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A bimetallic oxide Cu2O@MnO2 shows superior dynamic HCHO removal efficiency and pathogen inactivation ability, which is attributed to the electron-rich region at the phase-interface inducing the capture and activation of O2 on the material surface.

Perovskite solar cells (PSCs) have received tremendous attention because of their advantages of low fabrication cost and rising power conversion efficiency (PCE).

Single-mode plasmonic lasing has great potential for use in photonic and sensing applications. In this work, single-mode lasing is realized using a plasmonic-enhanced woven microfiber that shows ultrahigh sensitivity to the ambient environment. This plasmonic-enhanced microfiber is fabricated by spraying Ag nanospheres onto rhodamine 6G-doped polymer microfibers. Single-mode laser emission with an ultranarrow linewidth (0.1 nm) and a low threshold (18.8 kW/mm2) is achieved in the microfiber using the effects of mode selection and plasmonic enhancement provided by the Ag nanospheres. A large wavelength shift in the single-mode lasing is observed when the proposed laser is used as a sensor and exposed to a humid or acidic environment. The wavelength shift is attributed to refractive index variations in the microfiber caused by either moisture absorption or chemical reactions. In humidity sensing, the laser's sensitivity is as high as 826.6 pm/% relative humidity (RH) and the detection limit is 0.051% RH. An innovative strategy for acetic acid gas sensing is proposed that uses the chemical reaction with rhodamine 6G, and its minimum response time is 5 min. Because of the microfiber's excellent fabric compatibility, a wearable sensor is fabricated by weaving the plasmonic-enhanced microfiber into clothes, and this sensor demonstrates extreme bending stability. The results reported here provide a novel approach to the design and fabrication of ultrasensitive wearable sensors for multifunctional sensing applications.

When the power conversion efficiency (PCE) of perovskite solar cells (PSCs) rapidly approaches that of commercial solar cells, the stability becomes the most important obstacle for the commercialization of PSCs. Aside from the widely studied slow PCE degradation, the PSCs also show a unique rapid PCE degradation. Although the degradation due to oxygen and humidity can be avoided by encapsulation, that due to bias voltage, light and heat could not be effective suppressed and will lead to considerable degradation. Usually, the rapid PCE degradation is believed to be from ion migration. However, a systematic investigation is yet to be carried out. This work quantitatively and systematically investigated the relationships between external fields (bias voltage, light or heat), ion migration and device performance. By comparing the performance of reference PSCs after 90 min degradation under these fields, we conclude that (1) the electric field affects the spatial distribution of mobile ions; (2) the light field changes the mobile ion densities and drives the ion migration; (3) the heat field results in perovskite decomposition as well as changing the mobile ion densities. In addition to the analysis of the reference device, we experimentally proved that the improved device stability upon introducing phenethylammonium iodide (PEAI) or poly-methyl methacrylate (PMMA) layers originates from the inhibition of mobile ion density and migration.

Hybrid lead halide perovskites have made great strides in next-generation photovoltaic and optoelectronic devices. Random lasers based on perovskite materials have been intensively investigated, but the miniaturization of perovskite random lasers has not been achieved up to now. Here, we report the fabrication of perovskite random lasers based on perovskite films deposited on the optical fiber facets using a dip-coating method. Under optical pumping conditions, random lasing was observed with minimum threshold energy of 32.3 μJ/cm2 at ~550 nm; also, the lasing threshold decreased with increasing diameter of the optical fiber. The results show that the random lasing emission originates from the scattering between the perovskite crystal grains, and the decreased threshold is attributed to the increased active area of the perovskite film. The directionality of perovskite random lasers indicates that the divergence angle of the laser beam is less than 60°. We also demonstrate that the perovskite random laser on the fiber facet can prevent speckle formation and improve image quality. These results may promote the applications of random lasers in compact sources and integrated optoelectronic devices.

