Synthesis of Cs3PMo12O40/Bi2O3 composite with highly enhanced photocatalytic activity under visible-light irradiation

A novel visible-light-active Cs 3 PMo 12 O 40 /Bi 2 O 3 (CsPMo/Bi 2 O 3 ) composite was prepared by a simple dissolution-precipitation method. The as-prepared samples were characterized by XRD , XPS , FT-IR, SEM , UV–Vis DRS , N 2 adsorption-desorption isotherms and electrochemical analysis . The results revealed that Bi 2 O 3 was successfully modified by trace CsPMo. After the addition of H 3 PMo 12 O 40 acid (HPMo), the surface of Bi 2 O 3 can be roughed. Subsequently, the presence of Cs 2 CO 3 can neutralize the protons of HPMo forming CsPMo precipitate on Bi 2 O 3 . Comparing to naked Bi 2 O 3 and CsPMo, the binary composite exhibited many beneficial characteristics in charge generation and separation, such as formation of p-n heterojunction , decreased band gap, enhanced photocurrent response and greatly reduced charge transfer resistance. The photocatalytic activities of the as-prepared samples were evaluated by the degradation of phenol under visible light . The calculated pseudo-first-order rate constants for phenol degradation were 2.7 and 14.8 times relative to that on Bi 2 O 3 and CsPMo, respectively. Dramatically enhanced photocatalytic performance can be observed when the optimal CsPMo/Bi 2 O 3 composite (2.5% CsPMo) was applied. The major active species involved in the degradation process are in the following order: superoxide radical (O 2 − ) > hydroxyl radical ( OH) ≈ hole (h + ). Besides, the CsPMo/Bi 2 O 3 composite also displayed good stability in cyclic experiments.