INFEWS N/P/H2O: Collaborative Research: Catalytic Dephosphorylation Using Ceria Nanocrystals

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Phosphorus (P) is a crucial element for sustaining life and is economically important in agriculture. The current production of P fertilizers, however, relies on depleting limited feedstocks such as phosphate rocks. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Chao Wang from Johns Hopkins University and Dr. Ye Xu from Louisiana State University are collaborating to develop chemicals, known as heterogeneous catalysts, which promote the removal f phosphorus of renewable biomass to produce phosphorous which can be used to synthesize fertilizers. In Dr. Chao Wang's group, advanced synthesis techniques, X-ray and molecular spectroscopic characterization, and catalytic studies are combined to explore novel dephosphorylation catalysts based on rare-earth oxide "nanocrystals" whose dimensions are on the order of 0.00000005 inches. Meanwhile, Dr. Ye Xu's group creates atomic -scale theoretical models for these catalysts using density function theory (DFT) to calculate the reaction pathways and barriers that control the reaction rates and energy consumption. of the phosphorus removal processes. The experimental and theoretical approaches are integrated to develop fundamental understanding of the catalytic mechanisms. Both Dr. Wang and Dr. Xu are actively engaged in outreach programs for promotion of education in the science, technology, engineering and mathematics (STEM) disciplines. These investigators have incorporated undergraduate students in their research and are involved in outreach with local schools. Professor Wang has been active through a STEM Achievement program in Baltimore Elementary Schools (SABES) project and with other schools in Baltimore in addition to the Woman in Science and Engineering (WISE) program at the university. Professor Xu works with the Louisiana State Science and Engineering Fair competition and local schools. This research develops innovative and renewable methods for phosphorus (P) production. This is important because phosphorous is a crucial element for sustaining life and is widely employed in fertilizer production crucial to modern agricultural practices. To tackle this challenge, Dr. Chao Wang from Johns Hopkins University and Dr. Ye Xu from Louisiana State University are collaborating to explore catalytic dephosphorylation using ceria nanocrystals. By integration of advanced nanomaterial synthesis, X-ray and molecular spectroscopic characterization, catalytic studies and density functional theory (DFT) calculations, the project identifies the important ceria surface structures, such as crystal facets and defects (cerium cation (Ce3+) and oxygen vacancies), and systematically evaluates them to establish the structure-property relationships and identify the active sites. Para-nitrophenyl phosphate (p-NPP) and monomethyl phosphate (MP) are first used as model molecules to perform comprehensive studies of the reaction kinetics, and the studies are then generalized to various types of phosphate ester molecules, including aryl and alkyl phosphates, nucleotides and phospholipids. The research enables the efficient recovery of phosphorus from biomass for the renewable production of phosphorus. This phosphorus can then be used in the production of fertilizers that are necessary for economical and productive agriculture. This work gains new, fundamental knowledge about the structure-property relationships of the ceria catalysts, particularly at the nanoscale and in aqueous solution environment. The two investigators are actively engaged in outreach programs for promotion of education in the science, technology, engineering and mathematics (STEM) disciplines. These activities include training graduate students with state-of-the-art experimental and theoretical skills and developing their independent research philosophy, providing undergraduate students with hands-on experiences at the cutting edge of science and engineering research, and engaging middle- and high-school students from diverse backgrounds to work in the investigators' laboratories as summer interns.