Electrochemical deposition has emerged as a novel approach to fabricate metal–organic framework (MOF) films. Here, for the first time, an aqueously cathodic deposition (ACD) approach is developed to fabricate ZIF-8 type of MOF membranes without addition of any supporting electrolyte or modulator. The fabrication process uses 100% water as the sole solvent and a low-defect density membrane is obtained in only 60 min under room temperature without any pre-synthesis treatment. The membrane exhibits superior performance in C3H6/C3H8 separation with 182 GPU C3H6 permeance and 142 selectivity, making it sit at the upper bound of permeance versus selectivity graph, outperforming majority of the published data up to 2019. Notably, this approach uses an extremely low current density (0.13 mA cm−2) operated under an ultrafacile apparatus set-up, enabling an attractive way for environmentally friendly, energy efficient, and easily scalable MOF membrane fabrications. This work demonstrates a great potential of aqueously electrochemical deposition of MOF membrane in the future research.
Over the past few decades, significant progress has been made in the field of photonic processing of electronic materials using a variety of light sources. Several of these technologies have now been exploited in conjunction with emerging electronic materials as alternatives to conventional high-temperature thermal annealing, offering rapid manufacturing times and compatibility with temperature-sensitive substrate materials among other potential advantages. Herein, recent advances in photonic processing paradigms of metal-oxide thin-film transistors (TFTs) are presented with particular emphasis on the use of various light source technologies for the photochemical and thermochemical conversion of precursor materials or postdeposition treatment of metal oxides and their application in thin-film electronics. The pros and cons of the different technologies are discussed in light of recent developments and prospective research in the field of modern large-area electronics is highlighted.
A titanium carbide (Ti3C2Tx) MXene is employed as an efficient solid support to host a nitrogen (N) and sulfur (S) coordinated ruthenium single atom (RuSA) catalyst, which displays superior activity toward the hydrogen evolution reaction (HER). X-ray absorption fine structure spectroscopy and aberration corrected scanning transmission electron microscopy reveal the atomic dispersion of Ru on the Ti3C2Tx MXene support and the successful coordination of RuSA with the N and S species on the Ti3C2Tx MXene. The resultant RuSA-N-S-Ti3C2Tx catalyst exhibits a low overpotential of 76 mV to achieve the current density of 10 mA cm−2. Furthermore, it is shown that integrating the RuSA-N-S-Ti3C2Tx catalyst on n+np+-Si photocathode enables photoelectrochemical hydrogen production with exceptionally high photocurrent density of 37.6 mA cm−2 that is higher than the reported precious Pt and other noble metals catalysts coupled to Si photocathodes. Density functional theory calculations suggest that RuSA coordinated with N and S sites on the Ti3C2Tx MXene support is the origin of this enhanced HER activity. This work would extend the possibility of using the MXene family as a solid support for the rational design of various single atom catalysts.
This review article presents and discusses the recent progress made in the stabilization, protection, improvement, and design of halide perovskite-based photocatalysts, photoelectrodes, and devices for solar-to-chemical fuel conversion. With the target of water splitting, hydrogen iodide splitting, and CO2 reduction reactions, the strategies established for halide perovskites used in photocatalytic particle-suspension systems, photoelectrode thin-film systems, and photovoltaic-(photo)electrocatalysis tandem systems are organized and introduced. Moreover, recent achievements in discovering new and stable halide perovskite materials, developing protective and functional shells and layers, designing proper reaction solution systems, and tandem device configurations are emphasized and discussed. Perspectives on the future design of halide perovskite materials and devices for solar-to-chemical fuel conversion are provided. This review may serve as a guide for researchers interested in utilizing halide perovskite materials for solar-to-chemical fuel conversion.
Metal oxides synthesized by the solvothermal approach have widespread applications, while their nanostructure control remains challenging because their reaction mechanism is still not fully understood. Herein, it is demonstrated how the competitive relation between Ostwald ripening and surface charging during solvothermal synthesis is crucial to engineering high-quality metal (oxide)–carbon nanomaterials. Using SnO2 as a case study, a new type of hollow SnO2–C hybrid nanoparticles is synthesized consisting of core–shell structured SnO2@C nanodots (which has not been previously reported). This new anode material exhibits extremely high lithium storage capacity of 1225 and 955 mAh g−1 at 200 and 500 mA g−1, respectively, and excellent cycling stability. In addition, full-battery cells are constructed combining SnO2–C anode with Ni-rich cathode, which can be charged to a higher voltage compared to commercial graphite anode and still demonstrate extraordinary rate performance. This study provides significant insight into the largely unexplored reaction mechanism during solvothermal synthesis, and demonstrates how such understanding can be used to achieve high-performance metal (oxide)–C anodes for rechargeable batteries.
MXenes are a class of two-dimensional (2D) transition metal carbides, nitrides and carbonitrides that have shown promise for high-rate pseudocapacitive energy storage. However, the effects that irreversible oxidation have on the surface chemistry and electrochemical properties of MXenes are still not understood. Here we report on a controlled anodic oxidation method which improves the rate performance of titanium carbide MXene (Ti 3 C 2 T x, T x refers to -F, =O, -Cl and -OH) electrodes in acidic electrolytes. The capacitance retention at 2000 mV/s (with respect to the lowest scan rate of 5 mV/s) increases gradually from 38% to 66% by tuning the degree of anodic oxidation. At the same time, a loss in the redox behavior of Ti 3 C 2 is evident at high anodic potentials after oxidation. Several analysis methods were employed to reveal that preserving the structure and surface chemistry while simultaneously introducing defects, without compromising electrochemically active sites, are key factors for improving the rate performance of Ti 3 C 2 T x . This study demonstrates improvement of the electrochemical performance of MXene electrodes by controlling the surface chemistry and transition metal stoichiometry.
