Mixed 1T–2H Phase MoS₂/Reduced Graphene Oxide as Active Electrode for Enhanced Supercapacitive Performance

Abstract

A hybrid aerogel, composed of MoS sheets of 1T (distorted octahedral) and 2H (trigonal prismatic) phases, finely mixed with few layers of reduced graphene oxide (rGO) and obtained by means of a facile environment-friendly hydrothermal cosynthesis, is proposed as electrode material for supercapacitors. By electrochemical characterizations in three- and two-electrode configurations and symmetric planar devices, unique results have been obtained, with specific capacitance values up to 416 F g and a highly stable capacitance behavior over 50000 charge-discharge cycles. The in-depth morphological and structural characterizations through field emission scanning electron microscopy, Raman, X-ray photoelectron spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller, and transmission electron microscopy analysis provides the proofs of the unique assembly of such 3D structured matrix. The unpacked MoS structure exhibits an excellent distribution of 1T and 2H phase sheets that are highly exposed to interaction with the electrolyte, and so available for surface/near-surface redox reactions, notwithstanding the quite low overall content of MoS embedded in the reduced graphene oxide (rGO) matrix. A comparison with other "more conventional" hybrid rGO-MoX electrochemically active materials, synthesized in the same conditions, is provided to support the outstanding behavior of the cosynthesized rGO-MoS.

Strong Charge Transfer at 2H–1T Phase Boundary of MoS2 for Superb High‐Performance Energy Storage

“…The corresponding gravimetric capacitance of 272 F g −1 achieved in the present work compares favorably with most of the literature values, e.g., ≈100 F g −1 ( Table 1 ). For example, a competitive value of 416 F g −1 was reported for the MoS 2 /G 3D structured matrix . However, the foam‐type electrode materials possess an apparently low packing density (<0.8 g cm −3 in most cases), and therefore there exists large unused empty space within the electrode, which could greatly lower the volumetric capacitance value.…”

One‐Pot Hydrothermal Synthesis of Ternary 1T‐MoS2/Hexa‐WO3/Graphene Composites for High‐Performance Supercapacitors

“…These peaks were attributed to (W‐O‐W) stretching modes of bridging oxygen (254 and 325 cm −1 ) and the (O‐W‐O) bending modes (693 and 805 cm −1 ) . In the ternary M‐W‐rGO composite, the two additional characteristic peaks at 375.3 and 403 cm −1 correspond to 2H‐MoS 2 , confirming the presence of a small amount of the 2H phase of MoS 2 . Furthermore, the peak at 980 cm −1 corresponds to the symmetric mode of the terminal W−O bond of hexa‐WO 3 .…”

“…[49] In the ternary M-W-rGO composite, the two additional characteristic peaks at 375.3 and 403 cm À1 cor- respondt o2 H-MoS 2 ,c onfirming the presence of as mall amount of the 2H phase of MoS 2 . [50] Furthermore, the peak at 980 cm À1 corresponds to the symmetric mode of the terminal WÀOb ond of hexa-WO 3 . [51] In the Ramans pectra of all composites, the presence of Da nd Gb ands at Ramans hifts of 1347 and 1594 cm À1 correspond to the sp 2 and sp 3 bondedc arbon atoms of rGO.T hus, the characteristics Raman peaks of 1T-MoS 2 and hexa-WO 3 in the ternary M-W-rGO composite verify that both are homogeneously distributed on the rGOs urface.…”

Vanadium‐Incorporated Metallic (1‐T) Molybdenum Sulfide Nanoroses for High‐Energy‐Density Asymmetric Supercapacitors

“…The widely known layered structure of MoS 2 (MS) still garners attention considering its electrochemical behavior analogous to graphite . In the recent years, it has conveyed its potential with its unique structure and electronic properties .…”

“…The widely known layered structureo fM oS 2 (MS) still garners attentionc onsidering its electrochemical behaviora nalogous to graphite. [1][2][3][4] In the recent years, it has conveyed its potential with its unique structure and electronic properties. [5][6][7] The stacked SÀMoÀSs ingle-layer sheets hold each other through weak van der Waal forces, generating aw ide scope for their electrochemical applications.…”