Enhancing surface area, morphology, and electrocatalytic activity favouring triiodide reduction via surface sulfurization of metal oxide

Herein, a direct anionic exchange method was employed using Thioacetamide (TAA) and Phosphorous Pentasulfide (P2S5) by facile hydrothermal method. The preliminary results confirm that the sulfurization leads to amorphization and formation of MoS2. BET analysis demonstrates the substantial improvement in the surface area from 72.046 m2/g for pristine MoO3 to 104.402 m2/g, and 140.802 m2/g, for TAA and P2S5 treated MoO3 respectively, was achieved upon sulfurization. Cyclic Voltammetry (CV) studies show an excellent triiodide reduction ability in LiI/I redox system which is due to the improvement in electrocatalytically active sites and stability across the CE/electrolyte interface. The lower charge transfer resistance (Rct) values obtained from Electrochemical impedance spectroscopy (EIS) confirm the effective charge carrier transport that improved the conductivity across electrode/electrolyte interface. The power conversion efficiency (PCE) measured under our lab conditions found an improvement for pristine MoO3 i.e. 0.78% to a maximum PCE of 5.48% and 4.12% for the P2S5 and TAA sulfurized MoO3 respectively. In general, this work highlights the use of phosphorous pentasulfide which can also be utilized for direct anionic exchange with the advantage of phosphorous content in resultant products which could greatly improve various physio-chemical properties of the material.