Binary Hybrids Research Articles

(Invited) Two-Dimensional Layered Materials and Their Mixed-Dimensional Hybrids for Electrochemical Applications

Compared with their 3D counterparts, two-dimensional (2D) van der Waals (vdW) materials exhibit quantum confinement where charge carriers are spatially confined at the physical boundaries. Particularly, when mixing 2D materials with other low-dimensional (LD) materials, they exhibit enormous potential in electrochemical energy applications due to the unique properties arising from reduced dimensionality and, more importantly, material integration synergy.In this work, 2D transition metal dichalcogenides (MoS2) and their mixed low-dimensional hybrids (MLDHs) are introduced with an emphasis on the hybrid structure construction using the one-step solvothermal synthesis technique and their electrochemical applications. Fundamental insight into the synergistic effect of the MLDHs integration in terms of active site exposure, surface area enlargement, electrical conductivity improvement, and structural phase engineering for advancing the development of Li-ion batteries (LIBs) and electrocatalytic hydrogen evolution reaction (HER) will also be discussed. Specifically, in the case of LIBs, 2D-based binary hybrids (i.e., MoS2/MXene) deliver a Li-ion storage capacity of 540 mA h g−1 at 100 mA g−1 and a stable cycle performance up to 300 cycles. In sharp contrast, the 2D-based ternary MLDHs (i.e., MoS2/MXene/CNT) exhibit a higher Li-ion storage capacity (1500 mAh g−1 at 100 mA g−1), outstanding cycle stability (up to 300 cycles) and excellent rate capability (500 mAh g−1 at 4000 mA g−1) as an anode of LIBs. In the case of HER, the MLDH heterostructures show an overpotential of 169 mV with a low Tafel slope of 51 mV/dec and can be cycled to 1000 cycles. Leveraging the unique microreactor platform based on the 2D vdW platform, a mechanistic understanding of charge transport dynamics at the electrified electrode and current collector interface will be highlighted.The knowledge gained on how mixed-dimensional physics and chemistry will shed light on the design principle of the electrode materials for electrochemical energy storage and conversion and deepen the understanding of the process-structural-property-performance (PSPP) relationship of the vdW-based hybrid structures.

Ternary Triazole-Based Organic-Inorganic Proton-Conducting Hybrids Based on Computational Models for HT-PEMFC Application.

We reported a new ternary hybrid anhydrous proton-conducting material based on triazole (Tz), wherein it interacted with TiO2 and cesium hydrogen sulfate (CHS) constructed based on the acid-base interaction. It exhibited high proton conductivity derived by the two acid-base interactions: between CHS and Tz and between Tz and TiO2. As a starting point of discussion, we attempted to theoretically predict the high/low proton conductivity using the push-pull protonated atomic distance (PAD) law, which makes it possible to predict the proton conductivity in the acid-base part based on density functional theory. The calculations indicate the possibility of achieving higher proton conductivity in the ternary composites (CHS·Tz-TiO2) involving two acid-base interactions than in binary hybrids, such as CHS·Tz and TiO2-Tz composites, suggesting the positive effect of two simultaneous acid-base interactions for achieving high proton conductivity. This result is supported by the experimental result with respect to synthesized materials obtained using the mechanochemical method. Adding TiO2 to the CHS·Tz system causes a change in the CHS·Tz interaction and promotes proton dissociation, producing a new and fast proton-conducting layer through the formation of Tz-TiO2 interaction. Applying CHS·Tz-TiO2 to high-temperature proton exchange membrane fuel cells results in improved membrane conductivity and power-generation properties at 150 °C under anhydrous conditions.

All-solid-state flexible supercapacitor based on a binary transition metal dichalcogenide grown on 2D/2D heterostructure materials

