We use electrospinning to modify ZnO NWs with POMs. The composite exhibits the features of a p-type semiconductor and matches the Eg of ZnO. The PDs prepared by POMs@ZnO NWs can work under zero bias conditions and show good light responsivity.

The development of high-performance and low-cost durable triboelectric nanogenerators (TENGs) is essential for converting mechanical energy into electrical energy. Many organic polymer friction materials used widely have thermal stability problems , which makes TENGs with semiconductors as friction materials stand out. Here, we report a semi-flexible TENG based on metal and TiO 2 modified by polyoxometalates (POMs) as pure inorganic friction materials. Six different POMs are firstly selected to modify the friction materials of TENGs, and the output performance of TENGs with different POMs-modified semiconductors and different metals as friction materials are tested. Compared with the unmodified TENGs, the open-circuit voltage ( V OC ) of the optimal Ag-K 6 P 2 Mo 18 O 62 (P 2 Mo 18 )/TiO 2 TENG device is increased by more than 4 times, which is mainly attributed to the strong electron-accepting and storage capabilities of POMs. This study has demonstrated that TENGs modified by POMs have potential application prospects and provided a new method for increasing the electrical output of TENGs.

A simple doping method was used to modify SnO2 with polyoxometalate {Mo132}. The doped composite material not only has a more matched energy level and improves conductivity, but can also improve the quality of the perovskite film grown on it.

2D materials have strong intermolecular van der Waals forces, and 2D superlattice heterostructures have exhibited many dramatic photo-electrochemical properties for energy conversion and storage. Herein, based on the excellent properties of reduced graphene and superlattice structures, we constructed a 2D flexible superlattice polyoxometalate/rGO heterojunction with enhanced electron-hole separation via interfacial self-assembly engineering to further fabricate DSSCs based on the heterojunction-modified photoanode, which exhibited good electron transport properties. Selecting two kinds of Dawson POMs (P2W15V3, P2W18 and the corresponding heteropoly blue) as the research object, the polyoxometalate superlattice structure was obtained by the self-assembly strategy, and characterized by IR, UV-Vis, XRD, EDX and XPS. The TEM and AFM results indicated that the monolayer POM superlattice structure and superlattice polyoxometalate/rGO heterojunction were successfully obtained. The superlattice P2W18(HPB)/rGO heterojunction was introduced into the DSSCs photoanode, and electrochemical tests indicated that the superlattice polyoxometalate/rGO heterojunction improved the electron-hole separation rate, inhibited the electron recombination, and improved the photoelectric conversion efficiency to 8.09%. The 2D superlattice heterojunction remarkably improved the electrochemical performances of the energy storage and conversion systems.

Highly dispersed POM nanoparticles as functional components have been deposited on CNTs to produce periodic functionalized CNTs. The obtained Co4PW9/CNTs CE exhibits the best photovoltaic performance with a PCE of 7.60%, higher than both pure CNTs and Pt CE.

Molybdenum carbide/molybdenum nitride hybrid N-doped graphene (abbreviated as Mo2C/MoN/NG), as an efficient electrocatalyst for the hydrogen evolution reaction (HER), was synthesized via simple ion-exchange resin synthesis followed by a two-step annealing process, which increased the dispersion degree of the electrocatalyst’s active sites on the support skeleton and simplified the synthetic conditions. Additionally, N-doped graphene (NG) enhanced the electron transfer and reduced the inner resistance. The material has a graphene-like morphology and highly dispersed Mo2C/MoN nanoparticles about 2 nm in diameter on the NG. X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy revealed that Mo2C/MoN/NG consisted of Mo2C and MoN composited together. Finally, Mo2C/MoN/NG exhibited remarkable performance as an electrocatalyst for the HER with a small overpotential of 78.82 mV and a small Tafel slope of 39.3 mV·dec−1 in a 0.5 mol·L−1 H2SO4 solution. Its activity was approximately 30% lower than that of 20% Pt/C and 60% higher than that of NG. Also, it exhibited a low onset overpotential of 24.82 mV, which is similar to the theoretical HER potential. Our work provides a foundation for advanced HER applications of molybdenum compounds.

Electrochemical capacitors or “supercapacitors” essentially bridge the gap between traditional capacitors and rechargeable batteries with their high specific power and moderate energy densities. Commercial supercapacitors typically comprise activated carbon (AC) electrodes, which rely on electrostatic double layer charge storage mechanisms. Pseudocapacitors, on the other hand, benefit from surface redox reactions which lend them superior capacitance than their double layer counterparts. Conducting polymers and transitional metal oxides (TMOs) account for pseudocapacitors in general and among TMOs, manganese oxides have widely been investigated owing to their high specific capacitances, low cost, and environmental benignity. In this work, porous manganese oxide (MnO x ) thin films were synthesized via electrostatic spray deposition (ESD) and evaluated as pseudocapacitive electrode materials in aqueous media. Very interestingly, the gravimetric specific capacitance of the ESD based MnO x electrodes underwent a marked enhancement upon electrochemical cycling, from 72Fg -1 to 225Fg -1 , with a concomitant improvement in kinetics and conductivity. The change in capacitance and resistivity is attributed to a partial electrochemical phase transformation from the spinel type hausmannite Mn 3 O 4 to the conducting layered birnessite MnO 2 . Furthermore, the films were able to retain 88.4% of the maximal capacitance after 1000 cycles. Upon verifying the viability of the manganese oxide films for pseudocapacitive applications, the thin films were integrated onto carbon micro-pillars created via carbon microelectromechanical systems (C-MEMS) for examining their application as potential microelectrode candidates. In a symmetric two-electrode cell setup, the MnO x /C-MEMS microelectrodes were able to deliver specific capacitances as high as 0.055 Fcm -2 and stack capacitances as high as 7.4Fcm -3 , with maximal stack energy and power densities of 0.51 mWhcm -3 and 28.3 mWcm -3 , respectively. The excellent areal capacitance of the MnO x -MEs is attributed to the pseudocapacitive MnO x as well as the three-dimensional architectural framework provided by the carbon micropillars.