The photochernical properties of crystal facets with obviously distinct atomic and geometric structures have been studied widely to date. However, little work has been performed for two or more facets with very similar atomic and geometric structures. Herein, we, mainly report the photochemical properties of {001} and {1001 facets of Bi2O2(CO3)(1-x)S-x with very similar atomic and geometric structures. The simulation and experimental results show that over {100} facets, sulfur prefers to substitute for the carbonate anion, leading to the formation of an interesting serpentine internal electric field that greatly inhibits the charge recombining of electrons and holes, which has rarely been demonstrated; over {001} facets, however, sulfur preferentially adsorbs in oxygen vacancies, which greatly reduces the surface energy of {001} facets, leading to 80% of the high-energy {001} facets exposed, As a result, the photochemical properties of nanosheets have been greatly improved. This study could help us to fully understand the photochemical properties of semiconductors.