The spellbound effect of two-dimensional (2D) materials over the industry of nanotechnology and opto-electronic devices is a trending topic during the past decade or so. Among the plethora of 2D materials, transition metal dichalcogenide (TMDs), MXenes and other graphene analogue materials have been frontiers in the research of energy storage application. To overcome the low energy density, long-standing restacking issues of these material-based supercapacitors, herein a facile in situ hydrothermal method has been reported for the synthesis of a ternary MoWS2@[email protected]3C2TX MXene as an electrode material for high performance and efficient all-solid-state supercapacitor device. The pristine, binary (MoWS2@BCN) and ternary (MoWS2@[email protected]3C2TX) electrodes are vividly characterized by various microscopy and spectroscopy techniques. The electrochemical studies revealed that the solid-state symmetric device exhibited an areal capacitance of 289 mF/cm2 at 0.6 mA/cm2 with the energy and power density of 19.73 μWh/cm2 and 538.09 μW/cm2 respectively. Further, device upheld a robust 91 % cyclic stability and 95 % coulombic efficiency over 5000 rhythmic charge-discharge cycles. The flexible all-solid-state device based on MoWS2@[email protected]3C2TX MXene ternary electrode can be a torch bearer for the real time application of efficient supercapacitors. Further to analyse the structural and electronic properties of binary and ternary electrodes, the first principle simulations are performed. We have presented the orbital interactions, charge transfer and quantum capacitance for binary and ternary hybrids. The estimated quantum capacitance has shown the improvement in an order which is in the same line as experimentally observed specific capacitance. The inter-layer interactions involve transfer of charge from the Mo 4d orbital of MoWS2 and C 2p orbital of BCN to the C 2p orbital of MXene which may be one of the basic driving forces behind the improvement charge transfer performance of ternary MoWS2@[email protected]3C2TX.

Simple design of Sn/reduced graphene oxide/carbon nanofibers ternary hybrids for lithium-ion batteries

Novel Sn/reduced graphene oxide/carbon nanofibers ternary hybrids have been designed via a facile one-step synthesis process. In the hybrids, Sn nanoparticles, uniformly sandwiched in the layers of reduced graphene oxide, are in good contact with carbon nanofibers. The ternary hybrids have demonstrated superior lithium storage performance to the Sn/reduced graphene oxide and Sn/carbon nanofibers binary hybrids. The reversible capacity of the ternary hybrids is 643 mAh g−1 after 90 cycles. Importantly, electrochemical impedance spectroscopy measurements confirm that the integration of Sn, reduced graphene oxide and carbon nanofibers can reduce the charge transfer resistance effectively.

Enhanced Mechanical Energy Harvesting in Triboelectric Nanogenerator by the Reinforcement of Polypyrrole‐Decorated rGO Sheets in PDMS

Energy harvesting triboelectric nanogenerators (TENGs) to scavenge unused mechanical energy have received significant attention in this decade. Herein, the development of reduced graphene oxide (rGO):polypyrrole (PPy) hybrid‐modified polydimethylsiloxane (PDMS) as TENG for various device applications is reported. The bulk of PDMS is altered by different fillers such as rGO, PPy, and the binary hybrids of rGO and PPy with varying weight ratios. Among various PDMS composites, 1 wt% of 1:8 rGO:PPy–PDMS composite exhibits higher TENG responses than other PDMS composite. The superior TENG performances of 1 wt% 1:8 rGO:PPy–PDMS composite are attributed to the formation of intensified negative charges inside the PDMS matrix. This charge intensification in the composite is due to various mechanisms, including the charge trapping ability of rGO:PPy filler, microcapacitor formation by introducing hybrid filler in the system with proper conducting networks, and the electron‐donating nature of PPy conducting polymer. A 3D stacked device proposed using 1 wt% 1:8 rGO:PPy–PDMS composite delivered a short‐circuit current of 16 μA and an open‐circuit potential of 60 V by simple palm pressing. Also, the ability of the stacked device for charging/powering portable devices and light‐emitting diodes is demonstrated.

Synergistic photothermal conversion and photocatalysis in 2D/2D MXene/Bi2S3 hybrids for efficient solar-driven water purification.

