Lead halide perovskites are promising for photocatalysis due to their excellent optoelectronic properties, high extinction coefficients, and long electron-hole diffusion lengths. However, severe recombination of photogenerated carriers limits their photocatalytic activity. Herein, we describe a perovskite-based step-scheme (S-scheme) heterojunction by interfacing CsPbBr₃ perovskite nanocrystals with sulfur (S) doped graphitic carbon nitride (g-C₃N₄) ultrathin nanosheet. The formation of S-scheme heterojunction was substantiated by in-situ x-ray photoelectron spectra, showing a negative shift for Cs 1s, Pb 4f, and Br 3d binding energy in CsPbBr₃, while a positive shift for C 1s, N 1s, and S 2p in S-doped g-C₃N₄ upon light irradiation. Moreover, alignment of Fermi levels in both semiconductors results in constructing a built-in electric field in the heterojunction, which enhances S-scheme electron transfer from g-C₃N₄ to CsPbBr₃, favorable for electron (CsPbBr₃) and hole (g-C₃N₄) separation for enhanced carbon dioxide (CO₂) photoreduction. Indeed, compared with CsPbBr₃, the developed CsPbBr₃/S doped g-C₃N₄ composite showed a ∼16-fold improvement in the photocatalytic CO₂ reduction rate (∼83.6 μmol h⁻¹ g⁻¹), thus holding great potential for photocatalysis applications in environmental and energy fields.

卤化铅钙钛矿因其优异的光电性能、高消光系数和长电子-空穴扩散长度而有望用于光催化。然而，光生载流子的严重复合限制了它们的光催化活性。_{在此，我们通过将 CsPbBr 3}钙钛矿纳米晶体与硫 (S) 掺杂的石墨氮化碳 (gC ₃ N ₄ ) 超薄纳米片连接，描述了一种基于钙钛矿的阶梯式 (S-scheme) 异质结。原位 X 射线光电子能谱证实了 S 型异质结的形成，显示 CsPbBr ₃中的 Cs 1s、Pb 4f 和 Br 3d 结合能负移，而 C 1s、N 1s 的结合能正移，和 S 2p 在 S 掺杂 gC ₃N ₄在光照射下。此外，两种半导体中费米能级的排列导致在异质结中构建了一个内建电场，这增强了从 gC ₃ N ₄到 CsPbBr ₃的 S 型电子转移，有利于电子 (CsPbBr ₃ ) 和空穴 (gC ₃ N ₄ ) 分离增强二氧化碳 (CO ₂ ) 光还原。事实上，与 CsPbBr ₃相比，开发的 CsPbBr ₃ /S 掺杂 gC ₃ N ₄复合材料的光催化 CO ₂还原率提高了 16 倍（~83.6 μmol h^-1 g ^-1 )，因此在环境和能源领域具有巨大的光催化应用潜力。