Advanced Functional Materials Paper - Asst Prof Tan Kwan Wee

"Ultrafast Crystallization of Ordered Mesoporous Metal Oxides and Carbon from Block Copolymer Self-Assembly and Joule Heating" 

(published in Advanced Materials Interfaces)

Conventional heat treatments to generate well-ordered and crystalline mesoporous oxide and carbon structures are limited by long durations and annealing temperatures that can cause mesostructural collapse. This paper describes a facile strategy coupling block copolymer-directed self-assembly with high-power Joule heating to form highly crystalline and well-ordered mesoporous oxide and carbon nanostructures within second timeframes. The combined approach is compatible with various functional self-assembled hybrid systems with a range of crystallization temperatures, generating mesoporous composites of γ-Al₂O₃-carbon, γ-Al₂O₃/MgO-carbon, and anatase-TiO₂-carbon with p6mm symmetry, non-close-packed mesoporous carbon, as well as hierarchical mesoporous α-Fe₂O₃-carbon structures. Removing the polymer/carbon gives well-defined, highly crystalline mesoporous all-γ-Al₂O₃ and all-anatase-TiO₂ structures. Impregnation of chloroplatinic acid followed by Joule heating yields platinum nanoparticles decorated on the channel walls of mesoporous γ-Al₂O₃-carbon structures. The resultant Joule-heating-induced well-ordered crystalline mesoporous oxide and oxide-carbon structures have high thermal and structural stabilities and exhibit better performances in CO₂ adsorption capacity and lithium-ion batteries than conventional heat-treated counterparts. This approach represents an energy-efficient and time-saving route toward ordered porous materials with high surface area and pore accessibility for a wide range of environmental applications such as carbon sequestration, renewable energy storage, and environmental filtration. (DOI: https://doi.org/10.1002/admi.202200151)

Advanced Materials Interfaces publishes applied, top-level research on functional interfaces and surfaces and their specific applications, driving forward our understanding of interfacial processes. Considering that interfaces between solids, liquids, and gases play an essential role in virtually all materials and devices, the journal's scope encourages an interdisciplinary blend of physics, chemistry, materials science, and life sciences. According to the Journal Citation Reports (Clarivate Analytics, 2022), the journal has a 2021 impact factor of 6.389.

"Fabrication of PtIrPd Noble Metal Medium Entropy Alloy Thin Film by Atomic Layer Deposition"

(Co-authored with Assoc Prof Alfred Tok; published in Advanced Engineering Materials)

Noble metal medium entropy alloy (MEA) thin films have recently attracted enormous research interests recently because of their great potential in the catalytic application. However, conventional bottom-up fabrication methods for MEA thin film such as magnetron sputtering face enormous challenges including precise control over film thickness and consumption of costly high-purity noble metal targets. Herein, a facile and tunable approach is developed coupling sequential atomic layer deposition (ALD) of noble metal layers with electric Joule heating (EJH) alloying process to grow platinum-iridium-palladium (PtIrPd) MEA thin films. The PtIrPd MEA thin film with a thickness of ≈20 nm and an atomic ratio of 35:35:30 is successfully fabricated. The effect of EJH processing temperature on the film morphology and structure evolution is investigated. ALD provides flexibility in the metal deposition sequence with meticulous thickness control and atomic composition precision, while the ultrafast EJH ramping/cooling rates promote homogeneous alloying of MEA combinations inhibiting phase separation. Furthermore, the integrated method circumvents a major obstacle of finding a common ALD temperature window for different noble metal precursors as well as opens new pathways for the controllable synthesis of multicomponent metal alloy thin films with potential catalytic, magnetic, and optical properties. (DOI: https://doi.org/10.1002/adem.202201263)

Advanced Engineering Materials focuses on all the latest breakthroughs in engineering materials. The journal covers a variety of key topics, such as composites, ceramics, intermetallics, and coatings, and also high-temperature, cellular, and biomedical materials, as well as innovative manufacturing techniques. According to the Journal Citation Reports (Clarivate Analytics, 2022), the journal has a 2021 impact factor of 4.122.