Moisture‑Electric–Moisture‑Sensitive Heterostructure Triggered Proton Hopping for Quality‑Enhancing Moist‑Electric Generator

Moisture-enabled electricity(ME)is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can be directly applied to energy harvesting and signal expression.However,ME can be unreliable in numerous applications due to its sluggish response to moisture,thus sacrificing the value of fast energy harvesting and highly accurate information representation.Here,by constructing a moisture-electric-moisture-sensitive(ME-MS)heterostructure,we develop an efficient ME generator with ultra-fast electric response to moisture achieved by triggering Grotthuss protons hopping in the sensitized ZnO,which modulates the heterostructure built-in interfacial potential,enables quick response(0.435 s),an unprecedented ultra-fast response rate of 972.4 mV s^(−1),and a durable electrical signal output for 8 h without any attenuation.Our research provides an efficient way to generate electricity and important insight for a deeper understanding of the mechanisms of moisture-generated carrier migration in ME generator,which has a more comprehensive working scene and can serve as a typical model for human health monitoring and smart medical electronics design.

Laser fabrication of functional micro-supercapacitors

Due to the rapid development of portable,wearable and implantable electronics in the fields of mobile communications,biomonitoring,and aerospace or defense,there is an increasing demand for miniaturized and lightweight energy storage devices.Micro-supercapacitors(MSCs)possessing long lifetime,high power density,environment friendliness and safety,have attracted great attention recently.Since the performance of the MSCs is mainly related to the structure of the active electrode,there is a great need to explore the efficient fabricating strategies to deterministically coordinate the structure and functionality of microdevices.Considering that laser technology possesses many superior features of facility,high-precision,low-cost,high-efficiency,shape-adaptability and maneuverability,herein we summarize the development of laser technologies in MSCs manufacturing,along with their strengths and weaknesses.The current achievements and challenges are also highlighted and discussed,aiming to provide a valuable reference for the rational design and manufacture of MSCs in the future.

On the mechanism of H2 activation over single-atom catalyst: An understanding of Pt1/WOx in the hydrogenolysis reaction

Owing to the atomic dispersion of active sites via electronic interaction with supports,single-atom catalysts(SACs)grant maximum utilization of metals with unique activity and/or selectivity in various catalytic processes.However,the stability of single atoms under oxygen-poor conditions,and the mechanism of hydrogen activation on SACs remain elusive.Here,through a combination of theoretical calculation and experiments,the stabilization of metal single atoms on tungsten oxide and its catalytic properties in H2 activation are investigated.Our calculation results indicate that the oxygen defects on the WO3(001)surface play a vital role in the stabilization of single metal atoms through electron transfer from the oxygen vacancies to the metal atoms.In comparison with Pd and Au,Pt single atoms possess greatly enhanced stability on the WOx(001)surface and carry negative charge,facilitating the dissociation of H-2 to metal-H species(Hδ-)via homolytic cleavage of H2 similar to that occurring in metal ensembles.More importantly,the facile diffusion of Pt-H to the WOx support results in the formation of Bronsted acid sites(Hδ+),imparting bifunctionality to Pt1/WOx.The dynamic formation of Br?nsted acid sites in hydrogen atmosphere proved to be the key to chemoselective hydrogenolysis of glycerol into 1,3-propanediol,which was experimentally demonstrated on the Pt1/WOx catalyst.

Preface to the Special Issue of the International Symposium on Single‐Atom Catalysis(ISSAC‐2016)

Catalysis is one of the most important chemical processes for production of goods and for environmental remediation.Almost 80% of chemical manufacturing involves either heterogeneous or homogeneous catalysts, mostly consisting of expensive noble metals. Designing highly active, selective and stable catalysts with most efficient use of rare and expensive metals becomes Grand Challenge of heterogeneous catalysis and is critical to the sustainable development of our planet.

Applying dynamic light scattering to investigate the self-assembly process of DNA nanostructures

Understanding the dynamic assembly process of DNA nanostructures is important for developing novel strategy to design and construct functional devices.In this work,temperature-controlled dynamic light scattering(DLS)strategy has been applied to study the global assembly process of DNA origami and DNA bricks.Through the temperature dependent size and intensity profiles,the self-assembly process of various DNA nanostructures with different morphologies have been well-studied and the temperature transition ranges could be observed.Taking advantage of the DLS information,rapid preparation of the DNA origami and the brick assembly has been realized through a constant temperature annealing.Our results demonstrate that the DLS-based strategy provides a convenient and robust tool to study the dynamic process of forming hieratical DNA structures,which will benefit understanding the mechanism of self-assembly of DNA nanostructures.

