Recent advances in black phosphorus: Synthesis, characterization, surface functionalization, defect tailoring and photocatalytic applications

Black phosphorus (BP) is a layer two-dimensional material with a tunable direct bandgap, high carrier mobility, and pronounced in-plane anisotropy, making it highly attractive for energy and photocatalytic applications. Its unique electronic and optical properties enable efficient light absorption, rapid charge transport, and effective electrons-holes separation, which are essential for sustainable energy technologies. In the context of the ongoing energy crisis, BP-based materials have shown great promise in photocatalytic performance such as hydrogen production, overall water splitting, oxygen evolution, CO2 reduction, nitrogen fixation, and pollutant degradation, offering a pathway toward renewable and clean energy generation. This review comprehensively covers recent advances in BP, including its crystal and band structure, characterizations, anisotropic behavior, defect engineering, surface properties, morphology, and functionalization, as well as state-of-the-art synthesis techniques that enhance stability and photocatalytic performance. By integrating these aspects, our review highlights strategies to overcome current limitations, making it a valuable roadmap for developing next-generation BP-based photocatalysts and energy conversion systems.