Research Projects

The development of high performance multifunctional electrocatalysts is critical in advancing clean energy technologies, such as fuel cells and electrolyzers. Three-dimensional (3D) nanostructures exhibit excellent catalytic performance for important electrochemical reactions. Considerable focus is being devoted to synthesizing and fine-tuning these structures, paying particular attention to the morphology, controlled assembly, and positioning of active sites. The precise assembly of various nanoparticles can significantly boost catalytic activity by altering the active material’s d-band centers to favorable positions, which enhances reactant adsorption and promotes charge transfer. A tailored design of active monometallic or bimetallic systems and good catalytic support are essential to regulate their catalytic properties and durability. For example, the state-of-the-art catalyst Pt/C for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) suffers from mass transfer limitations and effective utilization of triple phase boundaries due to the randomly organized Pt/C layers. Controlling the structure, heterojunctions, and morphology is essential for improving electrocatalytic performance across various electrochemical reactions. Although substantial interest has been devoted to the development of the superlattice/multicomponent catalytic system, very little progress has been made till now. At this juncture, the multicomponent colloidal crystals (MCCs) with good periodicity are particularly interesting in enhancing the catalytic activities, making them valuable for clean energy generation and storage applications. However, fabricating MCC crystals with uniformity and periodicity over a large area remains challenging, especially with the nanoscale objects (because of their increased Brownian fluctuations). This project proposes the design and development of large area 3D multicomponent colloidal crystals (binary and ternary systems) comprising different types of nanoparticles selective to the electrochemical reactions of interest. The method relies on generating optically-controlled flows (Marangoni flows) in a thin liquid film containing different nanoparticles and utilizing the flow to guide and assemble the nanoparticles in the desired positions. The controlled assembly over a large area (~cm2) will be achieved by generating the desired optical landscape using diffractive optical elements. Considering that the external aid, light, drives the colloidal assembly and uses the size ratio and charge of the nanoparticles to control the final morphology, the method can be used to create a wide variety of nanoparticle assemblies tailored for particular reactions, giving versatility in the design of selective catalysts. In the initial stage, we focus on the effective utilization of Pt by fabricating controlled assemblies and junctions with other metals to tune the d-band center alignment, Pt nanoporous assembled structure to mitigate the mass transfer limitations, maintaining the nanostructures in the nanoporous assembly to increase the accessible triple phase boundaries and controlling the layer thickness to a few layers to achieve cost-effectiveness. In the later stages, other metal and transition metal oxides will be used in the binary/ternary system. These nanoarchitectures, with the precisely tunable assembly of selective electrocatalysts, can significantly contribute to the realization of high-performing, cost-effective, and durable electrocatalysts for clean energy technologies.