The poor stability of perovskite solar cells is a crucial obstacle for its commercial applications. Here, we investigate the thermal stability of the mixed cation organic–inorganic lead halide perovskites (FAPbI3)1−xMAPb(Br3−yCly)x films and devices in air atmosphere. The results show that with the increase of heat treatment from 25 to 250 °C, the MA-perovskite decomposed into PbI2 firstly and the efficiency of corresponding solar cells reduced linearly. For the perovskite film, the increased heat treatment temperature can bring the redshift of the absorption edge leading to the decrease of band gap from 1.569 to 1.508 eV and increase of defect density from 3.87 × 1017 cm−3 to 9.03 × 1017 cm−3. However, a proper heat treatment time (10 min) at certain temperature (85 °C) can passivate defects effectively and improve the efficiency to 16.50%, realizing a 15% relative improvement of average efficiency. This work reveals a detailed thermal decomposition behavior of perovskite material and solar cells, which may provide insights into the stability of perovskite solar cells.

Flexible perovskite solar cells (F-PSCs) are attracting tremendous research interest due to their light weight and flexibility. However, the poor quality of perovskite films caused by deformation of flexible substrates during a general heat treatment process hinders the fabrication of high efficiency flexible cells. Here, a simple gradient heat treatment (GHT) process is developed to effectively improve the crystal quality of perovskite films and the efficiency of F-PSCs. The results show that a smaller temperature fall-off gradient will be beneficial to the further growth of perovskite films, which helps to further enhance the crystalline quality. Compared with the conventional method, the power conversion efficiency (PCE) of F-PSCs fabricated by a GHT process with a relatively small gradient significantly improved by 31%, and the maximum PCE increased to 17.37%. This work provides a new idea for ameliorating the quality of perovskite films and enhancing the performances of F-PSCs.

Hybrid organic–inorganic perovskites have attracted tremendous attention for solar cell application due to their outstanding properties. However, further studies are still needed to fully address the carrier recombination issue at grain boundaries which lowers the device performance, and its environmental stability issues. Fluoride additive engineering is found to be a good method to successfully passivate defects in perovskite films. Here, we developed a simple method to improve the device power conversion efficiency as well as its environmental stability, by introducing the polytetrafluoroethylene (PTFE) additive within the perovskite organic precursor in a two-step deposition method. The built-in electric field effect induced by PTFE induces the migration of photo-generated carriers, suppressing the electron–hole recombination, thus improving the short circuit current and then the photovoltaic performance. We obtained a maximum efficiency of 20.48% for PTFE 5%-based PSCs compared to the pristine one which was only 14.27%. Furthermore, it is also demonstrated that the PTFE-based PSC device exhibits strong environmental stability. The device presented only 5% PCE loss over 42 days of storage in an ambient environment.

Single-atom catalysts provide an effective approach to reduce the amount of precious metals meanwhile maintain their catalytic activity. However, the sluggish activity of the catalysts for alkaline water dissociation has hampered advances in highly efficient hydrogen production. Herein, we develop a single-atom platinum immobilized NiO/Ni heterostructure (PtSA-NiO/Ni) as an alkaline hydrogen evolution catalyst. It is found that Pt single atom coupled with NiO/Ni heterostructure enables the tunable binding abilities of hydroxyl ions (OH*) and hydrogen (H*), which efficiently tailors the water dissociation energy and promotes the H* conversion for accelerating alkaline hydrogen evolution reaction. A further enhancement is achieved by constructing PtSA-NiO/Ni nanosheets on Ag nanowires to form a hierarchical three-dimensional morphology. Consequently, the fabricated PtSA-NiO/Ni catalyst displays high alkaline hydrogen evolution performances with a quite high mass activity of 20.6 A mg−1 for Pt at the overpotential of 100 mV, significantly outperforming the reported catalysts., While H2 evolution from water may represent a renewable energy source, there is a strong need to improve catalytic efficiencies while maximizing materials utilization. Here, authors examine single-atom Pt on nickel-based heterostructures as highly active electrocatalysts for alkaline H2 evolution.

