Abundant Heterojunction Research Articles

Heterostructured Nanoglue Design for Durable Lithium‐Ion Battery Anodes

AbstractHybrid and heterostructures exhibit intriguing and significant properties that can endow unique properties to high‐performance batteries. However, their applications are often hampered by limited structural stability due to inevitable material agglomeration and structural collapse during repeated electrochemical cycles. Here, an efficient strategy to utilize an intermediate nanoglue to bond the substrate and heterojunction phase and increase the overall structural stability is reported. After screening the possible Fe‐based oxides, tunnel‐type FeOOH satisfies the principle of relatively high affinity to both Ti3C2Ox support and Fe3O4 phase, thus strengthening heterostructure stability. Furthermore, functional FeOOH quantum dots as nanoglue and graft them onto high‐surface‐area Ti3C2Ox support is experimentally utilized, then load high‐capacity Fe3O4 nanoparticles onto the nanoglue. The designed heterostructured nanoglue not only yields abundant heterojunctions with continuous channels for ion/electron transfer but maintains excellent electrochemical reversibility. Serving as anode for lithium storage, Ti3C2Ox/FeOOH/Fe3O4 hybrid enables a high discharging capacity of 790.4 mAh g−1 at 1.0 A g−1 after 500 cycles and superior cycling stability. The design principle is general and can be expanded to other hybrid materials.

Engineering fast diffusion channels in metal Sulfide/Selenide heterostructures via confinement effect for high-performance sodium storage

Structural modulation plays a pivotal role in enhancing the energy storage properties of electrochemical hybrids by adjusting their interfacial and electronic characteristics. Nevertheless, facile and effective strategies for tuning the structural properties of these hybrids at the nanoscale remain scarce. In this study, we propose a novel in-situ electrochemically self-driven strategy for embedding FeSe/FeS heterostructures with rich phase boundaries concurrently encapsulated into one-dimensional porous N, S-doped carbon tubes with inner void (FeSe/FeS@SNC). This approach facilitates the creation of heterogeneous interface phases via a simple electrochemical conversion from FeS0.75Se0.25. Notably, the resultant unique one-dimensional porous structure with inner void, along with a highly conductive N/S-co-doped carbon matrix, promotes charge transfer and reinforces structural stability. in-situ/ex-situ microscopic and spectroscopic characterizations, supported by theoretical simulations, validate that FeSe/FeS heterostructures offer rapid electron transport pathways, while the abundant heterojunctions with strong electric fields facilitate ion migration and Na adsorption. As an anode in sodium-ion batteries, the FeSe/FeS@SNC electrdoe exhibits exceptional rate capability (347 mAh/g at 10 A/g) and stable cycling performance (91% capacity retention after 12000 cycles).

MOF-on-MOF-derived Fe[sbnd]Zr bimetal oxides supported on hierarchically porous carbonized wood to promote photo-Fenton degradation of ciprofloxacin

MOF-on-MOF derivatives have served as promising heterogeneous Photo-Fenton (hetero-PF) catalysts, but its self-aggregation instability and limited photocatalytic activity inhibit the effective ciprofloxacin (CIP) removal. In this study, a novel hetero-PF catalyst, dual MOF-derived FeZr bimetal oxide embedded in a wood-converted porous carbon skeleton (ZrO2@Fe3O4/WPC), was successfully synthesized via a straightforward in-situ growth strategy combined with co-pyrolysis. The as-prepared hybrid photocatalysts, featuring a large surface area, effective porous structures, efficient light absorption and a narrow band gap demonstrated superior photo-Fenton activity, accomplishing approximately 99.1 % degradation of CIP within 120 min under neutral conditions. Furthermore, the ZrO2@Fe3O4/WPC hetero-PF system showed satisfactory performance in treating real water matrices. It can be inferred that the abundant heterojunctions, resulting from the synergistic effect of FeZr mixed oxide and the porous carbonized wood substrate, contributed to the rapid separation and migration of photogenerated electron-hole pairs. Meanwhile, the FeZr site in the graphitized carbon framework activates H2O2 to accelerate the generation of the OH and O2− radicals, leading to a heightened degradation efficiency of CIP. Besides, the photodegradation pathway of CIP is obtained by liquid chromatography-mass spectrometry (LC-MS). This study indicates that combining porous carbonized wood and heterometallic MOF derived materials provides a promising method for realizing high-efficiency photo-Fenton degradation of antibiotic water pollutions.

