Nanosheet Heterostructure Research Articles

Electrochemical Reversible Reforming between Ethylamine and Acetonitrile on Heterostructured Pd-Ni(OH)2 Nanosheets.

Rational design of electrocatalysts is essential to achieve desirable performance of electrochemical synthesis process. Heterostructured catalysts have thus attracted widespread attention due to their multifunctional intrinsic properties, and diverse catalytic applications with corresponding outstanding activities. Here, we report an in-situ restoration strategy for the synthesis of ultrathin Pd-Ni(OH)2 nanosheets. Such Pd-Ni(OH)2 nanosheets exhibit excellent activity and selectivity towards reversible electrochemical reforming of ethylamine and acetonitrile. In the acetonitrile reduction process, Pd acts as reaction center, while Ni(OH)2 provide proton hydrogen through promoting the dissociation of water. Also ethylamine oxidation process can be achieved on the surface of the heterostructured nanosheets with abundant Ni(II) defects. More importantly, an electrolytic cell driven by solar cells was successfully constructed to realize ethylamine-acetonitrile reversible reforming. This work demonstrates the importance of heterostructure engineering in the rational synthesis of multifunctional catalysts towards electrochemical synthesis of fine chemicals.

Electrochemical Reversible Reforming between Ethylamine and Acetonitrile on Heterostructured Pd‐Ni(OH)2 Nanosheets

AbstractRational design of electrocatalysts is essential to achieve desirable performance of electrochemical synthesis process. Heterostructured catalysts have thus attracted widespread attention due to their multifunctional intrinsic properties, and diverse catalytic applications with corresponding outstanding activities. Here, we report an in situ restoration strategy for the synthesis of ultrathin Pd‐Ni(OH)2 nanosheets. Such Pd‐Ni(OH)2 nanosheets exhibit excellent activity and selectivity towards reversible electrochemical reforming of ethylamine and acetonitrile. In the acetonitrile reduction process, Pd acts as reaction center, while Ni(OH)2 provide proton hydrogen through promoting the dissociation of water. Also ethylamine oxidation process can be achieved on the surface of the heterostructured nanosheets with abundant Ni(II) defects. More importantly, an electrolytic cell driven by solar cells was successfully constructed to realize ethylamine‐acetonitrile reversible reforming. This work demonstrates the importance of heterostructure engineering in the rational synthesis of multifunctional catalysts towards electrochemical synthesis of fine chemicals.

Magnetic-assisted exciton-plasmon interactions modulated Bi2S3 nanorods@MoS2 nanosheets heterojunction: towards a split-type photoelectrochemical sensing of profenofos.

A split-type photoelectrochemical (PEC) sensor was designed for the detection of profenofos (PFF) depending on the magnetic-assisted exciton-plasmon interactions (EPI) between the semiconductor substrate and Au NPs. The core-shell Bi2S3 nanorods@MoS2 nanosheets (Bi2S3 NRs@MoS2 NSs) heterostructure nanomaterial with fascinating performance was synthesized and used as the photovoltaic conversion substrate and signal molecules absorption platform. The PEC sensor is operated by co-incubating with the released Au NPs-cDNA from the surface of magnetic beads, originating from the target-triggered DNA double-stranded structure opening event. Due to the strong EPI effects, the photocurrent of Bi2S3 NRs@MoS2 NSs decreased and varied with the PFF concentrations. The proposed PEC sensor exhibited outstanding analytical performances, including a wide linear range (1.0 pg mL-1~1.0 μg mL-1), low detection limitation (0.23 pg mL-1, at 3 σ/m), excellent specificity, high stability, and applicability. Overall, this work provides a new signal strategy for PEC biosensors and extends its application in environmental analysis.

