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.