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Smooth and pin-hole free CoO films obtained from homogeneous colloidal solution are exploited as the hole transport layers of perovskite solar cells. Inorganic p-type materials show great potential as the hole transport layer in perovskite solar cells with the merits of low costs and enhanced chemical stability. As a p-type material, cobalt oxide (CoO) has received so far not that level of attention despite its high hole mobility. Herein, solution-processed p-type CoO nanocrystalline films are developed for inverted mixed perovskite solar cells. The ultrafine CoO nanocrystals are synthesized via an oil phase method, which are subsequently treated by a ligand exchange process using pyridine solvent to remove the long alkyl chains covering the nanocrystals. From this homogeneous colloidal solution CoO films are obtained, which exhibit a smooth and pin-hole free surface morphology with high transparency and good conductivity. The ultraviolet photoelectron spectrum also indicates that the energy levels of the CoO film match well with the mixed perovskite Cs 0.05 (FA 0.83 MA 0.17) 0.95 (I 0.83 Br 0.17) 3. Inverted solar cells based on crystalline CoO films with ligand exchange show a reasonable energy conversion efficiency, whereas devices based on CoO films without ligand exchange suffer from a strong S-shape JV-characteristic. Thus, the crystalline CoO films are foreseen to pave a new way of inorganic hole transport materials in the fields of perovskite solar cells. [ABSTRACT FROM AUTHOR]

2D Ag-ZIF interlayer plays a dual-passivation effect in terms of passivating both the oxygen vacancies on the SnO 2 and the uncoordinated Pb2+ at the bottom of the perovskite layer. [Display omitted] • 2D Ag-ZIFs are synthesized by a solvent modulated strategy. • 2D Ag-ZIF interlayer passivates the defects at perovskite/SnO 2 interface. • PSCs based on 2D Ag-ZIFs modified SnO 2 yield the champion PCE of 21.25%. • PSCs with 2D Ag-ZIFs exhibit enhanced UV and environmental stability. Despite the fact that perovskite solar cells (PSCs) have made rapid progress as a promising photovoltaic technology, defect management at the interface between the electron transport layer (ETL) and perovskite layer remains critical to significantly reduce energy loss of devices. Therefore, developing a robust and effective interlayer is imperative. Herein, 2D Ag doped ZIF-67 (Ag-ZIF) is designed by a solvent modulated strategy based on mixed N, N-dimethylformamide and ethanol, and further applied as an interfacial modifier in PSCs. Since the exposed dimethylimidazole ligands carried by Ag-ZIF and the metal ions, the oxygen vacancies on the SnO 2 surface and the uncoordinated Pb2+ and halogen ions at the bottom of the perovskite layer could be passivated effectively. Thus, suppressed non-radiative recombination and accelerated electron transport are achieved. Meanwhile, the robust framework and ultraviolet (UV)-resistant ability of Ag-ZIF could regulate the crystallization of perovskite film and prevent device from UV degradation. Consequently, the efficiency of PSC is remarkably boosted from 18.49% to 21.25% in accompany with enhanced UV and environmental stability. [ABSTRACT FROM AUTHOR]

Graphical abstract Monodispersed SnO 2 microspheres assembled from tiny primary nanocrystallites with high specific surface area, excellent crystallinity and tunable building units demonstrate great potential in dye-sensitized/perovskite solar cells. Highlights • A novel approach is exploited for the synthesis of monodispersed SnO 2 microspheres. • The sizes of primary nanocrystals are tunable with adscititious water. • Dye-sensitized solar cells based on the microspheres yield an efficiency of 3.83%. • Perovskite solar cells based on the microspheres yield an efficiency of 15.41%. Abstract Mesoporous SnO 2 microspheres assembled from densely-packed nanocrystalline building units are a class of useful nanomaterials and have extensive optoelectronic applications, but so far it is still a challenge to acquire monodispersed microspheres. Here, monodispersed SnO 2 microspheres consisted of aggregated small primary nanocrystallites are synthesized via a surfactant-free solvothermal method. These SnO 2 microspheres have high specific surface area, excellent crystallinity and tunable building units. By precisely controlling the nucleation and growth, the obtained microspheres exhibit narrow size distribution, whose diameters are 200 ± 17 and 191 ± 16 nm from pure n-propanol and n-propanol/water mixed solvents, respectively. The sizes of primary nanocrystals slightly increase with the adscititious water. The SnO 2 microspheres exhibit large specific surface areas, leading to efficient sensitizer-loading in both dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). The sub-micron-sized microspheres could also enhance the light-harvesting of the solar cells due to their light-scattering capability. As the primary nanocrystal multiply contacts densely to neighbouring grains, such intergrowth would improve the electron transport through the grain boundaries. Eventually, a power conversion efficiency of 3.83% is yielded for pure SnO 2 -based DSSCs when the SnO 2 microspheres are used as the scattering layers, and an efficiency of 15.41% is obtained when they are used as the electron transport layers in PSCs. [ABSTRACT FROM AUTHOR]

Abstract Tin dioxide (SnO 2) is regarded as an effective electron transport material for attaining high-performance perovskite solar cells (PSCs). Herein, vertically aligned SnO 2 nanorod arrays are grown directly on fluorine-doped tin oxide (FTO) substrates in an acidic solution via hydrothermal method, where the area density of the nanorod arrays is tailored by varying the precursor concentration. Particularly, the mean diameters of the nanorods increase from 15 to 25 nm and the corresponding area densities decrease from 660 to 460 μm−2 with increasing the concentration of tin(IV) chloride pentahydrate. X-ray diffraction and X-ray photoelectron spectroscopy measurements reveal that the nanorod arrays are pure tetragonal rutile SnO 2 with a high degree of crystallinity. Mixed perovskites of (FAPbI 3) 0.85 (MAPbBr 3) 0.15 are infiltrated into these SnO 2 nanorod arrays, and the perovskite solar cells show an enhanced photovoltaic performance as compared to the nanoparticle counterpart. Perovskite solar cells based on SnO 2 nanorod arrays with the optimized area density exhibit the best power conversion efficiency of 15.46% which is attributed to an accelerated electron transport and a decreased recombination rate at SnO 2 /perovskite interface. Graphical abstract Image 1 Highlights • New approach is exploited for the synthesis of SnO 2 nanorod arrays. • The area density of the nanorod arrays could be tailored. • PSCs using SnO 2 nanorod arrays as ETL yield a high efficiency of 15.46%. • Interfacial charge transfer is systematically investigated. [ABSTRACT FROM AUTHOR]

Single-crystalline SnO 2 nanorods with tunable length are synthesized via a facile and surfactant-free solvothermal route based on an aqueous–organic solvent system. The length of the nanorods can be facilely controlled by adjusting the solvent ratio. Particularly, the average length increases from 14.6 to 98.0 nm when the volume ratio of cyclohexane to water is varied from 20:30 to 49:1. The morphological evolution of the SnO 2 nanorods is systematically investigated, and a growth mechanism involving three stages of nucleation, rearrangement and oriented growth is proposed, based on the free migration of the nanoparticles at the two immiscible interfaces thereby offering special path for the self-assembly. The synthesized SnO 2 nanorods are used as photoanodes for dye-sensitized solar cells (DSSCs) and the photovoltaic performance is studied as a function of the morphology. UV–vis absorption spectra show the dye-loading capabilities of the DSSCs are gradually weaken with the length increase of the SnO 2 nanorods. Electrochemical impedance spectroscopy analysis indicates that the charge transfer resistances at the SnO 2 /dye/electrolyte interfaces decrease and the electron lifetimes increase along with the increase of nanorod-length. As a consequence, DSSCs fabricated from medium-sized nanorods achieve the best power conversion efficiency of 3.50% due to the equilibrium between fast electron transport and large specific surface area. [ABSTRACT FROM AUTHOR]

