Negative Electrocatalytic Effects of p-Doping Niobium and Tantalum on MoS2 and WS2 for the Hydrogen Evolution Reaction and Oxygen Reduction Reaction
- Xing Juan Chua, Jan Luxa, Alex Yong Sheng Eng, Shu Min Tan, Zdeněk Sofer, Martin Pumera*
Transition-metal dichalcogenides (TMDs) are at the forefront of research for their promising catalytic abilities and unique materials properties. With great interest in the study of mono- or few-layered TMDs, we seek to fundamentally explore the effects of doping on bulk TMDs, particularly MoS2 and WS2 for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) with p-dopants Nb and Ta. Despite promises reported in the computational studies of doped TMDs on the HER, our results show otherwise. Doped bulk TMDs display less catalytic activity in comparison to their undoped counterparts for the HER A similar effect is observed for ORR catalysis. Characterization was done to shed light on its surface elemental composition, properties, and morphologies. It was found that doped WS2 has a high percentage of IT phase but this does not correlate with a lower overpotential for the HER at -10 mA cm(-2), which contradicts the general consensus. We therefore show that p-dopants have a negative electrocatalytic effect on the HER. These findings are of high importance for the field of TMD electrochemistry, as they challenge the current consensus that doping always improves the electrocatalysis of TMDs.
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