Photoelectrochemical water splitting to produce hydrogen fuel from solar energy conversion has been a hot topic for at least the past few decades. Nevertheless, Solar-to-Hydrogen efficiency levels have been severely limited due to many factors, including light absorption, charge separation and transport, surface chemical reaction rate [1]. Novel and emerging materials that may just address key bottlenecks are some of the transition metal dichalcogenides (TMDCs) due to their tuneable band gap and an ability to be doped n-type or p-type [2]. In recent times, nanometer thickness control, uniformity and large area growth of continuous films have been demonstrated by rapid deposition methods in manufacturing-compatible processes [3]. However, little is known about the effect of different impurity concentrations incorporated into TMDCs, particularly on the semiconductor transport properties; the structural, chemical, and physical stability; and their photoelectrochemical properties. In this work, we focus on the enhanced water splitting capability as photoanodes/photocathodes and tandem diode cells when combined with novel doped transition metal dichalcogenide (TMD) materials in an acidic aqueous medium. We use thermally assisted conversion (TAC) processes to form n-type and p-type TMDCs by converting transition metals to sulphide-based TMDCs with different impurity concentrations. The photoelectrochemical responses were assessed by standard potential sweep methods and electrochemical impedance spectroscopy. To determine transport properties, TMDCs were studied with 4-point resistivity measurements and AC Hall-effect …