Acid-induced topological morphology modulation of graphitic carbon nitride homojunctions as advanced metal-free catalysts for OER and pollutant degradation

Topological morphology that dominates the surface electronic properties of nanostructures plays a key role in producing desired materials for versatile functions and applications in many fields,but its modulation for specific functions remains a big challenge.Herein,we report an acid-induced method to prepare S-doped graphitic carbon nitride/graphitic carbon nitride(S-CN/CN)homojunction by simply pyrolyzing a supramolecular precursor synthesized from melamine and H_(2)SO_(4).The topological morphology and electronic structure of CN homojunction can be easily adjusted only by changing the ratio of raw materials.Moreover,the topological morphology of S-CN/CN homojunction can be further adjusted from hollow cocoon to 2D nanosheets by changing the annealing conditions.The optimized S-CN/CN homojunction shows highly efficient in charge transfer and separation and exhibits superior OER activity and high ability to degrade organic pollutants.Impressively,S-CN/CN nanosheets only demand low overpotential of301 m V to drive a current density of 10 m Acm^(-2)in 1 M KOH media,and the corresponding Tafel slope is only 57.71 m V/dec,which is superior to the most advanced precious metal Ir O_(2)catalyst.Moreover,under visible light irradiation,its photodegradation kinetic rate of Rh B is 2.38,which is 47.6 times higher than that of bulk CN.This work provides useful guidance for designing and developing efficient multifunctional metal-free catalysts.

Fluffy hybrid nanoadjuvants for reversing the imbalance of osteoclastic andosteogenic niches in osteoporosis

Osteoporosis is majorly caused by an imbalance between osteoclastic and osteogenic niches. Despite thedevelopment of nationally recognized first-line anti-osteoporosis drugs, including alendronate (AL), their lowbioavailability, poor uptake rate, and dose-related side effects present significant challenges in treatment. Thiscalls for an urgent need for more effective bone-affinity drug delivery systems. In this study, we produced hybridstructures with bioactive components and stable fluffy topological morphology by cross-linking calcium andphosphorus precursors based on mesoporous silica to fabricate nanoadjuvants for AL delivery. The subsequentgrafting of -PEG-DAsp8 ensured superior biocompatibility and bone targeting capacity. RNA sequencing revealedthat these fluffy nanoadjuvants effectively activated adhesion pathways through CARD11 and CD34 molecularmechanisms, hence promoting cellular uptake and intracellular delivery of AL. Experiments showed that smalldoseAL nanoadjuvants effectively suppress osteoclast formation and potentially promote osteogenesis. In vivoresults restored the balance between osteogenic and osteoclastic niches against osteoporosis as well as theconsequent significant recovery of bone mass. Therefore, this study constructed a drug nanoadjuvant withpeculiar topological structures and high bone targeting capacities, efficient intracellular drug delivery as well asbone bioactivity. This provides a novel perspective on drug delivery for osteoporosis and treatment strategies forother bone diseases.