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A novel and high-efficiency Pd/TMxOy-rGO/CFP (TMxOy = Co3O4, Mn3O4, Ni(OH)2) electrocatalyst for directly integrated membrane electrode was synthesized by controllable cyclic voltammetry electrodeposition combined with hydrothermal process. The results showed excellent performance towards methanol oxidation reduction. The Pd/Co3O4-rGO/CFP as-prepared catalyst has the best electrocatalytic activity, and mass activity is 5181 mA·mg−1Pd, which is about 40 times and 4.3 times that of the commercial Pd/C and Pt/C catalyst (JM). It can be attributed that the small size of Pd nanoparticle, uniformity of distribution, and the synergistic interaction between transition metal oxide on the support surface and Pd nanoparticles. The prepared Pd/TMxOy-rGO/CFP composite electrode is a promising catalyst for integrated membrane electrode assembly of proton exchange membrane fuel cells in the future.

Direct ethanol fuel cell (DEFC) as a promising device for converting chemical energy to electricity has been paid ever-increasing attention. However, the slow kinetics of ethanol electrooxidation at an anode hinders the application of DEFCs. Although Pt is the best catalyst among all the pure metal catalysts, it still has a relatively poor ability to break the C C bond, is deactivated by the accumulated COad intermediates, and undergoes unwanted desired structure change over long-term operation. In recent years, the addition of other metals to form binary, ternary, and quaternary catalysts have significantly improved electroactivity and stability. Ternary catalysts can have numerous element combinations and complicated architectures and, therefore, have been the subject of considerable research. In this review, most of the reported ternary catalysts will be summarized and categorized according to their structure while discussing the essence of the role of each component.

Lead halide perovskite nanocrystals (CsPbX3 NCs) have been regarded as promising materials in photocatalysis. Combining metal single atoms with CsPbX3 NCs may be a practical way in exploring perovskite-based catalysts. However, such hybrids have not been achieved experimentally yet, mainly due to the weak interaction between the metal atom and the CsPbX3 surface. Here, we demonstrate that Pt single atoms can be deposited on CsPbBr3 NCs through a photoassisted approach, in which the surface was partially oxidized first, followed by the anchoring of Pt single atoms through the formation of Pt-O and Pt-Br bonds. The deposition of Pt single atoms can significantly change the photophysical properties of CsPbBr3 NCs by inducing the generation of deep trap states in the band gap. The as-prepared Pt-SA/CsPbBr3 can be used as efficient and durable catalysts for photocatalytic semi-hydrogenation of propyne. A CsPbBr3 nanocrystal might be a suitable substrate for anchoring other metal single atoms, such as Cu, Au, Ag, Pd, and so on.

Controllable fabrication of Fe-N-C based single-atom catalysts (SACs) for enhanced electrocatalytic performance is highly desirable but still challenging. Here, an in situ surface-confined strategy was demonstrated for the synthesis of single atomic Fe-N4 on N-doped carbon nanoleaves (L-FeNC). The in situ generated Zn3[Fe(CN)6]2 could not only serve as a protection layer against collapse of nanoleaves but also provide abundant Fe source for the formation of Fe-N moieties during pyrolysis, leading to high surface area and high graphitization degree of L-FeNC simultaneously. Benefiting from abundant Fe-N4 active sites, enhanced mass and charge transfer, the as-prepared L-FeNC manifested a half-wave potential of 0.89 V for oxygen reduction reaction (ORR) in 0.1 M KOH. A maximum power density of 140 mW cm−2 and stable discharge voltage even after operation for 50,000 s have been demonstrated when the L-FeNC was used as air cathode for Zn-air battery. This work not only provided a unique surface-confined strategy for the synthesis of two-dimensional nanocarbons, but also demonstrated the significant benefit from rational design and engineering of Fe-N-C SACs, thus offering great opportunities for fabrication of efficient energy conversion and storage devices.

Electrochemical reductions of CO2 (ECRR) and N2 (ENRR) can not only reduce CO2 emissions in the air but also make use of N2 and H2O, the most extensive resources on earth, to produce high value-added chemicals, which has become one of the hot research directions. In this study, the formation energy (Ef) and dissolution potential (Udiss) of 96 two-dimensional catalysts derived from different defect sites of monoclinic crystal boron nitride (BN) were calculated, and the catalysts with thermodynamic and electrochemical stability were selected. The suitable catalysts for producing HCOOH (Ga/In@N-BN), CO (Sn@BN), and CH3OH (Co@N-BN) by ECRR and NH3 (Fe@BN) by ENRR were predicated based on a selective calculation method. The results obtained can provide guidance for the design and development of new catalysts for ECRR and ENRR.

