Seeking to increase the triboelectric charge density on a friction layer is one of the most basic approaches to improve the output performance of triboelectric nanogenerators (TENGs). Here, we studied the storage mechanism of triboelectric charge in the friction layer and discussed the function of carrier mobility and concentration in the charge-storing process. As guided by these results, a kind of composite structure is constructed in the friction layer to adjust the depth distribution of the triboelectric charges and improve the output performance of TENGs. To further elucidate this theory, a simple TENG, whose negative friction layer is a composite structure by integrating polystyrene (PS) and carbon nanotubes (CNTs) into polyvinylidene fluoride (PVDF), was fabricated, and its performance test was also carried out. Comparing with a pure PVDF friction layer, the composite friction layer can raise the triboelectric charge density by a factor of 11.2. The extended residence time of electrons in the friction layer is attributed to a large sum of electron trap levels from PS.

Transition metal dichalcogenides (TMDs) have attracted considerable interest for exploration of next-generation electronics and optoelectronics in recent years. Fabrication of in-plane lateral heterostructures between TMDs has opened up excellent opportunities for engineering two-dimensional materials. The creation of high quality heterostructures with a facile method is highly desirable but it still remains challenging. In this work, we demonstrate a one-step growth method for the construction of high-quality MoS2–WS2 in-plane heterostructures. The synthesis was carried out using ambient pressure chemical vapor deposition (APCVD) with the assistance of sodium chloride (NaCl). It was found that the addition of NaCl played a key role in lowering the growth temperatures, in which the Na-containing precursors could be formed and condensed on the substrates to reduce the energy of the reaction. As a result, the growth regimes of MoS2 and WS2 are better matched, leading to the formation of in-plane heterostructures in a single step. The heterostructures were proved to be of high quality with a sharp and clear interface. This newly developed strategy with the assistance of NaCl is promising for synthesizing other TMDs and their heterostructures.

The electrocatalytic activity of Pt-based alloys exhibits a strong dependence on their electronic structures, but a relationship between electronic structure and oxygen reduction reaction (ORR) activity in Ag-based alloys is still not clear. Here, a vapor deposition based approach is reported for the preparation of Ag M (M = Cu, Co, Fe, and In) and Ag Cu (x = 0, 25, 45, 50, 55, 75, 90, and 100) nanocatalysts and their electronic structures are determined by valence band spectra. The relationship of the d-band center and ORR activity exhibits volcano-shape behaviors, where the maximum catalytic activity is obtained for Ag Cu alloys. The ORR enhancement of Ag Cu alloys originates from the 0.12 eV upshift in d-band center relative to pure Ag, which is different from the downshift in the d-band center in Pt-based alloys. The activity trend for these Ag M alloys is in the order of Ag Cu > Ag Fe > Ag Co . These results provide an insight to understand the activity and stability enhancement of Ag Cu and Ag Cu catalysts by alloying.

A highly efficient Ag‐Cu electrocatalyst is synthesized by the electrodeposition method and characterized with respect to its catalytic activity in the oxygen reduction reaction (ORR) and its tolerance to carbonate ions in a zinc‐air battery. Cyclic voltammetry and rotating‐disk electrode analyses suggest that the Ag50Cu50 electrocatalyst is 2.5 times more catalytically active in the ORR than a pure Ag catalyst and catalyzes the ORR through a four‐electron pathway. Field‐emission TEM characterization shows that the surface‐roughened Ag‐Cu electrocatalyst comprises small nanoplatelets with diameters of 40–50 nm. Cu atoms are partially alloyed in Ag lattices in these nanoplatelets. The Ag‐Cu electrocatalysts are assembled into the primary and secondary zinc‐air batteries as carbon‐free and binder‐free catalyst layers. The open circuit voltage and the discharge voltage of the primary zinc‐air battery at 20 mA cm−2 are 1.49 and 1.17 V, respectively. The round‐trip efficiency and increased polarization of the rechargeable zinc‐air battery are 56.4 and 0.2 %, respectively, after 100 cycles at 20 mA cm−2. The Ag‐Cu electrocatalyst shows good catalytic activity in the oxygen evolution reaction in an alkaline battery and good tolerance of carbonate ions on the cathode side.

A novel one-pot approach for synthesizing the dealloyed nanomaterials at room temperature is introduced for the first time. In such a synthetic strategy, applying modulated potentials effectively simplifies the traditional dealloying route, which usually requires additional corrosion process to dissolve nonprecious metals. The dealloyed AuNi nanodendrites (AuNi NDs) with tunable composition and uniformly elemental distribution are well developed by the one-pot strategy. Impressively, the as-synthesized AuNi NDs exhibit a higher electrochemically active area and definite improvements in electrocatalytic activity for oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) compared to the commercial Pt/C. In particular, the AuNi NDs are 81 mV more positive in half-wave potential and about 3.1 times higher in specific activity (at 0.85 V) for the ORR than Pt/C, together with excellent stability and methanol tolerance. The superior BOR activity is highly promising compared to the previously reported catalysts. The unique nanodendritic structure with Au-rich surface and bimetallic electronic effect is the main factor to greatly enhance the bifunctional catalytic performance for the AuNi NDs. Furthermore, such a newly developed facile method is of great significance because it is one of the first examples to effectively engineer dealloyed bimetallic nanostructures via the practical and low-cost route for electrocatalytic applications.