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Developing conjugated three-dimensional (3D) covalent organic frameworks (COFs) still remains an extremely difficult task due to the lack of enough conjugated 3D building blocks. Herein, condensation between an 8-connected pentiptycene-based

Intercalation-type layered oxides have been widely explored as cathode materials for aqueous zinc-ion batteries (ZIBs). Although high-rate capability has been achieved based on the pillar effect of various intercalants for widening interlayer space, an in-depth understanding of atomic orbital variations induced by intercalants is still unknown. Herein, we design an NH 4 + -intercalated vanadium oxide (NH 4 + -V 2 O 5 ) for high-rate ZIBs, together with deeply investigating the role of the intercalant in terms of atomic orbital. Besides extended layer spacing, our X-ray spectroscopies reveal that the insertion of NH 4 + could promote electron transition to 3 d xy state of V t 2 g orbital in V 2 O 5 , which significantly accelerates the electron transfer and Zn-ion migration, further verified by DFT calculations. As results, the NH 4 + -V 2 O 5 electrode delivers a high capacity of 430.0 mA h g −1 at 0.1 A g −1 , especially excellent rate capability (101.0 mA h g −1 at 200 C), enabling fast charging within 18 s. Moreover, the reversible V t 2 g orbital and lattice space variation during cycling are found via ex-situ soft X-ray absorption spectrum and in-situ synchrotron radiation X-ray diffraction, respectively. This work provides an insight at orbital level in advanced cathode materials.

The Chang 7 oil-bearing layers from the Ansai area of the Ordos Basin are abundant in oil and gas resources. These layers are chiefly comprised of shales interbedded with tight sandstone. In the regions where the exploration level is relatively low and the structures are gentle in the Ansai area, the distribution of fractures in shale reservoirs and tight sandstone reservoirs is significant for predicting sweet spots and determining the success rate of hydraulic fracturing. In this research, the results acquired from the scanning electron microscope (SEM), cores, thin sections, and image logging determined the developmental characteristics of fractures. Moreover, the Himalayan stress field was modeled using ANSYS, whereas the two-factor method is used to predict the distribution of tectonic fracture by combining stress field and fracture criterion. The results indicate a gradually decreasing trend of the maximum principal stress from east to west. The minimum principal stress in the western part is less than that in the eastern part. The differential stress that can indicate the degree of tectonic deformation ranges from 17 Mpa to 25 MPa. The fracture density ranges from 0 strip/m to 1.5 strip/m. In addition, the areas with more fractures are mainly located in the western and southeastern parts, where shale oil is relatively rich. Similarly, the comparison of different maps illustrates that the distribution of tectonic fracture is related to mechanical parameters and stress fields.

A robust HOF has been employed as cathode for LIBs. The decoration of rich redox-active moieties in HOFs introduces the surface-controlled capacitive mechanism in LIBs, accessing a high capacity, high rate capability and excellent cycling stability.

A bipolar-type 2D COF has been fabricated through the condensation of TPPDA and Cu-TFPP. The COF cathode with p- and bipolar-type redox-active centers exhibits good performance for Li-ion batteries.

The rapid development of the Internet of Things has resulted in the harvesting of distributed sustainable energy receiving increasing attention. Recently, a study on triboelectric nanogenerators (TENGs) for collecting low-frequency and irregular-amplitude ocean wave energy has attracted significant interest. Herein, a self-powered seesaw-structured spherical triboelectric–electromagnetic hybrid nanogenerator (SSTE-HNG) combining various working modes is presented for harvesting wide-frequency wave energy from different directions and self-powered sea surface wireless positioning. The electrical output performances were systematically investigated and optimized via studying the effects of the configuration parameters, including the central slider mass, oscillation frequency, and swing amplitude of each module and the entire device; the instantaneous maximum output power densities of the origami zigzag-multilayer structured (OZ), freestanding layer rolling (FL), and electromagnetic generator (EMG) modules can reach 17, 4.8, and 9.8 W m−3, respectively, at an oscillation frequency of 0.7 Hz, and around 410 LEDs can be lit when operating the SSTE-HNG. Finally, the output voltage of the SSTE-HNG was stabilized using a transistor-controlled power management circuit for charging a 4.7 mF commercial capacitor in the range of 2.7 to 3.3 V; the seesaw-structured spherical buoy was used to drive a global positioning system (GPS) module for dynamic sea surface real-time wireless positioning, and our lab building on campus was successfully located upon installing the SSTE-HNG in a water tank. This study provides an ingenious design for achieving synchronized movements among hybrid effect/mode-based generators, and a self-powered buoy with a hybrid nanogenerator for sea surface wireless positioning was realized, which has the potential to be integrated with distributed electronics, such as sensors that collect sea surface meteorological information, in the future in the field of smart marine technology.

