Polymer-embedded fabrication of low dimensional materials for energy conversion and storage

Abstract

The development of highly efficient catalysts and electrode materials toward energy conversion and storage applications is a long-term but urgent world-wide challenge. Transition-metal based 2D nanomaterials, combined with functional carbon supporting materials, have been intensively studied in the past ten years. The recent breakthrough on transition-metal/carbon composites have shed bright light in not only lab-scale but also industrial-level applications in energy-related researches. In this PhD thesis, guided by theoretical calculations and technical experiences, we have struck up a series of strategies to engineer advanced architectures composed of transition-metal based 2D nanocrystals and carbon-based supports. Briefly, A) Co₂P nanoparticles encapsulated in N, P-doped graphene sheets for hydrogen evolution catalysis, the heteroatom-doped graphene shell structure can provide additional active catalytic sites and anti-corrosion protection for long cycling test; B) MoSe₂ single-crystals on N-doped graphene sheets, the further perforated structure on MoSe₂ basal plane brings abundant active edge sites, which leads to significantly improved hydrogen evolution catalytic performance; C) Mo_(1-x)W_xSe₂ nanocrystals on N-doped MWCNT, the ~10 atom% W doping in MoSe₂ basal lattice induces the optimal catalytic activity from both theoretical calculations and experimental observations; D) sub-5 nm size ReSe₂ crystals grown on N-doped MWCNT with Pt-like HER performance and stable anode material for sodium-ion battery; E) Co₃O₄ clusters fabrication on 3D graphene foam as free standing electrodes for overall water splitting; F) future work and research proposal on Sn-based TMDs grown on graphene foam as high-capacity and long-term sodium-ion battery. Generally, we applied graphene oxides, CNT and graphene foam as conductive supports, transition-metal based nanocrystals as active materials, and investigated their potential applications and underlying mechanism in hydrogen/oxygen evolution reactions and alkaline ion batteries. Our work presents a comprehensive series of 2D transition-metal/carbon composite materials, including the rational design, facile synthesis, all-around characterization and insightful study on energy-related applications. This thesis will enrich the fabrication routes of well-engineered 2D materials, and also benefit the future development of transition-metal based materials toward energy-related applications, especially for the catalysts and battery electrode materials.

Date of Award	2018
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology