Novel integrated strategies toward efficient and stable unassisted photoelectrochemical water splitting

© 2020 Unassisted photoelectrochemical (PEC) water splitting for hydrogen evolution has been regarded as a sustainable route for the harvest and utilization of solar energy. To achieve such unassisted PEC water splitting, two novel integrated strategies have been developed: to design tandem structures of photoanodes/photocathodes and to construct hybrid devices of solar/PEC cells. Some key unsolved problems, however, still limit the further development of high-performance unassisted PEC water splitting, such as low efficiency, poor stability, and high cost. Herein, we present a brief summary of the latest development in this area and propose perspectives for further enhancing this state-of-the-art solar-to‑hydrogen conversion technology, including all-metal oxide photoelectrodes, nanoarray design, surface modification, device coupling, monolithic configuration, and multi-integration

General Forms of Solutions for Linear Impulsive Fuzzy Dynamic Equations on Time Scales

A class of linear impulsive fuzzy dynamic equations on time scales is considered by using the generalized differentiability concept on time scales. Some novel criteria and general forms of solutions are established for such models whose significance lies in proposing the possibility to get unifying forms of solutions for discrete and continuous dynamical systems under uncertainty and to unify corresponding problems in the framework of fuzzy dynamic equations on time scales. Finally, some examples show the applicability of our results

Simultaneously efficient light absorption and charge transport of CdS/TiO2 nanotube array toward improved photoelectrochemical performance

CdS has been widely used to modify TiO2-based photoanodes for photoelectrochemical (PEC) water splitting. Due to the poor interface contact between chalcogenides and oxides, however, such CdS modified TiO2 materials usually exhibit inefficient separation and transport of charges, leading to an unsatisfactory efficiency during the PEC water splitting process. Addressing this issue, we herein report a CdS/TiO2 nanotube array (CdS/TNA) photoanode that was fabricated through a successive ion layer absorption and reaction (SILAR) method with an additional subsequent annealing. This post-annealing process is essential to enhance the interface contact between the CdS and the TNAs, resulting in an accelerated transfer of photogenerated electrons from the CdS to the TNAs. In addition, the post-annealing also improves the light absorption capability of the CdS/TNA photoanode. The simultaneous enhancement of charge transport and light absorption provided by the post-annealing is essential for improving the PEC performance of the CdS/TNA photoanode. The CdS/TNA photoanode obtained by this strategy exhibits a much enhanced PEC performance in water splitting, and its photocurrent density and solar-to-hydrogen conversion efficiency could reach 4.56 mA cm−2 at 1.23 V vs. reversible hydrogen electrode and 5.61%, respectively. This simple but effective route can provide a general strategy for obtaining high-performance oxide-based photoelectrodes

Anisotropy of the crystallographic orientation and corrosion performance of high-strength AZ80 Mg alloy

A high-strength AZ80 Mg alloy was prepared through multi-direction forging, thermal extrusion, and peak-aged heat treatment. The microstructure, crystallographic orientation and corrosion performance of extrusion-direction, transverse-direction, and normal-direction specimens were investigated using scanning electron microscopy, electron backscatter diffraction, and atomic force microscopy, respectively. Experimental results showed that crystallographic orientation significantly influenced the corrosion performance of AZ80 Mg alloy. Corrosion rates largely increased with decreased (0 0 0 1) crystallographic plane intensity, whereas the (1 0 −1 0) and (2 −1 −1 0) crystallographic plane intensities increased. This study showed that the corrosion rates of alloy can be modified to some extent by controlling texture, thereby promoting the applications of high-strength AZ80 Mg alloys in the aerospace and national-defense fields