The presence of heterogeneous interfacial defects limits the efficiency and long-term stability of the perovskite solar cells (PSCs). Rational passivation of interfacial defects and reduction of nonradiative recombination at the perovskite active layer are effective ways to achieve efficient PSCs. Here, a heterointerface engineering strategy is presented by employing a multifunctional molecule of reduced l -glutathione (GSH). The introduction of GSH improves the crystallization of SnO 2 , resulting in a continuous and conformal coverage of SnO 2 on the FTO surface. And the GSH buffer layer improves the affinity between SnO 2 and perovskite, resulting in the formation of large grains of perovskite. In addition, GSH bridges the perovskite to SnO 2 through multi-dentate ligands (-COOH, –NH 2 , –CONH–, –HS), which passivates the multiple defects at the heterogeneous interfaces while accelerates the electron transport. As a result, the PCE of the GSH-SnO 2 ETL based PSC significantly increases to 21.66% with no noticeable hysteresis. Meanwhile, compared with the control PSC, the unencapsulated GSH-SnO 2 based PSC exhibits better environmental stability, which maintains more than 80% of its initial PCE after 600 h of placement in atmospheric environment. GSH bridges the perovskite to SnO 2 through multi-dentate ligands, which passivates the multiple defects at the heterogeneous interfaces while accelerates the electron transport. [Display omitted] • GSH-SnO 2 has a contiguous and conformal coverage on the FTO substrate. • Multidentate ligands dually passivate various defects at the SnO 2 /perovskite heterogeneous interface. • An electron transport bridge is constructed between SnO 2 and perovskite layer. • The GSH-SnO 2 based PSCs achieve an enhanced PCE of 21.66%. [ABSTRACT FROM AUTHOR]

Perovskite solar cells based on thiourea-treated SnO 2 nanorod arrays exhibit a high power conversion efficiency of 20.18%. [Display omitted] • The micro-morphology of SnO 2 nanorod arrays is optimized to reduce the charge recombination. • Surface sulfuration passivates the interfacial defects at perovskite/ETL interface. • A record PCE of 20.18% is achieved for SnO 2 NRAs based PSCs. Vertically aligned one-dimensional nanorod arrays (NRAs) show great potential as electron transport layers (ETLs) for perovskite solar cells (PSCs) because of the unique characteristic which could realize the directional charge transport and enhanced charge collection. However, the severe charge recombination at the heterointerface between the NRAs ETL and perovskite layer often leads to the unsatisfactory power conversion efficiency (PCE). Here, we remarkably boost the performance of SnO 2 NRAs ETL through microstructural and surface chemical engineering. First, the longitudinal size of NRAs is adjusted to alleviate the charge accumulation at the heterointerface. Next, the surface affinity of SnO 2 NRAs is improved by thiourea sulfuration for a better penetration of perovskite precursor. More importantly, the strong interaction between the sulfur and the uncoordinated Pb2+ effectively passivate the buried interfacial defects of perovskite layer. Surface sulfuration reconstructs the gradient energy level and promotes the interfacial electron transfer between the ETL and the perovskite layer. As a result, a record PCE of 20.18 % is achieved for the S-SnO 2 NRAs based PSCs till now. Meanwhile, the operational stability of the device is enhanced especially in the near-ultraviolet region, which maintains above 80 % of the initial PCE after 72 h of continuous irradiation under ultraviolet light. [ABSTRACT FROM AUTHOR]

Three-dimensional titania network was in-situ constructed on Ti foil via sequential acid and hydrogen peroxide treatments. The titania network was pure anatase phase and homogeneously covered on the titanium grain surface, which largely enhanced the roughness of the Ti foil. The as-received Ti foil and the treated one were used as the flexible substrates of DSSCs, and energy conversion efficiencies of 3.74% and 4.98% were obtained, respectively. Such remarkable increment can be ascribed to the good electrical contact between the nanocrystalline TiO 2 and the Ti foil, the improved electron percolation pathways and recombination inhibition of electrons in Ti substrate with triiodide ions in electrolyte. Flexible DSSCs based on the treated Ti foil showed relatively good mechanical stability, which exhibited 97.3% retention of the initial efficieny after twenty consecutive bending. [ABSTRACT FROM AUTHOR]

Hierarchical anatase TiO 2 submicrospheres were synthesized by direct hydrothermal method at 120 °C using Ti(SO 4 ) 2 and (NH 4 ) 2 SO 4 mixed solution as precursor. The calcined spheres in particle size of 150–200 nm, which consisted of closely connected nanocrystals in a crystallite size of about 24.2 nm and had a relatively high specific surface area of 43.2 m 2 g −1 compared to microspheres. In presence of TiO 2 submicrospheres as the scattering layer on top of semitransparent layer, the power conversion efficiency of dye-sensitized solar cells (DSSCs) was increased to as high as of 9.07% from 7.24%. This remarkable improvement compared to commercial scattering particles (efficiency of 8.33%) is mainly attributed to their higher surface area for increasing the loading of dye molecule as well as a lower resistance under 1 sun irradiation. The relationship between the conversion efficiency of DSSCs with interfacial resistance under 0.1 to 1.0 sun illumination was further investigated, the decrease of the light power density led to the increase of interfacial resistance. Moreover, even under 0.1 sun irradiation, DSSC still had an efficiency of 7.18% but a slightly lower V oc of 0.597 V. [ABSTRACT FROM AUTHOR]

Hierarchical TiO 2 hollow microspheres were synthesized by a 2-step process consisting of thermal hydrolysis and subsequent solvothermal reaction. Quasi-monodispersed solid TiO 2 microspheres aggregated by amorphous particles were firstly obtained by the controlled thermal hydrolysis of titanium sulfate, and then the solid structures transformed to hollow ones and crystallized during the subsequent solvothermal treatment. SEM and TEM images of the samples revealed that the morphological evolution was in perfect accordance with the inside-out Ostwald ripening mechanism. The rich porosity and unique hierarchical hollow structure endow the TiO 2 microspheres with a large specific surface area of 108.0 m 2 g −1 . As an effective anode material for dye-sensitized solar cells, TiO 2 hollow microspheres showed good capability of dye adsorption and strong light scattering, leading to a comparable energy conversion efficiency to the commercial 18NR-T transparent titania. Finally, a high efficiency of 7.84% was achieved for the bi-layer DSSC by coating the hollow microspheres on top of the 18NR-T titania as the light scattering layer. [ABSTRACT FROM AUTHOR]

In this article, a novel and facile strategy to load low-cost and earth-abundant oxygen evolution catalyst NiFeO x by spin-coating on Ti-doped α-Fe 2 O 3 films was reported. The NiFeO x modified hematite photoanode was prepared by a two-step process, which consisted of a hydrothermal method and a subsequent NiFeO x loading step. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) were used to characterize the resulting photoanode. The highest photocurrent increment and lowest onset potential were observed with 30 mM NiFe precursor treatment. Increasing the loading content in a range from 10 to 90 mM, the photocurrent density increases from 0.998 for the pristine α-Fe 2 O 3 to 1.126 mA/cm 2 at 1.23 V vs RHE (i.e., 12.7% increment) with 30 mM NiFe precursor treatment. Concomitant with this improvement was a cathode shift in the onset potential by nearly 55 mV and higher incident-photon-to-current efficiencies. Hematite photoanodes after NiFeO x deposition showed better performance than pristine samples, because of a lower overpotential for water oxidation resulted from NiFeO x modifying. [ABSTRACT FROM AUTHOR]

Zinc-cobalt layered double hydroxide (LDH) was electrodeposited on Ti-doped hematite photoanodes for the first time, and a significant enhanced performance for photoelectrochemical water splitting was demonstrated over the composite photoanodes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS) were characterized with the resulted photoanodes. With the electrodepositing treatment, the photocurrent density increased from 1.27 mA/cm 2 for pristine hematite to 1.73 mA/cm 2 for modified materials at 1.23 V vs. RHE (i.e. 36% improvement). The photocurrent improvement is mainly attributed to a suppression of electron–hole recombination and reduced overpotential for water oxidation at the hematite-electrolyte interface due to the formation of Zn-Co LDH layer on hematite. [ABSTRACT FROM AUTHOR]

