Search

Redox mediators (RMs) have become a significant point in the now-established Li-O2 battery system to reduce the charging overpotential in the oxygen evolution process. Nevertheless, a major inherent barrier of the RM is the redox shuttling between the Li metal anode and mobile RM, resulting in the corrosion of Li and depletion of RM. In this study, taking iodide/triiodide as a model RM, we propose an effective strategy by immersing the Li metal anode in I2 steam to create a 1.5 μm thick surface protective layer. The resultant ionic conductive LiI layer on the Li metal anode can not only suppress Li dendrite growth but also act as a buffer layer between the RM and bare Li. By combining the iodide/triiodide RM with the LiI protective layer, the Li-O2 battery shows low and steady charge voltage plateaus of ∼3.6 V over 70 cycles. Importantly, the symmetrical cell using the LiI-protected Li electrode exhibited small Li plating/stripping overpotentials (∼20 mV, 480 h), far superior to that of the bare Li electrode (∼70 mV, 300 h). The in situ interfacial observation shows that dendrite growth on the Li metal can be effectively suppressed by optimizing the LiI protective layer.

The existence of defects in perovskite films is a major obstacle that prevents perovskite solar cells (PSCs) from high efficiency and long-term stability. A variety of additives have been introduced into perovskite films for reducing the number of defects. Lewis base-based additive engineering has been considered as an effective way to eliminate defects, especially the defects caused by the uncoordinated Pb2+. In this work, for the first time, a bilateral cyano molecule (succinonitrile, SN) which is a commonly used plasticizer in solid electrolyte of solid-state lithium batteries was selected as an additive to modify organic–inorganic hybrid perovskite films in PSCs. SN is featured with two cyano groups (–C≡N) distributing at both terminals of the carbon chain, providing two cross-linking points to interact with perovskites crystals via coordinating with uncoordinated Pb2+ and forming hydrogen bonds with –NH2 groups in perovskite. It was found that the addition of SN into perovskite precursor solution could effectively reduce defects, particularly inhibit the appearance of Pb0 and thus suppress trap-assisted nonradiative charge carrier recombination. As a result, the efficiency of CH3NH3PbI3(Cl) (MAPbI3(Cl))-based PSCs was improved from 18.4% to 20.3% with enhanced long-term stability at N2 and humid air atmosphere. This work provides a facile and effective strategy to enhance the PCE and stability of PSCs simultaneously, facilitating the commercialization of PSCs.

Searching for the highly active and low cost electrocatalysts with fast-charging capability for rechargeable zinc-air batteries are paramount in terms of their commercial-scale application. Here, we propose an innovative cation/anion-codoped nickel nitrides (FC-Ni3N) along with creating 3D architecture by integrating N-doped carbon nanotubes (NCNT), which is found to be an outstanding bifunctional oxygen electrocatalyst for Zn-air batteries with ultrafast charging rate (Potential =2.02V at 50 mA cm−2 with area capacity of 4 mAh cm−2) and long cycling life (700 cycles at 20 mA cm−2). Through varying the cation/anion moiety, the optimal FC-Ni3N/NCNT shows low overpotential of 260 mV at 10 mA cm−2 and Tafel slope of 46 mV dec−1, much outperforming the RuO2 benchmark with overpotential of 337 mV and Tafel slope of 91 mV dec−1. The extraordinary oxygen evolution reaction performance (corresponding to the charge process) stems from the simultaneous regulation of charge- and mass-transport kinetics in air electrodes. The proposed strategy and results may pave the way for promoting commercial application of rechargeable zinc-air batteries or other metal-air batteries.

Electrochemical water splitting is an attractive technique to produce renewable hydrogen gas. However, considerable challenges remain before the catalytic anodic oxygen evolution reaction (OER) can...

A few mode fiber temperature sensor filled with PDMS based on vernier effect is proposed. It uses single mode fiber (SMF), few mode fiber (FMF), and polydimethylsiloxane (PDMS) to form the SMF-air microcavity-FMF-PDMS-FMF structure. It is to slot the glass capillary tube, place the two FMFs in the slot at a suitable distance, and fill the slot with PDMS multiple times and seal it. The PDMS is used as a sensing microcavity. We insert the SMF from the other end of the glass capillary tube, adjust the distance, fix the SMF and seal the connection. Two end faces of the SMF and the first FMF form an air reference microcavity. Since the refractive index of each medium is different, multiple reflective surfaces are formed to reflect. Because the second FMF is infinitely long, whose right end is beveled, it is considered that the sensor has four reflected beams. When the temperature changes, the length and refractive index of the PDMS microcavity will change, which will cause a change in the interference spectrum of the sensor. And because the vernier effect is formed by the superposition of the two microcavities, the temperature sensitivity can be amplified and the temperature can be measured with high sensitivity. The experimental results show that in the range of 40–56°C, the transmission spectrum of the sensor appears red shift with the increase of temperature, and the temperature sensitivity can reach 3.89nm/°C. The sensor is simple to manufacture, has high sensitivity, and has good application prospects.