Catalytically active metals atomically dispersed on supports presents the ultimate atom utilization efficiency and cost‐effective pathway for electrocatalyst design. Optimizing the coordination nature of metal atoms represents the advanced strategy for enhancing the catalytic activity and the selectivity of single‐atom catalysts (SACs). Here, we designed a transition‐metal based sulfide‐Ni3S2 with abundant exposed Ni vacancies created by the interaction between chloride ions and the functional groups on the surface of Ni3S2 for the anchoring of atomically dispersed Pt (PtSA‐Ni3S2). The theoretical calculation reveals that unique Pt‐Ni3S2 support interaction increases the d orbital electron occupation at the Fermi level and leads to a shift‐down of the d ‐band center, which energetically enhances H2O adsorption and provides the optimum H binding sites. Introducing Pt into Ni position in Ni3S2 system can efficiently enhance electronic field distribution and construct a metallic‐state feature on the Pt sites by the orbital hybridization between S‐3p and Pt‐5d for improved reaction kinetics. Finally, the fabricated PtSA‐Ni3S2 SAC is supported by Ag nanowires network to construct a seamless conductive three‐dimensional (3D) nanostructure (PtSA‐Ni3S2@Ag NWs), and the developed catalyst shows an extremely great mass activity of 7.6 A mg−1 with 27‐time higher than the commercial Pt/C HER catalyst., A transition‐metal sulfide‐Ni3S2, with abundant exposed Ni vacancies in the outside layers, to anchor and modulate atomically dispersed Pt as the durable catalyst (PtSA‐Ni3S2) for efficiently electrocatalytic hydrogen evolution.

Perovskite solar cells (PSCs) have gained tremendous research interest because of their tolerance of defects, low cost, and facile processing. In PSC devices, PbI2 has been utilized to passivate defects at perovskite film surfaces and GBs; however, a systematic mechanism of PbI2 in situ passivation for enhancing the solar cells efficiency has not been fully explored. Here, this work, we systematically studies the effect of the precise PbI2 ratio and the PbI2 in situ passivation mechanism based on trap density, carrier lifetime, Fermi level, and so forth. This study finds the appropriate ratio of I/Pb to be around 2.57:1 using energy-dispersive spectroscopy. After the moderate excess PbI2 in situ passivation, the trap density is reduced from 6.12 × 1016 to 3.38 × 1016 cm-3, and the carrier lifetime is extended from 168.35 to 368.77 ps by using fs-TA spectroscopy. This result indicates that the moderate excess PbI2 in situ passivation can reduce the trap density and suppress the nonradiative recombination. The efficiency of solar cell has shown a nearly 11.3% improvement of 19.55% for an I/Pb ratio of 2.57:1 compared with 2.69:1. It also demonstrates that the efficiency of PSCs can be enhanced effectively by PbI2 in situ passivation.

In recent years, due to their high photo-to-electric power conversion efficiency (PCE) (up to 23% (certified)) and low cost, perovskite solar cells (PSCs) have attracted a great deal of attention in photovoltaics field. The high PCE can be attributed to the excellent physical properties of organic–inorganic hybrid perovskite materials, such as a long charge diffusion length and a high absorption coefficient in the visible range. There are different diffusion lengths of holes in electrons in a PSC device, and thus the electron transporting layer (ETL) plays a critical role in the performance of PSCs. An alternative for TiO2, to the most common ETL material is SnO2, which has similar physical properties to TiO2 but with much higher electron mobility, which is beneficial for electron extraction. In addition, there are many facile methods to fabricate SnO2 nanomaterials with low cost and low energy consumption. In this review paper, we focus on recent developments in SnO2 as the ETL of PSCs. The fabrication methods of SnO2 materials are briefly introduced. The influence of multiple SnO2 types in the ETL on the performance of PSCs is then reviewed. Different methods for improving the PCE and long-term stability of PSCs based on SnO2 ETL are also summarized. The review provides a systematic and comprehensive understanding of the influence of different SnO2 ETL types on PSC performance and potentially motivates further development of PSCs with an extension to SnO2-based PSCs.

