Scalable synthesis of two-dimensional nano-sheet materials with chlorophyll extracts: enhancing the hydrogen evolution reaction

Abstract

Developing strategies for preparing high-quality atomically thin two-dimensional (2D) nanomaterials is still an unaccomplished goal. Here we demonstrate that the major pigment used in natural photosynthesis, chlorophyll extracts, can effectively exfoliate bulk graphite, molybdenum dichalcogenides (MoS₂) and boron nitride (h-BN) to form high quality thin sheets. The exfoliated MoS₂ thin sheets were mixed with high-conducting single-walled carbon nanotubes (SWCNTs) and high surface/bulk ratio Pt nanoparticles (PtNPs) to form flexible MoS₂/PtNPs/SWCNT papers for enhanced hydrogen evolution reaction (HER). Detailed electrochemical characterization shows that the flexible MoS₂/PtNPs/SWCNT electrode (0.03 at% or 0.26 wt% Pt) exhibited excellent electrocatalytic activity toward the HER with an ultra-high exchange current density of 0.71 mA cm⁻² which is identical to that of bulk platinum (Pt), “the gold standard” for hydrogen production, an ultra-low onset potential of −11 mV, a Tafel slope of 38 mV dec⁻¹ and over 100 h of electrochemical durability.