Exploring layered metal chalcogenides : electrochemistry and application
Date of Issue2018-12-31
School of Physical and Mathematical Sciences
Layered metal chalcogenides have garnered considerable attention in recent years due to their vast array of applications. This class of materials was catapulted to fame by MoS2, a prominent transition metal dichalcogenide (TMD), upon the discovery of its unique electrochemical and catalytic properties that marked a significant milestone in the pursuit of naturally abundant electrocatalysts for hydrogen evolution reaction (HER) that may, in the future, displace expensive platinum-based electrodes. High cost of platinum catalysts is one of the key hurdles towards transitioning into an affordable hydrogen economy. This thesis aims to examine the feasibility of layered metal chalcogenides as alternatives to platinum by exploring their inherent electrochemistry and catalytic HER performance across the different families. The wide spectrum of layered metal chalcogenides, formed by diverse metal and chalcogen constituents, confers versatility to their properties that are governed by elemental composition, structure and anisotropy. Across the periodic table, their trends in electrochemistry and HER electrocatalysis are established. In a bid to exploit layered metal chalcogenides in HER catalysis, in particular the TMDs of outstanding catalytic attributes, various methods are also investigated to optimise and control the electrocatalytic efficiency of TMDs with an emphasis on Group 6 TMDs such as MoS2, WS2, MoSe2 and WSe2. Strategies explored in this thesis include transition metal doping of TMDs, electrosynthesis of porous TMD structures and hybrids as well as electrochemical tuning. The successful electrodeposition of active TMD and hybrid electrocatalysts highlights the simplicity and versatility of the technique in fabricating different TMD structures and composites. Knowledge of the fundamental electrochemical aspects, trends and techniques will be advantageous when maximising the properties of layered metal chalcogenides in prospective energy-related developments that embrace hydrogen economy.