In-Situ Construction of Anti-Aggregation Tellurium Nanorods/Reduced Graphene Oxide Composite to Enable Fast Sodium Storage.

Sodium-ion batteries (SIBs) as a replaceable energy storage technology have attracted extensive attention in recent years. The design and preparation of advanced anode materials with high capacity and excellent cycling performance for SIBs still face enormous challenges. Herein, a solution method is developed for in situ synthesis of anti-aggregation tellurium nanorods/reduced graphene oxide (Te NR/rGO) composite. The material working as the sodium-ion battery (SIB) anode achieves a high reversible capacity of 338 mAh g-1 at 5 A g-1 and exhibits up to 93.4% capacity retention after 500 cycles. This work demonstrates an effective preparation method of nano-Te-based composites for SIBs.

Enhanced Photodetection Range from Visible to Shortwave Infrared Light by ReSe2/MoTe2 van der Waals Heterostructure.

Type II vertical heterojunction is a good solution for long-wavelength light detection. Here, we report a rhenium selenide/molybdenum telluride (n-ReSe2/p-MoTe2) photodetector for high-performance photodetection in the broadband spectral range of 405-2000 nm. Due to the low Schottky barrier contact of the ReSe2/MoTe2 heterojunction, the rectification ratio (RR) of ~102 at ±5 V is realized. Besides, the photodetector can obtain maximum responsivity (R = 1.05 A/W) and specific detectivity (D* = 6.66 × 1011 Jones) under the illumination of 655 nm incident light. When the incident wavelength is 1550-2000 nm, a photocurrent is generated due to the interlayer transition of carriers. This compact system can provide an opportunity to realize broadband infrared photodetection.

Repression of Interlayer Recombination by Graphene Generates a Sensitive Nanostructured 2D vdW Heterostructure Based Photodetector.

Great success in 2D van der Waals (vdW) heterostructures based photodetectors is obtained owing to the unique electronic and optoelectronic properties of 2D materials. Performance of photodetectors based 2D vdW heterojunctions at atomic scale is more sensitive to the nanointerface of the heterojunction than conventional bulk heterojunction. Here, a nanoengineered heterostructure for the first-time demonstration of a nanointerface using an inserted graphene layer between black phosphorus (BP) and InSe which inhibits interlayer recombination and greatly improves photodetection performances is presented. In addition, a transition of the transport characteristics of the device is induced by graphene, from diffusion motion of minority carriers to drift motion of majority carriers. These two reasons together with an internal photoemission effect make the BP/G/InSe-based photodetector have ultrahigh specific detectivity at room temperature. The results demonstrate that high-performance vdW heterostructure photodetectors can be achieved through simple structural manipulation of the heterojunction interface on nanoscale.

Nano-Cu-Mediated Multi-Site Approach to Ultrafine MoO2 Nanoparticles on Poly(diallyldimethylammonium chloride)-Decorated Reduced Graphene Oxide for Hydrogen Evolution Electrocatalysis.

Catalysts with high atom utilization efficiency accompanied by improved reactivity and durability are highly desired. Metallic MoO2 with its small size easily agglomerates, making it difficult to use in water splitting to obtain hydrogen by electrolysis. Here, the nano-Cu-mediated multi-site method is proposed to prepare ultrafine MoO2 nanoparticles (NPs) dispersed on poly(diallyldimethylammonium chloride)-decorated reduced graphene oxide (denoted as MoO2 /PDDA-rGO). The introduction of Cu NPs increases the number of growth sites for MoO2 on the PDDA-rGO and simultaneously promotes the growth rate of MoO2 on PDDA-rGO. As a consequence, the resulting size of the MoO2 NPs is only 2 nm and these are evenly dispersed on PDDA-rGO. Significantly, the optimized catalyst has a low onset potential of -42 mV versus reversible hydrogen electrode (RHE), a calculated Tafel slope of only 42 mV dec-1 , and good cycling stability of more than 40 h. This favored hydrogen evolution reaction (HER) activity is caused by the synergistic effects of MoO2 and PDDA-rGO, rapid charge transport, and sufficient exposed active sites of MoO2 /PDDA-rGO.

Heterojunction and Oxygen Vacancy Modification of ZnO Nanorod Array Photoanode for Enhanced Photoelectrochemical Water Splitting.

Application of ZnO in the field of photoelectrochemical water splitting is limited because of its wide-band-gap and high recombination rate. Herein is reported the design of an efficient ZnO photoanode deposited with CoOx nanoparticles to achieve a heterojunction and oxygen vacancies. The CoOx nanoparticles with abundant oxygen vacancies were anchored onto the nanorod arrays by spin coating and calcination followed by a solvothermal treatment. CoOx nanoparticles serve the dual function of forming a p-n heterojunction to facilitate the separation of photogenerated carriers, and act as a cocatalyst to decrease water oxidation barrier. Finally, oxygen vacancies increase the number of active redox sites and act as hole traps, enabling their migration to the electrode/electrolyte interface. The composite photoanode exhibits a high incident photon-to-current conversion efficiency (76.7 % at 350 nm), which is twice that of pristine ZnO, and a photoconversion efficiency of 0.68 % (0.73 V versus RHE). The current approach can be expanded to fabricate other efficient photocatalysts.

Covalent functionalization of black phosphorus nanoflakes by carbon free radicals for durable air and water stability.

This work developed a simple and efficient method to covalently functionalize black phosphorus nanoflakes (BPNFs) with carbon free radicals from azodiisobutyronitrile (AIBN) molecules. BPNFs after successful modification (BPNFs-AIBN) not only had good stability in air and aqueous solution, but also still maintained good optical properties.

Dual Modification of a BiVO4 Photoanode for Enhanced Photoelectrochemical Performance.

Bismuth vanadate (BiVO4 ) has triggered extensive interest in photoelectrochemical (PEC) water splitting, owing to its narrow band gap and sufficiently positive valence band. However, some defects still exist to block the solar utilization efficiency and hydrogen evolution kinetics. Herein, the NiMoO4 semiconductor is combined with a BiVO4 photoanode, for the first time, and excellent PEC performance is achieved on the basis of heterojunction formation and favorable conductivity of NiMoO4 . In addition, it has been demonstrated that NiMoO4 promotes the light absorption ability, charge separation efficiency, and surface charge-transfer efficiency comprehensively. To further improve the photoconversion efficiency, cobalt phosphate, as an oxygen evolution reaction cocatalyst, is deposited on the above electrode and achieves a much enhanced utilization efficiency of 1.18 %, with a photocurrent density of 5.3 mA cm-2 at 1.23 V versus a reversible hydrogen electrode; this exceeds most results reported to date. This rational and unique photoanode construction provides a new thread for the photoelectrode designation.