One-pot Synthesis of PdCuAg and CeO2 Nanowires Hybrid with Abundant Heterojunction Interface for Ethylene Glycol Electrooxidation.

Introducing CeO2 into Pd-based nanocatalysts for electrocatalytic reactions is a good way to solve the intermediate toxicity problem and improve the catalytic performance. Here we reported a simple strategy to synthesize the PdCuAg and CeO2 nanowires hybrid via a one-pot synthesis process under strong nanoconfined effect of specific surfactant as templates. Owing to the structural (ultrathin nanowires, abundant heterojunction/interfaces between metal and metal oxide) and compositional (Pd, Cu, Ag, CeO2) advantages, the hybrid showed significantly enhanced catalytic activity (6.06 A mgPd -1) and stability, accelerated reaction rate, and reduced activation energy toward electrocatalytic ethylene glycol oxidation reaction.

Rational design of hollow flower-like MoS2/Mo2C heterostructures in N-doped carbon substrate for synergistically accelerating adsorption-electrocatalysis of polysulfides in lithium sulfur batteries

Lithium–sulfur (Li–S) batteries have been garnered significant attention in the energy storage field due to their high theoretical specific capacity and low cost. However, Li–S batteries suffer from issues like the shuttle effect, poor conductivity, and sluggish chemical reaction kinetics, which hinder their practical development. Herein, a novel hollow flower-like architecture composed of MoS2/Mo2C heterostructures in N-doped carbon substrate (H-Mo2S/Mo2C/NC NFs), which were well designed and prepared through a calcination-vulcanization method, were used as high-efficiency catalyst to propel polysulfide redox kinetics. Ex situ electrochemical impedance spectroscopy verify that the abundant heterojunctions could facilitate electron and ion transfer, revealed the excellent interface solid–liquid–solid conversion reaction. The adsorption test of Li2S6 showed that Mo2S and Mo2C formed heterostructure generate the binding of polysulfide could be enhanced. And cyclic voltammetry test indicate boost the polysulfide redox reaction kinetics and ion transfer of H-Mo2S/Mo2C/NC/S NFs cathode. Benefiting from the state-of-the-art design, the H-Mo2S/Mo2C/NC/S NFs cathode demonstrates remarkable rate performance with a specific capacity of 1351.9 mAh g−1 at 0.2 C, when the current density was elevated to 2 C and subsequently reverted to 0.2 C, the H-Mo2S/Mo2C/NC/S NFs cathode retained a capacity of 1150.4 mAh g−1, and it maintains exceptional long cycling stability (840 mA h g−1 at 2 C after 500 cycles) a low capacity decay of 0.0073% per cycle. This work presents an effective approach to rapidly fabricating multifunctional heterostructures as an effective sulfur host in improving the polysulfide redox kinetics for lithium sulfur batteries.

Tuning the Electrochemical Performance of Multiple Phased Selenides@C/MXene Composites via Controllable Synthesis of Multivariate Metal‐Organic Frameworks

