Discovering Novel Avenue For Engineering Emerging 2D MXene Family Via Precious Metals Atomic Layer Deposition Techniques

Abstract
In searching for unique and unexplored 2D materials, the authors try to investigate for the very first time the use of delaminated V-MXene coupled with precious metal ruthenium (Ru) through atomic layer deposition (ALD) for various contact and noncontact mode of real-time temperature sensing applications at the human–machine interface. The novel delaminated V-MXene (DM-V2CTx) engineered ruthenium-ALD (Ru-ALD) temperature sensor demonstrates a competitive sensing performance of 1.11% °C−1 as of only V-MXene of 0.42% °C−1. A nearly threefold increase in sensing and reversibility performance linked to the highly ordered few-layered V-MXene and selective, well-controlled Ru atomic doping by ALD for the successful formation of Ru@DM-V2CTX heterostructure. The advanced heterostructure formation, the mechanism, and the role of Ru have been comprehensively investigated by ultra-high-resolution transmission/scanning transmission electron microscopies coupled with next-generation spherical aberration correction technology and fast, accurate elemental mapping quantifications, also by ultraviolet photoelectron spectroscopy. To the knowledge, this work is the first to use the novel, optimally processed V-MXene over conventionally used Ti-MXene and its surface-internal structure engineering by Ru-ALD process-based temperature-sensing devices function and operational demonstrations. The current work could potentially motivate the development of multifunctional, future, next-generation, safe, personal healthcare electronic devices by the industrially scalable ALD technique.

A team of researchers, led by Professor Soo-Hyun Kim in the Graduate School of Semiconductors Materials and Devices Engineering and the Department of Materials Science and Engineering at UNIST has made significant progress in the discovery of precisely controlled precious metals (Ru, Ir, Pt, Pd) incorporation by atomic layer deposition (ALD).

In this groundbreaking study, the team successfully developed unique and unexplored two-dimensional (2D) nanomaterials V-MXene for the very first time coupled with precious metal ruthenium (Ru) through the ALD process. This breakthrough holds immense promise for various applications, both contact and non-contact mode of real-time temperature sensing at the human-machine interface.

Figure 1. A schematic of atomic layer deposition process and step coverage of ALD-Ru film.

The integration of Ru-engineered V-MXene through ALD has demonstrated a remarkable 300% enhancement in device sensing performance and durability, surpassing the capabilities of pristine V-MXene. This advancement not only paves the way towards the creation multifunctional, cutting-edge personal healthcare devices, but also holds great promises for the progression of clean energy conversion and storage technologies. Moreover, the utilization of the industrially scalable ALD technique used in this research enables precise engineering of MXene surfaces with precious metals, thereby opening up new possibilities for future applications.

“We are thrilled by the potential of this breakthrough,” said Professor Kim. “The precision-enabled integration of precious metals opens up a whole new world of possibilities in the development of a versatile, next-generation, and safe personal healthcare devices, as well as clean energy conversion and storage systems, with the potential to substantially impact people’s lives.”

Figure 2. As-synthesized bulk quantity delaminated V2CTX MXene (DM-V2CTX) to develop Ru-ALD Engineered DM-V2CTX (Ru@DM-V2CTX) for real-time skin temperature sensing, noncontact touch, proximity sensing, and breathing monitoring.

Dr. Debananda Mohapatra, an Associate Professor (Research) in the Graduate School of Semiconductors Materials and Devices Engineering at UNIST, emphasized the ease and versatility of engineering MXene surfaces with precious metals, using industrially favored ALD techniques. He also highlighted the potential for real-time applications in wearable healthcare devices and clean energy fields. He further stated that “This successful work marks the beginning of a thriving research field of focused on advancing 2D nanomaterials engineering and applications empowered by ALD.”

The research team further highlighted the vast potential for exploring the less investigated non-Ti-MXenes, such as Mo, V, and Nb-based MXenes, for surface-internal structure engineering using selective precious metals (Ru, Ir, Pt, Pd) ALD processes. By incorporating single atoms or atomic clusters of precious metals (Ru, Ir, Pt, and Pd), the resulting surface activity and the sensitivity/energy performance per atom can be significantly enhanced. This approach minimizes the use of these scarce and expensive precious metals.

Figure 3. Ru-ALD engineered DM-V2CTX MXene microstructure and elemental mapping. (A) HAADF STEM showing the presence of layered DM-V2CTX MXene structure and the distribution of Ru atoms/clusters, (B, C) HR-STEM of the well-defined layered structure of DM-V2CTX MXene throughout the sample and inset (B) confirms the opening of V2CTX MXene layers after the removal of Al-layers, (D) HR-STEM of both layered DM-V2CTX MXene and Ru lattices, (E) Super-X EDS elemental spectra confirming the elements V, C, Ru, and (F–I) their corresponding elemental mapping images. The atoms in Fig. 2B inset are shown with the same colors as illustrated in Figure 1 after the etching and delamination process.

The findings of this study have been published in the online version of Advanced Science on April 26, 2023. This study has been supported by the Ministry of Science and ICT (MSIT) and the National Research Foundation (NRF) of Korea.

Journal Reference
D. Mohapatra, S.-H. Kim et al., “Process Controlled Ruthenium on 2D Engineered V-MXene via Atomic Layer Deposition for Human Healthcare Monitoring,” Adv. Sci., (2023).