Dual-defect enhanced piezocatalytic performance of C3N5 for multifunctional applications

An effective piezocatalytic semiconductor (C3N5−x-O) was prepared with a two-step thermal polymerization/etching method. Experimental characterizations and structural simulations revealed that the dual-defects of O doping and N vacancy in C3N5 not only increases the asymmetry and the exposure of triangular pores, but also optimizes the band structure and charge distribution of the thin-layered C3N5−x-O, endowing it with an enhanced piezoelectricity and increased active surfaces. Piezocatalysis-mediated pollutant degradation and H2O2 production were achieved with substantially improved efficiencies over the pristine carbon nitrides. Under ultrasound-assisted piezocatalysis, tetracycline was degraded with a kinetic rate of 0.0356 min−1 and this figure was further increased to 0.0561 min−1 in piezocatalytic-Fenton. A yield of 0.615 mM/g/h for piezocatalytic production of H2O2 was achieved in pure water. The synergistic effect of the defect sites revealed in present work could facilitate the more rational design of nitrogen-rich carbon nitrides for environmental remediation and the production of value-added chemicals. [Display omitted] •Dual-defect C3N5 containing O doping and N vacancy was synthesized.•Defect engineering leads to an enhanced piezoelectricity and surface activities.•Dual-defect sites exhibit synergistic effect to improve piezocatalytic performance.•Effective piezocatalytic degradation, H2O2 evolution, and Fenton were demonstrated.•doping and N vacancy respectively act as O2 activation and TC adsorption sites.