Microdroplets exhibit a remarkable ability to accelerate chemical reactions and initiate redox processesthat are typically challenging to achieve in bulk phase. However, the underlying mechanisms governing electron transfer at the microdroplets interface remain unclear.
Recently, a research group led by Prof. WANG Feng and Assoc. Prof. JIA Xiuquanfrom the Dalian Institute of Chemical Physics(DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. Richard N. Zare's group from Stanford University, have realized chemoselective electro-dechlorination of organochlorine-containing wastewater using microcloud water enriched with charged microdroplets. This study was published in the Journal of the American Chemical Society.
The net charge of microdroplets plays a significant role in influencing reaction thermodynamics, facilitating electron transfer between charged droplets and thereby making the redox reactions thermodynamically feasible.
In this study, the researchers reported a controllable electrochemistry process enabled within microclouds by fast phase switching of water between the microdroplet, vapor, and bulk phase. Through atomization, charge separation occurred between droplets of varying sizes, leading to self-charging and discharging cycles that generated alternating voltage in the microcloud water. This process involves electron transfer, enriching hydrogen radicals at the bulk phase surface and hydroxyl radicals within the microdroplets.
The researcher demonstrated that the fast phase switching of water from bulk phase to the microdroplets enabled initial reductive dechlorination of dichloroethane in the bulk phase, followed by accelerated dehydrogenation of the dechlorination intermediate in the microdroplets. The researchers achieved a high selectivity of approximately 80% for vinyl chloride formation. The rapid phase-switching of water minimizes mass transfer limitations, overcoming the chemoselectivity challenges typical of bulk-phase electrochemical methods.
“Our study indicated that beyond water treatment, cloud electrochemistry is potential for broader applications, including chemoselective electrosynthesis and air purification,” said Prof. WANG.