AbstractMetal‐organic frameworks (MOFs) are excellent precursors for electrode materials preparations. Synergistic effects may exist between different metal centers in multivariate MOFs, making them often more effective than single‐metal MOFs. Herein, we propose an atom economic mechanochemical method to realize the efficient component regulation of target multivariate MOFs. Moreover, by combining the synthesis of multivariate MOFs and exfoliating MXene, multivariate MOF/MXene composites can be obtained via a one‐step strategy. A further selenization process can derive them into selenides@C/MXene composites. These derived composites contain multiple nanostructured metal selenides embedded in multi‐heteroatom doped carbon matrix. For these composites, abundant heterojunction structures are formed, which can build internal self‐built electric field and enhance the reaction kinetics effectively for sodium‐ion storage. More importantly, the electrochemical performance of NCMS@C/MX composites can be optimized due to the intrinsic characteristics of the containing metal selenides. Overall, experimental results demonstrate the universality of this solvent‐free synthesis route for controllable preparation of high‐performance selenides@C/MXene electrode materials. It provides a feasible and environmentally friendly method to adjust metal ratios for optimal energy storage performance. We hope this research inspires optimization strategies for high‐performance electrode materials and leads to the development of energy storage materials with more rational structures and better performance.

Low Overpotential Electroreduction of CO2 on Porous SnO2/ZnO Catalysts

Abstract SnO2-based materials are promising catalysts for CO2 electrochemical reduction due to their attractive selectivity for C1 products (formate and carbon monoxide) but they tend to suffer high overpotential and poor stability. Here, a porous SnO2/ZnO catalyst is synthesized via hydroxides coprecipitation, hydrothermal treatment, and carbon black template calcination. SnO2 nanocrystals are produced by calcination of tin hydroxides while the growth of ZnO nanocrystals is associated with carbon black template. The porous SnO2/ZnO catalyst presents a stable Faradaic efficiency of >90% for CO2 reduction at an applied voltage of −0.7 V versus reversible hydrogen electrode and a C1 current density of 9.53 mA/cm2 over a testing period of 100 h. The improved performance is originated from abundant hetero-junctions and lattice defects of SnO2 and ZnO nanocrystals, large specific surface area, and grain boundary. This study provides a facile method to fabricate porous and nanocrystal metal oxides electrocatalysts for electrochemical processes.

CuFeSe2/Cu2Se@C heterostructures as high-rate ultra-stable anodes for sodium ion half/full batteries

Transition metal selenides can be potentially implemented as a new generation of sodium storage anode owing to their abundance and high theoretical specific capacity. However, their practical applications are limited by large volume changes and slow kinetics. Therefore, the construction of transition metal selenide heterojunctions with long cycle stability and high capacity as anodes in sodium ion batteries remains challenging. In this study, carbon coated CuFeSe2/Cu2Se heterojunctions (CFS/CS@C) were successfully prepared via a simple aging and annealing strategy. The abundant heterojunction interfaces and carbon layers accelerated charge transfer, promoted the reaction kinetics, enhanced the electrical conductivity, and extended the cycle life. Consequently, the target material yielded ultra-long cycle stability (301.2 mAh/g at 10.0 A/g after 3000 cycles) and excellent rate performance (330.96 mAh/g at 20 A/g). The directly constructed full cell also exhibited remarkable cycling stability (138.6 mAh/g after 200 cycles at 0.5 A/g). Accordingly, this work demonstrated the construction of transition metal selenide composites as high-performance electrochemical energy storage electrodes.

Formation of large-scale MoS2/Cu2O/ZnO heterostructure arrays by in situ photodeposition and application for ppb-level NO2 gas sensing

Photodeposition has been used extensively for nanomaterial growth on a substrate, but direct photodeposition of 2D transition metal dichalcogenides (TMDs) remains challenging. An alternative approach is to deposit 2D TMDs on a suitable nanomaterial template. In this work, large-scale MoS2/Cu2O/ZnO heterostructure arrays are formed by low-temperature in situ photodeposition and the nanocomposites are used for chemiresistive gas sensing at room temperature. Using 254 nm UV irradiation, Cu2O nanoclusters are photodeposited in solution on hydrothermally grown ZnO nanorod arrays and Cu2O/ZnO heterostructure arrays are first formed. MoS2 nanoparticles are subsequently photodeposited on Cu2O and MoS2/Cu2O/ZnO heterostructure arrays with good uniformity on a sub-millimeter scale are consequently produced. The ternary nanocomposite with a 45 min MoS2 photodeposition time shows the highest response of 890% toward 500 ppb NO2 under UV-activated sensing. An excellent linear sensitivity of 18.7 ppm–1 has been achieved and the estimated lowest detection limit is 1.3 ppb, exhibiting good potential for monitoring of environmental NO2 content. The outstanding performance is attributed to the combined chemical and electronic sensitization effects of the abundant heterojunctions in the nanocomposite. The present work reveals that facile in situ photodeposition is suitable for synthesis of large-scale MoS2/Cu2O/ZnO heterostructure arrays with remarkable gas sensing performance.

