Three-Dimensional Heterostructures of MoS₂ Nanosheets on Conducting MoO₂ as an Efficient Electrocatalyst To Enhance Hydrogen Evolution Reaction

Abstract

Molybdenum disulfide (MoS2) is a promising catalyst for hydrogen evolution reaction (HER) because of its unique nature to supply active sites in the reaction. However, the low density of active sites and their poor electrical conductivity have limited the performance of MoS2 in HER. In this work, we synthesized MoS2 nanosheets on three-dimensional (3D) conductive MoO2 via a two-step chemical vapor deposition (CVD) reaction. The 3D MoO2 structure can create structural disorders in MoS2 nanosheets (referred to as 3D MoS2/MoO2), which are responsible for providing the superior HER activity by exposing tremendous active sites of terminal disulfur of S2(-2) (in MoS2) as well as the backbone conductive oxide layer (of MoO2) to facilitate an interfacial charge transport for the proton reduction. In addition, the MoS2 nanosheets could protect the inner MoO2 core from the acidic electrolyte in the HER. The high activity of the as-synthesized 3D MoS2/MoO2 hybrid material in HER is attributed to the small onset overpotential of 142 mV, a largest cathodic current density of 85 mA cm(-2), a low Tafel slope of 35.6 mV dec(-1), and robust electrochemical durability.

Two-Dimensional Material Molybdenum Disulfides as Electrocatalysts for Hydrogen Evolution

“…Finally, the anchored MoS 2 can also exert a positive effect on the reaction sites of CoSe 2 and enhance the catalytic activity. Besides the carbon-based substrates, a hybrid structure can also enhance the MoS2 HER performance [60][61][62][63][64]. Jaramillo's group designed vertically oriented core-shell MoO3/MoS2 heterostructure nanowires [60].…”

Phase‐Engineered Weyl Semi‐Metallic MoxW1‐xTe2 Nanosheets as a Highly Efficient Electrocatalyst for Dye‐Sensitized Solar Cells

“…To date, several semiconductive TMDs have been employed as electrocatalysts in the energy conversion systems, such as dye‐sensitized solar cells (DSSC) and hydrogen evolution reactions (HER) . In electrocatalytic reactions, the specific chalcogen ligands and grain boundaries of TMDs were regarded as the active sites (e.g., the bridging and terminal and the apical and unsaturated in MoS 2 ), whose catalytic activities can be improved by utilizing surface engineering strategies to create artificial vacancies/defects on the basal plane of semicondoctor‐based TMD catalysts . However, the lack of sufficient electron transfer on TMD‐based catalysts due to their semiconducting nature has been the major bottleneck to achieve high electrocatalytic performance .…”

Morphology‐Dependent Catalytic Performance of MoS2/MoOx Heterojunction Nanostructures for Hydrogen Evolution Reaction

“…To overcome the low conductivity hindrance in MoS 2 , conductive supporting materials such as reduced graphene oxide (rGO), carbon black (CB), and carbon nanotubes have been often adopted. However, catalyst loading on HER inactive materials often decreases the active sites of MoS 2 …”

“…The good interfacial contact of MoS 2 /MoO x can improve charge transport, while defective interface of MoS 2 /carbon results in degraded HER performance in few cycles. Furthermore, high durability of MoS 2 in acidic solution can behave as a protective layer for corrosive MoO x core . However, complete covering of MoS 2 shells on MoO x core can decrease the exposure of MoS 2 edge sites.…”

“…After formation of the basal MoO 3 , its surface was substituted into MoS 2 by infusion of sulfur by annealing sulfur powder in heating zone to enhance HER catalytic performance and durability. During the sulfurization, the morphologies of the solid MoO 3 were maintained, and the morphology‐dependent catalytic performance can be investigated …”