Our research program aims to expand our understanding of materials, surfaces, and interfaces and to apply this knowledge to make advances in a number of technologically emerging and societally critical areas. Currently, at the fundamental level, we are interested in low-dimensional materials, hybrid organic/inorganic materials, metal oxides and silicates. In these materials systems, we aim to establish synthesis-structure-property relationships, and to understand and control their surfaces and interfaces. These insights are helping to guide our interest in impacting areas such as environment, health, sustainability and energy as detailed below.
Fundamental understanding of MOX-based sensors:Chemiresistive sensors, which transduce target gas concentrations based on the change in resistance of a sensing material, provide sensitive, low-cost detection of gaseous analytes in applications such as environmental monitoring, quality control, and clinical diagnostics. Semiconducting metal oxides (MOX) such as SnO2 are an industry-standard material system for chemiresistive sensing. We aim to develop MOX-based sensors with stable long-term characteristics by investigating how the structural and electronic properties of MOX respond to different operating temperatures, durations, and environments. To enhance the stability, sensitivity, and selectivity of our sensors, we are also investigating catalytically active noble metals, such as Pt, Au, and Pd, loaded onto MOX materials to form noble metal-loaded MOX nanocomposites. These nanocomposites are integrated with interdigited electrodes to form fully functioning sensors. To understand the sensing mechanisms of pristine MOX and metal-loaded MOX nanocomposites, we are correlating charge transport processes elucidated by impedance spectroscopy with structural and chemical information conveyed by X-ray photoelectron spectroscopy. Mature sensors will leverage energy-efficient (~15 mW to reach 500 °C) poly-Si and SiC microheater platforms previously developed by our group to enable robust, low-power gas microsensors for a variety of applications.
Materials innovations:Atomically dispersed supported metal catalysts (also referred to as single atom catalysts) constitute a new class of materials that contains isolated individual atoms or synergistically coupled few-atom ensembles dispersed on, and/or coordinated with the surface atoms of appropriate solid supports. Examples include noble metals such as Pd and Pt on metal oxides, graphene, graphene oxide and various other two-dimensional materials. These materials have emerged as a rapidly developing class of catalysts offering the advantage of the most efficient use of noble metals combined with unique properties considerably different from their conventional nanoparticle equivalents. These include excellent selectivity for gas adsorption, electron transport and improved resistance to poisoning and coke formation. Herein, we aim to develop atomically dispersed Pd catalysts supported on two different support materials, namely graphene oxide and tin (IV) oxide for the fabrication of robust gas sensors for in-door air quality monitoring. Sensitivity, selectivity and response of the fabricated sensors towards the target gases, and recovery time, detection limit, stability, and working temperature of the sensors at different humidity levels are being investigated. We strive to elucidate their gas sensing mechanisms relevant to target gases (e.g., H2, CO and CH4) through their detailed structural, chemical, electrical and optical characterization. A classic challenge in gas sensing is the tunability of the sensing material for the selective absorption of target gases without interference from unwanted species. Metal-organic frameworks (MOFs), made up of metal-cluster nodes connected by organic linkers, can achieve selective adsorption owing to their high chemical and structural tunability. Their selectivity and flexibility make MOFs attractive for gas sensing, as realized in novel low-power, low-footprint, on-chip devices such as the chemical-sensitive field-effect transistor, previously demonstrated by our group. In this project, we aim to explore the large library of MOFs (consisting of different metal nodes and organic linkers) towards novel electronic sensor arrays. This effort includes investigating the underlying electronic transduction mechanisms of MOFs through resistance measurement, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and infrared and Raman spectroscopies, targeting important polluting and toxic gases such as CO2, CH4, CO, CH2O.
- August 2023 – Maboudian lab goes to space! Our graphene aerogel produced aboard ISS in collaboration with Stanford (article)
- April 2023 – Anthony receives the SURF Rose Hill Fellowship!
- April 2023 – Stuart receives the NSF Graduate Fellowship!
- February 2023 – Xiaohong Zhu receives the EBI-Shell Postdoctoral Fellowship!
- May 2022 – Veronica receives the SURF Rose Hill Fellowship!
- May 2022 – Jeffrey graduates with the highest honors and heads to Stanford for graduate studies!
- March 2022 – Zhou successfully completes his PhD and joins Stanford as a postdoc!