Electrostatic co-assembly of FePS₃ nanosheets and surface functionalized BCN heterostructures for hydrogen evolution...

Advances in the hydrogen evolution reaction (HER) are intricately connected with addressing the current energy crisis and quest for sustainable energy sources. The necessity of catalysts that are efficient and inexpensive to perform the hydrogen evolution reaction is key to this. Following the ground-breaking discovery of graphene, metal thio/seleno phosphates (MPX₃: M - transition metal, P - phosphorus and X - S/Se), two dimensional (2D) materials, exhibit excellent tunable physicochemical, electronic and optical properties, and are expected to be key to the energy industry for years to come. Taking this into account, a facile time-effective electrostatic restacking synthesis procedure has been followed to synthesize a 2D/2D heterostructure (FePS₃@BCN) involving FePS₃, one of the prominent MPX₃ materials, with borocarbonitride (BCN), for hydrogen evolution reaction (HER). The piled up nanosheets of FePS₃ and BCN are held together by an electrostatic force, and display extreme robustness under the harsh conditions of HER application. The amalgamated electrocatalyst achieved an overpotential of 187 mV at a current density of 10 mA cm^-2 with a shallow Tafel slope of 41 mV dec^-1, following the Volmer-Heyrovsky mechanism. The resilience of the electrocatalyst has been examined through chronoamperometric testing for long term stability, and it is stable for more than 14 hours, which shows the excellent electrocatalytic activity for hydrogen evolution reaction owing to the strategic approach to the catalyst design, the use of numerous electrochemically active sites, large surface area and a barrier-free channel for quick ion transfer.