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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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Photocatalytic performance of K2Ti6O13 whiskers to H2 evolution and CO2 photo-reduction
摘要： K 2 Ti 6 O 13 whiskers were synthesized by conventional sol-gel method, sono-chemical assisted and microwave assisted sol-gel method in order to obtain catalysts with different particle sizes and to modify their optical, textural and electrochemical properties. These modifications improved their photocatalytic activity for H 2 evolution and CO 2 photo-reduction. Long K 2 Ti 6 O 13 whiskers prepared by ultrasound assisted sol-gel method are the most active photocatalysts for the hydrogen evolution reaction using pure water as reactant (U-SG, 10,065 μmol g ?1 ). In contrast, an opposite behavior was observed using a mixture of ethanol-water, where the highest activity was achieved by the shortest and less crystalline K 2 Ti 6 O 13 whiskers (C-SG, h32871 μmol g ?1 ). In case of CO 2 photo-reduction, long whiskers that were also prepared by the sono-chemical assisted sol-gel method were the most active to transform CO 2 to formaldehyde, methane, methanol and hydrogen. The E FB value of this catalyst is located very close to the potential for formaldehyde production and favors the selectivity to this organic product.
关键词： Sol-gel,Whiskers,Hydrogen evolution,K 2 Ti 6 O 13,CO 2 reduction
更新于2025-09-10 09:29:36
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A green one-pot approach for mesoporous g-C3N4 nanosheets with in situ sodium doping for enhanced photocatalytic hydrogen evolution
摘要： Synchronous nano-structuring and element-doping of g-C3N4 were realized via a green one-pot approach to improve its photocatalytic activity. Na-doped mesoporous g-C3N4 nanosheets of ~5 nm in thickness were facilely synthesized by calcining a mixture of dicyandiamide and sodium chloride. NaCl not only serves as a con?ning-reactor to con?ne the growth of g-C3N4 into mesoporous nanosheets, but also acts as a sodium source for Na-doping. The nanosheets own greater speci?c surface area, stronger optical absorption and lower recombination of photo-induced electron-hole pairs than bulk g-C3N4, and exhibit an excellent visible-light photocatalytic hydrogen evolution ef?ciency which is about 13 times that of bulk g-C3N4. Moreover, the thermostable and hydrosoluble NaCl is simply removed and recycled by water and then directly reused in a new synthesis, making the process to be environmental-friendly and sustainable.
关键词： g-C3N4,Sodium chloride,Photocatalytic hydrogen evolution,Sodium doping,Mesoporous nanosheet
更新于2025-09-10 09:29:36
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Dimensional Impact of Metal-Organic Frameworks in Catalyzing Photo-Induced Hydrogen Evolution and Cyanosilylation Reactions
摘要： Metal-organic frameworks (MOFs) have been widely studied as heterogeneous catalysts. Compared to the MOFs with three dimensional (3D) topologies, two dimensional (2D) MOF nanosheets can allow facile access to the active sites on their external surface, thus having huge potentials in catalysis. Herein, we fabricate 2D MOF nanosheets, UiO-67-NS, as photocatalyst for H2 evolution reaction, and study their photocatalytic performance in relation to their 3D bulk counterparts (UiO-67). The UiO-67-NS exhibit an 84-fold increase in photocatalytic efficiency compared to UiO-67. Postsynthetic cation grafting of the UiO-67-NS with titanium leads to further enhancement in photocatalytic efficiency, giving a hydrogen evolution rate of up to 393 μmol g-1 h-1, which is 13-times higher than that of the non-grafting nanosheets under the same condition. Our results indicate that the 3D-to-2D dimensionality reduction can be a viable strategy for the development of MOFs as efficient photocatalysts. In addition, we have demonstrated that the improvement of catalytic performance based on the strategy of 3D-to-2D framework dimensionality reduction can be easily extended to heterogeneous cyanosilylation reaction.
