Synergistic Effect of Fe Single-Atom Catalyst for Highly Efficient Microwave-Stimulated Remediation of Chloramphenicol-Contaminated Soil.

Chloramphenicol (CAP) has long been used extensively in agriculture and is severely toxic to the biological environment. Microwave catalysis appears a promising method for soil remediation due to its fast and effective heat transfer, but it is challenging to prepare catalysts with good electromagnetic wave absorption and robust catalytic activity. In this study, atomically dispersed Fe on three-dimensional N-doped carbon supports (3D Fe-NC) is firstly used for microwave remediation of soil. Thanks to the synergistic effect of microwave "hot spots" and reactive oxygen species (•OH, •O2 - ), 3D Fe-NC can completely remove 99.9% of CAP in 5 min. The removal rate constant is nearly twice that of commercial activated carbon. Significantly, the germination rate of lettuce seeds in microwave-repaired soil contaminated by CAP reaches 70%. This work demonstrates the application of Fe single-atom catalyst in microwave remediation of contaminated soil, providing a novel insight for agricultural soil remediation.

Divalent Oxidation State Ni as an Active Intermediate in Prussian Blue Analogues for Electrocatalytic Urea Oxidation.

Urea degradation is one of the most crucial links in the natural nitrogen cycle. Exploring the real active species in the urea electro-oxidation process is of great significance for understanding the urea electro-oxidation mechanism and designing catalysts. A highly active and stable Prussian blue analogue catalyst (PBA@NiFe/NF) loaded on nickel foam was synthesized for electro-oxidation of urea. In situ Raman spectra revealed that Ni in PBA@NiFe/NF was able to maintain a stable divalent nickel (Ni(II)) state for up to 3.5 h during the initial urea oxidation process, which is rarely reported in previous research studies. In addition, with the participation of iron, the Ni-Fe bimetallic center significantly improves the electro-oxidation of urea. Our work provides a new idea for prolonging the Ni(II) activity in electrocatalytic oxidation of urea.

Ion-in-Conjugation: A Promising Concept for Multifunctional Organic Semiconductors.

Most organic semiconductors (OSCs) consist of conjugated skeletons with flexible peripheral chains. Their weak intermolecular interactions from dispersion and induction forces result in environmental susceptibilities and are unsuitable for many multifunctional applications where direct exposure to external environments is unavoidable, such as gas absorption, chemical sensing, and catalysis. To exploit the advantages of inorganic semiconductors in OSCs, ion-in-conjugation (IIC) materials are proposed. An IIC material refers to any conjugated material (molecules, polymers, and crystals) in Kekule's structural formula containing stoichiometric ionic states in its conjugated backbone in the electronic ground state. In this review, the definitions, structures, synthesis, properties, and applications of IIC materials are described briefly. Four types of IIC material, including zwitterionic conjugated molecules/polymers, conjugated ionic dyes, π-d conjugated molecules and polymers, and coordinatively doped polymers, are reported. Their applications in gas sensing, humidity sensing, resistive memory devices, and thermal/photo-/electro-catalysis are demonstrated. The challenges and opportunities for future research are also discussed. It is expected that this work will inspire the design of new organic electronic information materials.

Construction of Perylene-based Amphiphilic Micelle and Its Efficient Adsorption and In Situ Photodegradation of Bisphenol A in Aqueous Solution.

Low mass-transfer efficiency and reaction-driving force make it difficult to realize thorough purification in traditional low-concentration pollutant treatments. Herein, we propose an "adsorption/catalysis in situ" perylene based bifunctional micelle for efficient, accurate and rapid adsorption and catalytic degradation of low-concentration bisphenol A (BPA). They show super-fast (within 10 s), high capacity (448 mg g-1 ) and selectivity for BPA adsorption, due to π-π, hydrophobic interactions and hydrogen bonding. The BPA degradation efficiency improves by up to 8 times after forming micelles compared with simple perylene nanorods, which is primarily due to the superior mass-transfer from adsorption. Moreover, self-assembly can optimize the stacking of the perylene moieties and facilitate charge transfer in micelle, and the regular π-π stacking of inside perylene units enhances the response to visible light, resulting in high catalytic capacity and good cycling stability.