Photo-thermal CO_(2) reduction with methane on group Ⅷ metals:In situ reduced WO_(3) support for enhanced catalytic activity

Photo-thermal CO_(2) reduction with methane(CRM)is beneficial for solar energy harvesting and energy storage.The search for efficient photo-thermal catalysts is of great significance.Here,we reveal that group Ⅷ metal catalysts supported by optical material WO_(3) are more effective for photo-thermal CRM,giving catalytic activities with visible light assistance that are 1.4-2.4 times higher than that achieved under thermal conditions.The activity enhancement(1.4-2.4 times)was comparable to that achieved with plasmonic-Au-promoted catalysts(1.7 times).Characterization results indicated that WO_(3) was partially reduced to WO_(3-x) in situ under the reductive CRM reaction atmosphere,and that WO_(3-x) rather than WO_(3) enhanced the activities with visible light assistance.Our method provides a promising approach for improving the activity of catalysts under light irradiation.

Non‐noble metal single‐atom catalyst with MXene support:Fe1/Ti_(2)CO_(2) for CO oxidation

MXenes have attracted considerable attention owing to their versatile and excellent physicochemi‐cal properties.Especially,they have potential applications as robust support for single atom cata‐lysts.Here,quantum chemical studies with density functional theory are carried out to systemati‐cally investigate the geometries,stability,electronic properties of oxygen functionalized Ti_(2)C(Ti_(2)CO_(2))supported single‐atom catalysts M_(1)/Ti_(2)CO_(2)(M=Fe,Co,Ni,Cu Ru,Rh,Pd,Ag Os,Ir,Pt,Au).A new non‐noble metal SAC Fe_(1)/Ti_(2)CO_(2) has been found to show excellent catalytic performance for low‐temperature CO oxidation after screening the group 8‐11 transition metals.We find that O_(2) and CO adsorption on Fe_(1) atom of Fe_(1)/Ti_(2)CO_(2) is favorable.Accordingly,five possible mechanisms for CO oxidation on this catalyst are evaluated,including Eley‐Rideal,Langmuir‐Hinshelwood,Mars-van Krevelen,Termolecular Eley‐Rideal,and Termolecular Langmuir‐Hinshelwood(TLH)mechanisms.Based on the calculated reaction energies for different pathways,Fe_(1)/Ti_(2)CO_(2) shows excellent kinet‐ics for CO oxidation via TLH mechanism,with distinct low‐energy barrier(0.20 eV)for the rate‐determining step.These results demonstrate that Fe_(1)/Ti_(2)CO_(2) MXene is highly promising 2D materials for building robust non‐noble metal catalysts.

Few‐layer carbon nitride photocatalysts for solar fuels and chemicals:Current status and prospects

Converting sunlight directly to fuels and chemicals is a great latent capacity for storing renewable energy.Due to the advantages of large surface area,short diffusion paths for electrons,and more exposed active sites,few‐layer carbon nitride(FLCN)materials present great potential for production of solar fuels and chemicals and set off a new wave of research in the last few years.Herein,the recent progress in synthesis and regulation of FLCN‐based photocatalysts,and their applications in the conversion of sunlight into fuels and chemicals,is summarized.More importantly,the regulation strategies from chemical modification to microstructure control toward the production of solar fuels and chemicals has been deeply analyzed,aiming to inspire critical thinking about the effective approaches for photocatalyst modification rather than developing new materials.At the end,the key scientific challenges and some future trend of FLCN‐based materials as advanced photocatalysts are also discussed.

Supramolecular Peptide Therapeutics:Host-Guest Interaction-Assisted Systemic Delivery of Anticancer Peptides

The poor stability of therapeutic peptides in physiological environments hampers their therapeutic efficacy.In this work,a strategy of supramolecular peptide therapeutics(SPT)was proposed for the improvement of the stability and anticancer efficacy of the peptides in vivo.N-Terminal phenylalanine-containing cytotoxic peptides were carried in the cucurbit[7]uril-containing polymer through host–guest interactions between the phenylalanine and cucurbit[7]uril,generating the supramolecular peptide complex with high peptide encapsulation efficiency(>97%).The formation of the supramolecular peptide complex reserved the biological activities of the peptide,presenting prolonged blood circulation and improved anticancer efficacy.This SPT strategy might provide a cucurbituril-and phenylalanine-functionalized approach for the design and the development of peptide-based pharmaceuticals.