The defect in structures is the major risk to the structural integrity, thus to perform the defect detections and evaluations efficiently is critical in assuring the structural safety. Magnetic flux leakage testing (MFLT) is an important non-destructive testing (NDT) method. Due to its high testing sensitivity and simple operating procedure, it has been widely used in detecting surface and near-surface defects in ferromagnetic components. To improve the accuracy of defect detection, it is necessary to find a suitable source magnetization distribution around a defect, and furthermore, to correlate the defect with the magnetic leakage signals. In this study, a magnetic charge model is proposed, in which both volume- and surface- densities of magnetic charges around a defect are considered. Then, this model is used for the calculation of the magnetic leakage signals caused by a known complex V-shape defect for the verification purpose. The results from the simulation match very well with that from the experiment. It indicates potentials that the magnetic charge model and the associated approach can be applied in MFLT with improved accuracy.

Solid oxide fuel cells (SOFCs) directly convert chemical energy that is stored in a wide range of fuels into direct current electricity, with high efficiency and low emissions, via a series of electrochemical reactions at elevated operating temperatures (generally 400–1000 °C). During such an energy conversion process, the properties of electrolyte materials determine the working principle and operating temperature of the SOFC. When considering the cost and stability, lowering the operating temperature is critical, and this has become one of the developing trends in SOFC research. The key point for realizing a reduction in operating temperature is to maintain low ohmic resistance of the electrolyte and low polarization resistance of the electrodes. In practice, the mechanical and chemical stability of the electrolyte is also a big concern. According to their differences in ion conduction mechanisms, there are three main types of electrolyte material available, namely, oxygen ion-conducting, proton-conducting, and dual ion-conducting electrolytes. In this review, we give a comprehensive summary of the recent advances in the development of these three types of electrolyte material for intermediate-temperature SOFCs. Both conductivity and stability are emphasized. In conclusion, the current challenges and future development prospects are discussed.

The structure, elastic, electronic and optical properties of two-dimensional (2D) MI2 (M = Pb, Ge, Cd) under strain are systematically studied by the first-principles method. It is proved that the monolayer structure of 2D-MI2 is stable by phonon spectra. Moreover, the large ideal strain strength (40%), the large range of strain and the elastic constants of far smaller than other 2D materials indicate that the single-layer PbI2 and GeI2 possess excellent ductility and flexibility. By applying appropriate strain to the structure of 2D-MI2, the band gaps of single-layer MI2 can be effectively controlled (PbI2: 1.04 ∼ 3.03 eV, GeI2: 0.43 ∼ 2.99 eV and CdI2: 0.54 ∼ 3.36 eV). It is found that the wavelength range of light absorbed by these three metal iodides is 82–621 nm, so 2D-MI2 has great absorption intensity for ultraviolet light in a large wavelength range, and the strain of structure can effectively regulate the optical parameters.

In this study, the oxygen reduction activity of PrBaCo2O5+δ (PBC) double perovskite is remarkably enhanced by rationally tuning the calcination temperatures of the cathode precursor for solid oxide fuel cells (SOFCs). Effects of the calcination temperatures on the phase structure, microstructure, surface area and oxygen reduction reaction (ORR) activity of PBC cathode is systematically investigated. The cathode with optimized calcination temperature (900 °C, PBC-900) shows excellent activity and stability for ORR at 600 °C in terms of area specific resistances (ASRs). A distinctive low ASR of 0.068 Ω cm2 is obtained at 600 °C for PBC-900, which is 92.6%, 34.6% and 15.0% lower than PBC-800, PBC-1000 and PBC-1100, respectively. After operating for 250 h in air at 600 °C, the ASR value of PBC-900 is not significantly reduced. Furthermore, a single cell with PBC-900 cathode delivers attractive peak power density of 1.60 W cm−2 at 600 °C. The present study suggests that the ORR activity of PBC cathode can be greatly boosted by rationally tailoring the calcination temperatures, which may bring new avenue for the design of highly active cathodes for SOFCs.

The solid-state Li-ion battery (SSB) is regarded as one of the most promising next-generation batteries due to its intrinsic safety and high energy density. Unfortunately, its development is plagued by the poor interface compatibility between the electrode and solid-state electrolyte. Herein, flame-retardant trimethyl phosphate (TMP) solvent along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and fuoroethylene carbonate (FEC) additive is utilized as a smart wetting agent to improve the interface compatibility between the Li-metal anode and the Li1.5Al0.5Ge1.5(PO4)(3) (LAGP) solid electrolyte. By taking advantage of such wetting agent, highly stable anodic and cathodic interfaces with improved physical contact and chemical stability are realized. As a result, the solid-state Li/LAGP/Li symmetrical cell with such wetting agent exhibits superior cycling performance over 1000 h with small polarization voltages. When adding such wetting agent to the solid-state Li/LAGP/LiFePO4 battery, we achieved a favorable initial capacity of about 140 mAh g(-1) at 0.5 C and can retain 80% of its initial capacity even after 700 cycles. Additionally, the solid-state Li-air battery with such wetting agent also shows stable cycling performance over 100 h. The strategy demonstrated here will encourage more research works on developing functional and safe wetting agents for solid-state batteries.

