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Low-Temperature Wafer-Scale Growth of MoS2-Graphene Heterostructures
摘要： In this study, we successfully demonstrate the fabrication of a MoS2-graphene heterostructure (MGH) on a 4-inch wafer at 300 oC by depositing a thin Mo film seed layer on graphene followed by sulfurization using H2S plasma. By utilizing Raman spectroscopy and high-resolution transmission electron microscopy, we have confirmed that 5–6 MoS2 layers with a large density of sulfur vacancies are grown uniformly on the entire substrate. The chemical composition of MoS2 on graphene was evaluated by X-ray photoelectron spectroscopy, which confirmed the atomic ratio of Mo to S to be 1:1.78, which is much lower than the stoichiometric value of 2 from standard MoS2. To exploit the properties of the nanocrystalline and defective MGH film obtained in our process, we have utilized it as a catalyst for hydrodesulfurization and as an electrocatalyst for the hydrogen evolution reaction. Compared to MoS2 grown on an amorphous SiO2 substrate, the MGH has smaller onset potential and Tafel slope, indicating its enhanced catalytic performance. Our practical growth approach can be applied to other two-dimensional crystals, which are potentially used in a wide range of applications such as electronic devices and catalysis.
关键词： PECVD,graphene,large-scale,heterostructure,hydrogen evolution reaction,MoS2
更新于2025-09-10 09:29:36
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Controllable synthesis of P-doped MoS2 nanopetals decorated N-doped hollow carbon spheres towards enhanced hydrogen evolution
摘要： In order to construct the molybdenum disulfide (MoS2) hybrid nanostructure with enhanced conductivity and more active sites towards electrocatalytic hydrogen evolution reaction (HER), hierarchical P-doped MoS2 nanopetals decorated N-doped hollow carbon spheres (N-C@P-MoS2) core-shell structures were synthesized via calcination and hydrothermal synthesis. N-C@P-MoS2 with optimized loadings exhibited favorable HER activities with low onset overpotential (117 mV), small Tafel slopes (68 mV/dec), and fine stability compared with pure MoS2 nanosheets and all undoped samples. This is largely ascribed to the synergy of MoS2 and carbon in the rational hierarchical structures, as well as the modified electronic structure with improved conductivity, increased active sites by virtue of N and P doping. Furthermore, P-doped MoS2 nanosheets were encapsulated in carbon spheres (N-C/P-MoS2 (inside)) by controlling the dropping rate of adding MoS2 precursors. As the active sites were hampered, it is found that the N-C/P-MoS2 (inside) revealed poor HER performance compared with the core-shell counterparts. The results demonstrate that the fabrication of hierarchical MoS2/carbon composites with the synergy of structural (morphology and content) and electronic (active sites and conductivity) effects induced by various nonmetal doping pave the way for enhanced electrocatalytic HER activities.
关键词： Hollow carbon sphere,structural and electronic effect,Nonmetal doping,Hydrogen evolution reaction,Molybdenum disulfide
更新于2025-09-10 09:29:36
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Wireless Addressing of Free-Standing MoSe2 Macro- and Microparticles by Bipolar Electrochemistry
摘要： Doping of a transition metal dichalcogenide deposited onto a conducting surface acting as bipolar electrode was recently reported. Here, free-standing macro- and microscale transition metal dichalcogenide substrates are successfully employed as effective bipolar electrodes without the need of using an additional conducting support. This is first demonstrated by achieving site-selective bipolar electrodeposition of several metals such as gold, silver, copper and nickel on macroscale MoSe2 substrates (typically 1 cm in size). Also, the superior efficiency of MoSe2 compared to a carbon substrate towards hydrogen evolution reaction, well-known in conventional electrochemistry, is demonstrated in the bipolar electrochemistry configuration. Such electrocatalytic properties can be advantageously used by combining this reduction with a given oxidation reaction in order to ease the electrochemical coupling. Also, as a wireless technique, bipolar electrochemistry enables the simultaneous addressing of large ensembles of bipolar electrodes with a single pair of driving electrodes. Therefore, in a bulk experiment, a suspension composed of thousands of individual MoSe2 microparticles (with a typical size of 20-80 μm) that are addressed simultaneously, is employed to significantly accelerate an electrolysis. Amplex? Red was selected as an oxidizable organic model dye. Such an electrolysis occurs on the timescale of several seconds which is definitely not achievable by addressing a single macroscale MoSe2 bipolar electrode. This performance is due to the collective behavior of the ensemble of MoSe2 bipolar electrodes because the oxidation process occurs simultaneously at each individual anodic pole.