Despite the outstanding power conversion efficiency (PCE) of perovskite solar cells (PSCs) achieved over the years, unsatisfactory stability and lead toxicity remain obstacles that limit their competitiveness and large‐scale practical deployment. In this study, in situ polymerizing internal encapsulation (IPIE) is developed as a holistic approach to overcome these challenges. The uniform polymer internal package layer constructed by thermally triggered cross‐linkable monomers not only solidifies the ionic perovskite crystalline by strong electron‐withdrawing/donating chemical sites, but also acts as a water penetration and ion migration barrier to prolong shelf life under harsh environments. The optimized MAPbI3 and FAPbI3 devices with IPIE treatment yield impressive efficiencies of 22.29% and 24.12%, respectively, accompanied by remarkably enhanced environmental and mechanical stabilities. In addition, toxic water‐soluble lead leakage is minimized by the synergetic effect of the physical encapsulation wall and chemical chelation conferred by the IPIE. Hence, this strategy provides a feasible route for preparing efficient, stable, and eco‐friendly PSCs. [ABSTRACT FROM AUTHOR]

TiO 2 nanocrystals derived from hydrothermal method were widely used as the photoanodes of dye-sensitized solar cells (DSSCs). Developing some alternative routes combining low-cost with high performance is eagerly expected. Well connected anatase TiO 2 nanocrystals were synthesized by one-step thermal decomposition of the double salt (NH 4 ) 2 TiO(SO 4 ) 2 (ammonium titanyl sulfate, ATS) at 700 °C for 2 h, and the fine tuning on aggregate sizes was achieved by adjusting the heating rate. The TiO 2 nanocrystals inside the aggregates were densely packed where each nanocrystal contacted well to neighbouring grains. The connected structure between the crystallites decreases the negative effects of electron grain boundary crossing and reduces recombination within the aggregate when used as photoelectrodes of dye-sensitized solar cells. Moreover, TiO 2 aggregates from ATS calcined at a faster heating rate (5 °C/min) had a wider pore size distribution and exhibited a higher light scattering abilities, while the ones from those calcined at a slower heating rate (3 °C/min) had a narrow pore size distribution but possessed a higher specific surface area (72.8 m 2 g −1 ) for adsorbing more dye. The DSSC based on two kind of TiO 2 nanoparticles as the photoelectrode all exhibited an excellent short-circuit current density (15.21 mA cm −2 and 15.94 mA cm −2 ) and a highly efficient power conversion efficiency (7.78% and 8.16%). The improvements of power conversion efficiency for two kinds of TiO 2 nanoparticles compared to commercial Aerosil process P25 nanoparticles are mainly attributed to a higher light scattering ability and superior dye adsorption property, respectively. The electrochemical impedance spectroscopy (EIS) analysis indicated the DSSCs with TiO 2 nanocrystals derived from solid state reaction had a lower charge transfer resistance than all P25 photoanodes at TiO 2 /dye/electrolyte interface due to the well connected structure provided multiple contacts to neighboring grains. [ABSTRACT FROM AUTHOR]

Highlights: [•] The anatase TiO2 sol with a crystallite size of 3.0nm was prepared. [•] Both TiO2 sol and titanium (IV) bis (ammonium lactato) dihydroxide were successfully used towards size-tunable anatase TiO2 nanocrystals. [•] The DSSC with an efficiency of 9.3% was archived by combining of TiO2 nanocrystals and sol treatment. [•] Improved interfacial contact was responsible to the performance enhancement of DSSCs. [ABSTRACT FROM AUTHOR]

Anatase TiO2 nanorods with large specific surface areas and high crystallinity have been synthesized by surfactant-free hydrothermal treatment of water-soluble peroxotitanium acid (PTA). X-ray diffraction and TEM analysis showed that all TiO2 nanorods derived from PTA in different hydrothermal processes were in the anatase phase, and high aspect ratio TiO2 nanorods with chain-shaped structures were formed at 150 °C for 24 h by oriented growth. The nanorods were fabricated as photoanodes for high-efficiency dye-sensitized solar cells (DSSCs). DSSCs fabricated from the chain-shaped TiO2 nanorods gave a highest short-circuit current density of 14.8 mA cm−2 and a maximum energy conversion efficiency of 7.28 %, as a result of the presence of far fewer surface defects and grain boundaries than are present in commercial P25 TiO2 nanoparticles. Electrochemical impedance spectroscopy also confirmed that DSSCs based on the TiO2 nanorods have enhanced electron transport properties and a long electron lifetime. [ABSTRACT FROM AUTHOR]

• Compound 1 possess liner trinuclear Zn(II) units and linked by 4,4′-bipy ligands to form a 2D layer with pseudo-square grid motifs. • Structural analysis showed that compounds 2 and 3 are isostructural 1D chains bridged by 4,4′-bipy ligands. • H...H interaction is the major contributor to the entire Hirshfeld surface interaction. Three Zn(Ⅱ) sulfonate compounds: {[Zn 3 (Ac) 4 (4,4′-bipy) 4 ]·2(3-pySO 3)·H 2 O} n (1), {[Zn(4,4′-bipy)(H 2 O) 4 ]·2(Me-phSO 3)} n (2), and {[Zn(4,4′-bipy)(H 2 O) 4 ]·2(NH 2 -phSO 3)} n (3), were synthesized through solvent diffusion method at room temperature (3-pySO 3 H = Pyridine-3-Sulfonic acid; Me-phSO 3 H = P-Toluene Sulfonic acid; NH 2 -phSO 3 H = Sulfanilic acid). Single-crystal X-ray diffractions reveal that the crystal structure of compound 1 contains a 2D cationic layer with pseudo-square grid motifs formed by trinuclear Zn(II) units which connected by 4,4′-bipy ligands. Water molecule forms hydrogen bonds with free 3-PySO 3 − anions which are located in the voids of the cationic grids. Compounds 2 and 3 show isostructural 1D [Zn(4,4′-bipy)(H 2 O) 4 ]2+ chains with sulfonate anions connected to the chain via hydrogen bonding. The weak interactions in the structures of the three compounds have been assessed using Hirshfeld surface analyses and 2D fingerprint plots. The Hirshfeld surface shows that the most important contributions for the crystal packing are from H···H and H··O/O··H interactions, which indicate dominant van der Waals interactions. In addition, the compounds were investigated by powder X-ray diffraction (PXRD), elemental analyses, UV–vis, FT-IR, solid-state fluorescence spectroscopy, and thermal analyses (TG-DSC). [ABSTRACT FROM AUTHOR]

We present a compelling strategy for fabricating a hierarchical OER electrode, successively consisting of the nickel foam (NF) conductive substrate, carbon-incorporated cobalt oxide nanorod arrays, and nickel-iron hydroxide nanosheets (NF/CoO–C/NiFe–OH). Cobalt-based metal-organic framework (Co-MOF) derived porous CoO–C matrix increases electrical conductivity, facilitates charge transfer, and provides more surface sites for the NiFe–OH deposition. Furthermore, the CoO–C and NiFe–OH heterostructure alters the electronic states of active components, consequently achieving a synergistic role that promotes the OER process. The resulting NF/CoO–C/NiFe–OH exhibits prominent OER activity, with the overpotentials of 281, 347, and 466 mV at 50, 100, and 200 mA cm−2 of current densities, respectively. In the meantime, it also possesses a lower Tafel slope of 39 mV dec−1, larger electrochemical surface area, faster turnover frequencies, and lesser charge transfer resistances. Additionally, the electrode reveals superior stability without significant morphological changes and element valence states. The OER mechanism and electrochemical performance of hierarchical heterostructure regulated by nickel-iron oxyhydroxides on carbon-incorporated cobalt oxide nanorod arrays on the NF substrate (NF/CoO–C/NiFe–OH). [Display omitted] • The in-situ strategy of CoO–C/NiFe–OH hierarchical heterostructure is used. • The CoO–C matrix improves surface structure and electronic states of NiFe–OH. • The NF/CoO–C/NiFe–OH electrode has superior OER performance and durability. • The promoting mechanism of the CoO–C layer on the OER process is proposed. [ABSTRACT FROM AUTHOR]