Interface engineering of zinc metal anodes is a promising remedy to relieve their inferior stability caused by dendrite growth and side reactions. Nevertheless, the low affinity and additional weight of the protective coating remain obstacles to their further implementation. Here, aroused by DFT simulation, self-assembled monolayers (SAMs) are selectively constructed to enhance the stability of zinc metal anodes in dilute aqueous electrolytes. It is found that the monolayer thiol molecules relatively prefer to selectively graft onto the unstable zinc crystal facets through strong Zn-S chemical interactions to engineer a covalent interface, enabling the uniform deposition of Zn

Sluggish charge transfer in perovskite film induced by inherent defects such as uncoordinated Pb2+ undoubtedly hinders the rapid response of self-powered photovoltaic-typed detector. Based on interaction between Lewis acids and bases, herein, we employ thiourea molecule as a multifunctional Lewis base to significantly improve the quality of all-inorganic CsPbIBr2 perovskite film. After careful characterizations, the quality of perovskite film has been well regulated. Arising from the reduced defect and the reinforced the interfacial charge extraction owing to the strong interaction between uncoordinated Pb2+ ions and the -C = S groups in thiourea and the formation of hydrogen bond at perovskite/TiO2 interface, an enhanced responsivity of 0.335 A W−1 and specific detectivity of 3.92 × 1012 Jones has been achieved for the self-powered, carbon-electrode based photodetector, which is comparable to the state-of-the-art device based on CsPbIBr2 film. More importantly, the device free of encapsulation remains 82.8% of initial performance after storage over 56 days in ambient atmosphere, promoting the practical deployment of perovskite products.

Artificial photosynthesis of H

Fully aromatic conjugated covalent organic frameworks (FAC-COFs) with excellent physicochemical stability have been emerging as active semiconductors for diverse potential applications. Developing efficient synthesis methods for fabricating FAC-COFs will significantly facilitate the exploration over their material and photonic/electronic functionalities. Herein, a facile solvent-free strategy is developed for the synthesis of 2D phthalocyanine-based FAC-COFs (FAC-Pc-COFs). Cyclopolymerization of benzo[1,2-b:4,5-b']bis[1,4]benzodioxin-2,3,9,10-tetracarbonitrile (BBTC) and quinoxalino[2',3':9,10]phenanthro[4,5-abc]phenazine-6,7,15,16-tetracarbonitrile (QPPTC) in ZnCl

The poor electronic and ionic conductivities of covalent organic frameworks (COFs) severely restrict the development of COF-based electrodes for practical rechargeable batteries, therefore inspiring more research interest from the direction of both material synthesis and technology. Herein, a dual-porous COF, USTB-6, with good crystallinity and rich redox-active sites is conceived and fabricated by the polymerization of 2,3,8,9,14,15-hexa(4-formylphenyl)diquinoxalino [2,3-a:2',3'-c]phenazine and 2,7-diaminopyrene-4,5,9,10-tetraone. In particular, the heterogeneous polymerization of the same starting materials in the presence of graphene affords uniformly dispersed COF nanosheets with a thickness of 8.3 nm on a conductive carbon substrate, effectively enhancing the electronic conductivity of the COF-based electrode. Such a graphene-supported USTB-6 nanosheets cathode when used in a lithium-ion battery exhibits a specific capacity of 285 mA h g

