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Electric Field Assisted Hydrogen Evolution Using Metallic Molybdenum Disulfide Catalysts https://doi.org/10.17863/CAM.117109 Li, Jiahang Chhowalla, Manish Hydrogen utilization is a prospective approach for alleviating the increasing global energy crisis and environmental pollution issues. Metallic phase molybdenum disulfide (MoS2) has emerged as a promising non-precious metal catalyst for hydrogen evolution reaction (HER). Numerous studies have focused on enhancing its catalytic performance with complex structural engineering. Recently, field assisted catalysis has been explored due to its relatively facile and controllable nature, among which electric field-related studies have drawn great attention. Chapter 1 provides the basics and fundamentals of electrocatalytic hydrogen evolution and a comprehensive review of HER catalyst modification based on structural engineering and field modulation. Inspired by the electric field-assisted catalysis, I investigated the influence of electric field on HER of metallic MoS2. The relevant experimental methodology is introduced in Chapter 2. I designed a new electrochemical setup with external bias in Chapter 3, providing compelling evidence of field-tuned catalysis. A more practical system was then designed by combining MoS2 with electroactive poly(vinylidene fluoride-co-trifluoroethylene) copolymer in Chapter 4 to facilitate HER by localized dielectric polarization. Enhanced reaction kinetics were observed due to increased hydrogen accessibility and accelerated mass transport, as supported by mechanistic studies. To further overcome some limitations of the binary hybrid, a ternary catalyst was designed and tested in Chapter 5, including MoS2, poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer and carbon black. Notably, a distinctive improvement of HER performance was observed with an increase in current density (~310%) and a reduction in overpotential at 10 mA cm-2 (~80 mV). Chapter 6 provides conclusions and outlook of this research. By building a localized electric field assisted system, the contribution of dielectric polarization was elaborated on electrocatalytic hydrogen production by metallic MoS2. This unique system provides a novel way for future development of effective HER catalysts using MoS2. University of Cambridge 2024-12-25 Thesis Doctoral Doctor of Philosophy (PhD) eng https://www.repository.cam.ac.uk/handle/1810/382124 https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/0ab34b3d-60ba-43d4-a43d-719e5603d420/download c058baed914e4f08197a72bb3a348702 https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/a2974e34-6504-4e77-ae4e-eea95efc70e3/download 87eda9de84448d1f82354d60eee3eb5f http://purl.org/NET/rdflicense/allrightsreserved hydrogen evolution reaction (HER) molybdenum disulfide (MoS2) field-assisted catalysis mass transport poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) localized dielectric polarization poly(vinylidene fluoride-co-trifluoroethylene)