Generating hydrogen from electrocatalytic water electrolysis is one of the most promising approaches as a clean-energy alternative to earth-polluting fossil fuels, and it is critically important to develop high-efficiency and low-priced electrocatalysts. Here, for the first time, we demonstrate a new strategy, taking the catalytic system based on Ni–Co wrapped Ag nanowires (Ni–Co@Ag NWs) for highly effective hydrogen evolution reaction (HER) via in situ electrochemical co-deposition. The introduction of Ag NWs provides a barrier-free network as an expressway for electron transfer to numerous catalytic sites. The synergy effect between Ni, Co and Ag further lowers the energy barrier for facile hydrogen atom adsorption and hydrogen desorption. Meanwhile, the obtained catalyst has a unique Setaria-inflorescence-structure with the Ag core as the “rachis” and the Ni–Co shell as the “pinnules”, providing abundant active sites and mass transport pathways. Consequently, this system exhibits a highly efficient hydrogen evolution with an overpotential of ∼33 mV at 10 mA cm−2, which is, to the best of our knowledge, the lowest value compared with those reported previously for Ni–Co binary catalysts. This work presents a new strategy to design high-performance and low-cost metal-based catalysts for the HER.

High-activity catalysts in alkaline media are compelling for durable hydrogen evolution reaction (HER). Single-atom catalysts (SACs) provide an effective approach to reduce the amount of precious metals meanwhile maintain their catalytic activity. However, the sluggish activity of SACs for water dissociation in alkaline media has extremely hampered advances in highly efficient hydrogen production. Herein, we developed a platinum SAC immobilized NiO/Ni heterostructure (PtSA-NiO/Ni) as an alkaline HER catalyst. It was found that Pt SACs coupled with NiO/Ni heterostructure enable the tunable binding abilities of hydroxyl ions (OH*) and hydrogen (H*), which efficiently tailors the water dissociation energy for accelerating alkaline HER. In particular, the dual active sites consisting of metallic Ni sites and O vacancies modified NiO sites near the interfaces of NiO/Ni in PtSA-NiO/Ni have preferred adsorption affinity for H* and OH* groups, respectively, which efficiently lowers the energy barrier of water dissociation of Volmer step. Moreover, anchoring Pt single atoms at the interfaces of NiO/Ni heterostructure induces more free electrons on Pt sites due to the elevated occupation of the Pt 5d orbital at the Fermi level and reaches a near-zero H binding energy (ΔGH*, 0.07 eV), which further promotes the H* conversion and H2 evolution. Further enhancement of alkaline HER performance was achieved by constructing PtSA-NiO/Ni nanosheets on the Ag nanowires to form a hierarchical three-dimensional (3D) morphology that provides abundant active sites and accessible channels for charge transfer and mass transport. Consequently, the fabricated PtSA-NiO/Ni catalyst displays extremely high alkaline HER performances with a quite high mass activity of 20.6 A mg-1 for Pt at the overpotential of 100 mV, which is 41 times greater than that of the commercial Pt/C catalyst, significantly outperforming the reported catalysts.

Organic–inorganic perovskite single crystals are promising in the field of optoelectronics due to their excellent optoelectronic properties. However, the ion transport of perovskite precursor is poor in confined spaces, which results in difficulty in the preparation of perovskite single-crystal films. Herein, MAPbBr3 films consisting of square grains were fabricated by the surface-confined process using the organic molecule PEAI (phenethylammonium iodide). Under the effect of oversaturation gradient, PEA+ is combined with the surface of perovskite grain from top to side, which constrains the lateral growth of grains and induces a downward growth of perovskite, leading to the formation of square grains. With the improvement of concentration PEAI, the perovskite film exhibits a decreased side length of grains (from 0.98 to 12.96 μm) and increased grain number and coverage, as well as crystallinity. The perovskite single crystalline grain films with PEAI showed double photoluminescence (PL) emission peaks due to the existence of iodine-rich perovskite. This work may provide a practical way to fabricate high-quality perovskite films for perovskite photoelectronic devices.

Several valuable scientific investigations have been conducted these last few years in materials design and device engineering for perovskite solar cells (PSCs) to make them competitive compared to traditional silicon-based photovoltaic technologies. Consequently, high power conversion efficiency beyond 25% is nowadays reported. However, their long-term stability remains a significant challenge to overcome. Herein, the influence of fluorinated compounds on each layer of PSCs devices and their impact on the resulted device performances and stability is spotlighted. The fluorinated compounds exhibit attractive properties due to their very high electronegativity attributed to the fluorine atom, and their strong hydrophobicity. Thus, the introduction of these compounds is found to be a successful strategy to positively suppress the surface trap states, enhancing charge collection and reducing interfacial charge recombination. Besides, a better film quality and better energy level alignment is obtained, resulting in the improvement of device photovoltaic parameters such as the open-circuit voltage (Voc ), short-circuit current (Jsc ), and fill factor (FF), and then, the device's overall power conversion efficiency (PCE). Their long-term stability is also found to further be improved.