关键词： electrodeposition,MoSe2,bipolar electrochemistry,transition metal dichalcogenide,hydrogen evolution reaction
更新于2025-09-10 09:29:36
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Plasmon-Enhanced Electrocatalytic Properties of Rationally Designed Hybrid Nanostructures at a Catalytic Interface
摘要： In recent years, a promising role of plasmonic metal nanoparticles (NPs) has been demonstrated toward an improvement of the catalytic efficiency of well-designed hybrid electrocatalysts. In particular, the coupling of plasmonic functionality with the metal-based core–shell architectures in plasmon-enhanced electrocatalysis provides a sustainable route to improve the catalytic performances of the catalysts. Herein, the rationally designed AuNPs wrapped with reduced graphene oxide (rGO) spacer along with PdNPs (AuNP@rGO@Pd) as the final composite are reported. The rGO is proposed to promote the reduction of PdO, greatly enhance the conductivity, and catalytic activity of these nanohybrid structures. The plasmon-enhanced electrocatalytic performance of optimized AuNP@rGO(1)@Pd exhibits an ≈1.9- and 1.1-fold enhanced activity for the hydrogen evolution reaction and oxygen evolution reaction, respectively. The final composite also exhibits a superior stability up to 10 000 s compared with the commercial Pd/C. The mechanism of the enhanced catalytic performance is monitored through in situ X-ray absorption spectroscopy by observing the generated electron density under light irradiation. The results demonstrate that the energetic charge carriers are concentrated in the incorporated PdNPs, allowing higher catalytic performances for the overall water-splitting reaction. The conclusions herein drawn are expected to shed light on upcoming plasmon-induced electrocatalytic studies with analogous hybrid nanoarchitectures.
关键词： plasmonic nanoparticles,heterogeneous catalysis,photo-electrocatalysis,oxygen evolution reaction (OER),hydrogen evolution reaction (HER)
更新于2025-09-09 09:28:46
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Interfacial Scaffolding Preparation of Hierarchical PBA-Based Derivative Electrocatalysts for Efficient Water Splitting
摘要： The development of highly efficient and durable electrocatalysts is crucial for overall water splitting. Herein, the in situ scaffolding formation of 3D Prussian blue analogues (PBAs) on a variety of 2D or 1D metal hydroxides/oxides to fabricate hierarchical nanostructures is first demonstrated. Typically, cobalt hydroxide or oxide nanoarrays are used as the precursor and structural oriented template for the subsequent growth of 3D PBA nanocubes. The mechanism study reveals that the interfacial scaffolding process can be reversibly controlled via the in situ ion exchange process with adjusting coordination ions. Thus, the facile, versatile strategy can extend to successfully fabricate a variety of hierarchical PBA-based nanostructures including on cobalt fluoride hydroxide, copper hydroxide, monometal or bimetal nickel–cobalt hydroxides, cobalt oxide, and manganese oxide nanosheets with structural tailor-ability and chemical diversity. More interestingly, the metal nitride derivatives obtained via controlled calcination process exhibit good electrocatalytic activity for water splitting with low overpotentials, and remarkable durability for 1200 h, thanks to the superior intrinsic activity of bimetal nature and the scrupulous hierarchical structure. This versatile strategy provides a paradigm for rational design of PBA-based functional nanomaterials, which is highly promising in energy conversion, storage, and electrocatalytic fields.
