Enhanced electrocatalytic hydrogen evolution via nitrogen-induced electron density modulation in ReSe2/2D carbon heterostructures

Abstract

The synthesis of heterostructures composed of transition metal dichalcogenides (TMDs) and carbon nanostructures has garnered a lot of attention in recent years. This is due to the synergistic effects that arise from these heterostructures that are advantageous in various applications. This includes but is not limited to the improvement in electron conductivity of TMDs that are grown on carbon nanostructures. This improvement in electron conductivity can increase the catalytic activity of TMDs towards the hydrogen evolution reaction (HER). Therefore, it is crucial to understand the formation of these heterostructures and how the interaction of the component materials can improve their performance as electrocatalysts in the HER. This study highlights how surface chemistry affects heterostructure formation and the catalytic performance of heterostructures in the HER. ReSe₂ nanocrystals were grown on 2D carbon nanostructures, specifically reduced graphene oxide (rGO), nitrogen doped reduced graphene oxide (N-rGO), and graphitic carbon nitride (g-C₃N₄). FTIR, XPS, and TEM analyses showed that functional groups on carbon surfaces play a key role in the formation of the heterostructures. Among the materials tested, rGO had the highest ReSe₂ loading due to the availability of oxygen containing functional groups on the surface of rGO. However, the performance of the heterostructures as catalysts in the HER showed that ReSe₂-N-rGO had the highest catalytic activity with the lowest onset potential (115 mV), Tafel slope (72 mV dec⁻¹), and overpotential (218 mV). The enhanced performance of the ReSe₂-N-rGO catalyst was due to the modulation of rGO by nitrogen doping which improved the electron transfer between ReSe₂ and N-rGO, this was further confirmed using computational studies and by ReSe₂-N-rGO having the lowest R_ct (65 Ω).