In industrial manufacturing, alloying can contribute to the passivation of active metals and markedly improve their corrosion resistance. This inspires us to solve the current critical problem of Ag nanowires (Ag NWs) that have poor stability against chemical and electrochemical corrosion. These problems have seriously limited the applications of Ag NWs in optoelectronic devices where they are used for transparent conductive electrodes. Here, a kind of transparent conductive electrode based on Ag@Pt alloy-walled hollow nanowires (Ag@Pt AHNWs) is successfully fabricated by introducing 12 mol % Pt into long Ag NWs to form Ag@Pt alloy. The as-synthesized electrodes exhibit better optical transmittance (82% at the wavelength of 550 nm) under high electrical conductivity (28.73 Ω/sq–1), high thermal stability up to 400 °C for 11 h, and remarkable mechanical flexibility (remaining stable after 5000 cycles bending), as well as high resistance against chemical and electrochemical corrosion. The Ag@Pt AHNWs electr...

We developed a high-efficiency rotating triboelectric nanogenerator (R-TENG)-enhanced multilayered antibacterial polyimide (PI) nanofiber air filters for removing ultrafine particulate matter (PM) from ambient atmosphere. Compared to single-layered PI nanofiber filters, the multilayered nanofiber filter can completely remove all of the particles with diameters larger than 0.54 μm and shows enhanced removal efficiency for smaller PM particles. After connecting with aR-TENG, the removal efficiency of the filer for ultrafine particles is further enhanced. The highest removal efficiency for ultrafine particulate matter is 94.1% at the diameter of 53.3 nm and the average removal efficiency reached 89.9%. Despite an increase in the layer number, the thickness of each individual layer of the film decreased, and hence, the total pressure drop of the filter decreased instead of increasing. Moreover, the nanofiber film exhibited high antibacterial activity because of the addition of a small amount of silver nanoparticles. This technology with zero ozone release and low pressure drop is appropriate for cleaning air, haze treatment, and bacterial control.

A square-grid triboelectric nanogenerator (SG-TENG) is demonstrated for harvesting vibrational energy and sensing impulsive forces. Each square of the three-dimensional (3D)-printed square grid is filled with an aluminum (Al) ball. The grid structure allows the SG-TENG to harvest vibrational energy over a broad bandwidth and operate at different vibrational angles. The most striking feature of the SG-TENG is its ability of being scaled and integrated. After connecting two SG-TENGs in parallel, the open-circuit voltage and short-circuit current are significantly increased over the full vibrational frequency range. Being integrated with a table tennis racket, the SG-TENG can harvest the vibrational energy from hitting a ping pong ball using the racket, where a direct hit by the racket generates an average output voltage of 10.9 ± 0.6 V and an average output current of 0.09 ± 0.02 μA. Moreover, the SG-TENG integrated into a focus mitt can be used in various combat sports, such as boxing and taekwondo, to monitor the frequency and magnitude of the punches or kicks from boxers and other practitioners. The collected data allow athletes to monitor their status and improve their performance skills. This work demonstrates the enormous potential of the SG-TENG in energy harvesting and sensing applications.

Ultrasonic waves are existing in water and in our living environment, but harvesting the sonic wave energy especially in water is rather challenging, simply because of the high pressure generated by water. In this work, a triboelectric nanogenerator (TENG) has been designed using spherical pellets as the media for performing the contact-separation operation during ultrasonic wave excitation for energy harvesting. The fabricated TENG can attain an instantaneous output current from several milliamps to about one hundred milliamps and achieve an output power of 0.362 W/cm 2 at an ultrasonic wave frequency of 80 kHz. The average power conversion efficiency of the TENG has reached 13.1%. The equivalent output galvanostatic current is 1.43 mA, which is the highest value reported so far. The developed TENG pellets has been demonstrated to continuously power up to 12 lamps with 0.75 W each, and can continuously drive a temperature-humidity meter, an electronic watch, and directly drive a health monitor. This study presents the outstanding potential of TENG for underwater applications.

