Chemically functionalized phosphorenes and their use in the water splitting reaction

Abstract

In the last 7 years, phosphorene (or few layer black phosphorus) has emerged as not only a superior optoelectronic material, but also a potential catalyst for the hydrogen evolution reaction (HER) from water splitting owing to its thickness dependent bandgap, broad spectrum light absorption, high charge-carrier mobility, and high density of surface-active sites. However, pristine phosphorene produces trace amounts of H₂ primarily due to its poor ambient stability and a large positive change in the Gibbs free energy of hydrogen (H*) adsorption/desorption (ΔG_H* > 0). Due to the recent surge of interest in metal-free HER catalysts, there have been many successful efforts on enhancing the stability as well as the catalytic activity of phosphorene through chemical functionalization, metal doping, and 2D heterocomposites. In this perspective, we present different types of interactions, including covalent, coordination, electrostatic, van der Waals, charge-transfer, and interfacial, which have been utilized in preparing modified phosphorenes. Then, we assess the noteworthy properties of phosphorene, which make it an efficient HER catalyst and discuss the developments in photocatalytic, electrocatalytic, and photo-electrocatalytic means of H₂ production using phosphorene based catalysts. We conclude the perspective with suggestions for exciting future developments.