SuFEx-Enabled Elastic Polysulfates for Efficient Removal of Radioactive Iodomethane and Polar Aprotic Organics through Weak Intermolecular Forces.

Capturing radioactive iodomethane and its vapors is a major challenge due to its low adsorption capacity. Herein, we have developed for the first time a pyridine-entrapped elastic crosslinked polysulfate gel (pyridine/TPC-cPS) as an efficient absorbent for iodomethane capture. Each pyridine-encased TPC-cPS network cell acts as a mini-reactor for salt formation between pyridine and iodomethane. The yield reaches up to 96.65 % and traps saturated iodomethane vapor of 1.573 g gpyridine/TPC-cPS -1 (equivalent to 18.103 g gTPC-cPS -1 ), which is the highest capacity reported to date. Both experiments and molecular dynamics simulations reveal that the unusual adsorption of polysulfate for polar aprotic organics can be attributed to the fact that the electrostatic interactions between the polar group (O=S=O) in the polymer backbone and the polar groups in the organic molecules fixed the solvent in the polymer matrix, while the van der Waals forces between the nonpolar groups in the polymer and molecules induced swelling.

Boosted Inner Surface Charge Transfer in Perovskite Nanodots@Mesoporous Titania Frameworks for Efficient and Selective Photocatalytic CO2 Reduction to Methane.

Exploring high-efficiency and stable halide perovskite-based photocatalysts for the selective reduction of CO2 to methane is a challenge because of the intrinsic photo- and chemical instability of halide perovskites. In this study, halide perovskites (Cs3 Bi2 Br9 and Cs2 AgBiBr6 ) were grown in situ in mesoporous TiO2 frameworks for an efficient CO2 reduction. Benchmarked CH4 production rates of 32.9 and 24.2 µmol g-1 h-1 with selectivities of 88.7 % and 84.2 %, were achieved, respectively, which are better than most reported halide perovskite photocatalysts. Focused ion-beam sliced-imaging techniques were used to directly image the hyperdispersed perovskite nanodots confined in mesopores with tunable sizes ranging from 3.8 to 9.9 nm. In situ X-ray photoelectronic spectroscopy and Kelvin probe force microscopy showed that the built-in electric field between the perovskite nanodots and mesoporous titania channels efficiently promoted photo-induced charge transfer. Density functional theory calculations indicate that the high methane selectivity was attributed to the Bi-adsorption-mediated hydrogenation of *CO to *HCO that dominates CO desorption.

Pt/MnO2 Nanoflowers Anchored to Boron Nitride Aerogels for Highly Efficient Enrichment and Catalytic Oxidation of Formaldehyde at Room Temperature.

The catalytic room temperature oxidation of formaldehyde (HCHO) is widely considered as a viable method for the abatement of indoor toxic HCHO pollution. Herein, Pt/MnO2 nanoflowers anchored to boron nitride aerogels (Pt/MnO2 -BN) were fabricated for the catalytic room temperature oxidation of HCHO. The three-dimensional Pt/MnO2 -BN aerogels demonstrated superior catalytic activity as a result of the improved diffusion of the reactant molecules within the porous structure. Furthermore, the porous aerogels displayed excellent HCHO adsorption capacities, which promote a rapid HCHO gas-phase concentration reduction and a subsequent complete oxidation of the adsorbed HCHO. The combined adsorption and oxidation properties of the Pt/MnO2 -BN aerogels enhance the oxidative removal of HCHO. The optimized Pt/MnO2 -BN demonstrated excellent catalytic activity toward HCHO (200 ppm) at room temperature, achieving a 96 % formaldehyde conversion after 50 min.