In this paper, the vibration response of the double-FG porous beam system (DFGPBS) acted by a moving load is investigated. The DFGPBS composed of two parallel FG porous beams with their material properties varying along both the axial and transverse directions, i.e., bi-directional FG material distribution, is taken into account. The porous imperfection is simulated by distributing the porosity along the beam thickness with even and uneven patterns. The governing equations of this bi-directional DFGPBS under a moving load are established with the aid of the Hamilton principle associated with the Timoshenko beam theory. The Ritz method is adopted to discrete the differential governing equations, which are solved by the Newmark-β approach. The validation of the present model is performed by comparing the numerical results with two previous works. Then, the parametric study is carried out to investigate the influences of bi-directional gradient indices, porosity volume fraction, boundary conditions, stiffness of elastic layer, and velocity of the moving load on the vibration response of bi-directional DFGPBSs excited by a moving load. It is demonstrated that the vibration response of the double-beam system subjected to moving loads can be governed by tailoring the distribution of the bi-directional FG materials. The present work can be used to guide the multi-functional design of a double-beam system under dynamic loadings.

Laminated composites are extensively employed in many aerospace structures due to their excellent mechanical properties. In this paper, a size-dependent model on the basis of the nonlocal strain gradient theory is adopted to reveal the vibration behavior of laminated nanoplate with piezo-magnetic face sheets in its upper and lower surfaces. The governing equations are derived by employing the Hamilton’s principle and Mindlin plate theory. The validation of the present study is carried out by comparison with two previous works and good agreements are achieved. By comparing the vibrational frequencies of composite laminated core sandwich nanoplate with and without the piezo-magnetic face sheets, it is demonstrated that the upper and lower piezo-magnetic face sheets will extensively enhance the vibrational frequencies of laminated core sandwich nanoplates. Furthermore, a comprehensive numerical investigation is performed to examine the influence of the cross-ply laminated type, external electric and magnetic potentials, thickness ratio, size scale parameters, as well as aspect and width-to-thickness ratios on the vibration of the laminated core piezo-magnetic sandwich nanoplate. It is expected that the current work can provide some helpful guidelines for employing the piezo-magnetic surfaces as sensors and actuators to control their vibration behaviors of composite laminated nanostructures.

Conventional templating synthesis confines the growth of seeds in rigid spaces to achieve faithful morphological replication. Herein, we explore the use of spherical shape-deformable polymeric nanoshells to regulate the anisotropic growth of Ag nanoplates. The flexible shells deform adaptively to accommodate the initial overgrowth of the seeds but restrict the growth in the directions where the shells are fully stretched, eventually producing nanoplates with an unconventional circular profile. The diameter of the final Ag nanoplates can be precisely predicted by stretching and flattering the nanoshells into a plate-like capsule while retaining their original internal surface area. Furthermore, unlike conventional templates, the polymer shells eventually turn themselves into a conformal coating that binds to the surface of the full-grown Ag nanoplates and significantly enhances their stability against oxidative etching.

One of the main challenges of all-inorganic cesium lead halide (CsPbX3) perovskite nanocrystals (NCs) in photocatalysis is their poor stability in hostile environments such as polar solvents. Herei...

The slow kinetics at the cathode of oxygen reduction reaction (ORR) seriously limits the efficiencies of fuel cells and metal-air batteries. Pt, the state-of-the-art ORR electrocatalyst, suffers from high cost, low earth abundance, and poor stability. Here a self-templated strategy based on metal-organic frameworks (MOFs) is proposed for the fabrication of hollow nitrogen-doped carbon spheres that are embedded with cobalt nanoparticles (Co/HNC). The Co/HNC manifests better ORR activities, methanol tolerance, and stability than commercial Pt/C. The high ORR performance of Co/NHC can be attributed to the hollow structure which provides enlarged electrochemically active surface area, the formation of more Co-N species, and the introduction of defects. This work highlights the significance of rational engineering of MOFs for enhanced ORR activity and stability and offers new routes to the design and synthesis of high-performance electrocatalysts.

Inorganic nanomaterials are widely used in heterogenous catalysis. With the development of nanoscience and nanotechnology, chemists can precisely control the size, morphology, and exposed facets of nanocrystals (NCs) in an elegant manner, further tailoring their catalytic performance towards diverse reactions. In this review, we focus on the design principles of high-performance catalysts using metal NCs and oxide NCs. Special attention is paid to the shape control and surface engineering of NCs. Some practically important heterogeneous catalytic reactions over nanocatalysts will be discussed. Finally, an outlook and perspective in nano-catalysis will be provided. The goal of this review is to discuss recent advances and perspective on heterogeneous catalysis using inorganic nanomaterials and motivate researchers to design efficient catalysts with high activity, selectivity and stability.

