B,N co-doped V2C nanoparticle embedded FeP nanoflake substrates as unique bifunctional electrocatalysts for overall water splitting in alkaline media

Abstract

Hydrogen energy as a solution to meet energy demands has highlighted the need for efficient and cost-effective electrocatalysts for hydrogen production through water electrolysis. Heterointerface materials with self-support have shown promising electrochemical performances due to their modulated electron structure, improved electrochemical surface area, and more active sites. In our study, we successfully synthesized a heterostructure material comprising iron phosphide (FeP) nanoflakes as a substrate, embedded with boron (B) and nitrogen (N) co-doped vanadium carbide (V₂C) nanoparticles through a hydrothermal method followed by pyrolysis. We prepared FeP@B,N-V₂C heterostructures to enhance efficiency using different weight ratios (5%, 10%, 15%, and 20%) of FeP substrates while adjusting B,N-V₂C nanoparticles accordingly. The catalytic applicability of these materials was evaluated in electrochemical water splitting in an alkaline medium. Compared to other heterostructures, 10% FeP@B,N-V₂C exhibited the highest catalytic activity, with overpotentials for the OER and HER in an alkaline medium of 260 mV and 235 mV, respectively, at a current density of 10 mA cm⁻². The low Tafel values were determined as 56.85 mV dec⁻¹ and 118 mV dec⁻¹, with remarkable stability over 24 hours with a higher efficiency of 97.3%. The effectiveness and stability of electrocatalysts were corroborated by its ability in the overall water splitting (OWS), which occurred at a lower onset potential of 1.57 V@10 mA cm⁻². The low overpotentials and Tafel values observed in these catalysts are attributed to the heterojunction formed between the FeP nanoflakes and B,N co-doped V₂C nanoparticles. The enhancement in electrochemical activity resulting from the heterojunction is due to the higher surface area, increased porosity, decreased electrochemical resistance and the introduction in electroactive centres due to B,N co-doping. Consequently, this study provides a promising platform for developing novel nanomaterials for energy conversion applications.