Breaking the scaling relations for efficient N_(2)-to-NH_(3) conversion by a bowl active site design:Insight from LaRuSi and isostructural electrides

The design of optimal heterogeneous catalysts for N_(2)-to-NH_(3) conversion is often dictated by the scaling relations,which result in a volcano curve that poses a limit on the catalytic performance.Herein,we reveal a bowl active site that can break the scaling relations,through investigating the catalytic mechanisms of N_(2)-to-NH_(3) conversion on the lanthanide intermetallic electride catalyst LaRuSi by first-principles modeling.This bowl active site,composed of four surface La cations and one subsurface Si atom rich in electrons,plays the key role in enabling efficient catalysis.With adaptive electrostatic and orbital interactions,the bowl active site promotes the adsorption and activation of N_(2) that delivers facile cleavage of N-N bond,while destabilizes the adsorptions of ^(*)NH_(x)(x=1,2,3)species,which facilitates the release of the final NH_(3) product.By comparison with other electride catalysts isostructural to LaRuSi,we confirm the breaking of scaling relations between the adsorptions of ^(*)NH_(x) species and that of^(*)N on the bowl active site.Thus,this bowl active site presents a design concept that breaks the scaling relations for highly efficient heterogeneous catalysis of N_(2)-to-NH_(3) conversion.

An Overview of Self-Assembly and Morphological Regulation of Amphiphilic DNA Organic Hybrids

In this review,we summarized the assembly behavior of DNA organic hybrids and listed reported strategies of tuning the morphology of assemblies.The self-assembly and morphological regulation of DNA organic hybrids provide an effective way to construct functional nanostructures with potential applications in nanomaterials,drug delivery and tissue engineering.The future directions are discussed.

CO oxidation on MXene(Mo_(2)CS_(2)) supported single-atom catalyst: A termolecular Eley-Rideal mechanism

Finding transition metal catalysts for effective catalytic conversion of CO to CO_(2)has attracted much attention.MXene as a new 2D layered material of early transition metal carbides,nitrides,and carbo-nitrides is a robust support for achoring metal atoms.In this study,the electronic structure,geometries,thermodynamic stability,and catalytic activity of MXene (Mo_(2)CS_(2)) supported single noble metal atoms (NM=Ru,Rh,Pd,Ir,Pt and Au) have been systematically examined using first-principles calculations and ab initio molecular dynamic (AIMD) simulations.First,AIMD simulations and phonon spectra demonstrate the dynamic and thermal stabilities of Mo_(2)CS_(2)monolayer.Three likely reaction pathways,LangmuirHinshelwood (LH),Eley-Rideal (ER),and Termolecular Eley–Rideal (TER) for CO oxidation on the Ru1-and Ir_(1)@Mo_(2)CS_(2)SACs,have been studied in detail.It is found that CO oxidation mainly proceeds via the TER mechanism under mild reaction conditions.The corresponding rate-determining steps are the dissociation of the intermediate (OCO-Ru_(1)-OCO) and formation of OCO-Ir_(1)-OCO intermediate.The downshift d-band center of Ru1-and Ir_(1)@Mo_(2)CS_(2)help to enhance activity and improve catalytst stability.Moreover,a microkinetic study predicts a maximum CO oxidation rate of 4.01×10^(2)s^(-1)and 4.15×10^(3)s^(-1)(298.15K) following the TER pathway for the Ru_(1)-and Ir_(1)@Mo_(2)CS_(2)catalysts,respectively.This work provides guideline for fabricating and designing highly efficient SACs with superb catalyts using MXene materials.

The Feasible Design of Quasi-Solid-State Aqueous Tin-Iodine Batteries

Aqueous rechargeable batteries with high safety have been considered as the main energy source to power portable and wearable electronics.Herein,we report the first construction of quasi-solid-state aqueous tin-iodine batteries by exploiting Sn foil as anode,carbon cloth as cathode,and gel electrolytes.The anode reversibly converts from K_(2)Sn(OH)_(6) to metal Sn,thus eliminating the formation of metal dendrites.Meanwhile,gel electrolytes alleviate anode corrosion and enhance the utilization of the anode.Therefore,the asfabricated quasi-solid-state batteries manifest an areal capacity of 700μAh cm^(-2)(211 mAh g^(-1) equal to theoretical capacity)and excellent cycling stability without obvious capacity degradation after 120 cycles at 1mA cm^(-2).Remarkably,the designed batteries sealed by different package materials including plastic,glass,wood,and cardboard operated steadily,thereby enlarging the application scenario for these batteries.This work enriches the family of aqueous rechargeable batteries and sheds light on the construction of high-performance quasi-solid-state aqueous batteries.