Plasmonic hybrids are regarded as promising candidates for water purification due to their structure-dependent photocatalysis and photothermal performance. It remains a challenge to develop materials that possess these two characteristics for efficient water purification. Herein, plasmonic Ti3C2Tx/Bi2S3 two-dimensional (2D)/2D hybrids were prepared for efficient solar-driven water purification via the combination of photothermal conversion and photocatalysis. Benefitting from broad light absorption, large 2D/2D interfaces, and efficient charge transfer, the binary hybrids showed high-efficiency photothermal conversion and photothermal-assisted photocatalytic activity. By depositing these 2D/2D hybrids on a hydrophilic and porous cotton piece, the Ti3C2Tx/Bi2S3 membrane displayed a high water evaporation rate and solar-to-vapor efficiency under one-sun irradiation. The solar-driven evaporation of seawater, heavy metal ion solution, and dye solution jointly indicated that the plasmonic membrane shows great potential for drinkable water generation and industrial wastewater treatment. Most importantly, the synergistic effect of photothermal evaporation and photocatalysis of the Ti3C2Tx/Bi2S3 membrane on water purification was demonstrated. The polluted water can not only be treated by evaporation, but also be degraded via photocatalysis under solar light irradiation. This work provides new insight into designing functional materials for water purification based on the combination of photothermal conversion and photocatalysis.

Comparative study of CdS&TiO2 based polyaniline/polyvinyl alcohol nanocomposites as electrode for supercapacitors

The researchers used the oxidative chemical polymerization of aniline to prepare the polyaniline/polyvinyl alcohol (PANI/PVA) blend and its nanocomposites loaded with cadmium sulfide and Titanium dioxide nanoparticles (CdS-NPs & TiO2-NPs) were synthesized by aniline oxidative chemical polymerization. CdS and TiO2 were incorporated into the prepared nanocomposite to reinforce the mechanical and electrical energy storage performance. XRD revealed the presence of CdS NPs & TiO2 NPs in the polymer matrix; meanwhile, SEM confirms they are well dispersion in the polymer matrix and are dispersed well on the superficies of the synthesized nanocomposites. The presence of characteristic peaks in the Fourier transforms infrared proved the compatibility of the investigated nanocomposite. This study demonstrates how stable the synthesized samples are, with residual material for TiO2/PANI/PVA exceeding 60% even at 800 °C and for CdS/PANI/PVA exceeding 33% at 800 °C. The capacitance of CdS/PVA/PANI nanocomposites (492.29 F.g−1) at 1 A.g−1. The CdS/PVA/PANI and TiO2/PVA/PANI nanocomposites possesses the maximum Es of 2343.65 Wh.kg−1 and 373.17 Wh.kg−1. The CdS/PVA/PANI nanocomposites had the highest energy storage and power density among these binary hybrids. A broadband dielectric spectroscopy was used to examine the electrical and dielectric properties of the prepared samples over a broad range of frequencies and at four selected temperatures. The growth in dc caused by the rise in temperature from 25 to 150 °C (from 10−12 to 10−7 S cm−1) was around five decades as well as the second nanocomposite, TiO2/PANI/PVA, has slightly higher conductivity. The study shows that the blend behaves similarly to its two nanocomposites in the activation plot. However, the blend has higher dc-conductivity by about four orders of magnitude, and an electrode polarization is developed accompanied by apparently colossal ε′ values. This makes it very promising for applications in many fields of advanced microelectronics.

Two Birds with One Stone: Prelithiated Two-Dimensional Nanohybrids as High-Performance Anode Materials for Lithium-Ion Batteries.

As an inexpensive and naturally abundant two-dimensional (2D) material, molybdenum disulfide (MoS2) exhibits a high Li-ion storage capacity along with a low volume expansion upon lithiation, rendering it an alternative anode material for lithium-ion batteries (LIBs). However, the challenge of using MoS2-based anodes is their intrinsically low electrical conductivity and unsatisfied cycle stability. To address the above issues, we have exploited a wet chemical technique and integrated MoS2 with highly conductive titanium carbide (Ti3C2) MXene to form a 2D nanohybrid. The binary hybrids were then subjected to an n-butyllithium (n-Buli) treatment to induce both MoS2 deep phase transition and MXene surface functionality modulation simultaneously. We observed a substantial increase in 1T-phase MoS2 content and a clear suppression of -F-containing functional groups in MXene due to the prelithiation process enabled by the n-Buli treatment. Such an approach not only increases the overall network conductivity but also improves Li-ion diffusion kinetics. As a result, the MoS2/Ti3C2 composite with n-Buli treatment delivered a high Li-ion storage capacity (540 mA h g-1 at 100 mA g-1), outstanding cycle stability (up to 300 cycles), and excellent rate capability. This work provides an effective strategy for the structure-property engineering of 2D materials and sheds light on the rational design of high-performance LIBs using 2D-based anode materials.