An Ion-In-Conjugation-Boosted Organic Semiconductor Gas Sensor Operating at High Temperature and Immune to Moisture.

Organic electrical gas sensors have been developed for many decades because of their high sensitivity and selectivity. However, their industrialization is severely hindered by their intrinsic humidity susceptibility and poor recovery. Conventional organic sensory materials can only operate at room temperature owing to their weak intermolecular interactions. Herein, we demonstrate using a croconate polymer (poly-4,4'-biphenylcroconate) that the "ion-in-conjugation" concept enables organic gas sensors to operate at 100 °C and 70 % relative humidity with almost complete recovery. The fabricated sensor had a parts-per-billion (ppb) detection limit for NO2 and showed the highest sensitivity (2526 ppm-1 at 40 ppb) of all reported NO2 chemiresistive sensors. Furthermore, charge transfer increased with temperature. Theoretical calculations and in situ FTIR spectra confirmed the ion-in-conjugation-inspired hydrogen bond as key for excellent sensitivity. A NO2 alarm system was assembled to demonstrate the feasibility of this sensor.

Built-in Electric Field Triggered Interfacial Accumulation Effect for Efficient Nitrate Removal at Ultra-Low Concentration and Electroreduction to Ammonia.

A built-in electric field in electrocatalyst can significantly accumulate higher concentration of NO3 - ions near electrocatalyst surface region, thus facilitating mass transfer for efficient nitrate removal at ultra-low concentration and electroreduction reaction (NO3 RR). A model electrocatalyst is created by stacking CuCl (111) and rutile TiO2 (110) layers together, in which a built-in electric field induced from the electron transfer from TiO2 to CuCl (CuCl_BEF) is successfully formed . This built-in electric field effectively triggers interfacial accumulation of NO3 - ions around the electrocatalyst. The electric field also raises the energy of key reaction intermediate *NO to lower the energy barrier of the rate determining step. A NH3 product selectivity of 98.6 %, a low NO2 - production of <0.6 %, and mass-specific ammonia production rate of 64.4 h-1 is achieved, which are all the best among studies reported at 100 mg L-1 of nitrate concentration to date.

Nanocage-Shaped Co3- x Zrx O4 Solid-Solution Supports Loaded with Pt Nanoparticles as Effective Catalysts for the Enhancement of Toluene Oxidation.

Nanocage-shaped Co3- x Zrx O4 solid-solution supports and the corresponding platinum loaded nanocomposites, yPt/Co3- x Zrx O4 (x =0.27, 0.50, 0.69; y = 0.5, 1.0, 2.0 wt.%), are successfully fabricated via a Cu2 O nanocube hard template method and a glycol reduction method, respectively. The hollow nanocage structures obviously improve surface areas; moreover, the Zr doping forms the Co3- x Zrx O4 solid-solution supports, and the corresponding yPt/Co3- x Zrx O4 catalysts promote the enhancement of catalytic performance. Catalytic activity toward toluene combustion is enhanced for the 2.0 wt% Pt/Co2.73 Zr0.27 O4 catalyst. The catalysts are characterized using multiple techniques. Pt nanoparticles are uniformly dispersed across the Co2.73 Zr0.27 O4 nanocage surface. The 2.0 wt% Pt/Co2.73 Zr0.27 O4 catalyst exhibits the highest catalytic activity among all the samples and demonstrates good stability, with 90% toluene conversion obtained at a temperature of 165 °C. The same catalyst accomplishes full toluene oxidation at 180 °C, at a weight hourly space velocity of 36 000 mL h-1 g-1 . The apparent activation energy (Ea ) over the yPt/Co2.73 Zr0.27 O4 samples are significantly lower than those over the Co3- x Zrx O4 supports, with the 2.0 wt% Pt/Co2.73 Zr0.27 O4 catalyst exhibiting the lowest Ea value. These findings demonstrate the potential of the 2.0 wt% Pt/Co2.73 Zr0.27 O4 catalyst as a promising catalyst toward atmospheric toluene removal.