Ni0.85Se@CoFe LDH heterostructure nanosheet arrays on Ni foam as efficient electrocatalysts for enhanced oxygen evolution

Exploring high-efficient, earth-abundant and stable electrocatalyst for oxygen evolution reaction (OER) is of vital importance for large-scale implementation of energy converting and storing. Thus, we fabricated a free-standing hierarchical heterostructure electrode of Ni0.85Se@CoFe LDH/NF via a rational combination of hydrothermal, selenization and electrodeposition process, among which the ultrathin CoFe LDH nanosheets intimately assembled onto the vertical aligned Ni0.85Se nanosheets supported on Ni foam. The constructed core-shell nanosheet arrays hold the plentiful hetero-interfaces and intimate interactions through metal-oxygen bonds between two individuals, which guarantee the fast OER kinetic processes. Additionally, CoFe LDH with crystalline/amorphous hybrid structure favors providing more reaction sites. Remarkably, the optimal Ni0.85Se@CoFe LDH/NF binary composites possess outstanding OER activity with a low overpotential of ∼223 and 280 mV at 10 mA cm−2 and 100 mA cm−2 in alkaline solution as well as good durability. This research offers an alternative approach for improving electrocatalytic water splitting through constructing 3D hierarchical heterostructures.

Pt clusters in carbon network to enhance photocatalytic CO2 and benzene conversion of WOx/g-C3N4 nanosheets

Noble metals in carbon networks dramatically improve the carrier separation and transfer efficiencies of layered graphic carbon nitride (g-C3N4) based heterostructures for efficient CO2 and benzene photocatalytic conversion. Here, Pt clusters are homogeneously incorporated into ultrathin g-C3N4 nanosheets via multi-step treatment method using the combinations of mechano-chemical pre-reaction and two-step thermal condensation processes. Small Pt nanoparticles with diameters of less than 5 nm are observed and WOx nanobelts with increased oxygen vacancies (as the active sites) are horizontally grown on the thin Pt-g-C3N4 nanosheets. The photocatalytic activities of the constructed composite materials are evaluated under full solar spectrum irradiation condition including water splitting, CO2 photoreduction, and benzene to phenol conversion. The WOx/Pt-g-C3N4 nanosheet heterostructures with optimized preparation condition and without adding any co-catalyst reveals enhanced H2 generation (5267 μmolg−1h−1) and CO2 photoreduction (5.89 and 3.12 μmolg−1h−1 for CO and CH4 conversion rate, respectively), as well as improved benzene to phenol conversion (89.0%) and selectivity (98.2%). The presence of Pt clusters in the heterostructures improves charge transport in-between g-C3N4 and WOx, thus enhances the charge separation efficiency of the composite material. Detailed photocatalytic mechanisms are discussed on the alteration from S-scheme WOx/g-C3N4 heterostructure to Z-scheme WOx/Pt-g-C3N4 heterostructure.

Cu2 P7 -CoP Heterostructure Nanosheets Enable High-Performance of 5-Hydroxymethylfurfural Electrooxidation.

Electrooxidation of 5-hydroxymethylfural (HMF) into 2,5-furandicarboxylicacid (FDCA) has been regarded as a promising sustainable approach to achieve value-added chemicals. However, it is still impeded by the unsatisfactory performance of electrocatalysts. Here, Cu2 P7 -CoP heterostructure nanosheets were reported to enable powerful HMF electrooxidation. The Cu2 P7 -CoP heterostructure nanosheets were fabricated by microwave-assisted deep eutectic solvent (DES) approach, along with subsequent phosphiding. The Cu2 P7 -CoP heterostructure nanosheets enabled a superb 100 % HMF conversion at 1.43 V (vs. RHE) with 98.8 % FDCA yield and 98 % Faradaic efficiency (FE), demonstrating its promising application in HMF electrooxidation. X-ray photoelectron spectroscopy (XPS) analysis, open-circuit potential (OCP) approach and density functional theory (DFT) calculation uncovered that the electron transfer and redistribution between Cu2 P7 and CoP improved the adsorption capacity of HMF and modulated the catalytic performance. This study not only offered a powerful electrocatalyst for HMF electrooxidation, but also provided a conceptually new strategy for the heterostructure catalyst design.

