Molybdenum disulfide (MoS2), with its active edge sites, is a proposed alternative to platinum for catalyzing the hydrogen evolution reaction (HER). Recently, the inert basal plane of MoS2 was successfully activated and optimized with excellent intrinsic HER activity by creating and further straining sulfur (S) vacancies. Nevertheless, little is known about the HER kinetics of those S vacancies and the additional effects from elastic tensile strain. Herein, scanning electrochemical microscopy was used to determine the HER kinetic data for both unstrained S vacancies (formal potential Ev0 = −0.53 VAg/AgCl, electron-transfer coefficient αv = 0.4, electron-transfer rate constant kv0 = 2.3 × 10(–4) cm/s) and strained S vacancies (Esv0= −0.53 VAg/AgCl, αsv = 0.4, ksv0 = 1.0 × 10(–3) cm/s) on the basal plane of MoS2 monolayers, and the strained S vacancy has an electron-transfer rate 4 times higher than that of the unstrained S vacancy. This study provides a general platform for measuring the kinetics of two-dimensional material-based catalysts.

Freestanding nanowires have ultrahigh elastic strain limits (4 to 7%) and yield strengths, but exploiting their intrinsic mechanical properties in bulk composites has proven to be difficult. We exploited the intrinsic mechanical properties of nanowires in a phase-transforming matrix based on the concept of elastic and transformation strain matching. By engineering the microstructure and residual stress to couple the true elasticity of Nb nanowires with the pseudoelasticity of a NiTi shape-memory alloy, we developed an in situ composite that possesses a large quasi-linear elastic strain of over 6%, a low Young's modulus of ~28 gigapascals, and a high yield strength of ~1.65 gigapascals. Our elastic strain-matching approach allows the exceptional mechanical properties of nanowires to be exploited in bulk materials.

Both the ligand effect and surface strain can affect the electrocatalytic reactivity. In that matter exists a need to be fundamentally understood; however, there is no effective strategy to isolate the strain effect in electrocatalytic systems. In this research we show how the elastic strain in a platinum nanofilm varies the catalytic activity for the oxygen reduction reaction, a key barrier to the wide applications of fuel cells. NiTi shape memory alloy was selected as the substrate to strain engineer the deposited Pt nanofilm in both compressively and tensilely strained states by taking advantage of the two-way shape memory effect for the first time. We demonstrate that compressive strain weakens the Pt surface adsorption and hence improves the ORR activity, which reflects in a 52% enhancement of the kinetic rate constant and a 27 mV positive shift of the half-wave potential for the compressively strained 5 nm Pt compared to the pristine Pt. Tensile strain has the opposite effect, which is in general agreement with the proposed d-band theory.

A variety of PbI 2 /MAPbI 3 perovskites were prepared and investigated by a rapid screening technique utilizing a modified scanning electrochemical microscope (SECM) in order to determine how excess PbI 2 affects its photoelectrochemical (PEC) properties. An optimum ratio of 2.5% PbI 2 /MAPbI 3 was found to enhance photocurrent over pristine MAPbI 3 on a spot array electrode under irradiation. With bulk films of various PbI 2 /MAPbI 3 composites prepared by a spin-coating technique of mixed precursors and a one-step annealing process, the 2.5% PbI 2 /MAPbI 3 produced an increased photocurrent density compared to pristine MAPbI 3 for 2 mM benzoquinone (BQ ) reduction at −0.4 V vs Fc/Fc + . As a result of the relatively high quantum yield of MAPbI 3 , a time-resolved photoluminescence quenching experiment could be applied to determine electron−hole diffusion coefficients and diffusion lengths of PbI 2 /MAPbI 3 composites, respectively. The diffusion coefficients combined with the exciton lifetime of the pristine 2.5% PbI 2 /MAPbI 3 (τ PL = 103.3 ns) give the electron and hole exciton diffusion lengths, ∼300 nm. Thus, the 2.5% PbI 2 /MAPbI 3 led to an approximately 3.0-fold increase in the diffusion length compared to a previous report of ∼100 nm for the pristine MAPbI 3 perovskite. We then demonstrated that the efficiency of liquid-junction solar cells for 2.5% excess PbI 2 of p-MAPbI 3 was improved from 6.0% to 7.3%.