One-dimensional nanorod arrays show great potential as electron transport layers of perovskite solar cells due to their unique characteristic of oriented electron transport. Herein, anatase phase TiO 2 nanorod arrays are successfully grown on FTO conductive glass by a facile hydrothermal method using tetrabutyl titanate as precursor. By regulating the concentration of tetrabutyl titanate, TiO 2 nanorods with the length of 50, 200, 300 and 1000 nm are synthesized. XRD and Raman spectra show that the nanorods are pure anatase phase, while SEM and TEM images reveal that they are polycrystalline structure. The anatase TiO 2 nanorod array films have homogeneous surface morphologies, which are beneficial to deposit compact and pinhole-free perovskite films. The light absorption, photoluminescence quenching and trap densities of the films are systematically investigated. Consequently, the perovskite solar cells based on 50 nm anatase TiO 2 nanorod arrays show the best photoelectric conversion efficiency of 15.3%, and those based on 200, 300, 1000 nm nanorod arrays achieve the photoelectric conversion efficiencies of 14.5%, 13.8% and 12.1%, respectively. Perovskite solar cells based on anatase TiO 2 nanorod arrays exhibit a high power conversion efficiency of 15.3%. Image 1 • New approach for the synthesis of anatase phase TiO 2 nanorod arrays. • Anatase TiO 2 nanorod arrays with tunable length ranged from 50 to 1000 nm. • PSCs based on anatase TiO 2 nanorod arrays yield a high efficiency of 15.3%. [ABSTRACT FROM AUTHOR]

Mesoporous SnO 2 microspheres are a class of promising electron transport materials for mesoscopic perovskite solar cells, but a smooth and dense film as requested by electron transport layer is difficult to realize using the microspheres. Here, a series of monodispersed SnO 2 microspheres with high specific surface area and good crystallinity are synthesized via a surfactant-free solvothermal method. These SnO 2 microspheres showing small diameters of about 75, 110 and 200 nm with narrow size distribution are achieved by precisely controlling the crystal growth process. They are suitable for constructing the electron transport layers whose thickness is only about hundreds nanometers. Besides, as the microspheres easily slip off from the substrate during the conventional spin coating process, the spray coating method is exploited to prepare high quality electron transport layers. As a result, a power conversion efficiency of 16.85% is yielded by using the 75 nm sized SnO 2 microspheres as the electron transport layers. This high power conversion efficiency is attributed to the fast electron transport and inhibited charge recombination. To further improve the charge transfer between the electron transport layer and perovskite layer, graphene quantum dots are added into the SnO 2 microspheres, and a best efficiency of 17.08% is obtained. Image 1 • SnO 2 microspheres with small diameters of 75, 110 and 200 nm are synthesized. • High quality SnO 2 microsphere electron transport layers are prepared by spray coating. • A high efficiency of 17.08% is obtained for the mesoscopic perovskite solar cells. [ABSTRACT FROM AUTHOR]

The practical application of aqueous zinc‐ion batteries (AZIBs) is limited by serious side reactions, such as the hydrogen evolution reaction and Zn dendrite growth. Here, the study proposes a novel adoption of a biodegradable electrolyte additive, γ‐Valerolactone (GVL), with only 1 vol.% addition (GVL‐to‐H2O volume ratio) to enable a stable Zn metal anode. The combination of experimental characterizations and theoretical calculations verifies that the green GVL additive can competitively engage the solvated structure of Zn2+ via replacing a H2O molecule from [Zn(H2O)6]2+, which can efficiently reduce the reactivity of water and inhibit the subsequent side reactions. Additionally, GVL molecules are preferentially adsorbed on the surface of Zn to regulate the uniform Zn deposition and suppress the Zn dendrite growth. Consequently, the Zn anode exhibits boosted stability with ultralong cycle lifespan (over 3500 h) and high reversibility with 99.69% Coulombic efficiency. The Zn||MnO2 full batteries with ZnSO4‐GVL electrolyte show a high capacity of 219 mAh g−1 at 0.5 A g−1 and improved capacity retention of 78% after 550 cycles. This work provides inspiration on bio‐based electrolyte additives for aqueous battery chemistry and promotes the practical application of AZIBs. [ABSTRACT FROM AUTHOR]

We report an in-situ construction strategy of Z-type In 2 O 3 @InP hydrogen evolution reaction (HER) electrocatalyst with well-defined core-shell structure on nickel foam (In 2 O 3 @InP/NF) via sequential hydrothermal, annealing, and phosphating steps. The phosphating time dramatically affects the morphology, crystal phase, elemental composition, and optical properties of In 2 O 3 @InP. The resulting electrode obtained with 2 h of phosphating time has smaller overpotentials and Tafel slope, larger TOF and ECSA, and lower charge transfer resistance compared to In 2 O 3 /NF. The better activity reveals the promoted roles of InP that can provide more active sites, facilitate charge transfer, and accelerate the adsorption of H* species. The photo-assisted electrocatalytic activity for HER is significantly enhanced attributed to the strong light absorption capacity of InP, superior energy level configuration of In 2 O 3 and InP, and excellent transient light response of In 2 O 3 @InP. Furthermore, the electrode has favorable stability and durability, and the morphology and surface chemical state have no essential changes after the photo-assisted HER stability test. The promoting mechanism of photo-assisted HER for the Z-type In 2 O 3 @InP/NF electrode and HER activities in the dark and under AM 1.5 G light illumination. [Display omitted] • The in-situ construction strategy of In 2 O 3 @InP core-shell heterostructure is used. • The InP layer enhances surface chemical states and optical properties of In 2 O 3. • In 2 O 3 @InP has superior photo-assisted activity, stability, and durability for HER. • The promoting mechanism of photo-assisted HER for Z-type In 2 O 3 @InP is determined. [ABSTRACT FROM AUTHOR]

With the advent of lithium-ion batteries (LIBs), the selection and application of electrode materials have been the subject of much discussion and study. Among them, graphite has been widely investigated for use as electrode materials in LIBs due to its abundant resources, low cost, safety and electrochemical diversity. While it is commonly recognized that conventional graphite materials utilized for commercial purposes have a limited theoretical capacity, there has been a steady emergence of new and improved carbonaceous materials for use as anodes in light of the progressive development of LIBs. In this paper, the latest research progress of various carbon materials in LIBs is systematically and comprehensively reviewed. Firstly, the rocking chair charging and discharging mechanism of LIBs is briefly introduced in this paper, using graphite anodes as an example. After that, the general categories of carbonaceous materials are highlighted, and the recent research on the recent progress of various carbonaceous materials (graphite-based, amorphous carbon-based, and nanocarbon-based) used in LIB anodes is presented separately based on the classification of the structural morphology, emphasizing the influence of the morphology and structure of carbon-based materials on the electrochemical performance of the batteries. Finally, the current challenges of carbonaceous materials in LIB applications and the future development of other novel carbonaceous materials are envisioned. [ABSTRACT FROM AUTHOR]

MnO, used as an anode material for lithium-ion batteries (LIBs), suffers from severe volume changes, poor conductivity and limited cycle performance. Herein, we applied carbon materials derived from metal–organic frameworks (MOFs) to obtain a considerable specific surface area and fitting aperture, which can be used to physically fix MnO nanoparticles. The ultrafine Co particles further anchor MnO nanoparticles through chemical interaction. The combination of physical and chemical anchoring of MnO alleviated the problem of volume changes during the intercalation reaction of LIBs. The composite of carbon material and the doping of transition metal Co improved the conductivity of MnO. In addition, the convenient channel provided by the porous structure for the diffusion of ions, the slowing down of volume changes during the process of lithiation/delithiation and the improvement in conductivity are propitious to electrochemical performance of LIBs. Therefore, Co–MnO/C delivered an ultrahigh capacity of 1653 mA h g−1 at 100 mA g−1. The specific capacity tested at 100 and 1000 mA g−1 can still reach 1414 and 772 mA h g−1, respectively, after about 300 cycles. Mn-based materials with their outstanding electrochemical performance, environmental friendliness and convenient synthesis strategy demonstrate the feasibility of Co–MnO/C composite materials in practical applications of LIBs. [ABSTRACT FROM AUTHOR]