Surface Engineering of g-C3 N4 by Stacked BiOBr Sheets Rich in Oxygen Vacancies for Boosting Photocatalytic Performance.

BiOBr containing surface oxygen vacancies (OVs) was prepared by a simple solvothermal method and combined with graphitic carbon nitride (g-C3 N4 ) to construct a heterojunction for photocatalytic oxidation of nitric oxide (NO) and reduction of carbon dioxide (CO2 ). The formation of the heterojunction enhanced the transfer and separation efficiency of photogenerated carriers. Furthermore, the surface OVs sufficiently exposed catalytically active sites, and enabled capture of photoexcited electrons at the surface of the catalyst. Internal recombination of photogenerated charges was also limited, which contributed to generation of more active oxygen for NO oxidation. Heterojunction and OVs worked together to form a spatial conductive network framework, which achieved 63 % NO removal, 96 % selectivity for carbonaceous products (that is, CO and CH4 ). The stability of the catalyst was confirmed by cycling experiments and X-ray diffraction and transmission electron microscopy after NO removal.

Construction of Hierarchical Hollow Co9 S8 /ZnIn2 S4 Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation.

Visible-light-responsive hierarchical Co9 S8 /ZnIn2 S4 tubular heterostructures are fabricated by growing 2D ZnIn2 S4 nanosheets on 1D hollow Co9 S8 nanotubes. This design combines two photoresponsive sulfide semiconductors in a stable heterojunction with a hierarchical hollow tubular structure, improving visible-light absorption, yielding a large surface area, exposing sufficient catalytically active sites, and promoting the separation and migration of photogenerated charges. The hierarchical nanotubes exhibit excellent photocatalytic H2 evolution and CrVI reduction efficiency. Under visible-light illumination, the optimized Co9 S8 /ZnIn2 S4 heterostructure provides a remarkable H2 generation rate of 9039 µmol h-1 g-1 without the use of any co-catalysts and CrVI is completely reduced in 45 min. The Co9 S8 /ZnIn2 S4 heterostructure is stable after multiple photocatalytic cycles.

3D Gold-Modified Cerium and Cobalt Oxide Catalyst on a Graphene Aerogel for Highly Efficient Catalytic Formaldehyde Oxidation.

A hard template method is used to prepare porous gold-doped cerium and cobalt oxide (Au-Cex Coy ) materials. A series of 3D Au-Ce x Coy /graphene aerogel (GA) composites is then fabricated by a facile heating method. The obtained catalysts possess a well-defined structure of ordered arrays of nanotubes and good performance in formaldehyde (HCHO) oxidation. The composition and surface elemental valence states of the catalysts are modulated by the Ce/Co molar ratio. The Au-Cex Coy catalyst and graphene oxide sheets are well compounded within 60 s through a diamine cross-linker to form 3D Au-Cex Coy /GA composites. In addition, the resulting catalyst of 3 wt% Au-Ce3 Co/GA achieves ≈55% conversion at room temperature and 100% conversion when the reaction temperature is raised at 60 °C. The synergistic effect between CeO2 and Co3 O4 promotes the migration of oxygen species and the activation of Au, which facilitates HCHO oxidation. The method used to prepare the 3D catalyst could be used to produce other catalytic materials with good replication of the template. In addition, these findings provide a simple method for rapid fabrication of catalyst/GA composites. The superior activity and stability of the 3D Au-Ce3 Co/GA catalyst make it potentially applicable in HCHO removal.

ZIF-67-Derived 3D Hollow Mesoporous Crystalline Co3 O4 Wrapped by 2D g-C3 N4 Nanosheets for Photocatalytic Removal of Nitric Oxide.