A smart floor is demonstrated by integrating a square-frame triboelectric nanogenerator (SF-TENG) into a standard wood floor. The smart floor has two working modes based on two pairs of triboelectric materials: one is purposely chosen polytetrafluoroethylene films and aluminum (Al) balls, and the other is the floor itself and the objects that can be triboelectrically charged, such as basketball, shoe soles, and Scotch tape, etc. Utilizing the Al balls enclosed inside shallow boxes, the smart floor is capable of harvesting vibrational energy and, hence, provides a nonintrusive way to detect sudden falls in elderly people. In addition, when the basketball is bounced repeatedly on the floor, the average output voltage and current are 364 ± 43 V and 9 ± 1 μA, respectively, and 87 serially connected light-emitting diodes can be lit up simultaneously. Furthermore, the friction between the triboelectrically chargeable objects and the floor can also induce an alternating current output in the external circuit without the vibration of the Al balls. Normal human footsteps on the floor produce a voltage of 238 ± 17 V and a current of 2.4 ± 0.3 μA. Therefore, this work presents a smart floor with built-in SF-TENG without compromising the flexibility and stability of the standard wood floor and also demonstrates a way to harvest ambient energy solely by using conventional triboelectric materials in our daily life.

We developed a high-efficiency rotating triboelectric nanogenerator (R-TENG) enhanced polyimide (PI) nanofiber air filter for particulate matter (PM) removal in ambient atmosphere. The PI electrospinning nanofiber film exhibited high removal efficiency for the PM particles that have diameters larger than 0.5 μm. When the R-TENG is connected, the removal efficiency of the filter is enhanced, especially when the particle diameters of the PM are smaller than 100 nm. The highest removal efficiency is 90.6% for particles with a diameter of 33.4 nm and the highest efficiency enhancement reaches 207.8% at the diameter of 76.4 nm where the removal efficiency enhanced from 27.1% to 83.6%. This technology with zero ozone release and low pressure drop offers an approach for air cleaning and haze treatment.

As a green and eco-friendly technology, triboelectric nanogenerator (TENG) can harvest energy from human motion to generate electricity, so TENGs have been widely applied in wearable electronic devices to replace traditional batteries. However, the surface of these TENGs is easily contaminated and breeds bacteria, which is a threat to human health. Here, we report an antibacterial composite film-based triboelectric nanogenerator (ACF-TENG) that uses Ag-exchanged zeolite (Ag-zeolite) and polypropylene (PP) composite film as the triboelectric layer. Adding a small amount of Ag-zeolite with excellent antibacterial properties can increase the dielectric permittivity and improve the surface charge density of composite films, which enhances the output performance of the ACF-TENG. The open-circuit voltage (VOC), short-circuit current (ISC), and transferred charge (QTr) of the ACF-TENG are about 193.3, 225.4, and 233.3% of those of a pure PP film-based TENG, respectively. Because of the silver in the Ag-zeolite, ...

Perovskite solar cells (PSCs) have gained tremendous research interest because of their tolerance of defects, low cost, and facile processing. In PSC devices, PbI

Indoor formaldehyde (HCHO) pollution has become a serious issue to threaten human health. Therefore, it is urgent to develop long-term and efficient HCHO removal materials and technology with low energy consumption. In this study, the MnOx was deposited in-situ by hydrothermal synthesis on the hydrolyzed PI fibers. By harvesting the kinetic energy of wind, triboelectric charges and electric field are generated between MnOx-PI and nylon fibers. The employment of triboelectric charges on the catalyst is an effective way to increase conversion rates of O*, which may help to accelerate the decomposition of intermediates, enhance efficiency, and enlarge the life of the catalyst. As a result, during the static testing, the HCHO removal efficiency reached 92.4% of MnOx-PI-1.0 h-nylon within 1100 mins at room temperature, which was much higher than that of the MnOx-PI-1.0 h sample (56.3%). In addition, the removal efficiency of the MnOx-PI-2.0 h-nylon remained above 95% during the 48-hours dynamic test. The present study provides a new route to achieve long-term efficient removal of HCHO in the indoor environment and extended the application for the nano-triboelectric in the catalytic field.

