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Issue 33, 2019
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Polymorph nickel titanate nanofibers as bifunctional electrocatalysts towards hydrogen and oxygen evolution reactions

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Abstract

Producing pure H2 and O2 to sustain the renewable energy sources with minimal environmental damage is a key objective of photo/electrochemical water-splitting research. Metallic Ni-based electrocatalysts are expensive and eco-hazardous. This has rendered the replacement or reduction of Ni content in Ni-based electrocatalysts a decisive criterion in the development of bifunctional electrocatalytic materials. In the current study, spinel/ilmenite composite nickel titanate (NTO) nanofibers were synthesised using sol–gel assisted electrospinning followed by pyrolysis at different soaking temperatures (viz., 773, 973, and 1173 K). The presence of a defective spinel NTO phase (SNTO) distributed uniformly along the nanofibers was confirmed by X-ray photoelectron and Raman spectroscopy. The electron micrographs revealed the morphological change of NTO nanofibers from a mosaic to bamboo structure with an increase in pyrolysis soaking temperature. The electrocatalytic activity of NTO nanofibers obtained at different pyrolysis soaking temperatures for alkaline water-splitting was studied. The highly defective SNTO manifests properties similar to metallic Ni and favours H2 evolution through the hydrogen evolution reaction (HER) by adsorbing more H+ ions on active sites. In contrast, the ilmenite NTO favours O2 discharge. These results are explained based on the morphology of the NTO nanofibers. The mosaic structure which has higher porosity and greater SNTO content shows excellent HER performance. In contrast, the large bamboo structured NTO nanofibers which have lesser porosity and SNTO content cage the bigger (OH)ads ions at their catalytic sites to facilitate OER performance.

Graphical abstract: Polymorph nickel titanate nanofibers as bifunctional electrocatalysts towards hydrogen and oxygen evolution reactions

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Publication details

The article was received on 09 May 2019, accepted on 22 Jul 2019 and first published on 22 Jul 2019


Article type: Paper
DOI: 10.1039/C9DT01932D
Dalton Trans., 2019,48, 12684-12698

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    Polymorph nickel titanate nanofibers as bifunctional electrocatalysts towards hydrogen and oxygen evolution reactions

    B. Sachin Kumar, K. Tarafder, A. R. Shetty, A. C. Hegde, V. C. Gudla, R. Ambat, S. K. Kalpathy and S. Anandhan, Dalton Trans., 2019, 48, 12684
    DOI: 10.1039/C9DT01932D

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