B.Sc.Engg., M.Sc.Engg. (MME, BUET)
Abstract
A novel CuO-MoS2 based heterostructure catalyst model system is proposed where a CuO nanosheet with exposed {001} facet with proper termination is the active surface for the catalysis and a MoS2 nanosheet is the supporting layer. Density functional theory (DFT) calculations were performed to validate the model. The MoS2 bilayer forms a stable heterostructure with {001} faceted CuO with different terminations exposing oxygen and copper atoms (active sites) on the surface. The heterostructure active sites with a low oxidation state of the copper atoms and subsurface oxygen atoms provide a suitable chemical environment for the selective production of multicarbon products from CO2 electrocatalytic reduction. Furthermore, our heterostructure model exhibits good electrical conductivity, efficient electron transport to active surface sites, and less interfacial resistance compared to similar heterostructure systems. Additionally, we propose a photoenhanced electrocatalysis mechanism due to the photoactive nature of MoS2. We suggest that the photogenerated carrier separation occurs because of the interface-induced dipole. Moreover, we utilized a machine learning model trained on a 2D DFT materials database to predict selected properties and compared them with the DFT results. Overall, our study provides insights into the structure–property relationship of a MoS2 supported 2D CuO nanosheet based bifunctional catalyst and highlights the advantages of heterostructure formation with selective morphology and properly terminated surface in tuning the catalytic performance of nanocomposite materials.
Selected Figures
Figure 1. Supercell structure of the (a) CuO nanosheet with Cu termination before coming into contact with MoS2; perspective view for the relaxed structures of (b) MoS2-CuO (001: Cu) or NC: Cu and (c) MoS2-CuO (001: O) or NC: O showing the CuO active layer. Top and side view of the slab and interface models of (d) pure MoS2 and MoS2-CuO heterostructure with Cu (NC: Cu) and O (NC: O) termination showing different interfacial distances after relaxation.
Figure 5. 2D color map of ELF before and after the contact between MoS2 (002) and (a) Cu (001): Cu and (b) Cu (001): O. ELF profile of the interfacial regions between neighboring atoms of S–Cu, Mo–S, and Cu–O for (c) NC: Cu and S–O, Mo–S and O–Cu for (d) NC: O. (e) Schematic illustrating the destacking of 2H-MOS2 layers due to interaction with CuO.
Figure 9. Optical absorption for MoS2 (MS) slab, NC: Cu, and NC: O structures for light irradiation along (a) lateral (along the z axis) and (b) transverse (along the symmetric x, y axis) directions and photoenhanced electrocatalytic CO2RR mechanism for both (c) lateral and (d) transverse cases.
Figure 10. Comparison of (a) band gap and (b) average refractive index (averaged along the x, y, and z directions) calculated with the DFT method and JARVIS-ML for MoS2, CuO, NC: Cu, and NC: O structures.
