparticles grew into nanosheets (Fig. 1b–e). The intriguing morphological evolution can be explained using “oriented attachment” and “self-assembly” models [15], [16]. The adjacent nanoparticles started to share the common crystallographic direction after 1 h of reaction, to reduce
Conclusions
In summary, CuCo2S4 single crystalline nanosheets were fabricated directly on CC substrates by a hydrothermal method. CuCo2S4@CC with large specific surface area and low charge transfer resistance can provide large number of active sites for I3−/I− couple and thus accelerate the charge transfer rate. The corresponding DSSC exhibits PCE of 7.68% versus Pt PCE of 7.39%.
Conflict of interest
All authors declared that they have no conflicts of interest to this work.
We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted
CRediT authorship contribution statement
Jie Yin: Methodology, Data curation, Writing - original draft. Chunyao Zhang: Software. Xingzhong Zhao: Investigation. Haonan Yu: Data curation. Yueming Sun: Writing - review & editing. Yuqiao Wang: Supervision, Writing - review & editing.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
This work was supported by National Natural Science Foundation of China (61774033) and Research Innovation Program for Academic Degree Graduate Students of Jiangsu Province (KYLX16-0195).
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