Due to the low material cost, simple preparation process, and no pollution to the environment, dye-sensitized solar cells (DSSCs) have become one of the important power conversion devices. The counter electrode (CE, also called cathode), an important part of DSSCs, plays a critical role in the photovoltaic performance of DSSCs. Platinum (Pt) with high electrocatalytic activity is the most commonly used CE material in DSSCs, which suffers from the problems of high price and poor stability, highlighting the importance of developing novel low-cost, active, and stable Pt-free CEs. In this work, a series of A-site deficient (La0.8Sr0.2)1–xFeO3-δ (x = 0, 0.02, 0.05, 0.1) perovskite oxides are designed to serve as CEs in DSSCs. Through investigating the influence of the A-site deficiency on the power conversion efficiency (PCE), it is found that the introduction of an appropriate deficiency in perovskite oxides is beneficial for catalytic activity of triiodide (I3–) reduction reaction (IRR) of the CE, thus improving the photovoltaic performance of DSSCs. Consequently, the (La0.8Sr0.2)0.98FeO3−δ/multiwalled carbon nanotubes (MWCNTs) CE-based device exhibits the highest PCE of 8.22%, while the Pt-based device only yields a PCE of 7.21%. The significantly enhanced efficiency of DSSCs is mainly attributed to the synergistic effect between the high oxygen vacancy concentration and the appropriate amount of Fe4+ as well as reduced particle size, which enhances the charge transfer capability and the I3– diffusion capability simultaneously. Furthermore, the decent IRR durability of (La0.8Sr0.2)0.98FeO3−δ/MWCNTs composites confers the corresponding DSSCs an excellent long-term stability. This work provides a facile way to design active and durable Pt-free perovskite oxide-based CEs in DSSCs, which may lay the foundation for the commercialization of DSSC technology.

Solid oxide fuel cells (SOFCs) based on Ni-based cermet anodes suffer from severe sulfur poisoning when operated on H2S-containing fuels (

Proton-conducting fuel cells (PCFCs) with a perovskite-type proton-conducting electrolyte show many advantages over conventional oxygen-ion-conducting ceramic fuel cells. Both electrode catalytic a...

Solid oxide fuel cells (SOFCs) as one of the clean electrochemical energy conversion devices have acquired increasing attention recently due to the high efficiency, low emission, and excellent fuel...

Although lead-based inorganic–organic perovskite solar cells (PSCs) have delivered the highest power conversion efficiency (PCE) to date of 25.2%, the toxic nature of lead and poor stability are th...

The cycling performance of lithium-sulfur (Li-S) batteries, which is a major parameter determining the practical application of such an advanced high-energy-density battery system (1675 mA h g(-1)), is strongly affected by the properties of the cathodic sulfur hosts. As a desirable sulfur host, it should possess high surface area, good electronic conductivity, and superior physisorption and chemisorption to polysulfides. Here, by taking advantage of the magnesiothermic denitriding technology, the graphitic carbon nitride (GCN) with a tunable nitrogen content, surface area, and pore volume has been designed as a sulfur host for high-performance Li-S batteries. With a nitrogen content of similar to 6%, a surface area of 594 m(2) g(-1), and a pore volume of about 2 cm(3) g(-1), the GCN-based host can retain sulfur and allow its reversible convention within cathodic region, thereby delivering a high capacity of 852.2 mA h g(-1) at 0.5 C with a low capacity decay of 0.12% per cycle within 300 cycles. This work provides a feasible way to design nitrogen-doped carbon materials with tunable nitrogen content and enlightens the host material design for practical Li-S batteries.

Renewable and clean energy supplies are highly critical for the reduction of greenhouse emissions and environmental pollution to realize a sustainable society. Among various techniques for using sustainable energy sources, such as solar energy, photocatalysis plays a crucial role in solving global problems, such as the energy crisis and environmental pollution. Thus, the design and development of Earth-abundant, low-cost, high-performance photocatalysts for water splitting and wastewater treatment are critical. Among these photocatalysts, Ruddlesden–Popper (RP) perovskites have attracted increasing attention in photocatalysis as a result of their unique structural, electronic, and optical characteristics. In this review, the recent advances of RP perovskites in photocatalysis are presented. The review begins with an introduction of the unique features of RP perovskites that are suitable for photocatalysis, which is followed by a discussion of the use of typical RP-type perovskite oxides as photocatalysts by highlighting several useful design strategies. Finally, the conclusions of this review, along with current challenges and future directions for the design of RP perovskites for photocatalysis, are presented and discussed. This review aims to provide helpful guidance for the future development of RP-type perovskite oxides for photocatalysis-based water splitting and wastewater treatment.

Solid-state Li-ion batteries (SSBs) have been regarded as the most promising systems to power electronic devices and electric vehicles because of their high energy density and safety. As the key co...

The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of crucial importance for the rational design of flexible rechargeable Zn‐air batteries (ZABs). Considering their good elasticity, high conductivity, and superior thermal and chemical stability, carbon nanotubes have been widely used as a catalyst support in various electrocatalysts, while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials. Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long‐term operating stability, in particular in flexible devices, pure carbon electrocatalyst is highly appreciated. Herein, a free‐standing air electrode with cobalt nanoparticles encapsulated N‐codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two‐step in situ growth method. Such a carbon‐based electrode shows outstanding activity for both ORR and OER. The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions. Moreover, the polarization and round‐trip efficiency for the flexible battery is 0.67 V and 64.4% at 2 mA/cm2, respectively, even after being operated for 30 hours. This study provides a feasible way to design all carbon‐based free‐standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices.

