Di Huang,Lingxi Yang,Xing lin Li,Lina Zou,Baoxian Ye
A novel electrochemical sensor was designed and constructed for high-sensitive detection of Taxifolin based on Co 3 S 4 @MoS 2 loaded on reduced graphene oxide (RGO-Co 3 S 4 @MoS 2 ) as modified materials. It’s the first time for Co 3 S 4 @MoS 2 was exploited to constructed electrochemical sensor. Owing to the Co 3 S 4 @MoS 2 providing a huge surface area to enrich more Taxifolin and the excellent electric conductivity of RGO, Taxifolin was detected sensitively with a linear range from 5.0 × 10 −9 to 1.0 × 10 −6 mol L − 1 and limit of detection down to 1.67 × 10 −9 mol L − 1 (S/N = 3). In addition, the sensor also demonstrated strong anti-interference properties in the presence of some metal ions and organic compounds. The proposed method was successfully applied for determination of Taxifolin in traditional Chinese medicine in fructus polygoni orientalis with satisfactory results.
In this study, hollow Co 3 S 4 polyhedron decorated with interlayer-expanded MoS 2 nanosheets (Co 3 S 4 -MoS 2 ) was devised and applied to absorb tetracycline (TC) from aqueous solution. The adsorption performances and mechanisms were systematically explored. The experimental results indicated that the adsorption kinetics well-fitted the pseudo-second-order kinetics model and the adsorption isotherms followed the Langmuir model. In terms of Langmuir model, the maximum adsorption capacity of Co 3 S 4 -MoS 2 was achieved with a record-high value of 1667.14 mg/g at 308 K, which was much higher than that of other reported adsorbents. The excellent adsorption performance of the adsorbent toward TC was presented under a wide pH range (3.0–8.0) and was enhanced by the addition of salinity. The high adsorption capacity of Co 3 S 4 -MoS 2 depended on the combined effects of multi-affinities including π-π interaction, hydrophobic effect, surface complexation and hydrogen bonding. These results suggested that Co 3 S 4 -MoS 2 was a high-efficiency adsorbent for treating wastewater that contains TC and provided new insights into the design of other hollow metal sulfides nanomaterials to treat antibiotic-containing wastewater.
Constructing suitable heterostructured electrocatalysts and understanding their interfacial effects have been considered as an effective strategy to improve the intrinsic activity of electrocatalytic hydrogen evolution reaction (HER). In this work, ultra-small Co 3 S 4 -MoS 2 heterostructure was synthesized using a precursor solubility controlling method. It is found that the electrocatalytic HER performance of the heterostructured catalysts exhibited a low overpotential of 260 mV at 100 mA cm −2 in 1.0 M KOH and possessed remarkable stability over 100 h continuous electrolysis at high current density (100 mA cm −2 ). Besides, Co 3 S 4 -MoS 2 electrocatalyst is applied as the cathode material for a homemade membrane electrode device for water electrolysis to produce hydrogen. It shows that the electrocatalyst has a comparable catalytic activity to that of 20% Pt/C catalyst at 70 °C. The outstanding performance of the ultra-small Co 3 S 4 -MoS 2 heterostructure is attributed to the efficient mass transport benefitting from its unique ultra-small hollow structure and the rapid electron transfer at the interface between Co 3 S 4 and MoS 2 . XPS characterizations and DFT calculations confirm that the interfacial polarization and the corresponding electron transfer from Co 3 S 4 to MoS 2 at the interface optimizes the charge state of the catalyst and tunes the binding strength to the intermediates during each elementary step of the HER process. To be exact, the electron transfer promotes the adsorption of OH* on the charge-depleted Co 3 S 4 sites and the adsorption of H* on the charge-enriched MoS 2 sites, respectively, thereby reducing the free energy barrier of the water dissociation step (rate-limiting step) and improving the reaction kinetics. The solubility controlling strategy may provide a novel idea for rational design and synthesis of superior stability transition metal sulfides HER electrocatalysts.
Xiangyu Zhang,Hong Li,Yanhui Li,Xianhui Wang,Hongbin Wang,Wenrong Yang,Jingquan Liu,Da Li
To replace the current expensive precious metal catalysts for water electrolysis, it is important to develop inexpensive and powerful bifunctional catalysts for hydrogen production. It is an effective way to improve catalytic performance using excellent templates and elemental doping. Here, a hierarchical structure Fe-Co3S4/MoS2 was synthesized using an Fe–ZIF precursor prepared by ion exchange, followed by hydrothermal sulfuration and annealing. It required overpotentials of only 93 mV and 243 mV to achieve a current density of 10 mA cm−2 in the HER and OER, respectively. It also showed excellent catalytic performance for overall water splitting, requiring only 1.42 and 1.71 V to achieve current densities of 10 and 100 mA cm−2 in 1 M KOH. The catalyst also demonstrated excellent ultra-long-term stability. The superb catalytic performance and stability can be attributed to the Fe doping, exposing more active sites while retaining the highly stable framework of the ZIF. The component modulation of Co3S4 and MoS2 by Fe doping induced high intrinsic activity and excellent transfer coefficients. This work presents a novel approach to prepare noble metal-free catalysts with highly stable rich interfaces and defects for overall water splitting.
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