ZIF-67-derived 3D hollow mesoporous crystalline Co3 O4 wrapped by 2D graphitic carbon nitride (g-C3 N4 ) nanosheets are prepared by low temperature annealing, and are used for the photocatalytic oxidation of nitric oxide (NO) at a concentration of 600 ppb. The p-n heterojunction between Co3 O4 and g-C3 N4 forms a spatial conductive network frame and results in a broad visible light response range. The hollow mesoporous structure of Co3 O4 contributes to the circulation and adsorption of NO, and the large specific surface area exposes abundant active sites for the reaction of active species. A maximum NO degradation efficiency of 57% is achieved by adjusting the mass of the Co3 O4 precursor. Cycling tests and X-ray diffraction indicate the high stability and recyclability of the composite, making it promising in environmental purification applications.

Nanostructured Metal-Organic Conjugated Coordination Polymers with Ligand Tailoring for Superior Rechargeable Energy Storage.

Conjugated coordination polymers have become an emerging category of redox-active materials. Although recent studies heavily focus on the tailoring of metal centers in the complexes to achieve stable electrochemical performance, the effect on different substitutions of the bridging bonds has rarely been studied. An innovative tailoring strategy is presented toward the enhancement of the capacity storage and the stability of metal-organic conjugated coordination polymers. Two nanostructured d-π conjugated compounds, Ni[C6 H2 (NH)4 ]n (Ni-NH) and Ni[C6 H2 (NH)2 S2 ]n (Ni-S), are evaluated and demonstrated to exhibit hybrid electrochemical processes. In particular, Ni-S delivers a high reversible capacity of 1164 mAh g-1 , an ultralong stability up to 1500 cycles, and a fully recharge ability in 67 s. This tailoring strategy provides a guideline to design future effective conjugated coordination-polymer-based electrodes.

Environmentally Robust Memristor Enabled by Lead-Free Double Perovskite for High-Performance Information Storage.

Memristors are emerging as a rising star of new computing and information storage techniques. However, the practical applications are severely challenged by their instability toward harsh conditions, including high moisture, high temperatures, fire, ionizing irradiation, and mechanical bending. In this work, for the first time, lead-free double perovskite Cs2 AgBiBr6 is utilized for environmentally robust memristors, enabling highly efficient information storage. The memory performance of the typical indium-tin-oxide/Cs2 AgBiBr6 /Au sandwich-like memristors is retained after 1000 switching cycles, 105 s of reading, and 104 times of mechanical bending, comparable to other halide perovskite memristors. Most importantly, the memristive behavior remains robust in harsh environments, including humidity up to 80%, temperatures as high as 453 K, an alcohol burner flame for 10 s, and 60 Co γ-ray irradiation for a dosage of 5 × 105 rad (SI), which is not achieved by any other memristors and commercial flash memory techniques. The realization of an environmentally robust memristor from Cs2 AgBiBr6 with a high memory performance will inspire further development of robust electronics using lead-free double perovskites.

Detection of NO2 Down to One ppb Using Ion-in-Conjugation-Inspired Polymer.

Nitrogen dioxide (NO2 ) emission has severe impact on human health and the ecological environment and effective monitoring of NO2 requires the detection limit (limit of detection) of several parts-per-billion (ppb). All organic semiconductor-based NO2 sensors fail to reach such a level. In this work, using an ion-in-conjugation inspired-polymer (poly(3,3'-diaminobenzidine-squarine, noted as PDBS) as the sensory material, NO2 can be detected as low as 1 ppb, which is the lowest among all reported organic NO2 sensors. In addition, the sensor has high sensitivity, good reversibility, and long-time stability with a period longer than 120 d. Theoretical calculations reveal that PDBS offers unreacted amine and zwitterionic groups, which can offer both the H-bonding and ion-dipole interaction to NO2 . The moderate binding energies (≈0.6 eV) offer high sensitivity, selectivity as well as good reversibility. The results demonstrate that the ion-in-conjugation can be employed to greatly improve sensitivity and selectivity in organic gas sensors by inducing both H-bonding and ion-dipole attraction.