Defect‐Engineered Graphene/Si3N4Multilayer Alternating Core‐Shell Nanowire Membrane: A Plainified Hybrid for Broadband Electromagnetic Wave Absorption

AbstractTo tackle the increasing electromagnetic pollution, broadband electromagnetic wave (EMW) absorption materials are urgently needed. Toward this goal, traditional strategies resort to the construction of multicomponent dielectric/magnetic hybrid materials, including ternary, quaternary, or even more complicated systems. However, they always suffer from many intrinsic drawbacks in practical applications. Herein, a theory‐directed strategy is presented to design plainified EMW absorption materials (binary hybrids) via amplified interface effects, which are based on well‐designed multilayer alternating core‐shell nanostructures by chemical vapor deposition (CVD). A defect‐engineered CVD graphene (DG) core composed of graphitic open edges and in‐plane defects is used as a lossy phase. Correspondingly, a CVD Si3N4layer with nanometer thickness is used as an impedance matching shell. By optimizing the alternating numbers of DG/Si3N4units, enhanced interface polarization and strong frequency dispersion behavior of permittivity (especially the real part, ε′) are obtained, which helps the plainified binary hybrids to reach an effective absorption bandwidth (EAB) of 8.0 GHz at a thickness of 2.7 mm. Moreover, these plainified hybrids show excellent thermal and pH stability. Even after 1000 °C oxidation, for example, an EAB of 7.44 GHz coupling with a minimum reflection coefficient of −77.3 dB is still achieved.

Efficient peroxymonosulfate activation and less metallic leaching through kaolin@MnCo2O4 for bisphenol A degradation in environmental remediation

In this work, a two-dimensional kaolin supported Mn/Co bimetal oxides (CK-Mn) was synthesized via a simple hydrothermal and calcination process. The resulting ternary hybrid sample exhibited a superior performance for activating peroxymonosulfate (PMS) towards bisphenol A (BPA) degradation, with a pseudo-first-order rate constant of 0.252 min−1, which outperformed other binary hybrids, unitary metal oxides and pristine kaolin. Meanwhile, this CK-Mn sample exhibited excellent stability and reusability after three cycles with extremely low metal ions leaching. The kaolin substrate can not only prevent the agglomeration and leakage of metal species, but it can also enhance the catalytic performance through the synergistic effect between kaolin and MnCo2O4. The CK-Mn/PMS system possessed wide pH application range (3.0 to 9.0) and trifling impacts from the inorganic anions. Multiple radical tests together revealed the dominant reactive oxygen species was sulfate radical (SO4•-) in CK-Mn/PMS system. Furthermore, the CK-Mn/PMS coupled with ultrafiltration membrane system was constructed, and it worked well in the coinstantaneous removing of BPA, turbidity and humic substances from surface water. This study brings forward a facile method for preparing kaolin supported bimetal catalysts for PMS activation and provides new insight into composites catalysis in water environmental remediation process.

Antibacterial self-cleaning binary and ternary hybrid photocatalysts of titanium dioxide with silver and graphene

The bacterial sterilization of TiO2 photocatalysts for self-disinfected and hygienic surfaces and coatings was explored to enhance by incorporating silver and reduced graphene oxide layers. Binary Ag/TiO2 and ternary Ag/TiO2/rGO (reduced graphene oxide) nanohybrids were developed by a hydrothermally modified sol-gel method preceded by the synthesis of Ag nanospheres by polyol method using cetyltrimethylammonium bromide (CTAB) as the capping agent. The metallic state and crystalline nature of Ag in the hybrids were affirmed using XRD, TEM, and XPS analyzes. The developed nanohybrids were studied for their visible-light-induced photocatalytic self-cleaning behavior determined from photo-induced wettability and photodegradation of methylene blue dye. Ag/TiO2/rGO ternary hybrid showed excellent photocatalytic antibacterial properties towards Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), under visible-light excitation. ~100% disinfection of bacterial environments (both E. coli and S. aureus) were achieved within 180 min of visible-light irradiation. Finally, a plausible mechanism for the visible-light-induced photocatalytic antibacterial behavior of the as-prepared binary and ternary hybrids of TiO2 is proposed. Surface plasmon resonance induced by visible-light excitation injects hot electrons from Ag nanoparticles to the conduction band of TiO2 with the simultaneous charge separation facilitated by graphene counterpart produces a high concentration of reactive oxygen species, which is accountable for the superior photocatalytic self-cleaning and the bacterial cell lysis by Ag/TiO2/rGO hybrid.