Constructing Ru particles decorated Co3B-CoP heterostructures as a highly active and reusable catalyst for H2 generation by catalyzing NaBH4 hydrolysis

Constructing an efficient and reusable catalyst for catalyzing NaBH4 hydrolysis for H2 production is of vital significance. Herein, the Ru particles decorated Co3B-CoP heterostructures are obtained by chemical reduction and gas-phase phosphating treatment. The strong electronic interaction and abundant heterojunctions between the Co3B-CoP substrate and Ru particles have been elucidated. The optimal Ru0.063/Co3B-CoP catalyst exhibits a fast hydrogen generation rate (8875.8 mL min−1 gcat−1) and a high turnover frequency (636.0 min−1) at 25 °C, superior to most ever reported catalysts. The excellent NaBH4 hydrolysis performance can be attributed to the lower activation energy (47.6 kJ mol−1) and the synergy between Co3B-CoP substrate and Ru particles. Density functional theory calculations show that electrons penetrate into Ru particles from Co3B-CoP substrate, in which the electron-rich Ru particles can selectively adsorb BH4− ions, while the electron-deficient Co3B-CoP facilitates the capture of H2O molecules, thereby synergistically promote the catalyzing NaBH4 hydrolysis to produce H2.

Facile Synthesis of ZnO/WO3 Nanocomposite Porous Films for High-Performance Gas Sensing of Multiple VOCs.

Volatile organic compounds (VOCs) in indoor environments have typical features of multiple components, high concentration, and long duration. The development of gas sensors with high sensitivity to multiple VOCs is of great significance to protect human health. Herein, we proposed a sensitive ZnO/WO3 composite chemi-resistive sensor facilely fabricated via a sacrificial template approach. Based on the transferable properties of self-assembled monolayer colloidal crystal (MCC) templates, two-dimensional honeycomb-like ordered porous ZnO/WO3 sensing matrixes were constructed in situ on commercial ceramic tube substrates with curved and rough surfaces. The nanocomposite thin films are about 250 nm in thickness with large-scale structural consistency and integrity, which facilitates characteristic responses with highly sensitivity and reliability. Furthermore, the nanocomposite sensor shows simultaneous responses to multiple VOCs that commonly exist in daily life with an obvious suppression sensing for traditional flammable gases. Particularly, a detection limit of 0.1 ppm with a second-level response/recovery time can be achieved, which is beneficial for real-time air quality assessments. We proposed a heterojunction-induced sensing enhancement mechanism for the ZnO/WO3 nanocomposite film in which the formation of abundant heterojunctions between ZnO and WO3 NPs significantly increases the thickness of the electron depletion layer in the bulk film and improves the formation of active oxygen species on the surface, which is conducive to enhanced responses for reducing VOC gases. This work not only provides a simple approach for the fabrication of high-performance gas sensors but also opens an achievable avenue for air quality assessment based on VOC concentration detection.

One-Step Calcination to Gain Exfoliated g-C3N4/MoO2 Composites for High-Performance Photocatalytic Hydrogen Evolution.