Perovskite-based oxides have emerged as promising oxygen evolution reaction (OER) electrocatalysts. The performance is closely related to the lattice, electronic, and defect structure of the oxides, which determine surface and bulk properties and consequent catalytic activity and durability. Further, interfacial interactions between phases in a nanocomposite may affect bulk transportation and surface adsorption properties in a similar manner to phase doping except without solubility limits. Herein, we report the development of a single/double perovskite nanohybrid with limited surface self-reconstruction capability as an OER electrocatalyst. Such superior performance arises from a structure that maintains high crystallinity post OER catalysis, in addition to forming an amorphous layer following the self-reconstruction of a single perovskite structure during the OER process. In situ X-ray absorption near edge structure spectroscopy and high-resolution synchrotron-based X-ray diffraction reveal an amorphization process in the hybrid single/double perovskite oxide system that is limited in comparison to single perovskite amorphization, ensuring high catalytic activity.

Although aprotic Li-air batteries offer an attractive option for achieving ultrahigh energy density of electrochemical energy storage devices, the now-established system has so far fallen short of its potential due to a daunting challenge related to its open configuration, which results in not only the rapid corrosion of Li metal anodes but also the gradual evaporation of organic liquid electrolytes. Here, we show that these issues can be well addressed by protecting the Li-air battery with a new O2-permeable silica-aerogel-reinforced polydimethylsiloxane external membrane (OPSP). The highly flexible OPSP basically benefiting from hydrogen-bond cross-linking can be constructed in situ on any substrate with particularly desirable properties such as being water-/electrolyte-proof, O2-permeable, high thermotolerance, and transparent, which allows stable cycling of coin-type and flexible Li-air batteries under harsh conditions, such as a highly volatile DMSO electrolyte (over 660 ​h), a humid air (O2) atmosphere (over 700 ​h) or circumstances in air (O2)-saturated liquid water (over 25 ​h). This work could potentially open a new research direction in developing O2-permeable membranes through hydrogen-bond cross-linking for the unfettered design of metal-air batteries.

Although organic–inorganic halide perovskite solar cells (PSCs) have shown dramatically enhanced power conversion efficiencies (PCEs) in the last decade, their long-term stability is still a critic...

A minor amount of CO2 in air usually causes a detrimental effect on oxygen activation over a solid oxide fuel cell (SOFC) cathode because insulating surface carbonate is easily formed, which inhibi...

The Li-metal anode plays a critical role in meeting the ever-growing demands for high-energy-density batteries. The rational design of an electrolyte to suppress dendrite formation is of great significance for the practical use of a Li-metal anode in rechargeable Li-metal batteries. In this work, by taking advantage of the lithiophilic polyacenequinone polymer filler, a novel polymer-filler-reinforced gel polymer electrolyte with the merits of high mechanical flexibility, high ionic conductivity, and superior dendrite-Li suppressing ability has been developed. When this gel polymer electrolyte is used in Li symmetrical cells, small and stable Li-plating/stripping overpotentials (∼25 mV) can be maintained over 700 hours. When equipped with a high-voltage cathode of LiNi0.6Co0.2Mn0.2O2 (NCM622) for Li-metal batteries, a high coulombic efficiency of about 99% can be retained after 100 repeated cycles. Such superiority is mainly ascribed to the smart lithiophilic carbonyl groups on the polyacenequinone polymer filler, which can guide uniform Li-ion flux at the Li electrode/electrolyte interface to fundamentally suppress Li dendrite growth during cycling. This work paves a way for designing dendrite-suppressed gel polymer electrolytes for Li-metal batteries and related energy conversion and storage devices.

Cost-effective electrocatalysts with high activity and long durability for the oxygen evolution reaction (OER) are key to water splitting and rechargeable metal–air batteries. Here, we report the development of a superior OER electrocatalyst with outstanding activity, favorable durability, and stable particulate morphology based on an ex situ ultra-fast cation exchange strategy that can result in fine tuning of the atom arrangement inside the oxide lattice, thus optimizing the electrocatalytic performance. O3-phase NaCo0.8Fe0.2O2 (O-NCF) is selected as the starting material, and the sodium in the oxide lattice is rapidly exchanged (several minutes) with hydronium ions (H3O+) in an acidic solution. The as-derived structure fine-tuned sample displays excellent OER performances in alkaline media with an ultra-low overpotential of only 234 mV at 10 mA cm−2 in oxide-based electrocatalysts and an ultra-small Tafel slope of 34 mV dec−1. The exchange of H3O+ with Na+ does not affect the oxidation state of cobalt and iron cations inside the oxide lattice, while protons in the inserted H3O+ promote the formation of the hydroxyl group to improve activity. As a general strategy, such cation exchange strategy can also be applied to many other layered sodium transition metal oxides.