Interfacial engineering of two-dimensional NiS2/VS heterostructure nanosheets as bifunctional electrocatalysts for urea-assisted energy-saving water electrolysis

Heterostructure electrocatalysts based on transition metal sulfides (TMS) have been extensively applied in renewable energy research because the rich interfaces afford high intrinsic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we have fabricated two-dimensional (2D) nickel sulfide and vanadium sulfide heterojunction nanosheets (NiS2/VS-3:1) arranged on carbon cloth as efficient bifunctional catalysts for electrocatalytic water splitting. The strong electronic interaction between NiS2 and VS in the NiS2/VS-3:1 heterostructure nanosheets was beneficial to tune the electronic structures and induce the formation of dual-functional reactive sites (Ni3+ for OER and V2+ for HER) in one heterojunction electrocatalyst, contributing to the promising catalytic activities toward electrocatalytic water splitting. The NiS2/VS-3:1 electrocatalyst has exhibited prominent catalytic activities toward HER and OER, which required low overpotentials of 74 and 235 mV to yield the current density of 10 mA cm−2 in 1 M KOH. Compared with pure NiS2 or VS, the NiS2/VS-3:1 electrocatalyst delivered faster reaction kinetics, improved electron-transfer ability, and enlarged electrochemical active surface area, which were mainly attributed to the fascinating heterostructure in the nanosheets. Some more easily oxidized substances have been added into electrolyte as adjuvants to realize energy-saving hydrogen production, pollutant degradation, and biomass upgrading.

Novel hierarchical FeWO4–FeNi3 heterostructure nanosheets for highly active water electrolysis at large current density

The development of efficient bifunctional catalysts for water electrolysis is of great significance, especially at large current density. Herein, a kind of heterostructure catalyst composed of FeNi3 nanoparticles and FeWO4 nanosheets is prepared by hydrothermal and calcination. It exhibits good activity for both oxygen evolution reaction and hydrogen evolution reaction , only 1.43 V and −43 mV are needed to obtain ±10 mA cm−2 respectively. Besides, it can work for 100 h at 1000 mA cm−2 under simulated industrial condition (6.0 M KOH solution, 60 °C) for overall water splitting , showing robust stability. This good performance could owe to: (1) Heterostructure facilitates the electrons transfer at the interface, thereby promoting the reaction process and enhancing the intrinsic catalytic activity; (2) Hierarchical array structure consisting of nanoparticles and nanosheet can expose more active areas and accelerate the transport of ions and charges, accelerating the release of bubbles for enhancing stability. Therefore, this work offers a promising method to design high-performance catalyst for practical water electrolysis.

Low-crystalline CoCu–MgAl oxide nano sheet heterostructures immobilized by crab shell-derived phosphorus-doped carbon for hydrazine dehydrogenation

Background: Hydrogen production and transportation can be made safe and efficient through hydrazine dehydrogenation heterogeneous catalysis. Methods: The phosphate mediation synthesized CoCu@MgAl2O4 Nano sheets (0.89 nm in diameter) are anchored to crab shell-derived carbon (CSDC). Bimetallic CoCu2+ must be strongly absorbed and dispersed in the phosphate-modified CSDC to produce highly dispersed ultrafine NPs. The phosphate group successfully dispersed the ultrafine CoCu NPs with a size of 1.24 nm on MgAl2O4/(P)CSDC. The optimized Co0.7Cu0.3@MgAl2O4/(P)CSDC system has exceptional catalytic activity for hydrazine dehydrogenation, with a TOF value of 11,070 h−1 at 298 K and 100% H2 selectivity. Significant findings: The introduction of the phosphate group favors the production of ultrafine and well-dispersed bimetallic CoCu NPs and also influences the electronic structure of metal catalytic sites. This implies that the prepared catalyst could improve the catalytic performance for catalyzing hydrazine dehydrogenation. This research might lead to an effective system for developing high-performance bimetallic Nano systems for future catalytic applications.

NiCo alloy nanoparticles anchored on mesoporous Mo2N nanosheets as efficient catalysts for 5-hydroxymethylfurfural electrooxidation and hydrogen generation

Construction of highly active and stable bifunctional catalysts for 5-hydroxymethylfurfural oxidation reaction (HMFOR) and hydrogen evolution reaction (HER) is meaningful but remains a challenge. Herein, the NiCo–Mo2N heterostructure nanosheets catalyst with excellent HMFOR/HER performance is obtained by a simple hydrothermal and calcination method. The heterogeneous interface between NiCo and Mo2N induces electron redistribution, regulating the electronic structure of the catalyst and thus optimizing the adsorption/desorption behavior of HMFOR/HER intermediates. Consequently, NiCo–Mo2N/NF exhibits superior catalytic activity with a potential of 1.14 VRHE/−17 mVRHE (HMFOR/HER) at ±10 mA cm−2, and the HMF conversion rate, FDCA yield, and Faradaic efficiency (FE) are ∼100%, 99.98%, and 98.65%, respectively. Besides, it only requires a low voltage of 1.36 V to achieve 100 mA cm−2 for HMFOR-assisted H2 production. This study provides a strategy for the development of efficient bifunctional catalysts for sustainable production of high value-added products and hydrogen.