A simple and novel method that combines the electrospinning technology with nonaqueous sol-gel method is developed to incorporate Fe2O3 nanoparticles into ZIF-8-derived nitrogen-doped highly porous carbon fibers (NPCFs). The size of Fe2O3 nanoparticles is about 5 nm. The interfacial interaction between Fe2O3 and NPCFs is investigated by thermogravimetric analysis, Raman spectrum and X-ray photoelectron energy spectrum. We found that Fe2O3 nanoparticles are anchored strongly in the NPCFs through the Fe-O-C covalent bond. The impact of the Fe2O3 content in the composites on electrochemical performance is also studied. When served as the flexible and free-standing anode of lithium-ion batteries (LIBs), the Fe2O3/NPCFs-66.9% exhibits superior electrochemical performance with the high discharge capacity of 1351 mA h g−1 at 50 mA g−1, remarkable rate capability (337 mA h g−1 even at 5000 mA g−1), and stable cycling performance (1106 mA h g−1 after 100 cycles at 100 mA g−1). The excellent anodic property can be ascribed to the ultra-small size of Fe2O3 nanoparticles, and the one-dimensional (1D) structure combined with the excellent electrical conductivity of NPCFs matrix. Moreover, the robust interfacial interaction Fe-O-C bond can restrain the aggregation of Fe2O3 nanoparticles and accommodate the volume change. This can effectively maintain the integrity of the whole electrode during the long-term cycles. The results show that the composite may be considered as a promising anode material for advanced LIBs. [ABSTRACT FROM AUTHOR]

Regulating the structural and interfacial properties of transition metal phosphides (TMPs) by coupling carbon-based materials with large surface areas to enhance hydrogen evolution reaction (HER) performance presents significant progress for water splitting technology. Herein, we constructed a composite substrate of a three-dimensional porous graphene oxide matrix (3D-GO) embedded in nickel foam (NF) to grow a Co2P electrocatalyst. Well-defined gladiolus-like Co2P nanowire arrays tightly anchored on the substrate show enhanced electrochemical characteristics for the hydrogen evolution reaction (HER) based on the promoting roles of 3D porous reduced GO (3D-rGO) derived from 3D-GO, which promotes the dispersion of active components, improves the rate of electron transfer, and facilitates the transport of water molecules. As a result, the obtained Co2P@3D-rGO/NF electrode exhibits superior HER activity in 1.0 M KOH media, achieving overpotentials of 36.5 and 264.7 mV at current densities of 10 and 100 mA cm−2, respectively. The electrode also has a low Tafel slope of 55.5 mV dec−1, a large electrochemical surface area, and small charge-transfer resistance, further revealing its mechanism of high intrinsic activity. Moreover, the electrode exhibits excellent HER stability and durability without surface morphology and chemical state changes. [ABSTRACT FROM AUTHOR]

Efficient and earth-abundant electrocatalysts for water oxidation are essential for renewable and sustainable energy conversion technologies. And Ni(Fe)O x H y especially attractive as a state-of-the-art best candidate catalyst for efficient electrochemical oxygen evolution reaction (OER). In previous research, Cr has been reported could benefit the Ni(Fe)O x H y catalysts with conflicting mechanism. Here, a series of ternary (Ni, Fe and Cr) amorphous metal oxide catalysts for OER are synthesized via a simple thermal decomposition method. We show that Ni 0.6 Fe 0.3 Cr 0.1 O x has a turnover frequency of 0.046 ± 0.004 s −1  at 300 mV overpotential which is ∼31% more active than an analogous Ni 0.6 Fe 0.4 O x film, 0.035 ± 0.007 s −1 , in 0.1 M KOH media. Using electrochemical voltammetry and AC impedance analysis, we demonstrate that Cr increases the number of electrochemically available active sites, as a pore forming agent, but does not affect the intrinsic per metal atom activity. We find that the Cr begins to leach immediately upon electrochemical testing, and the Cr is almost completely depleted after a 24 h stability test. Importantly, along with the decreased content of Cr, the catalyst activity is further promoted. Although the Cr itself may not be responsible for the improvement, its dissolution results in an ideal type of pore and/or active sites. We further optimize the deposition of high-surface-area and high-mass-loading Ni 0.6 Fe 0.3 Cr 0.1 O x on carbon-cloth electrodes and demonstrate an overpotential as low as 251 mV at 10 mA cm −2 in 1 M KOH. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of perovskite solar cells is extremely dependent on the crystallization and morphology of the perovskite film, which are affected by the deposition method. Here, we demonstrate a simple approach to form a microporous PbI 2 film, with subsequent conversion to a compact, highly crystalline perovskite film. The PbI 2 and corresponding perovskite films were further probed by two-dimensional X-ray diffraction. The resultant perovskite exhibited improved photovoltaic performance under ambient conditions with about 50% humidity. The PbI 2 microporous structure was formed by exchanging residual DMSO with DMF vapor in the PbI 2 film, which facilitated contact with the methylammonium iodide (MAI) solution. The process resulted in the formation of compact, smooth, pinhole-free perovskite films having no residual PbI 2 . Solar cells fabricated using this methodology exhibited power conversion efficiencies over 16% with negligible photocurrent hysteresis. [ABSTRACT FROM AUTHOR]

We report an in-situ construction method for the NiFe-based oxyhydroxide OER electrocatalyst supported on the nickel foam (NF) substrate with the polyaniline (PANI) interlayer by sequential electrochemical deposition steps (NF/PANI/NiFe–OH). The ultra-thin nanosheet for the nickel-iron (oxy)hydroxides tightly grown on the porous PANI exhibits the enhanced electrochemical characteristics associated with the promotion roles of the PANI layer, which increases the number of active sites, facilitates the charge transfer, and accelerates water transport across the interfaces of the electrode. The as-prepared NF/PANI/NiFe–OH has reliable lower overpotentials of 260, 340, and 490 mV without iR -correction at 50, 100, and 200 mA cm−2 of high current densities, respectively. The smaller Tafel slope, larger ECSA, and TOF values of the electrode reveal its high intrinsic activity. Moreover, the electrode shows good stability and durability without the damage of morphology, change of surface chemical state, and substantial loss of active components at high current density. The OER mechanism and stability of electrodeposited polyaniline/nickel-iron oxyhydroxide stabilized on nickel foam (NF/PANI/NiFe-OH). [Display omitted] • The in-situ construction method for electrodeposited PANI/NiFe–OH is used. • The PANI interlayer improves the surface structure and chemical state of NiFe–OH. • The PANI/NiFe–OH electrode has superior OER activity compared to NiFe–OH. • The promoting mechanism of PANI on electrochemical OER performance is determined. [ABSTRACT FROM AUTHOR]

With a high specific capacity, MoP2 has been identified as an ideal electrode material for LIBs. However, the specific capacity is negatively affected due to its poor conductivity and severe volume expansion during insertion and extraction of Li+. In this paper, MoP2-C synthesized by using a Mo-MOF as a precursor, with the generation of C, can effectively solve the agglomeration problem in the synthesis process and alleviate serious volume changes during cycling. Due to the lack of carbon sources provided by a Mo-MOF, the conductivity of MoP2-C cannot be greatly improved. Therefore, rGO and PPy are added to improve the conductivity of MoP2 and further increase the stability of the structure. Compared with MoP2/C and MoP2/C@PPy, MoP2/C@rGO exhibits the highest initial discharge specific capacity of 1208 mA h g−1 at a current density of 100 mA g−1 and rate performances of 830, 750, 630, 550, and 430 mA h g−1 with the current density increasing from 100 mA g−1 to 2000 mA g−1. Notably, the specific capacity remains at 640 mA h g−1 at a current density of 100 mA g−1 after 100 cycles. Followed by 200 cycles at a current density of 2000 mA h g−1, the specific capacity remains at 395 mA h g−1 with a capacity retention rate of 80%. [ABSTRACT FROM AUTHOR]

