An ion exchange mediated shape-preserving strategy for constructing 1-D arrays of porous CoS1.0365 nanorods for electrocatalytic reduction of triiodideElectronic supplementary information (ESI) available: Fig. S1: XPS Co 2p core spectra of Co3O4, Fig. S2: SEM images of ion exchanged nanorods, Fig. S3: XRD pattern of time dependant ion exchange, Fig. S4: TEM images of Co3O4 before and after the ion exchange reaction, Fig. S5: EDS profiles, Fig. S6: EDS line scanned profile of a single CoS nanorod

• Main Authors: Patil, Supriya A, Shinde, Dipak V, Lim, Iseul, Cho, Keumnam, Bhande, Sambhaji S, Mane, Rajaram S, Shrestha, Nabeen K, Lee, Joong Kee, Yoon, Tae Hyun, Han, Sung-Hwan
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c5ta00494b

Based on a coordination chemistry approach, the present work reports on the synthesis of thin films of various cobalt hydroxycarbonate nanostructures such as nanobeams, nanoneedles, and bending nanorods using three different cobalt precursors viz. Cl − , NO 3 − and CH 3 COO − . After pyrolysis in air, the hydroxycarbonate nanostructures are transferred into 1-D arrays of Co 3 O 4 nanorods. The obtained 1-D Co 3 O 4 nanostructures are then transformed into the corresponding analogous shaped 1-D arrays of porous cobalt sulfide (CoS 1.0365 ) nanostructures using a wet chemical transformation method based on an ion exchange approach. The nanostructured films before and after the ion exchange reaction are characterized using field emission electron scanning microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), and inductively coupled plasma mass spectroscopy (ICP-MS) measurements. As a proof-of-concept demonstration for the application, various shaped CoS 1.0365 nanorod films synthesized are investigated as a Pt-free counter electrode in dye-sensitized-solar cells (DSSCs). The influence of three different counter anions of the cobalt precursors on the structural, textural, and morphological aspects, and thereby their influence on electronic and electrochemical properties, has been investigated. A correlation among electrical conductivity, charge transfer resistance and electrocatalytic performance of various CoS 1.0365 nanorod films obtained from different cobalt precursors has been established. Among the various nanostructures, the thicker nanorod film synthesized using a chloride precursor has demonstrated the best electrocatalytic behavior toward triiodide reduction, which led to a short circuit current density of 18.04 mA cm −2 and energy conversion efficiency of 7.4% of the DSSC. This photovoltaic performance is highly competitive to a current density of 18.26 mA cm −2 and energy conversion efficiency of 7.7% exhibited by the standard Pt counter electrode. A solution based ion exchange mediated strategy for constructing 1-D arrays of porous CoS 1.0365 nanorod film from analogous 1-D array of Co 3 O 4 film derived from pyrolysis of nanostructured cobalt hydroxycarbonate film.