2D transition metal-based phospho-chalcogenides and their applications in photocatalytic and electrocatalytic hydrogen evolution reactions

Abstract

The utilization of hydrogen (H₂) as a renewable substitute for fossil fuel can mitigate issues related to energy shortage and associated global warming. The generation of H₂via water splitting by photo and electrocatalytic means is of significant importance. The employment of a semiconductor catalyst reduces the high energy barrier (237 kJ mol⁻¹) associated with a water-splitting reaction to yield H₂ and O₂. Sustainable H₂ production demands the utilization of noble-metal-free, efficient, and stable catalysts over a wide pH range. In recent times, layered transition metal thio(seleno) phosphates (MPX₃, X = S, Se) are reported to be highly efficient for H₂ evolution reaction owing to their earth-abundance, rich active sites, wide spanned band gap of 1.2 to 3.5 eV, and high chemical stability. In this perspective, advances in 2D monometallic and bimetallic MPX₃ compounds are reviewed comprehensively from the viewpoint of water splitting, especially the hydrogen evolution reaction (HER). This study includes the composition, structural engineering, heterostructure, and hierarchically structural design in enhancing the HER activity of MPX₃. Computational results providing insights into the intrinsic photo and electrocatalytic HER activity of 2D MPX₃ are presented. Finally, the challenges and opportunities in further improving MPX₃ activity towards HER and associated catalysis reactions are discussed.