All-inorganic lead halide perovskite nanocrystals (NCs) have been promising candidates in various optoelectrical fields. It is still challenging to further enhance their optical properties and stability to meet the requirements of practical applications. Herein, we develop a passivation strategy towards CsPbBr3 NCs by using inorganic phosphate and bromide anions. Phosphate can coordinate with lead ions on CsPbBr3 NCs as capping ligands; meanwhile, excess bromide can strengthen the repair of surface trapping sites. The treated NCs exhibit near-unity quantum yield and boosted radiative recombination. In addition, obvious enhancement has been realized in their durability against polar solvents. A white light emitting diode (WLED) has been fabricated by employing the passivated NCs as a green light source, which possesses high luminous efficiency and operational stability.

Lead halide perovskite NCs (APbX3, A = formamidinium (FA), methylammonium (MA) or Cs; X = Cl, Br, I or their mixture) have attracted unprecedented attention due to their excellent photophysical properties and wide application prospects. However, the inherent ionic structure of APbX3 NCs makes them very sensitive to external conditions such as water and oxygen, resulting in poor stability. As a feasible strategy, encapsulation is considered to be effective in improving the stability. In this minireview, we focus on single-particle-level coating, which not only can improve the stability but also maintain the nano effect of the original NCs. This review summarizes the fundamental information on APbX3 NCs and the necessity of single-particle-level coating. Subsequently, a variety of heterostructures at the single-particle level are introduced in detail. Then, their applications are summarized. Moreover, we discuss the challenges and prospects of the single-particle-level heterostructures based on APbX3 NCs.

In this work, we report a simple one-pot reprecipitation method of CsPbX3/Pb3(PO4)2 composite nanocrystals (NCs), which have significantly improved photophysical properties and stability. The as-obtained CsPbBr3/Pb3(PO4)2 NCs display bright green emission with a high PLQY of 95%. In addition, the product has an outstanding stability toward moisture and polar solvents, superior to that of pristine CsPbBr3 NCs. This work not only provides a facile method for preparing lead halide perovskite NCs with high quality, but also sheds some light on the potential of inorganic salts as passivators.

Due to the multi-functional requirements, more and more multi-dimensional functionally graded structures are reported, while their thermo-mechanical performances are still unclear. This paper aims at theoretically examining the thermo-mechanical behaviors of two-dimensional functionally graded (2D-FG) microbeam excited by a moving load. The formulation is established in the framework of the modified couple stress theory in combination with Hamilton's principle, and this problem is numerically solved through the finite element method (FEM). The material properties of the 2D-FG microbeam are treated as temperature-dependent parameters that vary smoothly along with both the axial and thickness directions, and three different thermal loads including the uniform, linear, and nonlinear temperature rises are taken into account. Both the fundamental frequency and the dynamic transverse deflection are analyzed with consideration of different axial and thickness gradient indexes, thermal load types, temperature rise amplitudes, and small scale parameters. The conclusion obtained in this paper can serve as a guideline for assessing the thermal performance of microstructures subjected to a moving load.

The production of CO from the CO2 reduction reaction (CO2RR) is of great interest in the renewable energy storage and conversion, the neutral carbon emission, and carbon recycle utilization. Silver (Ag) is one of the catalytic metals that are active for electrochemical CO2 reduction into CO, but the catalysis requires a large overpotential to achieve higher selectivity. Constructing a metal-oxide interface could be an effective strategy to boost both activity and selectivity of the catalysis. Herein, density functional theory (DFT) calculations were first conducted to reveal the chemical insights of the catalytic performance on the interface between metal oxide and Ag(111) (MOx/Ag(111)). The results show that the *COOH intermediates can be more stabilized on the surfaces of MOx/Ag(111) than pure Ag(111). The hydrogen evolution reaction on MOx/Ag(111) can be suppressed due to the significantly higher Gibbs free energy for hydrogen adsorption (ΔGH*), thereby enhancing the selectivity toward CO2RR. A series of MOx/Ag composites with the unique interface based on the DFT results were then introduced though a two-step approach. The as-obtained MOx/Ag catalysts boosted both the CO activity and selectivity at a relatively positive potential range, especially in the case of MnO2/Ag. The reduction current density on the MnO2/Ag catalyst can reach 4.3 mA cm-2 at -0.7 V (vs RHE), which is 21.5 times higher than that on pure Ag, and the overpotential of CO2 to CO (390 mV) possesses is much lower than that on pure Ag NPs (690 mV). This study proposes an effective design strategy to construct a metal-oxide interface for CO2RR based on the synergistic effect between metals and MOx.