Activable Ru-PdRu nanosheets with heterogeneous interface for High-efficiency alcohol oxidation reaction

Fabricating 2D nanomaterials with heterogeneous structure is a feasible way to improve catalytic performance owing to its large surface area and tunable electron structure. However, such a category has not been widely reported in the field of alcohol oxidation reaction (AOR). In this work, we reported a new type of heterostructure nanosheet with Ru nanoparticles decorated around the edge of PdRu nanosheets (Ru-PdRu HNSs). Particularly, strong electronic interaction and sufficient active sites attributed to the construction of heterogeneous interface, is the key to the superior electrocatalytic behavior of Ru-PdRu HNSs towards methanol oxidation reaction (MOR), ethylene glycol oxidation reaction (EGOR), and glycerol oxidation reaction (GOR). Remarkably, owing to the enhanced electron transfer brought by the introduction of the Ru-PdRu heterogeneous interface, these novel nanosheets are highly durable. Apart from being able to maintain the highest current density after 4000 s chronoamperometry test, Ru-PdRu HNSs can be reactivated with negligible activity loss in MOR and GOR test after four consecutive i-t experiments. Impressively, in the EGOR test, after reactivation, the current density is step-wisely increased, making it one of the best AOR electrocatalysts.

Slow Cooling and Transfer Dynamics of Hot Excitons in CsPbBr3 Perovskite Quantum Dots/g-CN Nanosheet Heterostructures: Implications for Optoelectronic Applications

Slow cooling and long-lived hot carrier (HC) population plays a crucial role in crossing the Shockley–Queisser limit and achieving high-efficiency perovskite photovoltaic devices up to 66%. Herein, we investigated the slow cooling of HCs via charge transfer in in-situ synthesized CsPbBr3 perovskite quantum dots-decorated graphitic carbon nitride nanosheet (CsPbBr3 PQDs/g-CN NS) heterostructures using ultrafast transient absorption (UTA) spectroscopy. Halide perovskites showed excitation energy-dependent HC cooling. We examined the HC dynamics at two different excitation energies with varying excitation pump fluences. UTA revealed significantly higher slow cooling and slow bleach recovery in CsPbBr3 PQDs/g-CN NSs (i.e., 632 fs and 845 ps) compared to pure CsPbBr3 PQDs (i.e., 512 fs and 371 ps) at an excitation energy of 3.54 eV and a fluence of 250 μW, suggesting that HCs transfer through the heterostructure interface. The observed slow cooling can be explained by the stronger interaction between the organic polymeric frameworks of g-CN NSs and CsPbBr3 PQDs, which passivates the trap states of CsPbBr3 PQDs and offers slow electron–hole recombination by slowing down the Auger recombination or the hot-phonon bottleneck effect. Additionally, density functional theory (DFT) calculations were carried out to shed light on band alignment at the interface to reveal the mechanism of efficient charge transfer in CsPbBr3 PQDs/g-CN NSs and validate the experimental findings. The insight of this study is quite beneficial for designing modified perovskite nanostructures for realization in perovskite solar cells in the near future.

NIR-responsive GO/Ag2S heterostructure for rapid bacteria-killing and wound healing

Many efforts have been made to treat infections; however, it is difficult to treat bacterial infections effectively with a single antibacterial strategy. Therefore, it is imperative to develop drugs or materials with multiple synergistic mechanisms. Graphene oxide/silver sulfide (GO/Ag2S) heterostructure would become potential nano-antibiotics that display a synergistic photothermal/photodynamic antibacterial mechanism. The material was characterized with different tests, meanwhile, density functional theory (DFT), electrochemical tests, and electron paramagnetic resonance (EPR) were also tested. The heterostructure nanosheets showed significant therapy via effective photothermal/photodynamic conversion and displayed antibacterial activity against both gram-positive S. aureus and gram-negative E. coli. In addition, we found that GO/Ag2S heterostructure could disrupt the integrity of bacterial membranes and inhibit the growth of bacteria. We confirmed its antibacterial effects in subcutaneous abscess models as well. Therefore, GO/Ag2S heterostructure could be a viable alternative option for antibiotic development.