关键词： oxygen evolution reaction,water splitting,Prussian blue analogue,electrocatalysis,hydrogen evolution reaction
更新于2025-09-09 09:28:46
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Growth of 1T’ MoTe <sub/>2</sub> by Thermally-Assisted Conversion of Electrodeposited Tellurium Films
摘要： Molybdenum ditelluride (MoTe2) is a transition metal dichalcogenide (TMD) which has two phases stable under ambient conditions, a semiconducting (2H) and semimetallic (1T’) phase. Despite a host of interesting properties and potential applications, MoTe2 is one of the less-studied TMDs, perhaps due its relatively-low abundance in nature or challenges associated with its synthesis, such as the toxicity of most precursors. In this report, we describe the fabrication of thin films of phase-pure 1T’ MoTe2 using pre-deposited molybdenum and electrodeposited tellurium layers, at the relatively low temperature of 450?C. This method allows control over film geometry and over the tellurium concentration during the conversion. The MoTe2 films are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and electron microscopies. When applied as a catalyst for the hydrogen evolution reaction, the films display promising initial results. The MoTe2 films have a Tafel slope of below 70 mV dec-1 and compare favorably with other MoTe2 catalysts reported in the literature, especially considering the inherently-scalable fabrication method. The variation in electrocatalytic behavior with thickness and morphology of the films is also investigated.
关键词： 1T’ phase,thin-film,hydrogen evolution reaction,Raman spectroscopy,MoTe2,electrocatalysis
更新于2025-09-09 09:28:46
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Outstanding hydrogen evolution performance of supported Pt nanoparticles: Incorporation of preformed colloids into mesoporous carbon films
摘要： Platinum is the best catalyst known so far for the hydrogen evolution reaction (HER) in acidic environments, but it is also a scarce and expensive resource. Maximizing its performance per metal atom is essential in order to reduce costs. The deposition of small Pt nanoparticles (2–3 nm) onto electrically conductive, highly accessible and stable carbon supports leads to active catalysts. However, blocking of pores and active sites by Na?on, which acts as a binding species, reduces the catalytic activity. Moreover, inaccessible Pt located in micropores diminishes an ef?cient exploitation of the noble metal. We report a new synthesis approach to ordered mesoporous carbon (OMC) coatings with preformed Pt nanoparticles. The particles are exclusively located inside the mesopores. Furthermore, no Na?on binder is needed. As a consequence, the PtNP/OMC catalyst ?lm outperforms Pt/C catalysts reported in literature particularly at high current densities. PtNP/OMC catalyst ?lms with a geometric Pt loading of 1.6 mgPt/cm2 achieve a current density of (cid:1)100 mA/cm2 at an overpotential of ca. (cid:1)70 mV.
关键词： Ordered mesoporous carbon,Noble metal colloids,Electrocatalysis,Mesoporous ?lms,Hydrogen evolution reaction
更新于2025-09-04 15:30:14
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Enhanced Photoelectrocatalytic H <sub/>2</sub> Evolution over Two-Dimensional MoS <sub/>2</sub> Nanosheets Loaded on Cu-Doped CdS Nanorods
摘要： Transition-metal ion doping and efficient decoration by using a co-catalyst have been proven to effectively inhibit the recombination of photogenerated electron-hole pairs and broaden the visible-light response region. Here, we have constructed MoS2 nanosheets decorated on a copper-doped CdS nanorod composite as a noble-metal-free photoelectrocatalyst. This kind of composite material was constructed through a simple solvothermal method. The morphology, structure, chemical states, photoelectrochemical properties, and other properties were tested by using a diverse range of analytical techniques. Owing to the Cu2 + doping and the excellent electron-capturing ability of MoS2, 5 % MoS2/Cu(cid:0) CdS (with 7 % Cu2 + doping in CdS) exhibits excellent hydrogen evolution reaction with a rate of 10.18 mmol h(cid:0) 1 g(cid:0) 1, which is about 48 times higher than that of pure CdS. A significant increase in the photoelectrochemical performance of the composite catalytic material benefits from the synergistic effect between CdS and MoS2 and fast interfacial charge transfer, owing to the Cu2 + doping. These findings provide a new thought for further research of the ion doping in photoelectrocatalytic field.
关键词： CdS,hydrogen evolution reaction,photoelectrochemical performance,MoS2,Cu2 + doping
更新于2025-09-04 15:30:14