A series of ZnSn(OH)(6) polyhedra are successfully explored with well-controlled area ratio of the exposed {100} and {111} facets. Band alignment of the exposed facet-based homojunction of the elegant polyhedron facilitates spatial separation of photogenerated electrons and holes on {111} and {100} surfaces, respectively. Optimal area ratio of {100} to {Ill} is the prerequisite for pronounced CO2 photocatalytic performance of high-symmetry cuboctahedra into methane (CH4). The synergistic effect of the excess electron accumulation and simultaneously the enhanced CO2 absorption and low dissociation activation energy on {III} reduction sites promote the yield of CO2 photocatalytic conversion product.