In this work, a honeycomb-shaped meso@mesoporous carbon nanofiber material incorporating homogeneously dispersed ultra-fine Fe2O3 nanoparticles (denoted as Fe2O3@g-C3N4@H-MMCN) is synthesised through a pyrolysis process. The honeycomb-shaped configuration of the meso@mesoporous carbon nanofiber material derived from a natural bio-carbon source (crab shell) acts as a support for an anode material for Li-ion batteries. Graphitic carbon nitride (g-C3N4) is produced via the one-step pyrolysis of urea at high temperature under an N2 atmosphere without the assistance of additives. The resulting favorable electrochemical performance, with superior rate capabilities (1067 mA h g−1 at 1000 mA g−1), a remarkable specific capacity (1510 mA h g−1 at 100 mA g−1), and steady cycling performance (782.9 mA h g−1 after 500 cycles at 2000 mA g−1), benefitted from the advantages of both the host material and the Fe2O3 nanoparticles, which play an important role due to their ultra-fine particle size of 5 nm. The excellent cycle life and high capacity demonstrate that this strategy of strong synergistic effects represents a new pathway for pursuing high-electrochemical-performance materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Regulating interfacial properties of electrocatalysts to enhance the performance of oxygen evolution reaction (OER) possesses practical significance for water splitting. Herein, we report a novel strategy to form a graphitic carbon nitride (g-C 3 N 4) interface layer on nickel foam (NF), followed by the growth of nickel-iron (oxy)hydroxides (NiFe-OH). The NiFe-OH nanosheets are tightly anchored on the g-C 3 N 4 layer, exhibiting enhanced surface and structural characteristics. Therefore, the as-prepared NF/g-C 3 N 4 /NiFe-OH demonstrates superior OER activity with low overpotentials of 272, 342, and 476 mV at the current densities of 50, 100, and 200 mA cm−2, respectively. The reduced Tafel slope and raised TOF values of the electrode compared to NF/NiFe-OH reveal the promoting roles of g-C 3 N 4 , which provides more active sites, induces charge redistribution, and facilitates electron transfer. Furthermore, the electrode presents reliable stability and durability without observable morphological damage, alteration in the surface chemical state, and significant depletion of active components. [Display omitted] • The in-situ strategy is used to form g-C 3 N 4 ultrathin interface layer on NF. • The g-C 3 N 4 interlayer improves surface structure and charge transport of NiFe-OH. • The promoting mechanism of g-C 3 N 4 for efficient OER of the electrode is determined. [ABSTRACT FROM AUTHOR]

Gallium oxide as a novel electrode material has attracted attention because of its high stability and conductivity. In addition, Ga2O3 will be converted to Ga during the charge and discharge process, and the self-healing behavior of Ga can improve the cycling stability. In this paper, we synthesized Ga2O3 nanoparticles with a size of about 4 nm via a facile sol–gel method. Meanwhile, we employed three types of carbon materials (reduced graphene oxide, mesoporous carbon nanofiber arrays, and carbon nanotubes) to avoid the aggregation of Ga2O3 nanoparticles and improve the conductivity of Ga2O3 during the discharge/charge process as well. Among the three samples, the deactivating defective sites and special carbon matrix of reduced graphene oxide can provide more attachment points for Ga ions, so the Ga2O3 nanoparticles can be more closely and uniformly distributed on rGO. Benefitting from the perfect combination of reduced graphene oxide sheets and Ga2O3 nanoparticles, a stable capacity of the Ga2O3/rGO electrode can be maintained at 411 mA h g−1 at a current density of 1000 mA g−1 after 600 cycles. We believe that this work provides a novel and efficient way to improve the electrochemical stability of Li-ion batteries. [ABSTRACT FROM AUTHOR]

Hindered by price and scarcity, the exploitation of supported Pt-based electrocatalysts with Pt single atoms or Pt nanoclusters is an alternative way to decrease the dosage of Pt and improve the electrocatalytic performance for hydrogen evolution reaction (HER) of water splitting. The anodization technology is used to modify the surface of nickel foam (NF) to form the porous NiF 2 network structure. Then Pt nanodots interfaced with Ni(OH) 2 (Pt/Ni(OH) 2) hybrid on the anodized NF has been in-situ synthesized by a simple hydrothermal decomposition method. Results show that Pt nanodots on the substrate have good dispersion with the average size of 3 nm, and the Pt loading is only 0.229 mg cm−2. The prepared electrode exhibits the low overpotentials of 25.9 mV and 211 mV at the current densities of 10 and 100 mA cm−2, respectively, a small Tafel slope of 37.6 mV dec−1, and the excellent durability for HER. The porous network nanostructure of Pt/Ni(OH) 2 hybrid, the large electrochemical surface area, the fast facilitated electron transport capability, and the firm adhesion of Pt nanodots with the anodized NF substrate contribute to the remarkable performance towards HER. Image 1 • A simple hydrothermal decomposition method was used to synthesize Pt nanodots. • The anodized NF contributes to the porous network nanostructure of Pt/Ni(OH) 2 hybrid. • The modification of the NF substrate enhances the HER performance of the electrodes. • The mechanisms of the efficient HER for the Pt/Ni(OH) 2 /NF-A electrode are explained. [ABSTRACT FROM AUTHOR]

• Non-metallic materials as anode materials for lithium-ion batteries. • Defects caused by hydrogen bonding facilitate the intercalation reaction in LIBs. • High self-healing properties facilitate real-time repair of reactive interfaces. • Simple preparation method and abundant elemental storage meet the economic cost. The replacement of metallic materials with non-metallic materials as anode electrodes for lithium-ion batteries (LIBs) is an increasing hot spot for constructing a new generation of energy storage field. Here, a novel deep eutectic composites material consisting of quaternary ammonium salts (QASs) and N-methyl pyrrolidone (NMP) on the basis of hydrogen bonding reaction is used as the anode material of LIBs, boasting numerous advantages, including facile synthesis, environmental friendliness, superb conductivity, self-healing property, and multiple active sites to provide capacity. Typically, tetraethylammonium chloride (TEACl)/NMP delivered a reversible specific capacity of 764.8 mAh/g at 100 mA/g after cycling 420 times and coulombic efficiency is maintained near 100 % after 1000 cycles at 100 mA/g. The availability of hydrogen bonding network reduces the lattice energy of its components and creates defects, which is more favorable for the intercalation reaction in LIBs. Concurrently, the effect of hydrogen bonding reaction and the natural mobility of the deep eutectic composites exhibit high self-healing properties, facilitating the repair of the reaction interface in real time. An abundance of active sites that can bind Li+ to form LiH is used to provide capacity, which is also confirmed by density functional theory (DFT) method. [ABSTRACT FROM AUTHOR]

A facile approach that combines the chemical etching with sulfidation of the sacrificial templates of the Fe-based MOFs is developed to prepare FeS 2 @ Porous Octahedral Carbon (FeS 2 @POC). The porous carbon shell can improve the conductivity of active materials, bring a high reversible capacity. Moreover, the void space between carbon and FeS 2 can accommodate the volume changes during cycling and the existence of carbon can prevent the aggregation of pulverized FeS 2 particles during Li ions insertion/extraction process, which are favorable to gain superior cycling stability. When used as an anode for lithium-ion batteries, the FeS 2 @POC shows superior electrochemical performance with a high specific capacity, excellent rate performance (381 mAh g−1 at 5000 mA g−1) and good cyclability (1074 mAh g−1 at 100 mA g−1 after 100 cycles, about 99% capacity retention). The results demonstrate that this product may be considered as a promising anode material for advanced lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A Ga/Ga2O3@C dodecahedron composite with a high specific capacity of about 542 mA h g−1 after 200 cycles at the current density of 1000 mA g−1 was synthesized by one-step hydrogen reduction. This hierarchical homogeneous structure combined the Ga, Ga2O3 and carbon frameworks (from Ga-MOF) to exhibit excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Antimony/reduced graphene oxide (Sb/rGO) composite is prepared successfully with the addition of rGO nanosheets via a facile one-step chemical deposition route using SbCl 3 as the precursor, which could form metallic Sb nanoparticles anchored on the rGO sheets submerging in N, N-dimethylformamide (DMF) without any other addition of surfactant. Microstructure characterization tests reveal the sheet-like Sb/rGO composite consisting of the ultrafine Sb nanoparticles uniformly and intimately dispersed on the rGO nanosheets. In this special structure, rGO nanosheets with the preponderance of ultra-thin and flexible not only restrain the tremendous volume change of Sb nanoparticles but also have a brilliant synergistic effect and strong bonding effect along with Sb nanoparticles and improve the conductivity of active material. Therefore, as an anode material with promoted electrochemical performance for lithium-ion batteries, Sb/rGO composite shows the high reversible capacity of 797.5 mAh g−1 and 562.9 mAh g−1 after 200 cycles at the current density of 80 mA g−1 and 430 mA g−1, respectively. And the rate performance is also improved due to the existence of rGO nanosheets as an indispensable role in the Sb/rGO composite. • Sb nanoparticles are anchored on rGO by one-step chemical deposition route. • Spherality metallic Sb particles are prepared by a novel method. • The Sb/rGO composite displays excellent electrochemical performance. • This new route can provide an idea to explore other metal/rGO composite. [ABSTRACT FROM AUTHOR]

