BiOCl possesses special internal electrostatic field and is perpendicular to the (Bi₂O₂)²⁺ layer, which makes it tend to form nanoplatelets. It is well-known, the morphology and band gap of nanomaterials have a decisive effect on its photocatalytic performance. In this paper, a solid-phase chemical reaction was firstly used to prepare Bi_xO_yCl_z porous nanorods with different stoichiometric ratios by adjusting the ratio of reactants. The influence of the change in stoichiometric ratio on the microscopic morphology, energy band structure and photocatalytic performance of bismuth oxychloride was studied. Due to the rich pore structure that could increase the catalytic active sites and the appropriate energy band structure that could improve the absorption capacity of visible light, Bi₁₂O₁₇Cl₂ nanorods displayed the best photocatalytic performance under visible light, which can completely degrading rhodamine B and bisphenol A within 60 minutes.

Defect modulation currently plays a decisive role in addressing the poor photoabsorption, sluggish electron hole separation, and high CO₂ activation barrier in photocatalytic CO₂ reduction. However, hunting for a straightforward strategy to balance the concentration of oxygen vacancy and metal cation defect in one photocatalyst is still a great challenge. Herein, a bismuth vacancies BiOBr nanosheets (BiOBr-1) on the exposed [001] facets were constructed via an acetic acid molecule modification strategy, which can repair oxygen defect by bismuth vacancy in low-temperature solid-state chemical method. Benefiting from the formed bismuth defects that can not only broaden light absorption and elevate charge separation efficiency, but also enhance adsorption and activation of CO₂ molecules, the evolution rates of photocatalytic CO₂ conversion into CO (71.23 μmol·g⁻¹·h⁻¹) and CH₄ (8.90 μmol·g⁻¹·h⁻¹) attained by BiOBr-1 are superior 7.1 and 11 times to that of plate-like BiOBr. The photocatalytic mechanisms including adsorption concentration and activation process of CO₂ are further revealed by the in situ diffuse reflectance infrared flourier transform spectra (DRIFTS). This finding of the existence of distinct defects in ultrathin nanosheets undoubtedly leads to new possibilities for photocatalyst design using two-dimensional materials with high solar-driven photocatalytic activity.