The difficulty of exposing active sites and easy recombination of photogenerated carriers have always been two critical problems restricting the photocatalytic activity of g-C3N4. Herein, a simple (NH4)2MoO4-induced one-step calcination method was successfully introduced to transform bulk g-C3N4 into g-C3N4/MoO2 composites with a large specific surface area. During the calcination, with the assistance of NH3 and water vapor produced by ammonium molybdate, the pyrolytical oxidation and depolymerization of a g-C3N4 interlayer were accelerated, finally realizing the exfoliation of the g-C3N4. Furthermore, another pyrolytical product of ammonium molybdate was transformed into MoO2 under an NH3 atmosphere, which was in situ loaded on the surface of a g-C3N4 nanosheet. Additionally, the results of photocatalytic hydrogen evolution under visible light show that the optimal g-C3N4/MoO2 composite has a high specific surface area and much improved performance, which is 4.1 times that of pure bulk g-C3N4. Such performance improvement can be attributed to the full exposure of active sites and the formation of abundant heterojunctions. However, with an increasing feed amount of ammonium molybdate, the oxidation degree of g-C3N4 was enhanced, which would widen the band gap of g-C3N4, leading to a weaker response ability to visible light. The present strategy will provide a new idea for the simple realization of exfoliation and constructing a heterojunction for g-C3N4 simultaneously.

Enhancing the surface polarization effect via Ni/NiMoOx heterojunction architecture for urea-assisted hydrogen generation

Electrocatalytic urea oxidation (UOR) has attracted significant interest as a promising anodic half-reaction to replace sluggish oxygen evolution reaction (OER) toward water splitting. However, the activation and decomposition of urea molecule maintains a challenge during electrocatalytic process because of its 6e− oxidation procedure. Herein, Ni nanoparticles decorated NiMoOx nanorod (Ni/NiMoOx) electrocatalyst with abundant heterojunction interfaces is fabricated and the density functional theory (DFT) calculation testifies that the interfaces are favorable for enhancing the conductivity and modulating the surface polarization of Ni/NiMoOx, thus improving its UOR’s activity. The Ni/NiMoOx performs superb electrocatalytic capacities toward UOR with a potential of 1.355 V (vs RHE) at 20 mA cm−2, and HER with an overpotential of 98 mV at 10 mA cm−2. A hybrid two-electrode water splitting cell is further assembled via applying the Ni/NiMoOx as both anodic and cathodic electrodes with presence of 0.33 M urea, delivering 50 mA cm−2 at voltage of 1.589 V. The findings help to provide a reliable strategy for rational reconstruction of Ni based metal oxide with rich interfaces for diverse electrocatalytic reactions.

Hierarchical magnetic-dielectric synergistic Co/CoO/RGO microspheres with excellent microwave absorption performance covering the whole X band

Based on the rational component regulation and micro-nano structure design, hierarchical dielectric-magnetic microspheres become the ideal functional materials in the microwave absorption field. Herein, unique three-dimension (3D) Co/CoO/reduced graphene oxide (RGO) (denoted as CCOR) microspheres with the hierarchical structure are prepared by a simple solvothermal method and annealing treatment. Due to the plentiful growth sites on the surface of graphene oxide, Co/CoO nanoparticles (NPs) homogeneously anchor on the RGO. Meanwhile, larger size Co/CoO particles connect 2D RGO nanosheets to form the hierarchical CCOR microspheres, which introduce abundant heterojunctions and interfaces. The electromagnetic parameters have been effectively adjusted by tuning the synergistic effect between the magnetic Co/CoO particles and highly conductive RGO nanosheets. The obtained CCOR composites exhibit excellent microwave absorption performance with the maximum reflection loss (RLmax) of −50.1 dB. The effective absorption bandwidth reaches 6.56 GHz covering the whole X-band frequency. The outstanding microwave absorption performance of CCOR microspheres stems from the followings: i) well micro-nano structure design provides abundant heterojunction interfaces, resulting in the enhanced interfacial polarization; ii) the magnetic-dielectric synergistic loss ability from rational Co/CoO and RGO component design, facilitating the microwave energy dissipation; iii) the Co/CoO particles induce multi-scale magnetic coupling effect and strengthen the magnetic response capability. Thus, as-synthesized Co/CoO/RGO microspheres demonstrate the huge potential for application of stealth in X band as microwave absorption materials.

