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Layered Crystalline and Amorphous Platinum Disulfide (PtS 2 ): Contrasting Electrochemistry
Author(s) -
Wang Yong,
Szokolova Katerina,
Nasir Muhammad Zafir Mohamad,
Sofer Zdenek,
Pumera Martin
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900331
Subject(s) - overpotential , amorphous solid , electrochemistry , materials science , platinum , chemical engineering , catalysis , transition metal , nanotechnology , inorganic chemistry , chemistry , electrode , crystallography , organic chemistry , engineering
Group 6 transition metal dichalcogenides (TMDs), such as MoS 2 and WS 2 have been extensively studied for various applications while few studies have delved into other TMDs such as platinum dichalcogenides. In this work, layered crystalline and amorphous platinum disulfide (PtS 2 ) were synthesized, characterised and their fundamental electrochemical properties were investigated. Both materials exhibited inherent oxidation and reduction reactions which would limit their operating potential window for sensing applications. Amorphous phase materials are considered to be promising electrocatalysts due to the porous, and nanostructured morphology with high concentration of unsaturated active sites. The electrocatalytic performances towards oxygen reduction (ORR) and hydrogen evolution reactions (HER) of crystalline and amorphous PtS 2 were analysed. Amorphous PtS 2 was found to exhibit superior electrocatalytic performances towards ORR and HER as compared to crystalline PtS 2 . For HER, amorphous and crystalline PtS 2 have overpotential values of 0.30 V and 0.70 V (vs. RHE) at current density of 10 mA cm −2 , respectively. The influence of electrochemical reduction pre‐treatment on their catalytic behaviours was also investigated. Electrochemical reduction pre‐treatment on both crystalline and amorphous PtS 2 removed the oxidized sulfate groups and increased the proportion of Pt 0 oxidation state which exposed more catalytic sites. As such, these materials were activated and displayed improved ORR and HER performances. Electrochemically reduced amorphous PtS 2 outperformed the untreated counterparts and exhibited the best HER performance with overpotential of 0.17 V (vs. RHE) at current density of −10 mA cm −2 . These findings provide insights into the electrochemical properties of noble metal PtS 2 in both crystalline and amorphous states which can be activated by electrochemical reduction pre‐treatment.