Homogeneous photocatalysis has considerably contributed to green applications such as energy production and environmental decontamination.

Lead-free organic-inorganic tin halide perovskites were prepared and investigated by a rapid screening technique utilizing a modified scanning electrochemical microscope (SECM). We studied liquid junction photoelectrochemical (PEC) solar cells based on p-type methylammonium tin halide (MASnI 3-x Br x) perovskites employing the benzoquinone (BQ) redox couple, BQ/BQ•-, in dichloromethane (CH 2 Cl 2). We found that the optimized Sn-based mixed halide perovskite, MASnI 0.5 Br 2.5 , exhibits enhanced performance and stability in liquid-junction PEC solar cells, with a power conversion efficiency of 1.51% (an increase of 20.8%) and a photovoltaic lifetime of 175 min (an increase of 75.0%), in comparison to MASnI 3 perovskites.

Elastic strain effects on Cu overlayers toward CO2 electroreduction reaction were studied.

Stretchable conductors have attracted broad attention recently because they play a key role in the development of stretchable electronics such as fl exible displays, stretchable circuits, functional electronic eyes, dielectric elastomeric actuators, and so on. [1][2][3][4][5] The major challenge towards stretchable conductors is the development of stretchable electrical wiring that is both conductive and stretchable. [ 6 ] To our knowledge, two strategies have been employed to achieve stretchable conductors: one is to fabricate wavy or net-shaped conductive structures by releasing a pre-strained rubber substrate with conductive materials lying on it, [7][8][9][10][11] and the other is to disperse the conductive material in a rubber matrix. [12][13][14] However, compared to common metal conductors, such as Cu, Ag, and Al, with good electrical conductivity ( ∼ 10 7 S m − 1 ), controllability, stability, and high strength, [ 15 ] the existing stretchable conductor materials fabricated by both methods mentioned above exhibit poor electrical conductivity (10 − 2 to 10 3 S m − 1 ), operability, and low strength (1 to 10 2 MPa), [ 4 , 14 ] which severely limit their practical applications in areas requiring high strength, high elasticity, and high conductivity.It is known that enameled copper wire is a composite consisting of a Cu core coated with a polymer sheath, which is used for insulation. Inspired by this structure, it is speculated that if the polymer sheath outside of the enameled copper wire is substituted by a material having high strength and high elasticity, the obtained composite may exhibit the expected properties of high strength, high elasticity, and high conductivity.The NiTi shape memory alloy (SMA) is known to possess both high strength and superelasticity (the recoverable strain is up to 8%) ( Figure 1 a-II). [ 16 ] Thus, we conjecture that it is possible to design a novel composite (Figure 1 a-III) which may simultaneously possess high elasticity and high electrical conductivity by effectively integrating the superelasticity of NiTi and the high conductivity of Cu. In this study, we achieved a novel coaxial NiTi-sheath/Cu-core composite wire fabricated by mechanical assembly, wire drawing, and mechanical pre-treatment, which simultaneously exhibits a large recoverable strain of over 7%, a high yield strength of ∼ 560 MPa, and a high conductivity of ∼ 2.1 × 10 7 S m − 1 . These properties can be useful in potential applications. For instance, the composite wires can be used as tendons and shock absorbers for robotic systems. Electromechanical systems that undergo repeated movements such as artifi cial tendons for robotic eyes and hands, or structural supports acting as shock absorbers for robotic legs, require high elasticity, a high modulus, and an electrical pathway for sensory measurements and feedback.A pure Cu wire of 3 mm diameter was inserted into a NiTi tube having an inner diameter of 3.2 mm and an outer diameter of 5.2 mm, and then they were cold-drawn into a thin wire of 0.42 mm in diamet...