Although lead halide perovskites are demonstrated to be promising photocatalysts for hydrogen evolution from hydrogen halide splitting, it still remains challenging to fabricate efficient and stabl...

Plant corrosion inhibitors in acid-pickling environment have the advantages of wide source, low cost and environmental protection. Pueraria lobata leaf extract (PLLE) was prepared by the combination of soaking method and ultrasonic extraction method. HPLC characterization found that PLLE contains some active ingredients, such as Puerarin, Biochanin, Daidzin and Daidzein. The corrosion inhibition of PLLE on 10# steel in 1.0 M HCl solution was studied by weight loss analysis, potentiodynamic polarization measurement, electrochemical impedance spectroscopy, scanning Kelvin probe test (SKP) and scanning electron microscopy. The results show that PLLE can effectively inhibit the corrosion of 10# steel in HCl, when the temperature is 25 °C, adding 0.5 g/L PLLE to 1.0 M HCl solution, the corrosion inhibition efficiency of 10# steel can reach up to 94.37%. The SKP results show that after adding PLLE to HCl, the surface potential difference and electrochemical non-uniformity of 10# steel are reduced, and the local corrosion tendency is significantly reduced. Polarization curves and electrochemical impedance spectroscopy indicate that PLLE is a mixed corrosion inhibitor. The adsorption process is mainly chemisorption and obeyed the Langmuir model.

The scaffold structures formed by the incorporation of reduced graphene oxide (RGO) nanomaterials can be studied to improve the 3D matrix properties in the applications of bone regeneration. On the other hand, RGO has delayed the incorporation into the mixtures that were determined to generate scaffolds on using 3D printing because of its poor colloidal stability of particles and weak solubility in water. Moreover, to produce RGO, the graphene oxide (GO) was treated with hydrazine hydrate solution, which was well known as a reducing agent that is highly hazardous. To outcome these drawbacks, an unique eco-friendly method was established to gather scaffolds that were 3D printed by the incorporation of RGO. This was obtained using the Gallic acid induced in situ reduction of the GO already existing on the gelatin/chitosan/tricalcium phosphate scaffolds. Moreover, scaffolds also exhibited antibacterial activity without conceding osteoblasts’ cell proliferation and viability. Furthermore, the obtained scaffolds showed good osteoblasts proliferation and viability indicating their possibility for applications in bone fracture healing.

A facile strategy for the preparation of a nanoconfined Ti3C2/Ru cocatalyst by direct reduction of Ru3+ ions without an additional reductant was developed. The in situ formation of TiO2 nanosheets on the Ti3C2/Ru surface ensures the separation of the semiconductor and cocatalyst (TiO2-Ti3C2/Ru), resulting in charge segregation and migration more effective than those achieved by traditionally prepared Ru-TiO2-Ti3C2. Owing to its low Fermi level, the self-assembled Ti3C2/Ru cocatalyst accepted the photogenerated electrons and promoted H2 evolution without an induction period, while exhibiting high surface structure stability. The changes in the work function and surface terminations of Ti3C2 during the photocatalysis were revealed by DFT calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy. The efficient electron transfer enabled by the structurally separated Ti3C2/Ru-based photocatalyst significantly reduced the electron-hole recombination, increasing the photocatalytic H2 evolution activity. This work provides a guiding design approach for future solar energy conversion with the semiconductor-cocatalyst system.

The utilization of structural water in chemical self-assembly has not only effectively eliminated the negative influences of solvents from solutions or gels but has also provided new insight into the fabrication of new materials in bulk. However, up to now, supramolecular polymerization triggered by structural water has been dominated more by serendipity than rational design. After carefully analyzing the chemical structures of artificial monomers and gaining a deep understanding of the water-triggered assembly process, we report herein the bulk formation of polymeric materials from water and low-molecular weight monomers by rational design instead of serendipity.

Solar-driven interfacial steam generation is a promising technique for clean water production because it can minimize thermal loss by localizing solar-to-heat conversion at the air/liquid interface. Here we report an integrated solar evaporator by partially growing 2D polypyrrole microsheets within a melamine foam through chemical vapor polymerization. These microsheets can induce multiple light reflections within the foam, enable omnidirectional light absorption, provide abundant surfaces to promote heat transfer, and achieve spatially defined hydrophobicity to facilitate vapor escape. Meanwhile, the inherent hydrophilicity of the bottom part of the foam promotes spontaneous upward water transport and suppresses heat loss. The composite foam exhibits an excellent apparent evaporation rate of ∼2 kg/(m

