Sustainability has gained momentum due to climate change and environmental pollution. Mankind is trying to look for safer fuels to meet the energy demands and conserve the world for future...

Over a decade in pursuit of photoluminescent carbon quantum dot has created opportunities and left a huge void in understanding the role of graphitic-N in tuning its emission properties. Among the proposed hypotheses on the origin of their emission properties, an emerging one that suggests the formation of molecular crystals lacks the foundations of molecular transformability. In this article, solvent reactiveness has been found to manipulate the emission properties of the products derived from a one-pot solvothermal reaction. The excellent superimposition of absorption and excitation spectra and excitation-energy-independent emission of green- and red-emissive products are suggestive of their molecular nature. The best-known graphitic-N in the carbon nanodot turns out to be the nitrogen of citrazinic acid. The synthesized emitters exhibit reverse solvatochromism, surfactant-induced aggregation, and electrostatic sequestration at the micellar surface. An unprecedented solvent-directed green switching of the red-emissive product (P R) has been presented here, and the transformed product (P R→G*) shows an uncanny resemblance of spectroscopic properties with the green-emissive product (P G). The products can easily bind to bovine serum albumin and retain their emissive properties in bound state, as signaled by the augmentation of fluorescence properties. Being a hybrid photosynthesis system, the chloroplast–red-emissive product is found to exhibit a markedly higher rate of reduction of ferricyanide than that of chloroplast alone.

Substrate-assisted product desorption often proposed in heterogeneous catalysis (nanozymes) denounces the catalytic deactivation of these catalysts. On the contrary, the catalytic deactivation of rigid heterogeneous catalyst becomes noticeable in a continuous flow reactor. Surprisingly, it has been addressed inadequately and in an isolated manner. In this study, we have developed a cost-effective non-lithographic method for the fabrication of a PDMS-based microchannelcoupled-millreactor. Immobilized nickel particles are resistant to leaching in the flow process. During continuous operation, millireactors show a strong catalytic activity for reduction of resazurin and p-nitrophenol with a conversion rate of almost 100 %. Catalytic poisoning is ubiquitous and gets gradually prominent whereas complete catalytic deactivation of magnetic Ni-microparticles is found to be an instantaneous process. Relatively large-sized resorufin binds predominantly to the surface and thereby blocks the access of the substrate to the Ni-particles. The dissociations of product molecules -resorufin and p-aminophenol are the rate-limiting steps that caused the abrupt deactivation of Ni-microparticle. The kinetic mechanism of heterogeneous derived from the Langmuir-Hinshelwood mechanism satisfactorily explains the catalytic poisoning and deactivation of nickel microparticles. This study sheds light on the intricacies of catalytic activity and poisoning of magnetic nickel microparticles.

No abstract

No abstract