Demystifying Synergistic\nMultifunctional Electrocatalysis\nof N‑Doped Graphene/WS<sub>2</sub> Heterostructure with Single-Atom\nCatalysts for Water Splitting and Fuel Cells

As the demand for sustainable energy continues to rise,\nelectrocatalysis\nhas become increasingly prominent in the advancement of clean energy\ntechnologies. By scrutinizing the material to function as a multifunctional\ncatalyst, the effectiveness of energy conversion processes is significantly\nenhanced. This study focuses on harnessing graphene/WS<sub>2</sub> van der Waals heterostructures for overall water splitting and fuel\ncell applications, using transition metals (TMs) from Sc–Zn\nas single-atom catalysts (SACs). Additionally, the research explores\nthe synergistic effect of nitrogen doping combined with SACs to modify\nthe material into multifunctional catalysts. The stability of all\nTMs as SACs in the vdW heterostructure (TM@GW) and nitrogen-doped\nTM@GW (TM@NGW) is validated with negative cohesive and formation energies,\nand thermodynamic stability is also corroborated with <i>ab initio</i> molecular dynamics (AIMD) analysis at both 300 and 500 K for 5 ps.\nThe observed electrocatalytic performance of TM@GW and TM@NGW depicts\nthat the Ni@NGW system exhibits trifunctional property with the lowest\noverpotentials {η<sub>HER</sub>; η<sub>OER;</sub> η<sub>ORR</sub> = 0.21; 0.42; 0.27 V}. Additionally, the Cr@NGW material\ndisplays bifunctional catalytic activity for the OER and ORR, with\noverpotentials of 0.53 and 0.37 V, respectively. The synergistic effect\nbetween N doping and SACs is further studied with the d, p band centers\nand density of states calculations. Furthermore, the scaling relation\nbetween the adsorption of intermediates and reaction kinetics is studied,\nwhich validates the coaction of N and SACs in the TM@NGW heterostructure.\nThis study demonstrates that the inclusion of SACs and nitrogen atoms\nin the GW heterostructure significantly enhances the catalytic performance\nby approximately 26%, effectively transforming the system into a multifunctional\ncatalyst. These findings emphasize the role of SACs in vdW heterostructures\nand N doping effects, providing valuable insights to guide the design\nof advanced catalysts for water splitting and fuel cell applications.