Covalent organic frameworks (COFs) are gaining increasing attention as renewable cathode materials for Li-ion batteries. However, COF electrodes reported so far still exhibit unsatisfying capacity due to their limited active site density and insufficient utilization. Herein, a new two-dimensional polyimide-linked COF, HATN-AQ-COF with multiple redox-active sites for storing Li

Triboelectric generators (TENGs) have been extensively studied as a new energy for low cost and the universally applicable prospect. Meanwhile, perovskites have been applied in TENG and show a good performance in view of high carrier mobility, long life and dielectric properties. The asymmetry structure of the orthogonal phase CsPbBr3 perovskite endows it with ferroelectric property and induces the misalignment of the positive and negative charge centers. Herein, the surface energy of halogen doped inorganic CsPbX3 (X = Cl-, Br-) perovskites are theoretically investigated by density functional theory (DFT) calculation, the crystal polarizability of pristine CsPbBr3 is improved from 0.47 Ry a.u. to 0.52 Ry a.u. (CsPbCl3), indicating the polarizability of CsPbCl3 is higher than CsPbBr3. In addition, the build-in electric field (Ebuild-in) of perovskite materials can be enhanced by the spontaneous polarization and the aligned dipoles in the Ebuild-in could further improve the tribo-electrostatic electric field by retaining more triboelectric surface charges. In the end, CsPbCl3 achieved a power of 3.06 W m-2 compared to the power of 1.34 W m-2 of CsPbBr3. This work focuses on the regulation of crystal planes using spontaneous polarization of perovskite toward achieving a high built-in electric field for enhancing triboelectric surface charge density.

Development of ocean energy conversion technique is a strategic requirement to optimize the energy structure and expand the "blue economic" space. Triboelectric nanogenerator (TENG) provides a potential approach for efficiently capturing wave energy with its unique advantages. Herein, a nodding duck structure multi-track freestanding triboelectric-layer nanogenerator (NDM-FTENG) is developed for ocean wave energy harvesting at a low-frequency range. Configuration parameters including track numbers, connection approach, oscillation frequency, and swing amplitude on electrical output performances of NDM-FTENG are systematically investigated and optimized; the maximum instantaneous power density of 4 W/m3 is obtained by one NDM-FTENG block with 320 LEDs lighted up simultaneously. Overall, NDM-FTENG is proved to be an efficient device for driving small electronics with excellent stability and durability in a real water wave environment, and the power potential can be further magnified by combining more NDM-FTENG devices in parallel to form a network toward large-scale blue energy harvesting.

The precise regulation of interfacial charge distribution highly determines the power conversion efficiency of perovskite solar cells (PSCs). Herein, inorganic (NiCo)1-y Fey Ox nanoparticle decorated graphene oxide (GO) is successfully demonstrated as a hole booster for all-inorganic CsPbIBr2 PSC free of precious metal electrode. Arising from the spontaneous electron transfer induced p-type doping of GO from edged oxygen-containing functional groups to (NiCo)1-y Fey Ox , the best all-inorganic CsPbIBr2 PSC achieves an efficiency of 10.95 % under one standard sun owing to the eliminated paradox between charge extraction and charge localization in GO surface. Furthermore, the champion device exhibits an excellent long-term stability at 10 % relative humidity without encapsulation over 70 days because of the suppressed ions migration.

Tailored optimization of perovskite solar cells (PSCs) is a persistent objective to achieve the ultimate commercialization purpose, in which the electron/hole transport layer with thickness on the ...

All-inorganic CsPbBr3 perovskite solar cells (PSCs) have attracted tremendous attention, owing to their excellent stability and rising power conversion efficiency. However, the mechanical flexibility of these solar cells has ground to a standstill because of the high-temperature requirement for ideal CsPbBr3 perovskite films. In this study, a flexible CsPbBr3 PSC with an efficiency of 5.71 % has been made by means of fabricating a heat-resistant conductive muscovite substrate, which demonstrates very high mechanical flexibility with nearly unchanged resistance even after 4000 bending cycles (12000 cycles of concave and convex bending for PSCs), owing to the weak van der Waals force and layered structure. Implementation of the muscovite substrate enables the fabrication of flexible PSCs under high-temperature conditions, providing a new path to increase the efficiency without lowering the crystallization temperature of state-of-the-art electron-transporting materials and perovskite films in the future.

