Functionalized Regulation of Metal Defects in ln₂S₃ of p-n Homojunctions

The introduction of metal vacancies into n-type semiconductors could efficiently construct intimate contact interface p-n homojunctions to accelerate the separation of photogenerated carriers. In this work, a cationic surfactant occupancy method was developed to synthesize an indium-vacancy (V_In)-enriched p-n amorphous/crystal homojunction of indium sulfide (A/C-IS) for sodium lignosulfonate (SL) degradation. The amount of V_In in the A/C-IS could be regulated by varying the content of added cetyltrimethylammonium bromide (CTAB). Meanwhile, the steric hindrance of CTAB produced mesopores and macropores, providing transfer channels for SL. The degradation rates of A/C-IS to SL were 8.3 and 20.9 times higher than those of crystalline In₂S₃ and commercial photocatalyst (P25), respectively. The presence of unsaturated dangling bonds formed by V_In reduced the formation energy of superoxide radicals (^•O₂^-). In addition, the inner electric field between the intimate contact interface p-n A/C-IS promoted the migration of electron-hole pairs. A reasonable degradation pathway of SL by A/C-IS was proposed based on the above mechanism. Moreover, the proposed method could also be applicable for the preparation of p-n homojunctions with metal vacancies from other sulfides.