Maneuvering charge polarization and transport in 2H-MoS2 for enhanced electrocatalytic hydrogen evolution reaction

Abstract

Semiconducting 2H-MoS 2 with high chemical stability is a promising alternative to the existing electrocatalysts for the hydrogen evolution reaction (HER); however, the HER performance largely suffers from the limited number of active S sites and low mobility for charge transport. In this work, we demonstrate that the limitations of 2H-MoS 2 for the HER can be overcome by forming hybrid structures with metallic nanowires. Taking the integration with Pd as a proofof-concept, we show with solid experimental evidence that the one-dimensional structure of metallic nanowires facilitates electron transport to active S sites, while the interfacial charge polarization between MoS 2 and Pd increases the electron density of the S sites for improved activity. As a result, the hybrid structure exhibits a current density of 122 mA·cm −2 at −300 mV versus RHE and a Tafel slope of 44 mV·decade −1 with excellent durability, well exceeding the performances of bare 2H-MoS 2 and metallic 1T-MoS 2 . This work provides insights into electrocatalyst design based on charge transport and polarization, which can be extended to other hybrid structures.

Amorphous Molybdenum Sulfide/Carbon Nanotubes Hybrid Nanospheres Prepared by Ultrasonic Spray Pyrolysis for Electrocatalytic Hydrogen Evolution

“…As demonstrated in Figure c, when the MoS x /CNTs hybrid nanospheres coated on electrode is applied with a negative potential, the electrons transfer process from electrode to CNTs and then to MoS x will be facilitated by the internal electric field, rapidly accumulating an excessive negative charge density on active sites. As a result, the polarized electrons will promote the HER performance in the corresponding electrochemical processes …”

MoS2 Nanosheets Supported on Hollow Carbon Spheres as Efficient Catalysts for Electrochemical Hydrogen Evolution Reaction

“…5−8 Among them, molybdenum disulfide (MoS 2 ) with a lamellar hexagonal structure similar to graphite has recently emerged as a very promising nonprecious metal HER catalyst with attractive electrochemical performance in acidic electrolytes. 9−13 Density functional theory (DFT) calculations predict that only the edges of S–Mo–S in the MoS 2 sheets are active for H* adsorption, whereas the basal plane is electrocatalytically inert. 14,15 In addition, it has also been shown that catalysts with moderate hydrogen adsorption have a higher HER activity.…”

One‐Pot Synthesis of Tensile‐Strained PdRuCu Icosahedra toward Electrochemical Hydrogenation of Alkene

“…But H ads will continue to consume one electron to complete HER through Heyrovsky step. [38] Therefore, the declined current density can be attributed to hydrogenation of MBE with H ads . Figure 4C shows the I-t curves at a fixed bias in the presence of MBE, and the current densities are positively correlated with the applied bias.…”