Muhammad Naeem Younis

We demonstrate that water microdroplets create a highly reactive interfacial environment that enables the rapid, room-temperature synthesis of boron nitride quantum dots (BNQDs). Using a borane ammonia complex (BH₃NH₃) and a boric acid-ammonia system as precursors, we obtain green- and blue-emissive BNQDs, respectively, under ambient conditions. Mass spectrometry reveals a dehydrogenative cyclization pathway for BH₃NH₃, delineates the size distribution of B_xN_y clusters, and reveals reaction kinetics accelerated by 6 orders of magnitude relative to conventional bulk hydrothermal synthesis. Hydroxyl radicals (OH^•), generated from interfacial water and entrained oxygen, act as key oxidants driving stepwise dehydrogenation of BH₃NH₃. For the boric acid-ammonia system, the dehydration and deamination process is accelerated on the air-water interface. In a spraying-recirculating microdroplet reactor, milligram-scale quantities of BNQDs with an average diameter of ∼8.5 nm are produced within 1 h, establishing a green, bottom-up route for nanomaterial synthesis by exploiting the intrinsic reactivity of water microdroplets.

The advancing effects of various alkali and alkaline earth metals (inclusive of K, Ca, and Sr) modified Cu/SiO₂ catalysts, prepared with a modified precipitation-gel method, were investigated for the production of ethanol via hydrogenation of methyl acetate. Our results showed that Sr-doped catalysts exhibited the best and most consistent results during catalytic tests. A series of techniques, including X-ray diffraction technique, Raman spectroscopy, N₂ adsorption/desorption, N₂O titration method, FTIR spectroscopy, and H₂ temperature, programmed desorption and reduction (TPD and TPR), and X-ray Photoelectron Spectroscopy, which was used to check the detailed characterization of Sr modification in the catalyst and its structural impacts on the properties of the catalyst. These results demonstrated that the addition of 5%Sr could strengthen the intrinsic stability of the catalyst by formulating the appropriate ratio of Cu⁺/(Cu⁰ + Cu⁺) to facilitate catalytic outcome improvement. The addition of 5%Sr-30%Cu/SiO₂ under the most favorable conditions, resulting in the peak conversion of MA (95%) and ethanol selectivity (96%), indicates its magnificent catalytic stabilizing effects. Furthermore, the best performing catalyst was compared and tested under various conditions (LHSV and temperatures) and a 300 h long life run.

Highly active and stable La-modified Cu/SiO₂ catalysts were fabricated for the vapor-phase hydrogenation of methyl acetate to ethanol.