Our lab was one of the first to report and explain the mechanisms behind the use of plasmonic metal nanoparticles (Ag, Au, and Cu) as a driver for photocatalytic enhancement on both semiconductors and directly on plasmonic metals. The unique dielectric properties of plasmonic metal nanoparticles allow them to focus incoming electromagnetic radiation (i.e. light) directly onto reactants adsorbed on the surface, thereby facilitating chemical transformations. Our group has experimentally demonstrated the utility of plasmonic nanoparticles in enhancing the rate and selectivity of industral reactions, and has analyzed the energy flow in plasmonic systems to further our understanding of plasmonic catalysis. We are now working on engineering hybrid plasmonic nanoparticles to broaden the applications of plasmonic catalysts. Current members working in this area include Bill Yan

Materials that have received the most attention in photoelectrochemical water splitting consist of semiconductor light absorbers coupled to metal electrocatalysts. In these multi-component systems, the semiconductor produces a photovoltage upon absorbing incident sunlight, and this voltage is used by respective electrocatalysts to drive the hydrogen evolution (HER) and oxygen evolution (OER) half- reactions. The objective of our work is to characterize and engineer interfaces between semiconductors and metal electrocatalysts and develop physical models to identify and mitigate loss mechanisms. To achieve this goal, we use advanced nanofabrication techniques and multi-scale modeling approaches. Current members working in this area include Ahmet Sert

Synthesis of well-defined multimetallic nanostructures is critical in discovering catalysts to replace platinum for the electrochemical oxygen reduction reaction. The synthesis of these nanostructures is often complicated by incompatibility of metals, dynamic reconstruction under operating conditions, and general characterization of the nanoparticles. Recently, we developed a synthesis in which we encountered and overcame these obstacles. We worked on improving alkaline ORR activity of Ag-based materials. While silver is less active material than Pt, it is also much less expensive. By improving the ORR activity of silver through alloying, we can make materials that are more competitive with Pt on a cost basis. Motivated by density functional theory calculations, we developed a synthesis to prepare Ag-Co nanoparticles that show superior ORR performance compared to monometallic Ag nanoparticles.

Our group focuses on understanding the interactions between plasma and liquids, a process known as plasma-driven solution electrolysis. By identifying the dominant reactive species, we can explore the unique opportunities presented by these highly reactive interfaces to drive both reductive and oxidative reactions. We demonstrated the feasibility of this type of chemistry in the synthesis of propylene oxide from propylene and water, where the hydrogen peroxide generated from plasma-liquid interaction serves as a selective oxidant for propylene towards propylene oxide. Current members working in this area include Han-Ting Chen and Yi Zhang

Our computational work focuses on gaining a better understanding of chemical transformations and catalytic activity using ab initio methods and developing physically transparent models. Alloying allows tuning of the electronic and geometric structure of catalysts to enhance certain reactions or to inhibit side reactions. We have used density functional theory calculations to predict that nickel/tin alloys could limit carbon mobility on the surface thus improving coking tolerance in high-temperature fuel cells. We have also used density functional theory to show that Ag(100) surfaces are more selective toward the partial oxidation of ethylene compared to Ag(111), suggesting that nanostructures dominated by Ag(100) facets could improve selectivity. In both of these cases, we were able to successfully synthesize the appropriate catalytic structures and verify our model predictions. Current members working in this area include Chenggong Jiang.

Thermal catalysis often involves studying catalytic systems at elevated temperatures, where deactivation of catalysts and sometimes thermodynamics can severely limit the catalytic performance. Our lab aims to combine theoretical insights derived from modeling with engineering principles to develop innovative catalytic systems that can overcome these challenges. We showcased this in our recent work on co-designing a catalyst-membrane system for propane dehydrogenation (PDH) with unprecedented PDH activity that surpasses thermodynamic conversion limits. Other reactions that we are actively investigating include oxidative coupling of methane, ethylene epoxidation, and carbon monoxide oxidation. Current members working in this area include Shawn Lu, Shiuan-Bai Ann, Charles Zhao and Jeanne Zhang