In this work, we synthesized a novel UIO-67@Se@PANI composite cathode material for Li–Se battery applications. Zr-MOFs (metal organic frameworks) were used as a support and a PANI (polyaniline) layer was employed as the coating. UIO-67@Se@PANI was expected to be one of the candidates for Li–Se batteries, with a high specific capacity of 248.3 mA h g−1 at 1C (1C = 675 mA g−1) after 100 cycles. In particular, stable capacities of 203.1 and 167.6 mA h g−1 were received after 100 cycles at high rates of 2C and 5C, respectively. To explain such a good electrochemistry performance of the composite cathode material, multiple characterization methods were carried out. And that can be attributed to the sandwich-like structure of the UIO-67@Se@PANI composite and the fact that UIO-67 can provide unsaturated sites to tether the selenium effectively and the PANI layer can improve the electronic conductivity of the whole electrode significantly. [ABSTRACT FROM AUTHOR]

In this study, we reported a new synthesis of ZIF-67@S@MnO 2 composite based on the ZIF-67, an universal porous MOF material with excellent thermal stability and chemical stability, which can effectively alleviate sulfur volume expansion and dissolution of polysulfide. Here, the ZIF-67 can provide more active sites for sulfur attachment after vacuum treatment. The MnO 2 coated on the surface of ZIF-67@S was introduced through the redox reaction of KMnO 4 under ice bath with high purities, which can also effectively form a sandwich structure to encapsulate the sulfur particles attached to the surface of the MOF. The MnO 2 can chemically bind polysulfdes strongly and further relieve volume expansion, which might enhance the performance of lithium-sulfur battery. This combination of physical adsorption of ZIF-67 itself and filling of MnO 2 can effectively encapsulate sulfur to obtain high specific capacity. When the ZIF-67@S@MnO 2 composite is initially discharged, the specific capacity can reach about 1250 mAh g−1 at 0.5 C. In addition, the as-obtained composite exhibits stable specific capacities of 895 mAh g−1 at 0.5 C, 686 mAh g−1 at 1 C and 484 mAh g−1 at 2 C after 100 cycles, respectively. The encouraging compartment structure and excellent electrochemical performance can be recommended for energy storage applications. • A novel composite was synthesized via employing Co-MOF(ZIF-67) and MnO 2. • The ZIF-67 provided the void sites for sulfur attachment after vacuum treatment. • The MnO 2 can alleviate the polysulfide dissolution and volume expansion. • Novel ZIF-67@S@MnO 2 material exhibited excellent cycle stability and high capacity. [ABSTRACT FROM AUTHOR]

• Well-crystallized perovskite films were prepared at near-room temperature of 50 °C. • Effect of Cs+ cations on diffusion of organic cations in intermediate phases was described. • The PSCs with corresponding perovskite layers possessed a highest PCE of 17.9%. Perovskite crystallizations under different temperature phases have tremendously effects on the performance of perovskite solar cells. Here, we report an effective near-room-temperature fabrication technique to prepare high quality organolead halide perovskite films. By doping a certain amount of cesium cations into precursor solution, smooth and well-crystallized perovskite films with no other impurity phase can be obtained at an annealing temperature of 50 °C. This phenomenon can be interpreted as relatively low energy required for the diffusion of cesium cations into intermediate phase framework, promoting the removal of DMSO and subsequent diffusion of organic cations. Corresponding PSCs has been prepared based on this technique, and the highest PCE of 17.9% has been obtained with annealing temperature of only 50 °C. This work exhibits a well balance between reducing of annealing temperature and increase of device performance and is expected to broaden the range of choices for substrate materials. [ABSTRACT FROM AUTHOR]

A novel strategy to boost the oxygen evolution reaction (OER) activity of NiFe-LDHs has been developed using reduced graphene oxide (rGO) as both the substrate and electronic carrier. Basically, a GO hydrogel is printed on Ni foam by the doctor blade technique, forming a GO matrix embedded in Ni foam, which is then freeze-dried to turn into a 3-dimensional (3D) porous GO (3D-GO) matrix. NiFe-layered double hydroxide (NiFe-LDH) nanoflakes anchored on the 3D-GO matrix embedded in Ni foam are synthesized by a hydrothermal process, together with the in situ reduction of 3D-GO. The obtained electrode has a high degree of reduction of the porous graphene oxide, the mechanical strength of the NiFe-LDH nanoflakes anchored on the matrix, large active surface area and excellent interface conjunction. Based on optimal conditions, the fabricated electrode shows outstanding electrocatalytic oxygen evolution reaction performance in 1 M KOH aqueous solution, achieving a small overpotential of 170 mV, a Tafel slope of 57 mV decade−1 at a current density of 20 mA cm−2 and a relatively stable operating potential after 2000 cycles of the CV test. [ABSTRACT FROM AUTHOR]

Bi2S3 is a promising negative electrode material for lithium storage owing to its high theoretical capacity. Nevertheless, the capacity of Bi2S3 decays very rapidly upon Li cycling. Here, Bi2S3 and Bi2S3/C were successfully synthesized by a novel route. Sulfur powder as a kind of sulfur source reacted with a metal organic framework based on bismuth and trimesinic acid―Bi(BTC)(DMF)·DMF·(CH3OH)2 (denoted as Bi-BTC). Trimesic acid further acted as a new type of carbon source to synthesize the Bi2S3/C composite. The particle sizes of the composite were smaller than those of pure Bi2S3, showing the suppression of Bi2S3 aggregation. Charge–discharge performance and cyclability for both the Bi2S3 and Bi2S3/C composites in lithium-ion batteries were measured. Specifically, the specific capacities of Bi2S3/C and Bi2S3 reached 765 and 603 mA h g−1, respectively, at 100 mA g−1 after 100 cycles. Because of its high capacity and excellent cycle life, Bi2S3/C is a promising energy storage material. [ABSTRACT FROM AUTHOR]

• Advanced SMS-FeX 3 anodes show promising performance in LIBs. • Fe trihalides (FeF 3 , FeCl 3 , FeBr 3) synergize with NMP, yielding SMS-FeX 3 materials of exceptional electrochemical performance. • SMS-FeX 3 anodes exemplify easy synthesis, sustainability, and leverage solid molten salts' electrochemical strengths. • SMS-FeX 3 anodes present a promising outlook for LIBs anodes, demonstrating substantial potential for practical utilization. Cost-effective metal trihalides exhibiting high specific capacity hold significant promise as anodes in lithium-ion batteries (LIBs). Within this study, the spotlight falls on innovative anode materials, denoted as solid molten salts (SMS-FeX 3 , X = F, Cl, Br), which are synthesized through the utilization of transition metal trihalides. SMS-FeX 3 anodes offer a range of advantages, including facile synthesis, environmental sustainability, and the electrochemical benefits stemming from the superior conductivity and electrochemical performance of solid molten salts. Leveraging the synergistic interaction between Fe trihalides (FeF 3 , FeCl 3 , FeBr 3) and N-Methyl-2-Pyrrolidone (NMP), these SMS materials exhibit exceptional electrochemical performance and remarkable cycle stability. Furthermore, a comprehensive comparison among the three Fe trihalides underscores their distinct characteristics: SMS-FeF 3 showcases a consistent Coulombic Efficiency of approximately 100 % throughout 400 cycles. SMS-FeCl 3 stands out with an initial specific capacity of 1258 mAh/g at 100 mA g−1, sustaining at 900 mAh/g after 400 cycles. Meanwhile, SMS-FeBr 3 , serving as a comparative material, exhibits commendable rate performance even at 2000 mA g−1. These captivating and pioneering SMS-FeX 3 anode materials offer a fresh perspective on the anode fabrication of LIBs, bearing exceptional promise for practical applications. [ABSTRACT FROM AUTHOR]