Electrocatalysis lies in the center of many clean energy conversion and storage technologies. Developing efficient electrocatalysts to promote the kinetics of the key chemical reactions involved in these processes represents an important research topic. Ruddlesden–Popper perovskites (An+1BnX3n+1), as a layered derivative of the perovskite family (ABX3), are an important class of solid-state materials, and are emerging as high-performing electrocatalysts due to their unique layered structure and rich chemical compositions. In this review, we provide a comprehensive understanding of the structure and properties of Ruddlesden–Popper perovskites in the context of their electrocatalysis applications. We also summarize the recent developments of Ruddlesden–Popper perovskites for catalyzing a breadth of electrochemical reactions at both low and high temperatures. We highlight how Ruddlesden–Popper perovskites can be tailored through a range of design strategies to achieve improved electrocatalysis. Finally, we provide perspectives on future research directions that further expand the electrocatalytic possibilities of Ruddlesden–Popper perovskites.

Double perovskites have emerged as efficient candidates for catalyzing the electrochemical oxygen evolution reaction (OER). Smart control of the composition of a B-site ordered double perovskite can lead to improved catalytic performance. By adopting a facile co-doping strategy, the OER-active elements are simultaneously introduced into the B-site and B'-site of a B-site-ordered double perovskite (A2 BB'O6 ), leading to an enhancement of the exposed reactive sites and an optimum surface chemical state. As a result, a model system built from the substitution of Co for Mo and Fe in the Sr2 FeMoO6-δ double perovskite (with a composition of Sr2 Fe0.8 Co0.2 Mo0.6 Co0.4 O6-δ ) shows significantly enhanced OER activity in alkaline media compared with the host material, requiring an overpotential of 345 mV to reach a 10 mA cm-2 current density (catalyst loading≈0.232 mgcat cm-2 GEO ) and a cell voltage of 1.57 V to afford the same current density for the overall water splitting when coupled with a Pt/C cathode (catalyst loading≈2 mg cm-2 ). It also demonstrates excellent electrochemical stability. The generalizability of the compositional control methodology has also been demonstrated in double perovskites incorporating transition metals other than Co (e.g., Ni).

Here a new strategy is unveiled to develop superior cathodes for protonic ceramic fuel cells (PCFCs) by the formation of Ruddlesden-Popper (RP)-single perovskite (SP) nanocomposites. Materials with the nominal compositions of LaSrx Co1.5 Fe1.5 O10-δ (LSCFx, x = 2.0, 2.5, 2.6, 2.7, 2.8, and 3.0) are designed specifically. RP-SP nanocomposites (x = 2.5, 2.6, 2.7, and 2.8), SP oxide (x = 2.0), and RP oxide (x = 3.0) are obtained through a facile one-pot synthesis. A synergy is created between RP and SP in the nanocomposites, resulting in more favorable oxygen reduction activity compared to pure RP and SP oxides. More importantly, such synergy effectively enhances the proton conductivity of nanocomposites, consequently significantly improving the cathodic performance of PCFCs. Specifically, the area-specific resistance of LSCF2.7 is only 40% of LSCF2.0 on BaZr0.1 Ce0.7 Y0.2 O3-δ (BZCY172) electrolyte at 600 °C. Additionally, such synergy brings about a reduced thermal expansion coefficient of the nanocomposite, making it better compatible with BZCY172 electrolyte. Therefore, an anode-supported PCFC with LSCF2.7 cathode and BZCY172 electrolyte brings an attractive peak power output of 391 mW cm-2 and excellent durability at 600 °C.

Utilizing the 1-3 piezoelectric composite and double-layer matching structure, the study discusses the research of piezoelectric air-coupled transducer from multi-layer parallel structure. The multi-layer parallel structure owns the benefits of better electrical impedance and larger piezoelectric strain constant and the experimental outcomes verify that it is effective to perfect the performance of piezoelectric air-coupled transducer. According to above research, this paper also presents a seven-element auto-focused air-coupled transducer. In the end, the internal defects of honeycomb composite are measured utilizing the seven-element auto-focused air-coupled transducer under pitch-catch mode.

Single-phase perovskite oxides that contain nonprecious metals have long been pursued as candidates for catalyzing the oxygen evolution reaction, but their catalytic activity cannot meet the requirements for practical electrochemical energy conversion technologies. Here a cation deficiency-promoted phase separation strategy to design perovskite-based composites with significantly enhanced water oxidation kinetics compared to single-phase counterparts is reported. These composites, self-assembled from perovskite precursors, comprise strongly interacting perovskite and related phases, whose structure, composition, and concentration can be accurately controlled by tailoring the stoichiometry of the precursors. The composite catalyst with optimized phase composition and concentration outperforms known perovskite oxide systems and state-of-the-art catalysts by 1-3 orders of magnitude. It is further demonstrated that the strong interfacial interaction of the composite catalysts plays a key role in promoting oxygen ionic transport to boost the lattice-oxygen participated water oxidation. These results suggest a simple and viable approach to developing high-performance, perovskite-based composite catalysts for electrochemical energy conversion.

We studied the photocatalytic reaction of methanol on the TiO2(110) surface in situ by surface sum frequency generation vibrational spectroscopy. The in situ vibrational spectra of the photo-oxidat...

With the synthesis of single-layer lead iodide (PbI2) in the laboratory in recent years, it has been widely used due to its stable structure and suitable bandgap (2.5 eV). We carried out first-prin...