One-spot autogenous formation of crystalline-amorphous Ni3S2/NiFeOxHy heterostructure nanosheets array for synergistically boosted oxygen evolution reaction

We proposed a convenient heterostructure engineering strategy to integrate ultra-small Nickel sulfide (Ni3S2) laminar nanocrystallines and amorphous NiFe-(oxy) hydroxides (NiFeOxHy) nanosheets as three-dimensional (3D) freestanding catalyst to regulate electric conductivity and boost mass transport by one-step hydrothermal method. These super-hydrophilic Ni3S2/NiFeOxHy heterostructure nanosheets with large specific surfaces can create strongly synergistic couplings of accessible active sites at the interfaces, expedite the electrolyte penetration and make gas bubbles to rapidly release the surface, significantly facilitating intrinsic the kinetics for oxygen evolution reaction (OER). Intriguingly, the self-supported Ni3S2/NiFeOxHy heterostructure nanosheets array displays remarkable OER activity with ultralow overpotentials of only 209 and 243 mV at 50 and 100 mA cm−2, small Tafel slope of 79.8 mV dec−1, as well as good stability up to 55 h. Also, the Ni3S2/NiFeOxHy heterostructure demonstrates an acceptable activity for hydrogen evolution reaction (HER) delivered 10 mA cm−2 at an overpotential of 172 mV. In addition, the Ni3S2/NiFeOxHy can also be served as bifunctional electrocatalyst assembled in a two-electrode configuration with a perfect voltage of 1.32 V to reach 10 mA cm−2 under industrial condition at 85 °C in 6 M KOH for overall water splitting.

Construction of nickel selenides heterointerfaces with electron redistribution for solar-driven water splitting

Developing heterostructures electrocatalysts was a promising method to improve the water splitting efficiency. However, due to the difficulty of synthesis, such low-cost and high-activity heterostructures electrocatalysts have not been developed. In this work, Ni3Se2/NiSe heterostructure nanosheets with rich-phase boundaries were synthesized by soaking at room temperature and annealing treatment using nickel foam as both Ni source and substrate. Such a nanosheet-like Ni3Se2/NiSe heterostructure could expose more active sites and efficient mass transfer at solid-liquid-gas three-phase interfaces, which exhibits a lower overpotential of 336 mV at 100 mA cm−2 and exceptional stability over 80 h at the current density of 300 mA cm−2 for OER in alkaline solution. Furthermore, the heterostructures electrode implements solar-driven water with a high solar-to-hydrogen efficiency of 18.3%. This heterostructure strategy might be a major breakthrough for improving the transition metal selenides and designing high-active and stable catalysts for electrochemical water oxidation.

M-N4-Gr/MXene Heterojunction Nanosheets as Oxygen Reduction and Evolution Reaction Catalysts: Machine Learning and Density Functional Theory Insights

MXene nanosheet materials with fast charge transfer characteristics and superior electrical conductivity are popular candidates for oxygen electrocatalysts. In this paper, the oxygen reduction and evolution reaction (ORR and OER, respectively) catalytic activities of 78 M-N4-Gr/MXene (Ti2C, Nb2C, and V2C) heterostructure nanosheets were investigated based on density functional theory (DFT) calculations and machine learning (ML) predictions. The random forest regression (RFR) algorithm proved to be the most desirable ML model for the prediction of catalytic activity with ORR/OER root mean square errors of 0.10 and 0.23 V, respectively. The obtained results show that Ni-N4-Gr/Nb2C (η*ORR = 0.31 V) and Ni-N4-Gr/V2C (η*ORR = 0.32 V) are effective ORR catalysts (prediction error of 0.03 V only), Ru-N4-Gr/Nb2C (η*OER = 0.40 V) is a promising OER catalyst, and Co-N4-Gr/V2C (η*ORR = 0.45 V/η*OER = 0.30 V) is an excellent bifunctional catalyst. Through further model analysis, the d band center of the metal active site was determined to be the most effective descriptor and a volcano curve relationship between the intrinsic descriptor and the overpotential was established based on the characteristic importance and Pearson correlation. The research approach adopted in this study may be used to screen and design other MXene heterojunction catalysts and remarkably accelerate catalyst design for many significant reactions.