Hydrochromic materials that can reversibly change color upon water treatment have attracted much attention owing to their potential applications in diverse fields. Herein, for the first time, we report that space-confined CsPbBr3 nanocrystals (NCs) are hydrochromic. When CsPbBr3 NCs are loaded into a porous matrix, reversible transition between luminescent CsPbBr3 and non-luminescent CsPb2 Br5 can be achieved upon the exposure/removal of water. The potential applications of hydrochromic CsPbBr3 NCs in anti-counterfeiting are demonstrated by using CsPbBr3 NCs@mesoporous silica nanospheres (around 100 nm) as the starting material. Owing to the small particle size and negatively charged surface, the as-prepared particles can be laser-jet printed with high precision and high speed. We demonstrate the excellent stability over repeated transformation cycles without color fade. This new discovery may not only deepen the understanding of CsPbX3 , but also open a new way to design CsPbX3 materials for new applications.

The electrochemical reduction of CO2 and H2O to syngas, a widely used precursor for chemical synthesis, has attracted increased attention. However, producing syngas over a wide range of CO:H2 ratios is important for its potential application. Herein, a facile method using an anodic oxidizing zinc plate has been developed to obtain lattice-dislocated ZnO, which exhibited higher faradaic efficiencies (above 90%) of syngas than that of ZnO without lattice dislocation. Moreover, the ratio of CO to H2 can be regulated in a wide range from 0.28 to 2.11 by applying different electrolyzing potentials, which is applicable to the synthesis of various chemicals. With density functional theory calculations, we conclude that the lattice dislocation defects in ZnO promote the electroreduction of CO2. In addition, stability and electrochemical noise tests show that lattice-dislocated ZnO can withstand long-term operation due to its effective corrosion resistance.

The widespread application of direct ethanol fuel cells is hampered due to the low activity, high cost and poor operation durability of electrocatalysts for ethanol oxidation reaction (EOR). Herein, we report a one-pot synthetic method to synthesize PdPb3 nanochains with well-defined shape, size and composition via a solution-phase reduction method. The morphology, composition distribution and structure characteristics of PdPb3 nanochains were investigated by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Thanks to the unique structure, the as-obtained PdPb3 nanochains can manifest much higher mass activity (2523 mA·mg−1) and higher operation durability than commercial Pd/C (1272 mA·mg−1) during the EOR measurements. More importantly, further CO-stripping measurements indicate that the incorporation of Pb species could favor the oxidative removal of CO intermediates on the Pd electrode at the negative potential and enhance the EOR activity and stability, making it possible to develop highly active and durable electrocatalysts.

Chemical design of multicomponent nanocrystals requires atomic-level understanding of reaction kinetics. Here, we apply single-particle imaging coupled with atomistic simulation to study reaction pathways and rates of Pd@Au and Cu@Au core-shell nanocubes undergoing oxidative dissolution. Quantitative analysis of etching kinetics using in situ transmission electron microscopy (TEM) imaging reveals that the dissolution mechanism changes from predominantly edge-selective to layer-by-layer removal of Au atoms as the reaction progresses. Dissolution of the Au shell slows down when both metals are exposed, which we attribute to galvanic corrosion protection. Morphological transformations are determined by intrinsic anisotropy due to coordination-number-dependent atom removal rates and extrinsic anisotropy induced by the graphene window. Our work demonstrates that bimetallic core-shell nanocrystals are excellent probes for the local physicochemical conditions inside TEM liquid cells. Furthermore, single-particle TEM imaging and atomistic simulation of reaction trajectories can inform future design strategies for compositionally and architecturally sophisticated nanocrystals., Rational design of multicomponent nanocrystals requires atomic-level understanding of reaction kinetics. Here, the authors apply single-particle liquid-cell electron microscopy imaging coupled with atomistic simulations to understand pathways and rates of bimetallic core-shell nanocubes undergoing oxidative dissolution.

Nowadays, hierarchically macro-/meso-/microporous 3D carbon materials have been paid more attention due to their imaginative application potential in specific electrochemistry. Here, we report a dual-template strategy using eutectic NaCl/ZnCl2 melt as airtight and swelling agent to obtain 3D mesoporous skeleton structured carbon from renewable lignin. The prepared lignin-derived biocarbon material (LN-3-1) has a high specific surface area (1289 m2 g−1), a large pore volume (2.80 cm3 g−1), and a well-connected and stable structure. LN-3-1 exhibits extremely high activity and stability in acidic medium for oxygen reduction reaction (ORR), superior to Pt/C catalyst and most non noble-metal catalysts reported in recent literatures. The prepared carbon material was used as a cathode catalyst to assemble a H2-O2 single fuel cell, and its excellent catalytic performance has been confirmed with the maximum power density of 779 mW cm−2, which is one of the highest power densities among non-metallic catalysts so far. Density functional theory (DFT) calculations indicate that the synergy of chlorine and nitrogen reconciles the intermediate adsorption energies, leading to an appropriate theoretical ORR onset potential. We develop a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in proton-exchange membrane fuel cells.

