Water Splitting by Doped Layered Metal Dichalcogenides

Das, Abir (2023) Water Splitting by Doped Layered Metal Dichalcogenides. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Abir Das (18MS179),) Thesis_18MS179.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMD) have emerged as potential materials for enhancing water splitting due to their unique physical and chemical properties. Water splitting has been studied for a long time, and it still stands in the limelight because of its possible useful products. Hydrogen is considered a clean fuel with zero emissions which promises energy solutions in the future. The other product is oxygen which is the lifeline of our survival. With the massive development of human civilization, nonrenewable energy resources are getting exploited exponentially; thus, it is high time that we convert to renewable energy resources. Herein, we have synthesized a bulk earth-abundant TMD material WS₂ with a predominant 1T phase possessing metallic character for high electrochemical activity and then doped with minimal amount of noble metal catalyst Ruthenium. The sample coded, Ru11 shows enhanced activity for Hydrogen Evolution Reaction (HER) in acid and alkaline media with an overpotential of 76 mV and 126 mV to reach a current density of -10 mA cm⁻². The Tafel plot suggests a slope of 72 mV dec⁻¹ and 158 mV dec⁻¹ for acidic and alkaline media, respectively, indicating improved charge transfer kinetics. And the surface reconstruction procedure significantly enhances the (Oxygen Evolution Reaction) OER in a alkaline medium with an overpotential of 340 mV at a current density of 10 mA cm⁻². The Tafel slope obtained for the reconstructed catalyst for OER was 43 mV dec⁻¹ which is significantly less than the benchmark RuO₂ catalyst suggesting enhanced charge transfer kinetics and high active sites. The catalyst exhibits bifunctional characteristics with enhanced activity in OER in alkaline medium and HER in both acidic and alkaline medium, exhibiting robustness in harsh conditions and thus can be used as a cost-efficient catalyst in the future.

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