A critical review on black phosphorus mediated Z-scheme heterojunctions: properties, synthesis, and mechanistic insights towards solar H2 evolution

Abstract

Over the past few decades, the application of semiconductor-driven photocatalysis has emerged as an emerging tactic addressing the growing sustainable energy demands. A significant advancement in this field involves the utilization of two-dimensional black phosphorus (2D BP) as a potential metal-free photocatalyst that offers distinct advantages, including a tunable band gap (depending on the number of layers), high charge mobility, broad light absorption, substantial surface area, and specific anisotropic structure, which has gathered significant attention. This review initially documented the inherent characteristics, mostly physicochemical, optoelectronic, and catalytic properties, assessing their viability as metal-free photocatalysts. This review also provides an overview of advanced fabrication methods for various dimensional configurations of BP, i.e., three-dimensional (3D) bulk, 2D nanosheets (2D NSs), and zero-dimensional quantum dots (0D QDs). Afterward, various strategies to enhance the stability of BP are also discussed in detail. The study also compiles various developments towards Z-scheme heterostructures and underlying catalytic mechanisms for boosting high photocatalytic H₂ evolution activity. Finally, challenges and future prospects in BP research are also discussed, highlighting its possibilities as a versatile material in the post-graphene era. We believe that this review may open up a new avenue for the research community toward sustainable generation of solar fuel using metal-free photocatalysts.