Nowadays, indoor air pollution of low-concentration formaldehyde (HCHO) is threatening seriously human health. In this work, a carbon cloth supported MnOx composite (MnOx-CC) with coaxial cable structure was synthesized as catalysts by electric-enhanced hydrothermal synthesis. The MnOx-CC catalysts showed a flower-liked MnOx nanospheres structure with interconnected nanosheets. During the static testing, the HCHO concentration can be reduced from 7 ppm to 0.074 ppm at 25 ℃, which is below the international guideline values (0.08 ppm). Under the WHSV of ~120,000 mL/(gMnOxh), the removal efficiency was as high as ~97% and the catalyst can keep working for 24 h without an significant drop at room temperature. A novel mechanism – synergistic catalytic effect mechanism of MnOx was proposed to illuminate the catalyst performance. It reveals that the mutual conversion process among different valences of MnO2, Mn2O3 and MnO is critical to the generation of active oxygen and decomposition of intermediates, and they jointly promote the effective degradation of HCHO. This work may provide a new strategy to synthesizing the catalysts for HCHO removal with high efficiency and present an insight for catalytic process of MnOx.

A series of dinuclear Dy(III) compounds with the general formula [Dy2(μ2-anthc)4(anthc)2(L)2] (anthc(-) = 9-anthracenecarboxylate, L = 2,2'-bipyridyl (1), 1,10-phenanthroline (2), and 4,7-dimethyl-1,10-phenanthroline (3)) were synthesized and magnetically characterized. These compounds exhibit single-molecule magnet (SMM) behavior in the absence of the direct-current field, which is rarely observed for carboxylate-bridged dinuclear Dy2 system. With the first coordination sphere of Dy(III) centers being fixed, the energy barrier was modulated by sequentially modifying the terminal neutral L ligands in this Dy2 system. Theoretical calculations revealed that the symmetry of the charge distribution surrounding the Dy(III) centers in 1-3 is the decisive factor to determine the relaxation of the SMMs. The combination of the larger charge distribution along the magnetic axis and lower charge distribution in the equatorial plane (hard plane) formed by five coplanar coordination atoms including two N atoms provided by an L ligand led to a strong easy-axis ligand field in these compounds. This work presents a rational method to modulate the dynamic magnetic relaxation of the lanthanide SMMs through fine-tuning electrostatic potential of the atoms on the hard plane.

Recently, triboelectric nanogenerator (TENG) has been invented as a new energy technology and widely utilized in renewable and sustainable energy harvesting. Here we report a regular dodecahedron device integrated with 12 sets of multilayer wavy-structured robust triboelectric nanogenerators (WS-TENGs) for harvesting water wave energy. Each WS-TENG is composed of a wavy-structured Cu–Kapton–Cu film and two fluorinated ethylene propylene (FEP) thin films sputtered with metal electrodes as a sandwich structure. A hard ball is enclosed inside a polyhedron made by WS-TENGs as the walls; a collision of the ball with the WS-TENG in responding to the kinetic motion of water wave converts mechanical energy into electricity. A high output voltage and current of about 250 V and 150 μA, respectively, are measured by a single unit of WS-TENGs in water. Considering the units can be connected into a net structure, the average output power is expected to be 0.64 MW from 1 km2 surface area in a depth of 5 m. By the virtues of cost effective, low-carbon and environmentally friendly, the development of WS-TENGs can be a significant step towards the large-scale water wave energy harvesting and have great prospects for the blue energy.

The triboelectric nanogenerator (TENG) has emerged as a new and effective mechanical energy harvesting technology. In this work, a theoretical model for a rotary-sliding disk TENG with grating structure was constructed, including the dielectric-to-dielectric and conductor-to-dielectric cases. The finite element method (FEM) was utilized to characterize the fundamental physics of the rotarysliding disk TENG working in both contact and non-contact modes. The basic properties of disk TENG were found to be controlled by the structural parameters such as tribo-surface spacing, grating number, and geometric size. From the FEM calculations, an approximate V–Q–α relationship was built through the interpolation method, and then the TENG dynamic output characteristics with arbitrary load resistance were numerically calculated. Finally, the dependencies of output power and matched resistance on the structural parameters and rotation rate were revealed. The present work provides an in-depth understanding of the working principle of the rotary-sliding disk TENG and serves as important guidance for optimizing TENG output performance in specific applications.