Lead-free perovskite ceramics with the formula of (1-x)BaTiO3-xBaCo0.5Nb0.5O3-δ ((1-x)BT-xBCN), exhibit structural phase transition, modified band-gap (Eg), ferromagnetic and ferroelectric orders at room-temperature (RT). All ceramics have no impurity phase but the structural transition from tetragonal to cubic phase is observed with the increase of x. A possible mechanism is proposed to explain the variation of crystal structure. Raman scattering analysis not only proves the existence of doping-induced phase transition but also indicates the changed bonding vibration modes between adjacent atoms. The appearance of two band-gaps in doping samples, the low Eg is about 1.3 eV, obviously smaller than that of 3.2 eV for pure BaTiO3 (BT), which is attributed to the electronic orbital of Co 3d within the gap of BT. Moreover, the RT ferromagnetic behavior is obtained at x = 0.05, which can be interpreted via the F center exchange model. These results show the potential applications for perovskite oxides on solar energy conversion apparatus and multiferroic devices.

Miniaturized stretchable strain sensors are key components in E-skins for applications such as personalized health-monitoring, body motion perception, and human-machine interfaces. However, it remains a big challenge to fabricate miniaturized stretchable strain sensors with high imperceptibility. Here, we reported for the first time novel ultraminiaturized stretchable strain sensors based on single centimeter-long silicon nanowires (cm-SiNWs). With the diameter of the active materials even smaller than that of spider silks, these sensors are highly imperceptible. They exhibit a large strain sensing range (45%) and a high durability (10 000 cycles). Their optimum strain sensing ranges could be modulated by controlling the prestrains of the stretchable cm-SiNWs. On the basis of this capability, sensors with appropriate sensing ranges were chosen to respectively monitor large and subtle human motions including joint motion, swallow, and touch. The strategy of applying single cm-SiNWs in stretchable sensors would open new doors to fabricate ultraminiaturized stretchable devices.

An incompletely covered CdS/ZnS core/shell is synthesized via a simple hydrothermal method. Due to the defect energy levels introduced by zinc vacancies, the typical type-I heterojunction of CdS/Zn...

An efficient Ni2P–CdS photocatalyst for photocatalytic hydrogen evolution was synthesized by phosphorizing β-Ni(OH)2 nanosheet with exposed (001) facets on CdS nanorods. The obtained Ni2P–CdS composite displays an outstanding and stable photocatalytic hydrogen generation rate of 68.47 mmol g−1 h−1 in 10 vol% lactic acid under visible light irradiation, more than 17 times higher than that for pure CdS nanorods. The transient photocurrent response, EIS measurement, Mott-Schottky plots, acidic LSV measurement, and PL spectra have proved that Ni2P loading can significantly improve the separation of photo-excited electron-hole pairs in CdS nanorods and enhance the hydrogen evolution capability for CdS. These improvements are achieved by features of Ni2P such as the high capability of trapping photo-generated electrons from CdS, lifting the total Fermi level and lowering the hydrogen evolution overpotential of the composite. The results show that β-Ni(OH)2 precursor with a high exposure degree of (001) facet is contributed to the epitaxial formation of (001)-facet-exposed Ni2P co-catalyst on CdS nanorods, resulting in that the Fermi level and the hydrogen evolution overpotential of the composite can be further lifted and lowered. This study has provided a novel precursor-derived route to fabricate high-performance co-catalysts with highly exposed active facets on CdS nanorods for effective photocatalytic hydrogen evolution.

Direct methanol fuel cells (DMFCs) and direct ethanol fuel cells (DEFCs) have drawn great attention as promising power sources for mobile and portable devices. However, the anodic reactions in DMFCs and DEFCs, namely the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), suffer from notoriously sluggish kinetics which seriously limited their large-scale applications. In this review, we will present a brief review on the interfacial engineering of noble metals for the MOR and EOR. This review starts by introducing the fundamental electrochemistry of the MOR and EOR and the performance evaluation of MOR and EOR electrocatalysts. We then move to summarize recent advances in the design and synthesis of MOR and EOR electrocatalysts in acidic and alkaline electrolytes, in which we emphasize the importance of rational engineering of the interface in noble metals (such as Pt, Pd and Rh) for enhanced activity and improved stability toward the MOR and EOR. Finally, challenges and prospects will be concluded for designing better MOR and EOR electrocatalysts.

