Bi-based layered material shows its great potential in constructing ultrathin two-dimensional (2D) structure, which has been demonstrated to be an effective strategy to improve the photocatalytic performance of various semiconductors. The ultrathin 2D configuration endows Bi-based photocatalyst with many inherent advantages, including large specific surface area, short charge migration distance, increased redox capability, and abundant surface reactive sites. While these unique features contribute to the superior activity of the 2D Bi-based nanosheet, the unique electronic properties of the 2D configuration also endue the material with great potential in a number of energy-related photoreactions (e.g., water splitting, CO₂ reduction and N₂ fixation) that are thermodynamically unfavorable on bulk photocatalyst. Herein, we provide a review on recent literatures relevant to Bi-based (layered or nonlayered) photocatalysts by distinguishing the ultrathin 2D architecture from bulk counterparts. This review focuses on the synthesis techniques and provides a fundamental understanding of the physicochemical, electronic, and optical properties of the 2D Bi-based photocatalysts. Recent advances of these ultrathin 2D Bi-based photocatalysts in a multitude of photocatalytic applications such as molecular oxygen activation, water splitting, CO₂ reduction, and N₂ fixation are appraised. Given that there remain challenges in realizing highly efficient solar energy conversion on ultrathin Bi-based photocatalyst, strategies regarding to increasing light absorption, facilitating charge separation and migration, and accelerating surface reaction kinetics, are therefore introduced. This review aims to provide a comprehensive survey and deep understanding on ultrathin 2D Bi-based photocatalysts from various aspects in order to inspire new research directions in designing high-performing photocatalysts.

Bi基层状材料在构建超薄二维（2D）结构方面显示出巨大潜力，已被证明是提高各种半导体光催化性能的有效策略。超薄二维构型赋予Bi基光催化剂许多固有优势，包括比表面积大、电荷迁移距离短、氧化还原能力增强、表面反应位点丰富等。虽然这些独特的特性有助于 2D Bi 基纳米片的卓越活性，但 2D 配置的独特电子特性也赋予该材料在许多与能量相关的光反应（例如，水分解、CO ₂还原和氮气₂固定）在热力学上对散装光催化剂不利。在此，我们通过将超薄二维结构与大块对应物区分开来，对最近与基于 Bi 的（层状或非层状）光催化剂相关的文献进行了综述。这篇综述侧重于合成技术，并提供了对 2D Bi 基光催化剂的物理化学、电子和光学性质的基本理解。_{这些超薄二维双基光催化剂在分子氧活化、水分解、CO 2}还原和 N ₂等多种光催化应用中的最新进展固定进行评价。鉴于在超薄铋基光催化剂上实现高效太阳能转换仍然存在挑战，因此引入了关于增加光吸收、促进电荷分离和迁移以及加速表面反应动力学的策略。本综述旨在从各个方面对超薄二维双基光催化剂进行全面的调查和深入的了解，以启发设计高性能光催化剂的新研究方向。