Tribotronics is a new field developed by coupling triboelectricity and semiconductor, which can drive triboelectric-charge-controlled optoelectronic devices by further introducing optoelectronics. In this paper, a tribotronic phototransistor (TPT) is proposed by coupling a field-effect phototransistor and a triboelectric nanogenerator (TENG), in which the contact-induced inner gate voltage by the mobile frictional layer is used for modulating the photodetection characteristics of the TPT. Based on the TPT, alternatively, a coupled energy-harvester (CEH) is fabricated for simultaneously scavenging solar and wind energies, in which the output voltage on the external resistance from the wind driven TENG is used as the gate voltage of the TPT for enhancing the solar energy conversion. As the wind speed increases, the photovoltaic characteristics of the CEH including the short-circuit current, open-circuit voltage, and maximal output power have been greatly enhanced. This work has greatly expanded the functionality of tribotronics in photodetection and energy harvesting, and provided a potential solution for highly efficient harvesting and utilizing multitype energy.

Coordination polymers constructed from metal ions and organic ligands have attracted considerable attention owing to their diverse structural topologies and potential applications. Ligands containing carboxylate groups are among the most extensively studied because of their versatile coordination modes. Reactions of benzene-1,4-dicarboxylic acid (H2BDC) and pyridine (py) with ZnIIor CoIIyielded two new coordination polymers, namely, poly[(μ4-benzene-1,4-dicarboxylato-κ4O:O′:O′′:O′′′)(pyridine-κN)zinc(II)], [Zn(C8H4O2)(C5H5N)]n, (I), andcatena-poly[aqua(μ3-benzene-1,4-dicarboxylato-κ3O:O′:O′′)bis(pyridine-κN)cobalt(II)], [Co(C8H4O2)(C5H5N)2(H2O)]n, (II). In compound (I), the ZnIIcation is five-coordinated by four carboxylate O atoms from four BDC2−ligands and one pyridine N atom in a distorted square-pyramidal coordination geometry. Four carboxylate groups bridge two ZnIIions to form centrosymmetric paddle-wheel-like Zn2(μ2-COO)4units, which are linked by the benzene rings of the BDC2−ligands to generate a two-dimensional layered structure. The two-dimensional layer is extended into a three-dimensional supramolecular structure with the help of π–π stacking interactions between the aromatic rings. Compound (II) has a one-dimensional double-chain structure based on Co2(μ2-COO)2units. The CoIIcations are bridged by BDC2−ligands and are octahedrally coordinated by three carboxylate O atoms from three BDC2−ligands, one water O atom and two pyridine N atoms. Interchain O—H...O hydrogen-bonding interactions link these chains to form a three-dimensional supramolecular architecture.

Organometal lead halides perovskites are promising solar cells material due to their outstanding properties such as tuneable bandgap, impressive tolerance to defects, long exciton diffusion length, high carrier mobility and absorption coefficient. Up to now, the organometal lead halides based solar cells (PSCs) have demonstrated impressive power conversion efficiency reaching 25.2% (not stabilised). However, their operating life-times are limited due to degradation of the organic components under some environmental conditions. Therefore, researchers have focused their interest on the all inorganic perovskite; especially on the caesium lead triiodide perovskite (CsPbI3) which exhibits a better compositional and chemical stability. Nevertheless, the phase instability of the black phase of this material constitutes its main limitation for its use in the solar cell devices production. This review aims to present the most impactful research giving insights on the factors that may cause the instability of all-inorganic lead halide perovskite materials, as well as the instability of the whole device. In addition to deposition methods, the composition, structure and optical properties of inorganic perovskite materials have also been presented. Furthermore, this review highlights the different strategies used in order to improve the phase stability of caesium lead halide perovskite material through either engineering on the material structure or the fabrication method.