The Schottky junction, composed of a rectifying metal–semiconductor interface, is an essential component for microelectronic and optoelectronic devices. However, due to the considerable reverse tunneling current, typical Schottky junctions cannot be widely applied in devices requiring high signal-to-noise ratios, such as photodetectors with high detectivity. Here, a van der Waals (vdW) Schottky junction is constructed by mechanically stacking a gold (Au) electrode onto a multilayer indium selenide (InSe) nanosheet, which shows an ultralow reverse current in sub-picoamperes and an excellent rectification ratio exceeding 106 at room temperature. The reverse current, which corresponds to the thermionic emission transport model, is independent of the applied reverse bias. As a result, the Au–InSe vdW Schottky junction device can function as an ultrasensitive photodetector with a photodetectivity over 2.4 × 1015 Jones, corresponding to a photoresponsivity of 853 A W−1 and a light on/off ratio exceeding 1 × 107. The work offers an idea for investigating electronic and optoelectronic devices with high signal-to-noise ratios based on vdW Schottky junctions.

In this paper, a low-noise charge-sensitive preamplifier (CSA) is designed based on passivation ion implanted planar silicon (PIPS: The Passivated Implanted Planar Silicon) detectors. This charge-sensitive preamplifier uses Junction Field-Effect Transistor (JFET) as the first stage of the amplifier. In order to maximize the signal-to-noise ratio and consider the resistance-capacitance matching problem, according to different PIPS detector junction capacitances, different numbers of junction field effect transistors are matched in parallel in the first stage. Slotting technology is used at the feedback end to reduce the influence of the parasitic capacitance of the PCB board on the feedback, and the feedback capacitor resistance is adjusted to achieve the best signal-to-noise ratio. Experimental test results show that the charge-sensitive preamplifier can achieve a signal-to-noise ratio greater than 100 at room temperature, the output signal rise time is less than 60 ns, and the electronic equivalent capacitance noise is 19 eV/pF. The charge-sensitive preamplifier is connected to the Canberra PD450-17-100AM PIPS detector, and the standard α source 238Pu is measured in a vacuum environment. The energy resolution can reach 17keV@5499keV.

In this paper, we present a diode-pump continuous wave laser amplifier chain where master the oscillator power amplifier (MOPA) architecture is used. The laser amplifier chain consists of two Yb:YAG surface-doped slab laser modules and the 1030nm fiber laser is used as seed. We theoretically calculate the conditions for obtaining high output laser power and systematically analyze the advantages of surface-doped slab. The maximum output power is 6.1 kW and the optical to optical conversion efficiency is 27% when the pump power is 22 kW at room temperature. The beam quality (β) is 2.8 times diffraction limit. These results demonstrate that the surface-doped slab structure has the potential to obtain high output laser power.

In order to realize the dream of the practical application of hydrogen energy from solar energy and water, it is necessary to use efficient and earth-abundant cocatalysts for photocatalytic H2 evolution. Compared with a one-component cocatalyst, the multicomponent cocatalysts with a synergistic effect can effectively accelerate the separation of photogenerated electron–hole pairs in photocatalysis. Hence, a novel bicomponent Co3S4/Co@C cocatalyst on a CdS semiconductor photocatalyst is successfully synthesized by a one-step hydrothermal method. The Co3S4/Co-CdS photocatalyst obtained exhibits a highly efficient photocatalytic H2 evolution rate of 15.17 mmol h−1 g−1, which is 2.8 times higher than that of Pt-CdS. Furthermore, the quantum efficiency of Co3S4/Co-CdS reaches a maximum value of 16.80% at 475 nm. The significant improvement in the performance is because of the unique energy level structure of the Co3S4/Co-CdS photocatalyst, which has the maximum efficiency of charge separation and migration. This work not only presents a new protocol for constructing bicomponent cocatalysts on a semiconductor structure, but also proves that the bicomponent Co3S4/Co@C is a promising and low-cost cocatalyst.

High-quality Pt-based catalysts are highly desirable for ethanol oxidation reaction (EOR), which is of critical importance for the commercial applications of direct ethanol fuel cells (DEFCs). However, most of the Pt-based catalysts have suffered from high cost and low operation durability. Herein a two-step method has been developed to synthesize porous Pt nanoframes decorated with Bi(OH)3, which show excellent catalytic activity and operation durability in both alkaline and acidic media. For example, the nanoframes show a mass activity of 6.87 A·mgPt−1 in alkaline media, which is 13.5-fold higher than that of commercial Pt/C. More importantly, the catalyst can be reactivated simply, which shows negligible activity loss after running for 180,000 s. Further in situ attenuated total reflection-infrared (ATR-IR) absorption spectroscopy and CO-stripping experiments indicate that surface Bi(OH)3 species can greatly facilitate the formation of adsorbed OH species and subsequently remove carbonaceous poison, resulting in a significantly enhanced stability towards EOR. This work may favor the tailoring of desired electrocatalysts with high activity and durability for future commercial application of DEFCs.