Lithium–sulfur (Li–S) batteries are of great interest due to their high theoretical energy density and potentially low cost. However, two of the key issues hindering their commercialization are the polysulfide shuttling and Li-dendrite growth, which result in severe capacity decay and serious safety hazards. Herein, liquid-phase delaminated birnessite (HxMnO2+x) nanosheets along with graphene and carbon nanotubes are utilized for the first time to create an “electronegative” coating layer for Li–S batteries to suppress the polysulfide shuttling and Li-dendrite growth. The as-prepared coating layer enables stable cycling of the Li–S battery with a low capacity decay rate of 0.04% per cycle over 1000 cycles at 1C. In addition, a Li-symmetrical cell with the coating layer shows suppressed dendrite growth even after being cycled over 1000 hours at 1 mA cm−2. This excellent performance is ascribed, in part, to the synergistic effect of the chemical and electrostatic interactions among polysulfides, Li ions, and [MnO2+x]x− ions, resulting in a homogeneous Li-ion flux distribution and a mitigated polysulfide shuttling. The proposed concept of an “electronegative” bifunctional coating layer illustrates a simple and effective way to develop highly stable and safe Li–S batteries.

Cost-effective and spectrally selective solar absorbers that possess high solar absorptance, low thermal emittance, and superior thermal stability are essential for photothermal conversion applications, e.g., industrial heating, solar desalination, photothermal catalysis, and concentrating solar power systems. Here, a new strategy using a selective leaching reaction is demonstrated for transfiguring the broad-spectrum and highly reflective aluminum alloys into plasmonic-nanostructure selective solar absorbers (PNSSAs). Enabled by surface plasmon resonance, this strategy via assembling copper nanostructured thin film on an alloy mirror yields tunable manipulation of the spectral selectivity, high and omnidirectional solar absorptance (0.94 from 0 to 60°), low thermal emittance (0.03 at 100 °C), and excellent thermomechanical stability. Featured with merits of competitive performance of spectral selectivity, the feasibility of solution-processed fabrication, and cost-effectiveness of raw materials and chemicals, selective-leaching-alloy to achieve PNSSAs is a promising and universal approach for achieving high photothermal efficiency (85%) of solar thermal energy harvesting. The compatibility of this strategy with other metal alloys, such as steel and superalloys, extends its applications to fabricating mid- and high-temperature selective solar absorbers.

The photocatalytic hydrogen (H2) generation relies heavily on the properties of photocatalysts, including their light absorption, charge transport, and oxygen vacancy of photocatalysts. In this work, we have successfully synthesized Ruddlesden-Popper (RP) perovskite Sr2TiO4 as photocatalysts for H2 evolution reaction (HER). Importantly, we adopted a facile and effective strategy of Ag doping and reducing pretreatment to tailor the properties of Sr2TiO4 photocatalysts. The synergistic effect of Ag doping and moderate reducing pretreatment confers Sr2TiO4 photocatalyst with improved morphological characteristics, increased specific surface area, optimized light absorption capability and band gap, suppressed charge carrier recombination as well as increased amount of surface oxygen vacancies. Benefiting from these merits, r-Ag0.05Sr1.95TiO4 with suitable amount of Ag doping and moderate reducing pretreatment displays an excellent photocatalytic performance for H2 generation, which presents average hydrogen production rates of 1695 μmol h-1 g-1 and 541 μmol h-1 g-1 under full range light irradiation (λ ≥ 250 nm) and visible light irradiation (λ ≥ 400 nm), respectively.

Perovskite oxides have been extensively investigated as catalysts for solar water splitting to generate hydrogen (H2) due to the easily tuned band gap, distinct optical/chemical properties and superior structural/compositional flexibility. Cation doping is widely used to boost the photocatalytic activity of perovskite oxides while the anion doping into the oxygen (O)-site of perovskite oxides is less investigated. Herein, we present a non-metal fluorine (F-) doping strategy to improve the photocatalytic activity of Ruddlesden-Popper Sr2TiO4 perovskites for H2 evolution reaction (HER). By optimizing the F- doping amount in Sr2TiO4-xFx, the highest H2 generation rate of 282 μmol h-1 g-1 is achieved by Sr2TiO3.97F0.03 under full-range sunlight illumination (λ ≥ 250 nm), which is 44% larger than that of Sr2TiO4 (195 μmol h-1 g-1). Such enhancement in the photocatalytic HER activity of Sr2TiO3.97F0.03 can be assigned to the increased surface oxygen vacancy amount, suppressed charge carrier recombination, more negative conduction band position as well as well-balanced band gap energy, particle size and specific surface area induced by the F- doping. Our current study presents a facile and effective strategy for the future design of highly efficient catalysts for solar water splitting.

Recently, laser ablation assisted spark induced breakdown spectroscopy (LA-SIBS) has been growing rapidly and continue to be extended to a broad range of materials analysis. Characterized by employing a specifically designed high voltage and pulse discharge circuit to generate a spark and used to enhance plasma emission produced by laser ablation, allows direct analysis of materials without prior sample preparation. This paper reviews recent development and application of laser ablation assisted spark induced breakdown spectroscopy for material analysis. Following a summary of fundamentals and instrumentation of the LA-SIBS analytical technique, the development and applications of laser ablation assisted spark induced breakdown spectroscopy for the analysis of conducting materials and insulating materials is described.

