Micron-sized droplets, seemingly simple and familiar, are now at the heart of one of the most exciting developments in modern chemistry and medicine. In 2011, our pioneering study (doi.org/10.1007/s13361-011-0188-7) laid the conceptual foundation for performing unusual chemical transformations in microdroplets that are absent in bulk solution. In the above report, we explicitly demonstrated for the first time that microdroplets can function as a “unique reaction vessel to induce a chemical reaction”, particularly through charge-induced chemical processes. Over the past decade, accumulating evidence has revealed that chemical reactions occurring at the gas–liquid interface, especially at the air–water interface of microdroplets, can proceed along entirely new pathways or occur millions of times faster than in conventional bulk environments. This remarkable reactivity in microdroplet chemistry originates from unique interfacial phenomena at the air–water boundary. These include interfacial charge accumulation and extreme local electric fields, corona discharge effects, a dehydrated droplet surface with partial solvation of reactants, preferential molecular orientation at the interface, confinement within micron-scale volumes, the emergence of superacidic or superbasic interfacial environments, and continuous evaporation-driven surface dynamics. Together, these features create a highly reactive, non-equilibrium microenvironment fundamentally distinct from bulk solution chemistry. We exploit sprayed microdroplets as powerful reaction platforms to enable chemical transformations under mild, catalyst-free conditions, advancing sustainable, green chemical processes.
Overall, at our lab, microdroplets are not merely microscopic particles—they represent a new paradigm in chemical reactivity, bridging physical chemistry, analytical innovation, sustainable synthesis, chemical biology, and environmental chemistry.
Our research demonstrates that microdroplet environments can initiate and accelerate chemical transformations without the need for added reagents, metal catalysts, or harsh reaction conditions. By exploiting the unique interfacial properties of sprayed microdroplets, we engineer alternative reaction pathways that are inaccessible in bulk solution. In our laboratory, we develop microdroplet-based synthetic strategies for the sustainable production of value-added chemicals, platform molecules, pharmaceuticals, and advanced materials. These approaches reduce chemical waste, minimize energy use, and eliminate unnecessary additives, paving the way for greener, more efficient chemical manufacturing. A significant focus of our current efforts is the translation and scale-up of microdroplet-enabled processes toward practical industrial implementation.
Our studies have demonstrated that microdroplet platforms offer a powerful means to intercept and investigate reactive intermediates that are otherwise too transient to detect in bulk solution. By leveraging the confined, non-equilibrium, highly charged, and solvent-depleted interfacial microenvironment of microdroplets, we enable rapid interception, stabilization, and mass spectrometric detection of highly reactive species generated within the reaction system. This approach allows real-time capture of fleeting intermediates that would otherwise escape observation. In our laboratory, we design strategies to stabilize, characterize, and mechanistically interrogate carbocations, carbanions, radicals, enzymatic intermediates, and other short-lived species directly in situ. Such capabilities permit continuous monitoring of chemical and biochemical transformations as they unfold, providing deep insight into reaction mechanisms, energy landscapes, and molecular dynamics that underpin both synthetic chemistry and biological processes.
For over a century, atmospheric and environmental microdroplets (such as tiny water droplets in clouds, fog, or aerosols) were generally regarded as passive media—simply small containers that hold reactants while chemical reactions occur within them. In this traditional view, the droplets themselves did not actively influence the chemistry; they merely provided a physical space where dissolved gases or particles could interact. However, this perspective largely overlooked the inherent reactivity of microdroplets. In reality, microdroplets can actively catalyze and accelerate many chemical reactions. The unique interfacial micro-environments can significantly alter reaction pathways and kinetics. Thus, rather than acting as inert carriers, microdroplets can function as dynamic, chemically active microreactors that promote, and even enable, reactions that may proceed slowly, or not at all, in bulk solutions. The emergence of microdroplet chemistry provided a powerful platform for uncovering chemical transformations at natural air–water interfaces. In our laboratory, we use sprayed microdroplets as model systems to mimic environmental interfaces and directly probe transient species and fast interfacial reactions. This approach allows us to reveal hidden oxidative, radical, and charge-induced processes that may play critical roles in atmospheric chemistry, pollutant transformation, and prebiotic chemical evolution. Through mechanistic insight and real-time detection, we aim to redefine how chemical reactivity is understood in nature’s confined microenvironments.
A central thrust of our research is to uncover the molecular physics and chemistry of the air–water interface—the intrinsically asymmetric boundary where bulk liquid meets the gas phase and new chemical behavior emerges. Unlike a homogeneous solution, this interface exhibits broken symmetry, steep dielectric gradients, anisotropic solvation, and dynamically fluctuating hydrogen-bond networks that fundamentally reshape molecular energetics and reactivity. Importantly, microdroplets in air—whether natural (sea spray, clouds, aerosols) or anthropogenic (sprays, combustion aerosols)—are rarely neutral. During droplet formation and breakup, asymmetric charge separation occurs via the Lenard effect, leading to net positive or negative charging of offspring droplets. This spontaneous electrification establishes intense local electric fields and surface charge densities through different mechanisms that profoundly influence interfacial acidity, redox chemistry, ion distribution, and reaction pathways. Our findings demonstrated that microdroplets in air can undergo spontaneous corona discharge at the air–water interface, generating a plasma-like microenvironment at the droplet surface. Such an interface also features water-isotopologue separation, enriching lighter isotopes at the droplet surface. By deciphering how charge, solvation asymmetry, confinement, and interfacial molecular ordering collectively govern reactivity, we aim to transform the air–water interface from a natural phenomenon into a programmable chemical platform for next-generation synthesis, environmental chemistry, and molecular innovation.
A growing focus of our research is to explore how microdroplet environments may have contributed to prebiotic chemical evolution. The air–water interface of micron-sized droplets provides a highly reactive, confined, and energy-rich microenvironment that can promote bond formation, molecular complexity, and reaction pathways that are inefficient or inaccessible in bulk aqueous systems. In our laboratory, we use microdroplet platforms to investigate plausible prebiotic transformations, including the formation of key organic building blocks under mild, catalyst-free conditions. By probing interfacial charge effects and intensive electric fields, evaporation-driven concentration, and partial solvation dynamics, we aim to understand how simple molecules could have evolved into chemically complex systems. This work seeks to illuminate the role of interfacial chemistry as a potential driver in the chemical origins of life.