Electrochemically activated Ni@Ni(OH)2 heterostructure as efficient hydrogen evolution reaction electrocatalyst for anion exchange membrane water electrolysis

Efficient and cost-effective catalysts are vital for sustainable hydrogen production via water electrolysis. In this study, we propose a facile method of fabricating a Ni@Ni(OH)2 heterostructure catalyst on a Ti paper substrate by combining electrodeposition and subsequent electrochemical activation. Detailed characterization and analysis revealed the formation of Ni (oxy)hydroxides. Ni@Ni(OH)2 underwent surface reconstruction, resulting in the formation of abundant heterojunctions and electron modulation during electrochemical activation, which substantially increased the exposed surface area facilitating the adsorption of intermediates during the hydrogen evolution reaction (HER). Thus, the resulting activated Ni@Ni(OH)2/Ti electrode exhibited significantly improved HER activity in the half-cell test, reaching a current density of −10 mA/cm2 at an overpotential of 58 mV with a Tafel slope of 83 mV/dec. When applied to anion exchange membrane water electrolysis, a single cell comprising an Ni@Ni(OH)2/Ti cathode and commercial IrO2/CP anode exhibited a maximum current density of 1.00 A/cm2 at a potential of 2.0 Vcell, demonstrating superior performance to commercial Pt/C electrodes in the high-current-density region above 2.0 A/cm2.

Spatially Confined “Edge‐to‐Edge” Strategy for Achieving Compact Na+/K+ Storage: Constructing Hetero‐Ni/Ni3S2 in Densified Carbons

AbstractTransition metal sulfides (TMS) are considered as promising anodes for sodium/potassium ion batteries (SIBs/PIBs), and compositing TMS with conductive nanocarbons is an effective mitigation for improving rate performance and cycling stability. However, such a coupling strategy often decreases the tap density and therefore the volumetric energy of electrode. To achieve fast electron/ion transport and high volumetric capacity simultaneously, herein, a compact nanostructure with hetero Ni‐Ni3S2 nanoparticles embedded in a densified S‐doped carbon matrix (Ni‐Ni3S2@SC) is constructed via a spatially confined “edge‐to‐edge” strategy. Experimental and theoretical results confirm that the carbon matrix and metallic Ni nanoparticles provide fast electron transport pathways at two scales, while the abundant heterojunctions with strong electric fields promote the ion migration and Na/K adsorption. As an anode in SIBs/PIBs, the Ni‐Ni3S2@SC exhibits superior rate capability (289/197 mA h g−1 at 2 A g−1), stable cycling performance (88.1/86.2% capacity retention after 100 cycles), and exceptional volumetric capacity (1048/850 mAh cm−3 at 0.05 A g−1). The impressive energy‐power characteristics for Ni‐Ni3S2@SC anode are further confirmed in full cell batteries and hybrid capacitors. The reported spatially confined “edge‐to‐edge” strategy might be adapted to the construction of various binary and/or ternary metal sulfide dense electrodes for advanced energy storage devices.

Ligand-directed construction of CNTs-decorated metal carbide/carbon composites for ultra-strong and broad electromagnetic wave absorption

• Ligand-directed strategy was developed to build CNTs-decorated Ni 3 ZnC 0.7 /C composites. • The multi-component composites feature hierarchical structure and large surface area. • The strong dielectric loss and impedance matching obtained by synergistic effects. • The composites exhibit ultra-strong and broadband electromagnetic wave absorption. Multi-component hierarchical carbon-based materials with large accessible specific surfaces and abundant heterojunctions have been regarded as promising candidates for high-performance electromagnetic wave (EMW) absorbers, yet rational construction is still challenging. Herein, we demonstrate “ligand-directed post-modification” as an effective strategy to transform bimetallic MOFs into well-defined multi-dimensional hierarchical composites. Using l -histidine ligand modified ZIF-8 as novel MOF precursor, Ni 2+ can be incorporated in a controlled manner via coordination, leading to the formation of Ni 3 ZnC 0.7 /carbon nanotube (CNT)/nano-porous carbon (NPC) composites after pyrolysis. The obtained composites exhibit the optimal reflection loss (RL) of −66.6 dB at 2.58 mm and broad effective absorbing bandwidth (EAB) covering 7.04 GHz at 2.49 mm. Moreover, the EAB range can be further expanded to 7.76 GHz by tuning the Ni content, which outperforms the majority of reported MOF-derived absorbers. The superior microwave absorption performance relies on the synergistic effects based on conduction loss and abundant dipole/interfacial polarization originating from the hierarchical structures composed of 0D Ni 3 ZnC 0.7 nanoparticles, 1D CNT and 3D porous carbon, as well as the optimized impedance matching characteristic arisen from the large specific surface area (≥373 m 2 /g) of the composites. Hence, this work presents a new strategy to rationally construct hierarchical multi-component carbonaceous materials derived from MOFs with desirable functionalities.

