Search

A three-dimensional (3D) MoS2/CoS2 composite with shell/core heterostructure is in situ synthesized, which is composed of CoS2 acicular nanorod arrays and edge-terminated MoS2 nanosheets vertically...

A combination of high surface area, fast-speed charge transportation, excellent intrinsic activity, and low material cost is desired for electrocatalysts’ applications, such as hydrogen production, counter electrodes of electrochemical solar cells, etc. In this regard, we originally develop a vertically aligned Co-doped MoS2 nanosheet array via a facile chemical vapour deposition (CVD) approach that utilizes the reaction between drop-coated CoCl2-MoCl5 precursor film and sulfur vapour released from elemental sulfur powder. Such structure that exposes primarily edge sites of the nanosheets provides reaction with more active centers and guarantees that electrons transport almost along high-electron-mobility basal plane of MoS2. Simultaneously, the catalytic activity of the in-plane S atoms of MoS2, exposing at the splits of MoS2 nanosheets, can be triggered via Co atom-doping. Such an array that is in-situ grown on graphite foil substrate performs as an efficient electrocatalyst for hydrogen evolution reaction with an overpotential of 185 mV at a current density of 10 mA·cm−2 and an extremely high TOF 0.56 s−1 at 200 mV overpotential, meanwhile, sponsoring as a counter electrode for efficient (8.99%) dye-sensitized solar cells.

Molybdenum disulfide (MoS2)/sulfur-doped carbon sphere nanohybrid is facilely synthesized via sulfuring a molybdenum chloride–carbon sphere precursor on a flexible graphite paper substrate. Sulfur-doping could enhances the electrocatalytic activity for triiodide reduction. Moreover, there is the existence of atomic and electronic interactions between MoS2 and S-doped carbon spheres in the nanohybrid composite. Due to the synergistic effect, the microstructure of MoS2 is much affected, and thus exposing more plane edges and plenty of lattice defects. Besides, the conductivity of the nanohybrid is much improved with the carbon sphere additive. As a result, the dye-sensitized solar cell using the nanohybrid as counter electrode shows higher photoelectric conversion efficiency (7.72%) than those based on pure MoS2 (6.73%) and platinized F-doped tin oxide rigid glass (6.74%).

Molybdenum disulfide (MoS2) is considered as a promising candidate to Pt-based catalysts. Literatures report the active centers of MoS2 locate at its edges, while the perfect in-plane domains are not active. In this study, a simple Co Mo S precursor decomposition approach is used to synthesize Co-doped MoS2 in-situ grown graphite paper (GP) substrate. Electrochemical analyses reveal the Co-doped MoS2 possesses excellent electrocatalytic activity comparable to Pt. Density functional theory (DFT) calculations indicate the inert in-plane S atoms neighboring the doped Co atoms become active towards triiodide reduction, as revealed by the adsorption energies (Ead) of iodine atom decreasing from 0.36 eV to −0.52 eV, identical with value obtained from Pt (−0.52 eV). Due to increased active sites, highly conductive of GP, and excellent electrical connection between Co-doped MoS2 and GP substrate, the dye-sensitized solar cell fabricated using Co-doped MoS2/GP as counter electrode (CE) shows higher photoelectric conversion efficiency (7.26%) than those based on MoS2/GP CE (6.57%) and platinized F-doped tin oxide (Pt/FTO) electrode (6.87%).

Development of economical, stable and high-efficient electrocatalysts gives vital incentives to promote the large-scale implementation of clean energy devices. Transition metal sulfides and carbon materials provide broad platforms for design of highly active electrocatalysts thanks to their flexibility, high electrical conductivity, and possessing various catalytically active sites towards different reaction systems. Herein, a ternary-component MoS2–Co9S8-NC nanohybrid is synthesized, in which Co9S8, MoS2, and N-doped carbon (NC) are integrated with each other. Owing to forming abundant varied active centers including Co9S8–MoS2 heterojunctions, and Co–N, Mo–N coupling centers locating at the contact interfaces between transition metal sulfides and N-doped carbon, the hybrid demonstrates greatly enhanced performances towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Such hybrid represents low overpotentials of 95 mV and 230 mV to achieve 10 mA cm−2 current density for HER and OER in 1.0 M KOH, respectively, and demonstrates favorable prospects for large-scale applications in overall water splitting.