Spinel and perovskite with distinctive crystal structures are two of the most popular material families in electrocatalysis, which, however, usually show poor conductivity, causing a negative effect on the charge transfer process during electrochemical reactions. Herein, a highly conductive inverse spinel (Fe3 O4 ) and anti-perovskite (Ni3 FeN) hetero-structured nanocomposite is reported as a superior oxygen evolution electrocatalyst, which can be facilely prepared based on a one-pot synthesis strategy. Thanks to the strong hybridization between Ni/Fe 3d and N 2p orbitals, the Ni3 FeN is easily transformed into NiFe (oxy)hydroxide as the real active species during the oxygen evolution reaction (OER) process, while the Fe3 O4 component with low O-p band center relative to Fermi level is structurally stable. As a result, both high surface reactivity and bulk electronic transport ability are reached. By directly growing Fe3 O4 /Ni3 FeN heterostructure on freestanding carbon fiber paper and testing based on the three-electrode configuration, it requires only 160 mV overpotential to deliver a current density of 30 mA cm-2 for OER. Also, negligible performance decay is observed within a prolonged test period of 100 h. This work sheds light on the rational design of novel heterostructure materials for electrocatalysis.

One challenge for the commercial development of solid oxide fuel cells as efficient energy-conversion devices is thermo-mechanical instability. Large internal-strain gradients caused by the mismatch in thermal expansion behaviour between different fuel cell components are the main cause of this instability, which can lead to cell degradation, delamination or fracture1-4. Here we demonstrate an approach to realizing full thermo-mechanical compatibility between the cathode and other cell components by introducing a thermal-expansion offset. We use reactive sintering to combine a cobalt-based perovskite with high electrochemical activity and large thermal-expansion coefficient with a negative-thermal-expansion material, thus forming a composite electrode with a thermal-expansion behaviour that is well matched to that of the electrolyte. A new interphase is formed because of the limited reaction between the two materials in the composite during the calcination process, which also creates A-site deficiencies in the perovskite. As a result, the composite shows both high activity and excellent stability. The introduction of reactive negative-thermal-expansion components may provide a general strategy for the development of fully compatible and highly active electrodes for solid oxide fuel cells.

Direct ammonia solid oxide fuel cell (DA-SOFC) is superior to low-temperature direct ammonia fuel cell using anion exchange membrane because of much improved anode reaction kinetics at elevated temperature. However, significant performance degradation due to severe sintering of conventional nickel cermet anode under operating conditions is a big challenge for realizing its practical use. Herein, a high-performance anode based on LaSrTiO (LST) perovskite substrate with its surface decorated with in situ exsolved and strongly coupled NiCo alloy nanoparticles (NPs) is designed and fabricated for DA-SOFCs, exhibiting superior catalytic activity for NH decomposition reaction due to balanced NH adsorption and N desorption processes. An electrolyte-supported single cell with infiltrated NiCo/LST on SmCeO scaffold anode delivers a maximum power density of 361 mW cm at 800 °C in NH fuel, superior to similar SOFCs with Ni or Co NP-decorated LST based anodes (161 and 98 mW cm). Furthermore, the SOFC with this newly developed anode displays favorable operational stability without obvious performance degradation at 700 °C for a test period of ≈120 h, attributed to its high antisintering capability. This study provides some strategies to develop highly active, stable, and antisintering perovskite-based nanocomposite for DA-SOFCs, facilitating the practical use of this technology.

Lithium-sulfur batteries have attracted a lot of attention in the recent years. However, the electrochemical performance of lithium-sulfur batteries is greatly affected owing to several issues. In this paper, we designed a polyaniline@spherical ordered mesoporous carbon/sulfur nanocomposite (PANI@S-OMC/S), and S-OMC/S was wrapped by PANI via in-situ polymerization. The inherently conducting nature of PANI increased conductivity of PANI@S-OMC/S electrode to improve the free transfer of electrons, and PANI shell also provided a barrier between the lithium polysulfides and electrolyte to further prevent the occurrence of the “shuttle effect”. Moreover, mesoporous pores are wonderful hosts to contain sulfur to trap the long-chain lithium polysulfides and prevent them from dissolving in electrolyte. A high initial discharge capacity of 1626 mAh/g was achieved for the PANI@S-OMC/S electrode in first cycle at 0.1 C, and the composite maintains 1338 mAh/g after 100 cycles while the coulombic efficiency still remains ∼98%.

In this work, microwave (MW) irradiation was used to activate Co/Al2O3, Mo/Al2O3, and Co–Mo/Al2O3 catalysts for dry reforming of methane (DRM) reactions. Experimental results indicate that single metallic catalysts of either Co or Mo are inactive for DRM under all the tested conditions due to their limited MW-absorbing ability. In contrast, Co–Mo bimetallic catalysts supported by Al2O3 exhibit high catalytic activity due to the formation of a magnetodielectric Co0.82Mo0.18 alloy, which plays the dual role of a good MW acceptor and the provider of active centers for the DRM reaction. The MW power level required to activate such bimetallic catalysts for DRM is significantly dependent on the molar ratio between Co and Mo. The CoMo2 catalyst (with a molar ratio of 2.0 Co to 1.0 Mo) supported on Al2O3 exhibits the best catalytic performance, converting 80% CH4 and 93% CO2 to syngas at a ratio of H2/CO of 0.80 at the total volumetric hourly space velocity (VHSV) of 10 L g−1 h−1 and MW power of 200 W. As compared to the reported C-based catalysts, the Co–Mo/Al2O3 catalyst delivers more favorable stability over 16 time-on-stream (TOS) by virtue of its intrinsic ability to absorb MW without the inclusion of auxiliary MW acceptors.

