(543b) Solution-Processable Route for Pristine and Alloyed 2D TMD Nanosheets for Energy Conversion Applications

The exceptional semiconducting properties of exfoliated transition metal dichalcogenide (TMD) nanosheets have inspired their use in energy conversion applications such as solar cells, photoelectrodes (e.g., water splitting), and thermoelectrics. Nano-TMDs are particularly desirable for their thickness tunable properties and amenability towards ultrathin, flexible devices. However, a major challenge in realizing large-area devices based on pristine and alloyed TMD-based devices is their large scale-production¹.

In this presentation we describe major advances that address this issue². Firstly, we detail a powder-based electrochemical pellet intercalation method for reliable production of high quality 2D TMD nanosheets.³ Compared to traditional methods (i.e., ultrasonication), 2D TMD nanosheets produced using this method yield ameliorated photoelectrochemical performance owing to high aspect ratios and low defect densities. These factors lead to high solar-to-chemical energy conversion efficiencies (APCE up to 90%) and improved photocurrent densities (J_ph).

We then demonstrate how this innovative method can be adapted to afford production of alloyed 2D TMD nanosheets from commercially available, pure-phase bulk TMD powders, providing an additional tool for fine tuning the properties of these materials.⁴ We show successful alloying of several metal-chalcogen combinations (Mo_xW_1-xS_ySe_2-y and SnS_ySe_2-y) and provide evidence of the atomic mixing within the nanosheets using atomic resolution scanning transmission electron microscopy (STEM). Furthermore, we show that control over the final composition of the nanosheets can be exerted by tuning the feed ratios of the TMD powders. Accordingly, we examine the unique electronic and optoelectronic properties that arise as a function of the chemical composition of the alloy. Indeed, we present a comprehensive route towards large-area flexible energy conversion devices based on high-performing, fully tunable 2D TMDs.

References

(1) Yu, X.; Sivula, K. Toward Large-Area Solar Energy Conversion with Semiconducting 2D Transition Metal Dichalcogenides. ACS Energy Lett. 2016, 1 (1), 315–322. https://doi.org/10.1021/acsenergylett.6b00114.

(2) Wells, R. A.; Sivula, K. Assembling a Photoactive 2D Puzzle: From Bulk Powder to Large-Area Films of Semiconducting Transition-Metal Dichalcogenide Nanosheets. Acc. Mater. Res. 2023, 4 (4), 348–358. https://doi.org/10.1021/accountsmr.2c00209.

(3) Wells, R. A.; Zhang, M.; Chen, T.-H.; Boureau, V.; Caretti, M.; Liu, Y.; Yum, J.-H.; Johnson, H.; Kinge, S.; Radenovic, A.; Sivula, K. High Performance Semiconducting Nanosheets via a Scalable Powder-Based Electrochemical Exfoliation Technique. ACS Nano 2022, 16 (4), 5719–5730. https://doi.org/10.1021/acsnano.1c10739.

(4) A. Wells, R.; J. Diercks, N.; Boureau, V.; Wang, Z.; Zhao, Y.; Nussbaum, S.; Esteve, M.; Caretti, M.; Johnson, H.; Kis, A.; Sivula, K. Composition-Tunable Transition Metal Dichalcogenide Nanosheets via a Scalable, Solution-Processable Method. Nanoscale Horizons 2024. https://doi.org/10.1039/D3NH00477E.