Simultaneously tailoring the interfacial energetics and healing the defective nanostructure of perovskite films is important for promoting the power conversion efficiency of perovskite solar cells (PSCs). Herein, a fluoroaniline molecule-terminated graphene oxide (GO) is fabricated as an interface modulator in all-inorganic CsPbIBr2 PSCs. Owing to the amidation reaction induced p–π conjugation effect with an adjacent benzene ring, the spontaneous electron transfer from oxygen-containing groups at the GO surface to the aniline unit causes the self-reduction and p-type doping of GO, benefiting hole extraction and delocalization. Together with the passivation effect by –F termination with under-coordinated Pb2+, the best device delivers an efficiency of 11.08% with superior stability originating from the presence of hydrophobic C–F bonds, the reduced defects and suppressed ion migration. Moreover, the functionalized GO can effectively capture and obstruct the leakage of Pb2+ ions from a destructive device, demonstrating its unique advantages in high-performance PSC platforms.

An O-hydroxyphenyl thiourea-modified chitosan (OTCS) with excellent Pb(II) adsorption performance and selectivity was prepared as an adsorbent. The structure and morphology of the adsorbent were systematically investigated by SEM, BET, FTIR, EDX, zeta-potential measurements, XPS and XRD. The impacts of the initial Pb(II) concentration, reaction time, temperature, pH value, and coexisting ions were explored. At pH 7 and 303 K, the maximal adsorption capacity of OTCS for Pb(II) was 208.33 mg/g, which was greater than those of other adsorbing materials reported in the literature. The metal ion adsorption kinetics and isotherm models were found to obey pseudo-second-order kinetics and the Langmuir isothermal model, indicating that the adsorption process was monolayer chemisorption. The adsorption process could proceed spontaneously, and the thermodynamic results revealed that the adsorption mechanism was an endothermic reaction. The ion exchange and chelation between the sulfur, nitrogen and oxygen groups on the adsorbent and lead ions endowed the material with excellent adsorption properties. Significantly, OTCS showed excellent selectivity toward Pb(II). Therefore, the adsorbent OTCS is expected to promote the wider application of chitosan in the adsorption of Pb(II).

Tin dioxide (SnO2) is generally regarded as a promising electron-transporting layer (ETL) for state-of-the-art perovskite solar cells (PSCs), however, the ubiquitous oxygen-vacancy-related defects at SnO2 surface and the large energy difference between conduction band of SnO2 and perovskite layer undoubtedly cause severe charge carrier recombination, resulting in sluggish charge extraction efficiency and non-negligible open-circuit voltage (Voc) loss. Herein, a chlorine-containing TiOxCl4-2x accessory layer is fabricated by immersing SnO2 layer into the TiCl4 aqueous solution to passivate the surface oxygen-vacancy-related defects of SnO2 layer and to set an intermediate energy level at ETL/perovskite interface in all-inorganic cesium lead tri-bromine (CsPbBr3) PSCs. Furthermore, the TiOxCl4-2x layer also improves the infiltration of SnO2 layer surface toward perovskite precursor for high-quality perovskite film. Finally, the hole-free, all-inorganic CsPbBr3 PSC with a structure of FTO/SnO2/TiOxCl4-2x/Cs0.91Rb0.09PbBr3/carbon achieves a champion efficiency of 10.44% with a Voc as high as 1.629 V in comparison to 8.31% for control device. Moreover, the optimized solar cell presents good stability in 80% humidity in air.

Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron-transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all-inorganic CsPbBr3 perovskite solar cells (PSCs) because of their higher crystallization temperatures and thermal expansion coefficients. Herein, the interfacial strain is released by fabricating a WS2 /CsPbBr3 van der Waals heterostructure owing to their matched crystal lattice structure and the atomically smooth dangling bond-free surface to act as a lubricant between ETL and CsPbBr3 perovskite. Arising from the strain-released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65 % with an ultrahigh open-circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity (80 %) attack over 120 days.

Improved charge extraction and wide spectral absorption promote power conversion efficiency of perovskite solar cells (PSCs). The state-of-the-art carbon-based CsPbBr3 PSCs have an inferior power output capacity because of the large optical band gap of the perovskite film and the high energy barrier at perovskite/carbon interface. Herein, we use alkyl-chain regulated quantum dots as hole-conductors to reduce charge recombination. By precisely controlling alkyl-chain length of ligands, a balance between the surface dipole induced charge coulomb repulsive force and quantum tunneling distance is achieved to maximize charge extraction. A fluorescent carbon electrode is used as a cathode to harvest the unabsorbed incident light and to emit fluorescent light at 516 nm for re-absorption by the perovskite film. The optimized PSC free of encapsulation achieves a maximum power conversion efficiency up to 10.85 % with nearly unchanged photovoltaic performances under 80 %RH, 80 °C, or light irradiation in air.

A new polyoxometalate (POM) pillared metal–organic framework (POMOF), [Cu24(Trz)16(H2O)Cl4(HPMo12O40)] (Cu-POM, Trz = 1,2,3-triazole), was synthesized and characterized. Crystal analysis reveals that the Keggin POMs are inserted into copper–triazole layers with a graphite-like structure generating a POM-supported porous three-dimensional framework. Owing to the combination of the multi-electron redox property of POM units and the open porous framework, Cu-POM can be utilized as an anode material for lithium ion batteries (LIBs), and exhibits a reversible capacity of 525 mA h g−1 at a current density of 100 mA g−1 after 100 cycles. Moreover, to illustrate lithium storage, the impedance spectra of compound Cu-POM during the first and 100th charge process have also been studied. The study of Cu-POM in this work might guide the development of POM-based electrode materials for LIBs.

The electron-transporting layer (ETL) plays a non-negligible role in determining the charge extraction and transfer behaviors from perovskite films under solar irradiation for high efficiency perovskite solar cells. A suitable band structure, good conductivity, high electron mobility and low trap state density are preferred for the desired ETL to maximize the electricity generation and minimize the charge recombination. Herein, we have demonstrated that the incorporation of antimony (Sb) dopants into the lattice of low-temperature processed TiO2 nanocrystals can effectively suppress the formation of under-coordinated Ti3+ and oxygen vacancies, leading to improved electronic conductivity and mobility. When assembling into all-inorganic, carbon-based CsPbBr3 planar perovskite solar cells free of noble metal electrodes, an enhanced efficiency of 8.91% with an ultra-high open-circuit voltage of 1.654 V and reduced hysteresis from 32% to 15% is achieved based on the Sb-doped TiO2 ETL. The mechanism behind this phenomenon is mainly attributed to the improved perovskite film quality and significantly reduced charge recombination. Taking the advantages of low temperature, low defect state density, high electrical conductivity and mobility into consideration, the Sb-doped TiO2 ETL demonstrates great potential in advanced perovskite solar cells even in flexible devices.

Triboelectric nanogenerators (TENGs) are preferred energy conversion devices to scavenge low-frequency mechanical energy sources from ambient environments due to their easy-to-operate principle structures, cost-effectiveness, and wide application areas. Halide perovskites have been demonstrated to be a good candidate as triboelectrification dielectric materials in TENGs, yet their triboelectrification behavior and charging affinity are still unclear. Herein, inorganic CsPbBr3 perovskites doped with halide ions (I− and Cl−) are systematically investigated focusing on their triboelectric behaviors through fabricating perovskite TENGs in vertical contact-separation mode. The charging polarities of different halide perovskites are qualified and ascertained by evaluating their triboelectric output signals, power density, charging capacity, and figure of merit (FOM), which are confirmed by the deviation of electron binding energy, carrier mobility, surface potential and dielectric properties affected by different halide ion incorporation. Meanwhile, the champion perovskite TENG demonstrates an excellent operational durability in an ambient atmosphere. A modified triboelectric series containing inorganic perovskites with various halide ions is established based on the empirical results. This work not only enriches the triboelectric series, but also expands the application of perovskite materials in mechanical energy harvesting fields.