The development of highly efficient latent fingerprints technology (LFPs) on different background remains extremely vital for forensic and criminal investigations. In this work, a pure organic molecular sensor (DPTPA1) was designed to image LFP with strong signal-to-noise ratio by optimizing the imaging technology. DPTPA1 exhibits aggregation-induced emission (AIE) properties in both aqueous solution and solid state. Two pyridine moieties and one aldehyde moiety were introduced as the end-capped units. DPTPA1 exhibits the typical solvatochromic effect whose maximum emission wavelengths red-shift from 410 nm to 540 nm with the increasing polarity of solvents. The obvious emission of DPTPA1 in the aqueous solution is observed around 500 nm (φ = 9.6%). Both cyanoacrylate glue fuming (CGF) and powder dusting (PD) methods were used to obtain the fluorescent images of LFP on glass, tinfoil, steel and plastic substrates. Among them, the CGF method can image the clear second level details of LFP on the glass and tinfoil. The PD method using DPTPA1-loaded silica gel material can obtain the high quality LFP images on the curved surface of all four substrates. This work provides a strategy for lowing the cost in the broad fields of LFPs imaging. An AIE-active dipyridnyltriphenylamine derivative (DPTPA) shows good fluorescent properties in aqueous solution, powder and silica gel complex, which can perform optimizing latent fingerprints imaging by using cyanoacrylate glue fuming and powder dusting methods. [Display omitted] • A dipyridnyltriphenylamie-based fluorescent agent (DPTPA) were synthesized. • DPTPA exhibits obvious aggregation-induced emission. • The aqueous solution of DPTPA outputs the fluorescence around 500 nm (φ = 9.6 %). • A low cost imaging agent and silica gel-based formula for LFPs imaging were provided. • LFPs imaging is processed by both cyanoacrylate glue fuming and powder dusting methods. [ABSTRACT FROM AUTHOR]

Abstract SnO x is considered as a promising anode candidate for lithium-ion batteries, but suffers from the low electrical conductivity and severe volume expansion during cycling. To solve these issues, we develop a simple and facile process of incipient wetness impregnation followed by pyrolysis gel molecules to prepare SnO x /mesoporous carbon nanofiber arrays, SnO x /graphene, SnO x /carbon nanotubes and SnO x /three-dimensionally ordered macroporous carbon materials. Notably, SnO x nanoparticles about 5 nm are prepared by a nonaqueous sol-gel method. We also explore the effect of different morphologies and pore structures of four carbon substrates on the electrochemical performance of the composites. Benefiting from the small size of SnO x nanoparticles and the synergistic effect between SnO x and the different carbon matrix materials, SnO x -Carbon electrode materials display excellent rate capability and cycle stability. SnO x /mesoporous carbon nanofiber arrays exhibits the best rate (522 mA h g−1 at 2000 mA g−1) and cycling performances (1327 mA h g−1 after 200 cycles at 100 mA g−1). The superior electrochemical performance, facile synthesized method and low cost of the Sn-based materials exhibit promising application for SnO x /mesoporous carbon nanofiber arrays as anode materials for next-generation lithium-ion batteries. Furthermore, the ex situ X-ray photoelectron spectroscopy studies on this electrode material under different states suggest that the Sn and Li 2 O could reversibly react to form SnO x during the charging process. [ABSTRACT FROM AUTHOR]

In this work, carboxyl groups were introduced on the organic ligands of ZIF-67 through post-synthetic modification (-CH 3 →-CH 2 Br→-CHO→-COOH). A thin layer of Ag nanoparticles (3 nm in diameter) coating was deposited on external surface of ZIF-67 crystals through the reaction between the aldehyde groups in the ligands and silver ammonia solution. The carboxyl groups can participate in the lithium storage while the Ag nanoparticles coating help in increasing the conductivity. Electrochemical properties of the modified ZIF-67 electrodes are examined by cyclic voltammetry and galvanostatic charge/discharge tests. Benefiting from the outstanding conductivity of Ag nanoparticles and the synergistic effect between Ag nanoparticles and the modified ZIF-67, the composite exhibits enhanced electrochemical performance compared to its ZIF-67 counterpart. Nearly an invariable capacity of 800 mA h g −1 is maintained up to 100 cycles at 0.28 C (1C = 137 mA g −1 ) with a Coulombic efficiency of 99%. Furthermore, the ex situ X-ray diffraction and X-ray photoelectron spectroscopy studies on the electrode material under different states suggest that the Co ions remain in the Co 2+ state during the charging/discharging process and the usual conversion reaction mechanism for lithium storage might not be suitable for the modified ZIF-67 electrode material. [ABSTRACT FROM AUTHOR]

Ellipsoidal TiO 2 mesocrystals (MCs) with varying particle sizes depending on the amount of titanium precursor are synthesized by solvothermal method using acetic acid and tetrabutyl titanate. The large one (MC-1) is predominant 700 nm in length and 400 nm in width, while the small one (MC-2) is 250 nm in length and 100 nm in width. SEM and TEM images reveal that the mesocrystals exhibit single-crystalline-like structures, which are constructed by the orderly aggregating of tiny primary TiO 2 nanocrystals. The specific surface areas of MC-1 and MC-2 are 119.5 and 132.4 m 2 /g respectively. The mesocrystals are potential photoanode materials in DSSCs, which can not only enhance the light scattering and dye adsorption, but also enhance the electron transport. The highest efficiency of 7.16% is achieved for the bi-layer NC-MC-2 DSSCs when the MC-2 is applied as a scattering layer on top of the nanocrystalline underlayer. The improvement of the efficiency is mainly attributed to the high specific surface area as well as the efficient light scattering, both of which result in the increase of light harvesting. Meanwhile, the electron transport of the photoanodes is also investigated. It is found that the electron transport of the single-crystalline-like mesocrystals is superior than nanoparticles, corresponding to the excellent energy conversion efficiency. [ABSTRACT FROM AUTHOR]

Luminescent organic dyes with tuning emission in widely visible gamut are still interesting challenging. Herein, we report two naphthalimide derivatives ( NAPP , NAPTPA ), which can output the variable emission colors covering the whole visible spectra from purple to far-red in aqueous solution. Both naphthalimide derivatives can exhibit bright emission in aqueous solution by introducing a phenyl ring into 4-site of naphthalimide, which acts as a π-bridge in delocalized system and not affects the intramolecular charge transfer process of naphthalimide dyes. Comparison with three analogues ( NAPDMP , NAPMOP and NAPDMA ), we evidenced the bright emissions in aqueous solution are from the amorphous emission different from the common crystal emission of naphthalimide dyes. We further fabricated the NAPP and NAPTPA into different nanoparticles matrixes to construct the multi-color toolbox, which could output four colors (purple, blue, green and red) in aqueous solution and yellow emission in crystal. Moreover, the white emission system was obtained through solution doping method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Precursor affected CeO 2 structure and the catalytic ability for imine synthesis. • CeO 2 from Ce(NO 3) 3 were better catalyst than those from Ce(OH) 4 and Ce(CH 3 COOH) 3. • Ethylene glycol coordinated differently with Ce precursor, H 2 O break these bonds. • Surface oxygen vacancies governed CeO 2 catalytic ability for imine synthesis. • Surface oxygen vacancies had more influences than the surface area and Ce3+ ratio. CeO 2 as catalysts for imine synthesis was synthesized from three different inorganic precursors (Ce(OH) 4 , Ce(COOCH 3) 3 ∙5H 2 O and Ce(NO 3) 3 ∙6H 2 O) in ethylene glycol (EG) as solvothermal solvent. The influences of some parameters were investigated, such as the surfactant polyvinylpyrrolidone (PVP), H 2 O as co-solvent, and CH 3 COOH or NaOH as mineralizer (exclusive for Ce(NO 3) 3 as the precursor). The different precursors influenced the coordination of EG with cerium, crystalline, surface structure and also the catalytic ability for imine synthesis. The highest imine conversion rate was obtained when CeO 2 was synthesized from Ce(NO 3) 3 + PVP + CH 3 COOH +EG. The mechanism was investigated by carefully checking the structures of the synthesized CeO 2 , such as XRD, morphology, surface area, XPS and so on, and figured out that the high catalytic activity of the best CeO 2 sample was much more related with the high proportion of surface oxygen vacancies than the surface area and the Ce3+ ratio. [ABSTRACT FROM AUTHOR]