g-C3N4/WTe2 Hybrid Electrocatalyst for Efficient Hydrogen Evolution Reaction

Recent experiments have highlighted the efficiency of nonprecious metal-based hybrid structures, such as g-C3N4/MoS2 and g-C3N4/graphene for hydrogen evolution reaction (HER). This work focuses on the interface effects of such hybrid heterostructures that could lead to the enhanced catalytic activity of g-C3N4. We have concentrated on the hybrid electrocatalysts with the architecture g-C3N4/X (X = WTe2, MoS2, and graphene), where the interface plays an important role in the overall HER. These promising candidates have been assessed using three main factors extracted from density functional theory calculations, namely: (i) the free energy of hydrogen adsorption on the catalytic site Delta G(H), (ii) Schottky barrier potentials, and (iii) induced charge polarization across the interface. We have found that particularly g-C3N4/WTe2 displays a suitable combination of the investigated properties standing out as a potential electrocatalyst for efficient hydrogen evolution reaction. Furthermore, the electronic structure fingerprints controlling the HER thermodynamics have been investigated. In particular, the N-H bonds have been found to display strong s-p hybridization and, additionally, Delta G(H) decreases as the center of N p-band approaches the Fermi energy. This is also a relevant result in understanding HER mechanisms of organic compounds.