Holy “Moly” - Structural Engineering of MoS₂ for Efficient Solar Energy Capture

Wan-Ting Chen^1*, Hung-Wei Shiu¹, Su Ling Cheng¹, Yu-Ling Lai¹, Yao-Jane Hsu¹

¹Nano Science Group, National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Wan-Ting Chen, email:chen.wt@nsrrc.org.tw

Over the past years, exfoliation of 3D materials towards 2D materials has received significant attentions because opening 2D materials is an effective method to alter the physical and chemical properties (bandgap, conductivity and thermoelectric property) for various energy-related applications. Among with numerous of semiconductors, 2D MoS₂ nanomaterials has received significant attentions in different electrocatalytic reactions owing to its remarkable physical, electronic and optical properties.

In our work, two hydrothermal (HT) synthesis methods of MoS₂ were employed to examine the effect of hydrothermal synthesis conditions (such as hydrothermal temperature, time, [Mo:S] ratio, and morphology) in relation to the performance of electrochemical CO₂ reduction reaction activity. Bulk characterization techniques such as XRD, Raman and SEM analysis were used to examine two series of MoS₂ samples. Powder XRD confirmed the presence of amorphous MoS₂ due to broad (002), (100) and (103) reflections via both synthesis methods. Raman was used to determine the vibrational properties of MoS₂, number of MoS₂ layers and identify the presence of 1T-phase MoS₂. Additional raman peaks at ~335 cm ^-1 (characteristic to 1T-MoS₂) was observed in series of samples. The surface properties of MoS₂ play a role in the adsorption of molecules and subsequent charge transfer to molecules in electrocatalytic reactions, which motivates the further investigation. Surface sensitive techniques such as XPS and NEXAFS measurements also confirmed the presence of 1T-MoS₂ and 2H-MoS₂. More interestingly, ratio of 1T-MoS₂ and 2H-MoS₂ can be controlled by the synthesis conditions which leads to the further investigation on its physical properties in relation to electrocatalytic activities.

Keywords: 2D materials, MoS₂, electrocatalysis, CO₂ reduction