Symmetrical synergy of hybrid Co9S8-MoSx electrocatalysts for hydrogen evolution reaction

Abstract

There exists a strong demand to replace expensive noble metal catalysts with efficient and earth-abundant catalysts for hydrogen evolution reaction (HER). Recently the Co-and Mobased sulfides such as CoS 2 , Co 9 S 8 , and MoS x have been considered as several promising HER candidates. Here, a highly active and stable hybrid electrocatalyst 3D flower-like hierarchical Co 9 S 8 nanosheets incorporated with MoS x has been developed via a one-step sulfurization method. Since the amounts of Co 9 S 8 and MoS x are easily adjustable, we verify that small amounts of MoS x promotes the HER activity of Co 9 S 8 , and vise versa. In other words, we validate that symmetric synergy for HER in the Co-and Mo-based sulfide hybrid catalysts, a long-standing question requiring clear experimental proofs. Meanwhile, the best electrocatalyst Co 9 S 8-30@MoS x /CC in this study exhibits excellent HER performance with an overpotential of-98 mV at-10 mA/cm 2 , a small Tafel slope of 64.8 mV/dec, and prominent electrochemical stability.

Nitrogen and Sulfur Co‐Doped Mesoporous Carbon Embedded with Co9S8 Nanoparticles: Efficient Electrocatalysts for Hydrogen Evolution

“…To tackle these issues, non‐noble metal contained materials have received considerable researches . Among all of the catalysts, numerous efforts have been focused on Co 9 S 8 ‐based composites, which are proved to reveal superior electrocatalytic performance for HER …”

Hydrothermal Synthesis of Hybrid Rod‐Like Hollow CoWO4/Co1−xS for High‐Performance Supercapacitors

“…From Figure (d), the Co 2 p spectrum exhibits two major peaks with binding energy at 778.3 and 793.4 eV, agreeing well with the Co 2 p 3/2 and Co 2 p 1/2 spin‐orbit peaks of Co 3+ in the sample. It also shows two intensive peaks located at 780.6 and 796.9 eV corresponding to the 2 p 3/2 and 2 p 1/2 core levels of Co 2+ , to sum up, the coexistence of Co 2+ and Co 3+ is evidenced . The W 4 f spectrum shows spin‐orbit splitting of W 4 f 7/2 at 35.3 eV and W 4 f 5/2 37.5 eV, which can be assigned to confirm the presence of W 6+ oxidation state .…”

Hierarchical Cobalt Sulfide/Molybdenum Sulfide Heterostructure as Bifunctional Electrocatalyst towards Overall Water Splitting

“…Hence, the high‐resolution XPS spectra of Co 2p, Mo 3d and S 2p for C 2 M 1 S were acquired and analyzed. Deconvoluted Co 2p spectra (shown in Figure b) suggested the presence of Co with 2 + and 3 + oxidation states in the material, however, all the peaks were blue‐shifted in comparison to the peaks at Co 2p spectra of CoS x (see in Table S1) . Co 3p spectra of C 2 M 1 S shifted towards higher binding energy (B. E.) in comparison to Co 3p spectra of CoS x (see Figure a).…”

“…Zhou et al. proved the “symmetric synergy” towards HER in case of Co 9 S 8 @MoS x composite due to the formation of Co‐S−Mo systems . In another example, Ganesan et al.…”