Full near-ultraviolet response photoelectrochemical ultraviolet detector based on TiO2nanocrystalline coated stainless steel mesh photoanode.

In order to solve the 'ultraviolet (UV) filtering problem' caused by traditional sandwich-type structure in photoelectrochemical (PEC) UV detector, we design a special electrode based on stainless steel mesh, which integrates the light absorption layer and the electron collection electrode in a simple way. In combination with an UV-transparent quartz substrate, UV light can directly reach the active material. The improved detector shows good visible-blind, self-powered, and linear response characteristics. The serious recombination caused by metal electrode is suppressed by depositing a barrier layer. The optimized device exhibits a high photoresponse of 0.103 A W-1at 296 nm, a short recovery time of 250 ms, and very sensitive switching ability. Furthermore, the response range of the detector is expanded from 300 to 400 nm to the full near-UV region. Our work provides an efficient strategy to solve the key problem of the PEC UV detector.

Role of N in Transition-Metal-Nitrides for Anchoring Platinum-Group Metal Atoms toward Single-Atom Catalysis.

Single-atom catalysts (SACs) with a maximum atom utilization efficiency have received growing attention in heterogeneous catalysis. The supporting substrate that provides atomic-dispersed anchoring sites and the local electronic environment in these catalysts is crucial to their activity and stability. Here, inspired by N-doped graphene substrate, the role of N is explored in transition metal nitrides for anchoring single metal atoms toward single-atom catalysis. A pore-rich metallic vanadium nitride (VN) nanosheet is fabricated as one supporting-substrate example, whose surface features abundant unsaturated N sites with lower binding energy than that of widely used N-doped graphene. Impressively, it is found that this support can anchor nearly all platinum-group single atoms (e.g., platinum, palladium, iridium, and ruthenium), and even be extendable to multiple SACs, i.e., binary (Pt/Pd) and ternary (Pt/Pd/Ir). As a proof-of-concept application for hydrogen production, Pt-based SAC (Pt1 -VN) performs excellently, exhibiting a mass activity up to 22.55 A mg-1 Pt at 0.05 V and a high turnover frequency value close to 0.350 H2 s-1 , superior to commercial platinum/carbon catalyst. The catalyst's durability can be further improved by using binary (Pt1 Pd1 -VN) SAC. This work provides inexpensive and durable nitride-based support, giving a possible pathway for universally constructing platinum-group SACs.

Synthesis on winged graphene nanofibers and their electrochemical capacitive performance.

Assembly techniques of graphene have attracted intense attention since their performance strongly depends on the manners in which graphene nanosheets are arranged. In this work, we demonstrate a viable process to synthesize winged graphene nanofibers (G-NFs) which could generate optimized pore size distribution by the fiber-like feature of graphene. The G-NF frameworks were achieved by processing the precursor graphene oxide nanosheets with the following procedures: microwave (MW) irradiation, salt addition, freeze-drying, and chemical reduction. The resultant framework composed of winged G-NFs with a diameter of 200-500 nm and a length of 5-20 µm. Moreover, the crimp degree of G-NFs can be rationally controlled by MW irradiation time. A formation mechanism of such winged G-NFs based on the synergistic effects from MW irradiation and solution ionic strength change has been proposed. With a practice in flexible electrode, after decorated with amorphous MnO2, the G-NF frameworks shows an enhanced specific capacitance compared to graphene nanosheets (G-NSs). This research has developed a controllable method to synthesis G-NFs, which can offer hierarchical pore structures, this kind of graphene nanostructure might enhance their performance in supercapacitor and related fields.

Facilitated charge transport in ternary interconnected electrodes for flexible supercapacitors with excellent power characteristics.

Flexible and high performance supercapacitors are very critical in modern society. In order to develop the flexible supercapacitors with high power density, free-standing and flexible three-dimensional graphene/carbon nanotubes/MnO2 (3DG/CNTs/MnO2) composite electrodes with interconnected ternary 3D structures were fabricated, and the fast electron and ion transport channels were effectively constructed in the rationally designed electrodes. Consequently, the obtained 3DG/CNTs/MnO2 composite electrodes exhibit superior specific capacitance and rate capability compared to 3DG/MnO2 electrodes. Furthermore, the 3DG/CNTs/MnO2 based asymmetric supercapacitor demonstrates the maximum energy and power densities of 33.71 W h kg(-1) and up to 22,727.3 W kg(-1), respectively. Moreover, the asymmetric supercapacitor exhibits excellent cycling stability with 95.3% of the specific capacitance maintained after 1000 cycle tests. Our proposed synthesis strategy to construct the novel ternary 3D structured electrodes can be efficiently applied to other high performance energy storage/conversion systems.