Date of Award

Winter 12-15-2023

Document Type

Thesis

Degree Name

Master of Materials Science and Engineering (MMatSE)

Department

Physics

First Advisor

Dr. Ram K. Gupta

Second Advisor

Dr. Serif Uran

Third Advisor

Dr. Khamis Siam

Abstract

High clean energy demand, dire need for sustainable development, and low carbon footprints are the few intuitive challenges, leading researchers to aim for research and development for high-performance energy devices. The development of materials used in energy devices is currently focused on enhancing the performance, electronic properties, and durability of devices. Tunning the attributes of transition metals using pyrophosphate (P2O7) ligand moieties can be a promising approach to meet the requirements of energy devices such as water electrolyzers and supercapacitors, although such a material’s configuration is rarely exposed for this purpose of study.

Herein, we grow Ni2P2O7, Co2P2O7, and Fe2P2O7 composites on conductive Ni-foam using a hydrothermal procedure. The results indicated that, among all the synthesized samples, Fe2P2O7 exhibited outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with the least overpotential of 220 and 241 mV to draw a current density of 10 mA/cm2. Further, wastewater rich in urea from sanitary units and industries is subjected to produce green energy through waste water-splitting. Thus, urea oxidation reaction (UOR) is the most widely promoted. We employed synthesized composites towards UOR investigation and it was found that Fe2P2O7 exhibits splendid performance with the low onset potential of 1.317 V (vs RHE) at 10 mA/cm2 of current density. The low Tafel slope, high turnover frequency, low charge transfer resistance, greater ECSA, and roughness factor contribute to enriching the performance of Fe2P2O7 as an effective electrocatalyst towards OER, HER, and UOR. Theoretical studies indicate that the optimal electronic coupling of the Fe site with the pyrophosphate enhances the overall electronic properties of Fe2P2O7, thereby, showing its electrocatalytic performance concerning freshwater and waste water-splitting. Moreover, the composite materials showed the best capacitive properties for supercapacitor energy storage applications. The specific capacitance offered by composite materials ranges from 8000-3000 mF/cm2 at 1 mA/cm2. Additionally, it possessed high capacitance retention and coulombic efficiency up to 5,000 charge/discharge cycles.

Consequently, this work suggests how to use pyrophosphate moieties to fabricate non-noble metal-based electrode materials to achieve good performance in electrocatalytic splitting water as energy conversion and supercapacitors as energy storage applications.

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