CdS nanocrystallites sensitized ZnO nanosheets for visible light induced sonophotocatalytic/photocatalytic degradation of tetracycline: From experimental results to a generalized model based on machine learning methods

CdS/ZnO nanosheets heterostructures ((x)CdS/ZNs) with different mole ratios of Cd/Zn ((x) = 0.2, 0.4, and 0.6) were synthesized by the impregnation-calcination method. PXRD patterns showed that the (100) diffraction of ZNs was the most significant in the (x)CdS/ZNs heterostructures, and it confirmed that CdS nanoparticles (in cubic phase) occupied the (101) and (002) crystal facets of ZNs with hexagonal wurtzite crystal phase. UV–Vis DRS results indicated that CdS nanoparticles decreased the band gap energy of ZNs (2.80–2.11 eV) and extended the photoactivity of ZNs to the visible light region. The vibrations of ZNs were not observed clearly in the Raman spectra of (x)CdS/ZNs due to the extensive coverage of CdS nanoparticles shielding the deeper-laying ZNs from Raman response. The photocurrent of (0.4) CdS/ZNs photoelectrode reached 33 μA, about 82 times higher than that for ZNs (0.4 μA, 0.1 V vs Ag/AgCl). The formation of an n-n junction at the (0.4) CdS/ZNs reduced the recombination of electron-hole pairs and increased the degradation performance of the as-prepared (0.4) CdS/ZNs heterostructure. The highest percentage removal of tetracycline (TC) in the sonophotocatalytic/photocatalytic processes was obtained by (0.4) CdS/ZNs under visible light. The quenching tests showed that O2•-, h+, and OH• were the main active species in the degradation process. The degradation percentage decreased negligibly in the sonophotocatalytic (84%–79%) compared to the photocatalytic (90%–72%) process after four re-using runs due to the presence of ultrasonic waves. For the estimation of degradation behavior, two machine learning methods were applied. The comparison between the ANN and GBRT models evidenced that both models had high prediction accuracy and could be used for predicting and fitting the experimental data of the %removal of TC. The excellent sonophotocatalytic/photocatalytic performance and stability of the fabricated (x)CdS/ZNs catalysts made them promising candidates for wastewater purification.

Improved Photo‐Excited Carriers Transportation of WS2‐O‐Doped‐Graphene Heterostructures for Solar Steam Generation (Small 19/2023)

Solar Steam Generation In article number 2204898, Dan Liu, Weiwei Lei, and co-workers report a viable and general method that allows an effective synthesis of transition metal dichalcogenides (TMDs)-O-doped graphene nanosheet heterostructures by utilizing commercial TMD powder and sucrose as precursors. The solar evaporators of WS2-O-graphene exhibit high-performance water evaporation due to the improved photo-excited carrier transportation. This study provides a general approach for the design of heterostructure materials for solar-driven steam evaporation.

Ultrafast optical nonlinearity in natural van der Waals heterostructure nanosheets of franckeite

Franckeite, a natural van der Waals heterostructure with excellent physicochemical characteristics, has shown great potential for high-performance optoelectronic device. Here, the few-layer franckeite nanosheets have been prepared by liquid phase-exfoliation method successfully, and the nonlinear optical absorption and carrier dynamics behaviors of the nanosheets have been studied experimentally. The franckeite nanosheets show wavelength- and intensity-dependent nonlinear absorption characteristics, and exhibit ultrafast carrier dynamic process. The ultrafast optical nonlinearity in franckeite nanosheets has been further validated via an Er3+-doped fiber laser to deliver stable femtosecond pulse. The experimental results reveal that franckeite heterostructure nanosheets can be an ideal candidate in the design and manufacture of ultrafast nonlinear optoelectronic devices.

In situ generated layered NiFe-LDH/MOF heterostructure nanosheet arrays with abundant defects for efficient alkaline and seawater oxidation

In situ generated layered NiFe-LDH/MOF heterostructure nanosheet arrays with abundant defects for efficient alkaline and seawater oxidation