PtO/Pt4+-BiOCl with enhanced photocatalytic activity: Insight into the defect-filled mechanism

Photocatalyst performance largely depends on the arrangement of surface atoms, especially nanomaterials. Herein, we proposed a novel defect-filled strategy by filling Bi defects on BiOCl surface with Pt4+ to achieve the controlled arrangement of BiOCl-surface atoms. The resulting PtO/Pt4+-BiOCl photocatalyst showed higher sulfamethoxazole (SMZ) degradation and photocatalytic nitrogen-fixation efficiency than PtO/BiOCl. The first-order kinetic constant of SMZ degradation over PtO/Pt4+-BiOCl (0.1312 min(-1)) was nearly twofold higher than that of PtO/BiOCl (0.0776 min(-1)). The photocatalytic nitrogen fixation activities of PtO/BiOCl and PtO/Pt4+BiOCl were 244.2 mol.L-1.h(-1) and 375.6 mol.L-1.h(-1), respectively. The enhanced photocatalytic activity mainly attributed to the increased light absorption ability and separation efficiency of electron-hole pairs by Pt4+ doping. The defect-filled mechanism was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Electron spin resonance (ESR), and Positron annihilation spectrometry. All these results indicated that the electrostatic interaction between Pt4+ in the precursor and Bi defects on the BiOCl surface was the key step in the defect-filled process. This work provides a new strategy for controlling the surface atom arrangement of nanomaterials.