关键词： Post-Synthetic Grafting,Metal-Organic Frameworks,Dimensional Impact,Photo-Induced Hydrogen Evolution,Metal-Organic Nanosheets
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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Graphene based nanocomposites for efficient photocatalytic hydrogen evolution: insight into the interface toward separation of photogenerated charges
摘要： Although the reduced graphene oxide (rGO) has been intensively applied to photocatalytic H2 evolution, no enough attention was given to study the interface between photocatalyst and rGO, which is the key point to affect the transportation of photogenerated electron. Herein, in order to research the heterojunctions interface, the series of SrTiO3 photocatalysts with different crystal facets were fabricated to load with rGO for photocatalytic H2 evolution. The characterization measurements and theory calculation verified that the rGO was mainly anchored on the Ti-O bond of SrTiO3. So, compared to {001} facets sample, the {110} facets of SrTiO3, exposed more Ti and O atoms, could form stronger bond with the rGO. Additionally, DFT study deduced that the photoinduced electron could immigrate rapidly from Ti-O bond to the rGO, which was in good agreement with the results of photoelectrochemical and photoluminescence (PL) experiments. Meanwhile, experimentally, the 1 % wt. rGO@SrTiO3 with {110} facets nanocomposite showed the superior photocatalytic H2 yield rate (3.82 mmol/h/g), which was 2.2 times and 3.2 times higher than that of pure SrTiO3 with the same facets and 1 % wt. rGO@SrTiO3 with {001} facets, respectively. Both experiments and theoretical calculations unveiled that the synergetic effect of SrTiO3 facets engineering and rGO loading effectively prompted the immigration of photoinduced electron at the nanocomposites interface. This work provides a rational thinking of a high efficiency rGO-based heterogeneous photocatalysts for solar energy conversion.
关键词： density functional theory study,rGO-based heterogeneous photocatalysts,separation of photogenerated charges,photocatalytic hydrogen evolution,SrTiO3,electron screening effect
更新于2025-09-09 09:28:46
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Rational Design of Graphic Carbon Nitride Copolymers by Molecular Doping for Visible-Light-Driven Degradation of Aqueous Sulfamethazine and Hydrogen Evolution
摘要： Carbon nitride is a promising metal-free visible light driven photocatalyst and sustainable material for address contaminant pollution and water splitting. However, the insufficient visible light absorption and fast charge recombination of carbon nitride have limited its practical application. Herein, the self-assembly carbon nitride (denoted as TCN) by molecular doping copolymerization of urea and 2-thiobarbitucid acid (TA) was prepared. XPS and elemental analytical results indicated that TA was doped in the framework of carbon nitride successfully. The self-assembly copolymerization would result in the change of morphology, intrinsic electron and band structure of carbon nitride. Theoretical calculations and experiments confirm that the band gap of TCN could be adjusted by changing the amount of 2-thiobarbitucid acid. Moreover, the efficiency of charge carrier transfer and separation was greatly enhanced. As a result, the optimized photocatalyst TCN-0.03 exhibited superior activity with a high reaction rate of 0.058 min-1 for the degradation of sulfamethazine under visible light irradiation, which is 4.2 times higher than that of urea based carbon nitride (U-CN). As a multifunctional photocatalyst, TCN-0.03 showed enhanced activity for hydrogen production (55 μmol h-1), which was 11 times higher than U-CN. The apparent quantum efficiency reached to 4.8% at 420 nm. A possible mechanism was proposed to explain the photocatalytic reaction process. This work provides insight into the rational design of modified carbon nitride by other organic monomers copolymerization to enhance the photocatalytic activity.
关键词： Photocatalytic degradation,Photocatalytic hydrogen evolution,Carbon nitride,Charge carriers transfer,Molecular doping copolymerization
更新于2025-09-09 09:28:46
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Cooperative effect between BaTiO3 and CaFe2O4 in a cocatalyst-free heterojunction composite for improved photochemical H2 generation
摘要： A series of novel BaTiO3/CaFe2O4 heterojunction composites with different weight ratios of CaFe2O4 vs BaTiO3 was successfully fabricated by sonication-calcination method using the pre-prepared BaTiO3 and CaFe2O4 powders synthesized in hydrothermal and sol-gel methods, respectively. The composites were well characterized using XRD, UVevis DRS, SEM, TEM, EDS and XPS to substantiate that BaTiO3 and CaFe2O4 coexist in the heterojunction composite. The highest photocatalytic hydrogen generation rate was obtained for BaTiO3/CaFe2O4 (40 wt%) compared to either of its individual counterparts and this improvement indicated the existence of a cooperative effect between BaTiO3 and CaFe2O4 in the heterojunction. Based on UV-vis-DRS, photoluminescence and time-resolved fluorescence lifetime measurements, the cooperative effect between BaTiO3 and CaFe2O4 originated from the improved photoresponse in the visible light region and efficient separation of the photogenerated electronehole pairs augmenting their availability for the photocatalytic reaction. A plausible photocatalytic mechanism was also deduced using electrochemical impedance spectroscopy measurements, describing the migration direction of the separated charge carriers. Moreover, the best composite BaTiO3/CaFe2O4 (40 wt %) exhibited fairly stable photoactivity for H2 production using the sacrificial agent (Na2S and Na2SO3) without the assistance of any noble metals as cocatalysts.
关键词： Cocatalyst free,BaTiO3/CaFe2O4 composite,Hydrogen evolution,Sonication-calcination method,Heterojunction
更新于2025-09-09 09:28:46