Enhanced hydrogen evolution reaction for hydrothermally prepared g-C3N4/MoS2 heterostructure

Hydrogen Evolution Reaction has recently gained a lot of attention as an affordable approach to address both environmental and energy-related concerns. In this context, this study focuses on advancement in the field of catalytic activity using the significant contribution of graphitic carbon nitride/molybdenum disulfide (g-C 3 N 4 /MoS 2 ) heterostructure. Heterostructure is synthesized through a hydrothermal method, effectively combining the advantageous characteristics of both g-C 3 N 4 and MoS 2 . Different characterisation techniques, including XRD, Raman spectroscopy, FE-SEM, XPS, UV-Vis Spectroscopy, and Mott-Schottky analysis were used to thoroughly examine structural, morphological, interfacial properties of pristine g-C 3 N 4 and MoS 2 and also their synthesized heterostructure, g-C₃N₄/MoS₂. XRD characterization is employed to investigate the crystal structure of the g-C 3 N 4, MoS 2 and the g-C₃N₄/MoS₂ heterostructure. In contrast, FE-SEM is used for surface morphological study of g-C 3 N 4 , which is found to have flaky sheets, MoS 2 had flower like spherical globules, and g-C₃N₄/MoS₂ heterostructure was seen to have nanoflowers grown on the sheets of g-C 3 N 4 . Raman Spectroscopy characterization technique used to determine the vibrational modes of molecules. For MoS₂, in- plane (E 2g 1 ) and out- plane (A 1g ) were examined carefully to confirm the layered structure. For g-C₃N₄, a distinct band near 710 cm − 1 corresponding to tri-s-triazine rings, around 1350 cm − 1 and 1570 cm − 1 associated with disordered or graphitic carbons and other low-frequency modes of systems may also be observed. X-ray Photoelectron Spectroscopy (XPS) determined Mo 3d doublet peaks that confirmed the valence state of Mo in MoS₂, while the C 1s and N 1s spectra verified the preserved polymeric heptazine structure of g-C₃N₄. Furthermore, Mott-Schottky analysis was used to determine the flat band potential which combined with UV- Vis spectrum determined possible band diagram. The charge transfer between g-C₃N₄ and MoS₂ provided the formation of heterojunction. To evaluate the composite’s efficiency for water splitting, with attention given to HER, the composite g-C 3 N 4 / MoS 2 shows excellent HER activity with a low potential, high current density, and a favourable Tafel slope, signifying effective electrocatalytic performance. EIS analysis confirms that the reduced resistance contributed to improving charge transfer. Charge transfer resistance (R ct ) values calculated by fitting the circuit results as 14,000 Ω, 2208 Ω and 967.6 Ω for g-C 3 N 4 , MoS 2 , and g-C 3 N 4 / MoS 2 , respectively. The composite shows excellent HER activity with low overpotential, favorable Tafel slope, and reduced charge-transfer resistance. Chronoamperometry measurement performed also proved good electrochemical stability. It is demonstrated by these results that the combined properties of g-C 3 N 4 and MoS 2 lead to the formation of a heterostructure, i.e., suitable for electrocatalytic HER and hydrogen production.