Facile construction of self-assembled Cu@polyaniline nanocomposite as an efficient noble-metal free cocatalyst for boosting photocatalytic hydrogen production

Photocatalytic Hydrogen production via water splitting is considered a sustainable ecofriendly pathway to replenish the current and future energy demands. In this study, the self-assembly synthesis of Cu nanospheres (∼8 nm) surrounded by a thin conductive layer of polyaniline (Cu@PANI) was rationally engineered via in˗situ polymerization. Afterward, it was successfully deposited onto the TiO2 surface to improve the photocatalytic activities for hydrogen production. The optimal Cu@PANI/TiO2 ternary photocatalyst produced a substantial hydrogen generation rate (HGR) of 17.7 mmol h−1 g−1, 207-fold higher than that of bare TiO2. The performance was considerably improved compared with (Cu–TiO2)/PANI and (PANI-TiO2)/Cu composites prepared by changing the deposition sequence of Cu and PANI. Such an improved activity was because of multiple transferring paths of photogenerated electrons in the composite. Interestingly, the as-prepared ternary photocatalyst exhibited superior hydrogen evolution compared with the binary hybrids (Cu/TiO2 and PANI/TiO2). The exceptional performance of Cu@PANI/TiO2 could be understood considering the distinctive electrical conductivity of PANI and heterojunction formed between PANI and TiO2, as well as the merits of the Schottky junction constructed between Cu and PANI. These superior features could efficiently suppress the recombination rate of the photogenerated electron–hole pairs and maximize the photocatalytic activity. This study provides new insights for understanding the effect of electron transfer pathways on photocatalytic activities.

Controlling the Emission Spectrum of Binary Emitting Polymer Hybrids by a Systematic Doping Strategy via Förster Resonance Energy Transfer for White Emission.

Tuning the emission spectrum of both binary hybrids of poly (9,9′-di-n-octylfluorenyl-2,7-diyl) (PFO) with each poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene] end-capped with Dimethyl phenyl (MDMO-PPV–DMP) by a systematic doping strategy was achieved. Both binary hybrid thin films of PFO/MEH-PPV and PFO/MDMO-PPV–DMP with various weight ratios were prepared via solution blending method prior to spin coating onto the glass substrates. The conjugation length of the PFO was tuned upon addition of acceptors (MEH-PPV or MDMO-PPV–DMP), as proved from shifting the emission and absorption peaks of the binary hybrids toward the acceptor in addition to enhancing the acceptor emission and reducing the absorbance of the PFO. Förster resonance energy transfer (FRET) is more efficient in the binary hybrid of PFO/MDMO-PPV–DMP than in the PFO/MEH-PPV. The efficient FRET in both hybrid thin films played the major role for controlling their emission and producing white emission from optimum ratio of both binary hybrids. Moreover, the tuning of the emission color can be attributed to the cascade of energy transfer from PFO to MEH-PPV, and then to MDMO-PPV–DMP.

Hierarchical MoS2/polyaniline binary hybrids with high performance for improving fire safety of epoxy resin

AbstractHere we report a facile strategy to fabricate phosphoric acid doped polyaniline/molybdenum disulfide (PANI/MoS2) hybrids as high‐performance nanofillers in epoxy (EP) resin for the first time. In situ growth of PANI on the surface of two‐dimensional MoS2 template resulted in the uniform dispersion and strong interfacial adhesion of PANI/MoS2 hybrids within EP matrix, which can be confirmed by the obvious increase (13.5°C) in glass transition temperature (Tg) of EP composites. The MoS2 nanosheets also acted as a critical component to generate synergistic effect with PANI on reducing the fire hazards of EP resin. It resulted in a remarkable removal of flammable decomposed products and a considerable reduction of toxic CO yield. The dramatical decreases in real‐time smoke density and total smoke production, and high‐graphitized char layer in condensed phase were obtained for EP composite with 5 wt% PANI/MoS2 hybrids. The multiple synergistic effects (synergistic dispersion and synergistic char formation) are believed to be the primary source for these obvious enhancements of properties of EP composites. This facile strategy may achieve the potential application of functionalized MoS2 in polymeric nanocomposites.