Promising thermal photonic management materials for sustainable human habitat

The spectral characteristics of outdoor structures,such as automobiles,buildings,and clothing,determine their energy interaction with the environment,from broad-spectrum absorption of light energy to high-efficiency thermal emission.Recently developed spectrally selective absorption(SSA)materials permit the reduction of energy loss from human habitat eco-system in the sustainable way and further reduce the utilization of fossil energy to achieve carbon neutrality.Here we review recent advances in SSA materials that enable rational and efficient management of thermal energy and provide new solutions for the resource base that supports human life like comfortable heat management,electricity production,and water supply.The basic principles of thermal photonic management,the regulation of SSA materials,and functional properties are summarized.An outlook discussing challenges and opportunities in SSA material energy management for comfortable living environments is finally presented,which expects the enormous potential of this interdisciplinary research in solving growing resource-shortage of human society.

Rational design of copper-based single-atom alloy catalysts for electrochemical CO_(2)reduction

Electrochemical CO_(2)-reduction reaction(CO_(2)RR)is a promising way to alleviate energy crisis and excessive carbon emission.The Cu-based electrocatalysts have been considered for CO_(2)RR to generate hydrocarbons and alcohols.However,the application of Cu electrocatalysts has been restricted by a high onset potential for CO_(2)RR and low selectivity.In this study,we have designed a series of Cu-based single-atom alloy catalysts(SAAs),denoted as TM1/Cu(111),by doping isolated 3dtransition metal(TM)atom onto the Cu(111)surface.We theoretically evaluated their stability and investigated the activity and selectivity toward CO_(2)RR.Compared to the pure Cu catalyst,the majority TM1/Cu(111)catalysts are more favorable for hydrogenating CO_(2)and can efficiently avoid the hydrogen-evolution reaction due to the strong binding of carbonaceous intermediates.Based on the density functional theory calculations,instead of the HCOOH or CO products,the initial hydrogenation of CO_(2)on SAAs would form the*CO intermediate,which could be further hydrogenated to produce methane.In addition,we have identified the bond angle of adsorbed*CO_(2)can describe the CO_(2)activation ability of TM1/Cu(111)and the binding energy of*OH can describe the CO_(2)RR activity of TM1/Cu(111).We speculated that the V/Cu(111)can show the best activity and selectivity for CO_(2)RR among all the 3d-TM-doped TM1/Cu(111).This work could provide a rational guide to the design of new type of single-atom catalysts for efficient CO_(2)RR.

Triazine COF-supported single-atom catalyst (Pd/trzn-COF) for CO oxidation

Single-atom catalysts(SACs) with well-defined and specific single-atom dispersion on supports offer great potential for achieving both high catalytic activity and selectivity. Covalent organic frameworks(COFs) with tailormade crystalline structures and designable atomic composition is a class of promising supports for SACs. Herein, we have studied the binding sites and stability of Pd single atoms(SAs)dispersed on triazine COF(Pd1/trzn-COF) and the reaction mechanism of CO oxidation using the density functional theory(DFT). By evaluating different adsorption sites, including the nucleophilic sp2C atoms, heteroatoms and the conjugated π-electrons of aromatic ring and triazine, it is found that Pd SAs can stably combine with trzn-COF with a binding energy around-5.0 eV, and there are two co-existing dynamic Pd1/trzn-COFs due to the adjacent binding sites on trzn-COF. The reaction activities of CO oxidation on Pd1/trzn-COF can be regulated by the anion–π interaction between a +δ phenyl center and the related-δ moieties as well as the electron-withdrawing feature of imine in the specific complexes. The Pd1/trzn-COF catalyst is found to have a high catalytic activity for CO oxidation via a plausible tri-molecular Eley-Rideal(TER) reaction mechanism. This work provides insights into the d–π interaction between Pd SAs and trznCOF, and helps to better understand and design new SACs supported on COF nanomaterials.