Platinum-Supported Zirconia Nanotube Arrays Supported on Graphene Aerogels Modified with Metal-Organic Frameworks: Adsorption and Oxidation of Formaldehyde at Room Temperature.

Precious-metal catalysts (e.g., Au, Rh, Ag, Ru, Pt, and Pd) supported on transition-metal oxides (e.g., Al2 O3 , Fe2 O3 , CeO2 , ZrO2 , Co3 O4 , MnO2 , TiO2 , and NiO) can effectively oxidize volatile organic compounds. In this study, porous platinum-supported zirconia materials have been prepared by a "surface-casting" method. The synthesized catalysts present an ordered nanotube structure and exhibited excellent performance toward the catalytic oxidation of formaldehyde. A facile method, utilizing a boiling water bath, was used to fabricate graphene aerogel (GA), and the macroscopic 3D Pt/ZrO2 -GA was modified by introducing an adjustable MOF coating by a surface step-by-step method. The unblocked mesoporous structure of the graphene aerogel facilitates the ingress and egress of reactants and product molecules. The selected 7 wt.% Pt/ZrO2 -GA-MOF-5 composite demonstrated excellent performance for HCHO adsorption. Additionally, this catalyst achieved around 90 % conversion when subjected to a reaction temperature of 70 °C (T90 % =70 °C). The Pt/ZrO2 -GA-MOF-5 composite induces a catalytic cycle, increasing the conversion by simultaneously adsorbing and oxidizing HCHO. This work provides a simple approach to increasing reactant concentration on the catalyst to increase the rate of reaction.

One-Step Fabrication of Bio-Compatible Coordination Complex Film on Diverse Substrates for Ternary Flexible Memory.

Recently, resistance random access memories (RRAMs) have been studied extensively, because the demand for information storage is increasing. However, it remains challenging to obtain a flexible device because the active materials involved need to be nontoxic, nonpolluting, distortion-tolerable, and biodegradable as well adhesive to diverse flexible substrates. In this paper, tannic acid (TA) and an iron ion (FeIII ) coordination complex were employed as the active layer in a sandwich-like (Al/active layer/substrate) device to achieve memory performance. A nontoxic, biocompatible TA-FeIII coordination complex was synthesized by a one-step self-assembly solution method. The retention time of the TA-FeIII memory performance was up to 15 000 s, the yield up to 53 %. Furthermore, the TA-FeIII coordination complex can form a high-quality film and shows stable ternary memory behavior on various flexible substrates, such as polyethylene terephthalate (PET), polyimide (PI), printer paper, and leaf. The device can be degraded by immersing it in vinegar solution. Our work will broaden the application of organic coordination complexes in flexible memory devices with diverse substrates.

Self-Healing Graphene-Reinforced Composite for Highly Efficient Oil/Water Separation.

One of the most pervasive environmental problems is oily sewage; emerging materials are needed that could effectively solve this global challenge. Special wetting materials typically combine micro/nanoscale hierarchical structures with a low surface energy, which could produce superhydrophobic performance and these superhydrophobic materials are very important for a wide variety of applications, including self-cleaning and antiadhesives. However, the majority of these manmade materials still suffer from poor durability, which seriously hinders their practical applications. A better choice is that use of supramolecular materials with self-healing ability, which could provide an efficient method to solve materials poor durability problem. However, lightweight materials with special wettbility and self-healing still remain a challenge. In this work, we confine polyborosiloxane (PBS) in an ultralight graphene network to form a robust, special function graphene foam that has the ability to self-repair. Hydroxyl terminated poly(dimethylsiloxane) and boric acid as the as raw material were used to synthesis PBS at room temperature. The as-prepared composite network could be compressed and their properties fully restored without an external stimulus after being subjected to repeated damage. In addition, the prepared composite foam retains the porosity of the original graphene foam. The present work suggests encouraging applications of the self-healing graphene/PBS foam in water/organic solvent separations.