Multifunctional Properties of Binary Polyrhodanine Manganese Ferrite Nanohybrids-From the Energy Converters to Biological Activity.

The PRHD@MnFe2O4 binary hybrids have shown a potential for applications in the biomedical field. The polymer cover/shell provides sufficient surface protection of magnetic nanoparticles against adverse effects on the biological systems, e.g., it protects against Fenton’s reactions and the generation of highly toxic radicals. The heating ability of the PRHD@MnFe2O4 was measured as a laser optical density (LOD) dependence either for powders as well as nanohybrid dispersions. Dry hybrids exposed to the action of NIR radiation (808 nm) can effectively convert energy into heat that led to the enormous temperature increase ΔT 170 °C (>190 °C). High concentrated colloidal suspensions (5 mg/mL) can generate ΔT of 42 °C (65 °C). Further optimization of the nanohybrids amount and laser parameters provides the possibility of temperature control within a biologically relevant range. Biological interactions of PRHD@MnFe2O4 hybrids were tested using three specific cell lines: macrophages (RAW 264.7), osteosarcoma cells line (UMR-106), and stromal progenitor cells of adipose tissue (ASCs). It was shown that the cell response was strongly dependent on hybrid concentration. Antimicrobial activity of the proposed composites against Escherichia coli and Staphylococcus aureus was confirmed, showing potential in the exploitation of the fabricated materials in this field.

Co-sensitization of mesoporous ZnS with CdS and polyaniline for efficient photocatalytic degradation of anionic and cationic dyes

Toxic pollutants such as organic dyes are released from different industries and discharged into water sources leading to a serious health problem. Herein, mesoporous ZnS with large surface area (207.4 m2/g) synthesized by a new and simple surfactant free method at room temperature. Next, ZnS modified with CdS to get a series of ZnS/CdS binary hybrids (ZC1, ZC2, ZC3 and ZC4). After that, various amounts of polyaniline (PANI) were added to produce a series of ZnS/CdS/PANI ternary composites (ZC2P1, ZC2P2, ZC2P3, and ZC2P4) for the first time. The sensitization with PANI led to an increase in surface area and pore diameter. The degradation percentage of ZnS, ZC2, and ZC2P3 is 54.7%, 81.1%, and 96.5%, respectively. The degradation rate constant of 20 mg/L RhB in presence ZnS, ZC2 and ZC2P3 is 0.5 × 10−2, 0.91 × 10−2, and 1.7 × 10−2 min−1, respectively. A possible mechanism for the enhanced photocatalytic activity is proposed.

Novel (Ni, Fe)S2/(Ni, Fe)3S4 solid solution hybrid: an efficient electrocatalyst with robust oxygen-evolving performance

Fabrication of high-activity electrocatalysts with operational stability is desperately needed to achieve efficient energy conversion. Herein, for the first time, we highlight a novel electrocatalyst based on binary nickel iron sulfide solid solution hybrids on carbon cloth for oxygen evolution reaction. Benefitting from the synergistic effect of varied phases and the interfacial connection between (Ni, Fe)S2 and (Ni, Fe)3S4 to accelerate the charge transport, the Ni incorporation to optimize the electronic structure of the hybrids and the downshift of the d-band center to facilitate the desorption of oxygen intermediates, the partial charge-transfer between Fe and Ni to boost the generation of catalytically active Ni3+ as well as the unique nanosphere structure to offer enough buffer area for the volume changes during constant redox reactions, the obtained binary nickel iron sulfide hybrids ((Ni, Fe)S2/(Ni, Fe)3S4) display high catalytic reactivity with a low overpotential of 210 mV to reach the current density of 10 mA cm−2, and excellent stability with negligible activity deterioration, making the hybrid a promising candidate for electrocatalytic alkaline water oxidation.

Double Effects of Interfacial Ag Nanoparticles in a ZnO Multipod@Ag@Bi2S3 Z-Scheme Photocatalytic Redox System: Concurrent Tuning and Improving Charge-Transfer Efficiency.