High performance H2 sensor based on rGO-wrapped SnO2–Pd porous hollow spheres

Hydrogen (H2) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO2–Pd porous hollow spheres composite (SnO2–Pd@rGO) for high performance H2 sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO2-based spheres with subsequent thermal reduction in H2 ambient. This sensor exhibited excellently selective H2 sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ∼8 to 0.1 ppm H2 in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H2 monitoring. Furthermore, this sensor demonstrated certain response to H2 at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions, the catalysis of the doped-PdOx, the relative hydrophobic surface from rGO, and the deoxygenation after H2 reduction.

Yb3+, Er3+ co-doped NaGdF4/BiVO4 embedded Cu2O photocathodes for photoelectrochemical water reduction with near infrared light

Upconverting near infrared light to photoelectrode absorbable visible light is desirable for enhancing photoelectrochemical hydrogen production. In this work, photocathodes were fabricated by embedding β-NaGdF4:Yb3+,Er3+ nanocrystals and BiVO4 microcrystals into Cu2O matrix, where β-NaGdF4:Yb3+, Er3+ nanocrystals were used for upconversion luminescence and the BiVO4 microcrystals were employed to form abundant hetero-junctions inside the Cu2O matrix. In comparison with the pristine Cu2O thin film, the NaGdF4:Yb3+,Er3+/BiVO4 embedded Cu2O photocathodes illustrated good response to near infrared light. Photocurrent produced by 980 nm light was enhanced by a factor of 40 to about 1 mA cm−2. The high photocurrent can be attributed to the widely distributed internal electric fields introduced by the BiVO4 in the bulk of the Cu2O, which inhibits the recombination of the electrons and holes excited by the NaGdF4:Yb3+,Er3+ emitted visible light in the vicinity. Furthermore, the 980 nm light induced temperature increment exhibits significant synergistic effect on the enhanced photocurrent.

Reduced miscibility between highly compatible non-fullerene acceptor and donor enables efficient ternary organic solar cells

The morphology of the photoactive layer within organic solar cells (OSCs) plays a key role in determining device performance. In addition to the film forming conditions, miscibility between donors and acceptors critically derives the corresponding morphology, which can be empirically evaluated by the Flory–Huggins interaction (χ). Herein, a new non-fullerene acceptor (NFA) with long alkyl chains and fluorinated end groups, BTP-4F–C9-20, is reported, which has sufficient solubility in common solvents and good miscibility with the polymer donor PM6. PM6:BTP-4F–C9-20 binary OSC achieved a maximum PCE of 16.5%, as a result of fine phase separation that creates abundant heterojunctions for exciton dissociation but insufficient bi-continuous pathways for charge transport. A chlorinated NFA Y7-BO with higher χ with PM6 is introduced into the PM6:BTP-4F–C9-20 host system, which increases phase separation with slightly enlarged domains to better shape the charge transport pathways. The PM6:BTP-4F–C9-20:Y7-BO (1:1.1:0.1) ternary OSC achieved a higher PCE of 17.3%, although Y7-BO provides limited complementary light absorption. This work demonstrates that the Flory–Huggins interaction is an effective parameter to fine tune the morphology of ternary OSCs to promote photovoltaic performance.