The application of liquid-exfoliated 2D transition metal disulfides (TMDs) as the hole transport layers (HTLs) in nonfullerene-based organic solar cells is reported. It is shown that solution processing of few-layer WS2 or MoS2 suspensions directly onto transparent indium tin oxide (ITO) electrodes changes their work function without the need for any further treatment. HTLs comprising WS2 are found to exhibit higher uniformity on ITO than those of MoS2 and consistently yield solar cells with superior power conversion efficiency (PCE), improved fill factor (FF), enhanced short-circuit current (JSC), and lower series resistance than devices based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and MoS2. Cells based on the ternary bulk-heterojunction PBDB-T-2F:Y6:PC71BM with WS2 as the HTL exhibit the highest PCE of 17%, with an FF of 78%, open-circuit voltage of 0.84 V, and a JSC of 26 mA cm−2. Analysis of the cells' optical and carrier recombination characteristics indicates that the enhanced performance is most likely attributed to a combination of favorable photonic structure and reduced bimolecular recombination losses in WS2-based cells. The achieved PCE is the highest reported to date for organic solar cells comprised of 2D charge transport interlayers and highlights the potential of TMDs as inexpensive HTLs for high-efficiency organic photovoltaics.
A simple approach that enables a consistent enhancement of the electron extracting properties of the widely used small-molecule Phen-NaDPO and its application in organic solar cells (OSCs) is reported. It is shown that addition of minute amounts of the inorganic molecule Sn(SCN)2 into Phen-NaDPO improves both the electron transport and its film-forming properties. Use of Phen-NaDPO:Sn(SCN)2 blend as the electron transport layer (ETL) in binary PM6:IT-4F OSCs leads to a remarkable increase in the cells' power conversion efficiency (PCE) from 12.6% (Phen-NaDPO) to 13.5% (Phen-NaDPO:Sn(SCN)2). Combining the hybrid ETL with the best-in-class organic ternary PM6:Y6:PC70BM systems results to a similarly remarkable PCE increase from 14.2% (Phen-NaDPO) to 15.6% (Phen-NaDPO:Sn(SCN)2). The consistent PCE enhancement is attributed to reduced trap-assisted carrier recombination at the bulk-heterojunction/ETL interface due to the presence of new energy states formed upon chemical interaction of Phen-NaDPO with Sn(SCN)2. The versatility of this hybrid ETL is further demonstrated with its application in perovskite solar cells for which an increase in the PCE from 16.6% to 18.2% is also demonstrated.
Pan, Jun; Li, Xiyan; Gong, Xiwen; Yin, Jun; Zhou, Dianli; Sinatra, Lutfan; Huang, Renwu; Liu, Jiakai; Chen, Jie; Dursun, Ibrahim; El-Zohry, Ahmed M.; Saidaminov, Makhsud I.; Sun, Hong-Tao; Mohammed, Omar F.; Ye, Changhui; Sargent, E.; Bakr, Osman(Angewandte Chemie (International ed. in English), Wiley, 2019-09-17)[Article]
Interest has been growing in defects of halide perovskites in view of their intimate connection with key material optoelectronic properties. In perovskite quantum dots (PQDs), the influence of defects is even more apparent than in their bulk counterparts. By combining experiment and theory, we report herein a halide-vacancy-driven, ligand-directed self-assembly process of CsPbBr3 PQDs. With the assistance of oleic acid and didodecyldimethylammonium sulfide, surface-Br-vacancy-rich CsPbBr3 PQDs self-assemble into nanowires (NWs) that are 20-60 nm in width and several millimeters in length. The NWs exhibit a sharp photoluminescence profile (≈18 nm full-width at-half-maximum) that peaks at 525 nm. Our findings provide insight into the defect-correlated dynamics of PQDs and defect-assisted fabrication of perovskite materials and devices.
All-oxide, fully-transparent thin film transistors and rectifiers, processed entirely by atomic layer deposition, have been developed for on-chip capacitive energy storage. Fully depleted thin film transistor (TFT) operation is achieved by optimizing the carrier concentration in the ZnO channels. The TFTs show an average saturation mobility of 10.5 cm2 V−1 s−1, a stable positive turn-on voltage of 0.88 V, a low subthreshold swing of 0.162 V dec−1, and the entire device achieves an overall transmittance of 85%. The field-effect rectifiers (FER) are fabricated based on short-circuiting the gate and drain electrodes of the TFT structure. Rectification ratio of 3.5 × 106 is achieved in DC measurements. Under AC input, the rectifiers can steadily operate at an input frequency up to 10 MHz and amplitude (peak to peak) up to 20 V. The rectifier can be used for signal processing applications with frequency up to 1 MHz. The energy storage utility of the rectifiers is demonstrated by rectifying AC input signals and successfully charging home-made electrochemical on-chip microsupercapacitors. The results demonstrate that integrated, all-oxide thin film rectifiers can be used for on-chip capacitive energy storage.
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