PdMn and PdFe nanoparticles supported reduced graphene oxide catalysts (RGO) are synthesized by sodium borohydride reduction using polyethylene glycol (PEG) as a protective agent. The prepared catalysts are used to electro-catalyse methanol under alkaline conditions. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The test results show that the dispersibility and size of the catalysts are modulated by the addition of the second metal. Cyclic voltammetry (CV) and chronoamperometry tests show that, compared with the Pd/RGO catalyst, the electrochemical activities of the PdMn/RGO and PdFe/RGO catalysts are enhanced, and their electrochemical stabilities are improved for methanol oxidation. Electrochemical tests show that PdMn/RGO and PdFe/RGO have lower initial potential for methanol oxidation than Pd/RGO, which indicates that the prepared Pd-based bimetallic catalysts have better electrochemical performance than Pd/RGO catalyst. Further, the electronic structure of Pd is also successfully changed, which has a significant impact on improving the stability and electrochemical activity for methanol oxidation. In summation, PdMn/RGO and PdFe/RGO catalysts show better electrochemical performance for methanol oxidation than the Pd/RGO catalyst.

Two-dimensional (2D) metal carbides, carbonitrides, and nitrides (MXenes) have recently emerged as promising candidates in catalysis due to their unique properties. In this work, we composited Ti3C...

The substitution of noble metal platinum catalyst is one of the important research contents for sustainable development and is also the key to the practical application of photoelectrochemical (PEC) hydrogen production. In this work, we loaded the 1T-2H mixed phase MoS2 on the hydrogenated anatase/rutile heterophase TiO2 (A-H-RTNA) by hydrothermal method to prepare a new MoS2/A-H-RTNA electrode material. The prepared material exhibited higher carrier density, lower PL intensity and higher conductivity than Pt/A-H-RTNA because 1T-MoS2 has more active sites and lower charge transfer resistance than Pt. With the bias voltage of −0.4 V, the optimized 16MoS2/A-H-RTNA as photocathode shows the largest PEC hydrogen production rate of 1840 mmol m−2 h−1, which is 2.9 and 2.2 times higher than those of A-H-RTNA (625 mmol m−2 h−1) and Pt/A-H-RTNA (848 mmol m−2 h−1), respectively. We innovatively used the prepared 16MoS2/A-H-RTNA film as counter electrode instead of Pt electrode to construct a PEC system without any noble-metal. The result demonstrates that the noble-metal-free MoS2 loaded on TiO2 electrode as counter electrode has 75% PEC activity of noble metal Pt electrode. This study develops a PEC method for hydrogen evolution, which no longer depends on precious metal platinum as cathode.

In this work, two-dimensional magnetic chitosan nanosheets (CSMNSs) for azo dye adsorption were successfully synthesised by a simple hydrothermal method. The as-prepared CSMNSs was characterised by scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and vibrating sample magnetometer. Then, the CSMNSs as the dye adsorbent were applied to the removal of two kinds of azo dyes (methyl orange and amido black). The effect of solution pH and adsorbent dosage, adsorption isotherm, adsorption kinetics and the reusability of CSMNSs were examined. Adsorption isotherms obeyed Freundlich model and adsorption kinetics was described as pseudo-second-order model. Furthermore, the CSMNSs have the advantage of simple synthesis route, high absorption efficiency, rapid magnetic separation from aqueous solutions and excellent reusability. The CSMNSs as the dye adsorbent was applied to removal of azo dyes with broad prospects.

A facile method of loading CoSx nanosheet onto CdS nanorod has been designed, and the prepared CdS-CoSx composite catalyst exhibited significantly improved performance for photocatalytic hydrogen evolution compared with CdS catalyst. This composite catalyst was also used as a photoanode for photoelectrochemical (PEC) hydrogen production. The hydrogen production rate reached 168.6 μmol cm−2 h−1 (37.77 L m−2 h−1) under the simulated solar light, which is 2.7 times that of CdS and the same as that of CdS–Pt. In addition, in the Na2S–Na2SO3 system for PEC hydrogen production, an abnormal relationship between photocurrent and the hydrogen production yield was found. By designing a series of experiments, the photocatalytic and photoelectrochemical characteristics for hydrogen production were reasonably revealed for the first time. In this work, the prepared structured catalyst is easy to be recycled, and CoSx can replace precious metal Pt, showing a promising application.