Triboelectric nanogenerators (TENGs) have attracted growing attention because they are advanced energy conversion devices to efficiently harvest low-frequency mechanical energy from nature. How to increase the permittivity of electrode materials as well as the surface charge density is technically important to improve the output performances of a robust TENG. In this study, an all-inorganic cesium lead bromide (CsPbBr3) perovskite film with semiconducting characteristics is combined with metallic nano-platinum to build bulk Pt/CsPbBr3 Schottky junctions, which are used as triboelectric electrode materials in vertical contact-separation perovskite TENGs. The systematic characterization demonstrates that the electron binding energy and dielectric properties of bulk Pt/CsPbBr3 Schottky junction tailored perovskite films are maximized by optimizing the Pt dosage. An open-circuit voltage of 273 V, a short-circuit current density of 30.3 μA cm−2 and an instantaneous maximum power density of 1295.5 mW m−2 are achieved by the champion Pt/CsPbBr3 TENG at a Pt dosage of 0.5%. A maximum energy storage of 3.96 mJ is stored in a 1 μF capacitor within a 300 s charging period. This work provides new insights into Schottky junction TENGs for enriching the fundamental principles of both halide perovskites and TENGs.

Triboelectric nanogenerators (TENGs) have received growing attention to efficiently harvest waste micromechanical energy from ambient atmosphere such as hydrodynamic energy from raindrops. The comprehensive understanding of the electrification mechanism and dynamic charging behavior between rain droplets and the collecting substrate is essential for multi-application scenarios of TENGs. Herein, a bi-electrode freestanding mode TENG (BF-TENG) is designed to harvest hydrodynamic energy from rain droplets with regard to the implementation at rooftops, terraces and greenhouse roofs. By placing the BF-TENG horizontally, an intriguing cumulative charging behavior of successive water droplets is in-depth investigated, which expands the fundamental charging mechanism for maximizing the surface charge storage capacity. Optimal configurations of the inclination angle and drop height of the BF-TENG system are further studied for improving the electrification charge density as well as power output and extending the application area to inclined surfaces such as rooftops and umbrellas. Through coupling of the cumulative charging behavior and the optimal configurations of BF-TENG, an instantaneous maximum power density of 1.838 W m−2 is achieved and 30 LEDs can be lit up when spraying tap water from a shower faucet on a BF-TENG installed on an umbrella, demonstrating the promising application of BF-TENGs for hydrodynamic energy harvesting and providing multi-implementation scenarios of BF-TENGs with the potential to be installed on the roof top, terrace, umbrella and car hood, which can be utilized as the warning light at rainy night for safe guarding.

Inorganic perovskites are regarded as “star” semiconductors with unique ferroelectricity due to their superior triboelectric behaviors to those of state-of-the-art dielectric polymers when applied in a triboelectric nanogenerator (TENG). An in-depth understanding on the charging mechanism of these inorganic halide perovskites may help design a robust TENG platform. Herein, alkali metal ion doped cesium lead tri-bromine Cs1−xAxPbBr3 (A = Li+, Na+, K+, and Ru+, x = 0–1) perovskites are systematically investigated concentrating on their triboelectric behaviors for the first time. The triboelectric charging affinities of these perovskites are ascertained by evaluating the electrical output performances and figures of merit of TENGs based on perovskite/poly(vinylidene fluoride) pairs in vertical contact-separation mode. Finally, a supplemented qualitative triboelectric series including Cs1−xAxPbBr3 perovskites is established regardless of the doping concentration, and can be utilized as a benchmark to guide the future dielectric selection for robust TENGs. This study not only casts light on the determination of an expanded triboelectric series, but also provides new insights into inorganic perovskites in the application of mechanical energy harvesting.