Selective hydrogenation of acetylene on graphene-supported non-noble metal single-atom catalysts

Large-scale production of polyethylene in industry requires efficient elimination of the trace amount of acetylene impurity.Currently,zeolite adsorption or the conversion of acetylene to ethylene via selective semi-hydrogenation on Pd catalysts is the commonly used method.In this work,we investigate the reaction mechanisms of acetylene hydrogenation on defective graphene(DG)supported singleatom catalysts(SACs),M1/SV-G and M1/DV-G(M=Ni,Pd and Pt)using density functional theory(DFT),where SV-G and DV-G represent DG with single and double vacancies,respectively.It is shown that the metal single-atoms(SAs)as well as their different coordination numbers both affect the activity and selectivity of the hydrogenation process.M1/DV-G provides better H2 dissociation ability than M1/SV-G,which accounts for the poor acetylene hydrogenation activity of M1/SV-G.Based on the reaction barriers,Pt1/DV-G and Ni1/DV-G are better catalysts than other systems considered here,with Ni1/DV-G exhibiting high selectivity for the semi-hydrogenation product of acetylene.These results provide insights for the design of highly selective and noble-metal-free SACs for acetylene hydrogenation on carbon materials.

Rational design of SnO_2-based electron transport layer in mesoscopic perovskite solar cells:more kinetically favorable than traditional double-layer architecture

Here,the interfacial synergism of discontinuous spot shaped SnO_2 and TiO_2 mesoporous nanocomposite as electron transfer layer（ETL） underlayer is presented in highly efficient mesoscopic perovskite solar cells（M-PSCs）. Based on this new strategy,strong charge recombination observed in previous SnO_2-based ETLs is suppressed to a great extent as the pathways of charge recombination and energy loss are blocked effectively. Meanwhile,the internal series resistance of entire M-PSC is decreased remarkably. The new ETL is more kinetically favorable to electron transfer and thus results in significant photovoltaic improvement and alleviated hysteresis effect of M-PSCs.

Catalytic mechanism and bonding analyses of Au–Pd single atom alloy(SAA):CO oxidation reaction

Single-atom catalysts(SACs),including metalmetal-bonded bimetallic ones named single-atom alloys(SAAs),have aroused significant interest in catalysis.In this article,the catalytic mechanism and bonding analysis of CO oxidation reaction on bimetallic gold–palladium(Au–Pd)model of single atom alloy Au37Pd1 are investigated by using quantum chemical calculations.The molecular geometries and adsorbate/substrate binding energies of CO@Au–Pd,O2@Au–Pd and CO/O2@Au–Pd configurations are identified.The core-shell structure is confirmed to be the most stable structure for Au–Pd SAA,where the Pd atom prefers to situate at the core site.Charge transfer from the Pd atom to the Au atoms has been confirmed to stabilize the structure.According to the binding energy and chemical bonding analysis,both CO and O2 prefer to bind to the Pd atom at the hex site with low coordination number.The formation of new co-adsorption species is identified,in which vertical and parallel bridging adsorptions of CO and O2 on the Au–Pd bonds are observed.CO oxidation on Au–Pd SAA is found to be feasible with low energy barriers and follows the Langmuir-Hinshewood(L-H)mechanism.Our work offers insights into the significant role of single atom of the SAAs in catalytic reactions and can provide evidence for designing new SAAs with high-performance catalytic activities.

Non-noble metal single-atom catalysts with phosphotungstic acid(PTA)support:A theoretical study of ethylene epoxidation

Geometric and electronic structures of phosphotungstic acid(PTA)supported single transition metal atom(Fe,Co,Ni,Ru,Rh,Pd,Os,Ir and Pt)catalysts have been systematically investigated by using the first-principles theoretical methods.Possible reaction mechanism for ethylene epoxidation was explored.The most possible anchoring site for the single transition metal atom is the fourfold hollow site on PTA.As the non-noble metal Fe1-PTA system possesses considerable adsorption energies towards both O2 and C2H4,the strong bonding interaction between Fe1 and PTA cluster was analyzed.It is found that the electron transfers from Fe atom to PTA cluster and strong covalent metal-support interactions(CMSI)between the Fe 3 d orbitals and O 2 p orbitals of PTA lay the foundation of high stability.The proposed catalytic reaction mechanism for ethylene epoxidation on Fe1-PTA single-atom catalyst(SAC)includes three steps:the O2 adsorbs on Fe1-PTA via electron transfer;the first ethylene attacks the adsorbed O2 molecule on Fe1-PTA followed by the formation of C2H4O;finally,the O atom remained on Fe1-PTA reacts with a second ethylene to form the product and accomplish the catalytic cycle.The Fe1-PTA has high selectivity and catalytic activity for ethylene epoxidation via an Eley–Rideal mechanism with low energy barriers.A potentially competitive pathway for the formation of acetaldehyde is not kinetically favorable.These results provide insights for the development of highly efficient heterogeneous SACs for ethylene epoxidation with non-noble metals.