Single source precursor route toward high entropy and multinary chalcogenides via metal dithiocarbamate and metal thio/selenourea complexes

Abstract

High Entropy (HE) metal chalcogenides are a new class of materials which consist of 5 or more elements in a disordered sub-lattice. These materials are stabilised by the high configurational entropy and they are attractive for renewable energy applications such as electrocatalysis and thermoelectric energy generation due to the synergistic effects. However, the synthesis of HE materials still remains challenge. In this thesis, we explored the synthesis of bulk HE zinc sulfide analogues containing four, five, and seven metals by using a single source precursor approach. In this route, metal dithiocarbamate complexes are decomposed simultaneously with a rapid and low-temperature annealing process to yield high entropy and entropy stabilised metal sulfides These materials were characterised by powder XRD, SEM and TEM analysis, along with EDX from both SEM and STEM. The entropy stabilized (CuAgZnCoMnInGa)S material was also demonstrated to be an excellent electrocatalyst for the hydrogen evolution reaction when combined with conducting carbon black and achieved a low onset overpotential of ~80 mV and η10 of ~255 mV. Then, we demonstrated a hot injection synthetic approach to high entropy (HE) sulfide nanoparticles by metal dithiocarbamates single source precursors in tandem with the support of density functional theory (DFT) calculations. More HE sulfides were synthesized by both solventless thermolysis and hot injection to form bulk powder and nanoparticle high entropy metal sulfides, respectively. Finally, novel metal selenoureato and metal thioureato precursors were explored to develop binary, ternary, and quaternary sulfilde selenide. The success confirms the possibility for HE sulfide selenides through precursors such as dithiocarbamates.

Date of Award	20 Nov 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Brian Saunders (Supervisor) & David Lewis (Supervisor)