Distinct functional materials in their combined form in a well-designed hybrid architecture offer great possibilities for creating a highly active photocatalytic system. Herein, a uniform multipod-shaped ZnO is synthesized through a natural template assisted route and progressively integrated with Ag nanoparticles (NPs) and Bi2S3 to form a three-component (3C) ternary photocatalytic system by a facile, two -step wet chemical approach. Encapsulation of polycrystalline Bi2S3 and assimilation of Ag NPs in between the interface of ZnO and Bi2S3 in the ternary hybrid are confirmed from electron microscopy and X-ray photoelectron spectroscopy, which resulted in improved UV-vis absorption, charge separation efficiency, and photocurrent response evaluated from optical absorption spectroscopy, photoluminescence, and photoelectrochemical cell measurements. This ternary hybrid shows high photoredox activity toward the hydrogen evaluation reaction (HER) (218.7 μmol h-1 g-1) and methyl orange (MO) oxidation (k = 3.21 × 10-2 min-1) compared to their binary and single counterparts. Moreover, on the basis of the estimation of the predominant active species (O2•-, •OH) in the photoredox catalysis and band edge positions from the Mott-Schottky plot, it was determined that both binary ZnO multipod@Bi2S3 and ternary ZnO multipod Ag@Bi2S3 hybrids undergo a Z-scheme electron transfer mechanism under irradiation of light. Here, the Ag ingredient in the ternary hybrids acts as an interfacial charge-transfer mediator to accelerate the Z-scheme electron transfer between Bi2S3 and ZnO along with plasmonic photosensitization to trigger the generation of plasmon-induced hot electrons. Such a cooperative concurrent dual role of Ag NPs in the Z-scheme ternary hybrid system considerably boosts the photoredox performance compared to direct Z-scheme binary hybrids. This work will enlighten and uncover the essential roles of metal NPs along with their cooperative synergy in Z-scheme photocatalytic systems as a prototypical example for substantial solar energy conversion.

Facile synthesis of hierarchically porous rGO/MnZn ferrite composites for enhanced microwave absorption performance

Reduced graphene oxide/MnZn ferrite (rGO/MZF) binary hybrids were synthesized via a facile solvothermal route. The effect of different amount of rGO on microstructure, morphology, magnetic and microwave absorption performance of rGO/MZF hybrids had been studied in detail. The results indicated that MZF microspheres with various morphologies and sizes were uniformly anchored onto the surface of rGO in all rGO/MZF composites. The dielectric and magnetic property of rGO/MZF composites could be simultaneously optimized by tuning the mass ratio of rGO. For rGO/MZF (1:6) sample, the optimal value of reflection loss (RL) could attain −60.9 dB at 12.4 GHz when the thickness was 2.75 mm. Moreover, the effective absorption bandwidth (EAB) could reach 5.6 GHz (12.4−18.0 GHz) at 2.38 mm, which almost covered the Ku band. And the possible microwave absorption mechanism was also discussed. Considering the excellent microwave absorption performance, the rGO/MZF composite could be applied as a newly efficient microwave absorbing materials.

Interfacial self-assembly of nanoZnO@multiporphyrin array hybrids as binary light-sensitizers for photocurrent generation and photocatalytic degradation of organic pollutants

Both porphyrins and nanoscale ZnO semiconductors (nanoZnO) are important eco-friendly light-sensitizers and photocatalysts in academic researches and industrial applications. Here, ultrathin films of multiporphyrin arrays were constructed on the surface of nanoZnO to produce binary hybrids based on the coordination reaction of Pd(II) ions and tetrapyridylporphyrin (TPyP). The hybrids of nanoZnO@(Pd–TPyP)n as-produced displayed an improved absorption ability from 200 to 700 nm and an effective energy transfer between the multiporphyrin arrays and nanoZnO cores. Benefit from such a synergistic effect, their photocatalytic performance was largely improved as compared with that of the original porphyrins and nanoZnO particles. Particularly, under only visible light radiation, the photocurrent density of nanoZnO@(Pd–TPyP)n hybrids was approximately 25 times stronger and the photocatalytic efficiency on the degradation of Rhodamine B was over 10 times higher as compared with that of the original nanoZnO particles. Finally, because the multiporphyrin arrays were anchored on the nanoZnO’s surfaces via the covalent and coordinative bonding, the present nano-hybrids displayed not only structural controllability at the molecular level but also well stability, reusability, and recyclability as the heterogeneous photocatalysts.