Inorganic lead (Pb)-free Cs2AgBiBr6 double perovskite is one of the most promising light absorbers in perovskite solar cells (PSCs) to solve the instability and Pb toxicity problems of organic–inorganic perovskites. However, the intrinsic and extrinsic defects of Cs2AgBiBr6 films strongly limit the power conversion efficiencies (PCEs) of Cs2AgBiBr6-based PSCs. Herein, the first investigation of additive engineering in Cs2AgBiBr6-based PSCs is reported to achieve an outstanding efficiency. The introduction of guanidinium thiocyanate (GuaSCN) additive effectively controls the nucleation of Cs2AgBiBr6 crystals during the film formation process, improves the perovskite film quality, suppresses the charge carrier recombination, and accelerates the charge extraction simultaneously. Consequently, after optimizing the GuaSCN amount, the device shows a stable PCE of 3.02% under maximum power point tracking (MPPT) condition. Furthermore, the introduction of GuaSCN additive remarkably improves the ambient stability of the devices. This work provides insights on additive engineering for enhancing the efficiency and stability of inorganic Pb-free Cs2AgBiBr6-based PSCs toward future industrialization of this technology.

Both the film quality and the electronic properties of halide perovskites have significant influences on the photovoltaic performance of perovskite solar cells (PSCs) because both of them are closely related to the charge carrier transportation, separation, and recombination processes in PSCs. In this work, an additive engineering strategy using antimony acetate (Sb(Ac)3 ) is employed to enhance the photovoltaic performance of methylammonium lead iodide (MAPbI3 )-based PSCs by improving the film quality and optimizing the photoelectronic properties of halide perovskites. It is found that Ac- and Sb3+ of Sb(Ac)3 play different roles and their synergistic effect contributed to the eventual excellent photovoltaic performance of MAPbI3 -based PSCs with a power conversion efficiency of above 21%. The Ac- anions act as a crystal growth controller and are more involved in the improvement of perovskite film morphology. By comparison, Sb3+ cations are more involved in the optimization of the electronic structure of perovskites to tailor the energy levels of the perovskite film. Furthermore, with the assistance of Sb(Ac)3 , MAPbI3 -based PSCs deliver much improved moisture, air, and thermal stability. This work can provide scientific insights on the additive engineering for improving the efficiency and long-term stability of MAPbI3 -based PSCs, facilitating the further development of perovskite-based optoelectronics.

In this paper, a few mode fiber temperature sensor based on vernier effect is proposed. The sensor consists of two cascaded microcavities and realizes temperature sensing based on vernier effect. The single mode fiber(SMF) and few mode fiber(FMF) are fixed by a capillary glass tube to form an air reference microcavity. The end of the FMF is dipped with an appropriate amount of polydimethylsiloxane(PDMS) to form a sensing microcavity with a certain thickness, which is an air microcavity-FMF–PDMS structure. Due to the different refractive index of each medium, the light is reflected on the four critical surfaces, and the four reflected light beams interfere, the vernier effect is formed by adjusting the microcavity length to a suitable length. When the external temperature changes, the microcavity length and refractive index of PDMS change, which leads to the change of interference spectrum. Therefore, the high sensitivity measurement of temperature can be realized by the change of reflection spectrum. The temperature characteristics of the sensor are studied experimentally. The results show that the temperature sensitivity is significantly improved compared with the traditional single microcavity sensor. In the temperature range of 35°C ∼ 45°C, the temperature sensitivity can reach 4.7nm/°C, and the linearity is very good. The sensor has the advantages of compact structure, simple fabrication and high sensitivity, so it has wide application prospects in the field of temperature sensing.

Constructing porous silicon is one of the effective ways to ease the volume change (~320%) of the silicon-based anode. Thus, the design and construction of the porous structure of silicon by the particle size of Mg, the reaction temperature, ramp rate, and time of magnesiothermic reduction (MR) have achieved increasing attention. Here, a controllable self-assembled mesoporous diatomite-derived silicon nanocrystals framework (MRHDE-Si) can be adjusted directly by employing sodium chloride (NaCl) as a “liquid” interface via a MR method. As the proportion of Mg powder and NaCl increases from 1:0 to 1:10, the pore morphology level of MRHDE-Si changes from open-pore morphology to closed pore and tends to be more regular and affects the electrochemical performance of the electrode. Among as-prepared electrodes, the MRHDE-Si-5 electrode exhibits the optimal cycle performance that shows the specific capacity remains as high as 1290.9 mAh g-1 after 50 cycles at a current density of 200 mA g–1. Due to its smallest particle size of 23 nm, a suitable pore structure, pore volume (0.69 cm−3 g−1), the most feasible pore size (12.64 nm), which can provide abundant ion channels and charge transfer channels, shorten the diffusion path of Li+, enhance charge transfer capability, and effectively adapt to the stress caused by the volume expansion of Si as a buffering region. This “liquid” interface self-assembled strategy provides a simple and easy-to-operate way to design and prepare controllable porous silicon composite materials for applications in the field of new energy.